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diff --git a/doc/canvas.n b/doc/canvas.n new file mode 100644 index 0000000..4e1c779 --- /dev/null +++ b/doc/canvas.n @@ -0,0 +1,1576 @@ +'\" +'\" Copyright (c) 1992-1994 The Regents of the University of California. +'\" Copyright (c) 1994-1996 Sun Microsystems, Inc. +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +'\" SCCS: @(#) canvas.n 1.58 97/10/31 12:58:45 +'\" +.so man.macros +.TH canvas n 4.0 Tk "Tk Built-In Commands" +.BS +'\" Note: do not modify the .SH NAME line immediately below! +.SH NAME +canvas \- Create and manipulate canvas widgets +.SH SYNOPSIS +\fBcanvas\fR \fIpathName \fR?\fIoptions\fR? +.SO +\-background \-highlightthickness \-insertwidth \-takefocus +\-borderwidth \-insertbackground \-relief \-xscrollcommand +\-cursor \-insertborderwidth \-selectbackground \-yscrollcommand +\-highlightbackground \-insertofftime \-selectborderwidth +\-highlightcolor \-insertontime \-selectforeground +.SE +.SH "WIDGET-SPECIFIC OPTIONS" +.OP \-closeenough closeEnough CloseEnough +Specifies a floating-point value indicating how close the mouse cursor +must be to an item before it is considered to be ``inside'' the item. +Defaults to 1.0. +.OP \-confine confine Confine +Specifies a boolean value that indicates whether or not it should be +allowable to set the canvas's view outside the region defined by the +\fBscrollRegion\fR argument. +Defaults to true, which means that the view will +be constrained within the scroll region. +.OP \-height height Height +Specifies a desired window height that the canvas widget should request from +its geometry manager. The value may be specified in any +of the forms described in the COORDINATES section below. +.OP \-scrollregion scrollRegion ScrollRegion +Specifies a list with four coordinates describing the left, top, right, and +bottom coordinates of a rectangular region. +This region is used for scrolling purposes and is considered to be +the boundary of the information in the canvas. +Each of the coordinates may be specified +in any of the forms given in the COORDINATES section below. +.OP \-width width width +Specifies a desired window width that the canvas widget should request from +its geometry manager. The value may be specified in any +of the forms described in the COORDINATES section below. +.br +.OP \-xscrollincrement xScrollIncrement ScrollIncrement +Specifies an increment for horizontal scrolling, in any of the usual forms +permitted for screen distances. If the value of this option is greater +than zero, the horizontal view in the window will be constrained so that +the canvas x coordinate at the left edge of the window is always an even +multiple of \fBxScrollIncrement\fR; furthermore, the units for scrolling +(e.g., the change in view when the left and right arrows of a scrollbar +are selected) will also be \fBxScrollIncrement\fR. If the value of +this option is less than or equal to zero, then horizontal scrolling +is unconstrained. +.OP \-yscrollincrement yScrollIncrement ScrollIncrement +Specifies an increment for vertical scrolling, in any of the usual forms +permitted for screen distances. If the value of this option is greater +than zero, the vertical view in the window will be constrained so that +the canvas y coordinate at the top edge of the window is always an even +multiple of \fByScrollIncrement\fR; furthermore, the units for scrolling +(e.g., the change in view when the top and bottom arrows of a scrollbar +are selected) will also be \fByScrollIncrement\fR. If the value of +this option is less than or equal to zero, then vertical scrolling +is unconstrained. +.BE + +.SH INTRODUCTION +.PP +The \fBcanvas\fR command creates a new window (given +by the \fIpathName\fR argument) and makes it into a canvas widget. +Additional options, described above, may be specified on the +command line or in the option database +to configure aspects of the canvas such as its colors and 3-D relief. +The \fBcanvas\fR command returns its +\fIpathName\fR argument. At the time this command is invoked, +there must not exist a window named \fIpathName\fR, but +\fIpathName\fR's parent must exist. +.PP +Canvas widgets implement structured graphics. +A canvas displays any number of \fIitems\fR, which may be things like +rectangles, circles, lines, and text. +Items may be manipulated (e.g. moved or re-colored) and commands may +be associated with items in much the same way that the \fBbind\fR +command allows commands to be bound to widgets. For example, +a particular command may be associated with the <Button-1> event +so that the command is invoked whenever button 1 is pressed with +the mouse cursor over an item. +This means that items in a canvas can have behaviors defined by +the Tcl scripts bound to them. + +.SH "DISPLAY LIST" +.PP +The items in a canvas are ordered for purposes of display, +with the first item in the display list being displayed +first, followed by the next item in the list, and so on. +Items later in the display list obscure those that are +earlier in the display list and are sometimes referred to +as being ``on top'' of earlier items. +When a new item is created it is placed at the end of the +display list, on top of everything else. +Widget commands may be used to re-arrange the order of the +display list. +.PP +Window items are an exception to the above rules. The underlying +window systems require them always to be drawn on top of other items. +In addition, the stacking order of window items +is not affected by any of the canvas widget commands; you must use +the \fBraise\fR and \fBlower\fR Tk commands instead. + +.SH "ITEM IDS AND TAGS" +.PP +Items in a canvas widget may be named in either of two ways: +by id or by tag. +Each item has a unique identifying number which is assigned to +that item when it is created. The id of an item never changes +and id numbers are never re-used within the lifetime of a +canvas widget. +.PP +Each item may also have any number of \fItags\fR associated +with it. A tag is just a string of characters, and it may +take any form except that of an integer. +For example, ``x123'' is OK but ``123'' isn't. +The same tag may be associated with many different items. +This is commonly done to group items in various interesting +ways; for example, all selected items might be given the +tag ``selected''. +.PP +The tag \fBall\fR is implicitly associated with every item +in the canvas; it may be used to invoke operations on +all the items in the canvas. +.PP +The tag \fBcurrent\fR is managed automatically by Tk; +it applies to the \fIcurrent item\fR, which is the +topmost item whose drawn area covers the position of +the mouse cursor. +If the mouse is not in the canvas widget or is not over +an item, then no item has the \fBcurrent\fR tag. +.PP +When specifying items in canvas widget commands, if the +specifier is an integer then it is assumed to refer to +the single item with that id. +If the specifier is not an integer, then it is assumed to +refer to all of the items in the canvas that have a tag +matching the specifier. +The symbol \fItagOrId\fR is used below to indicate that +an argument specifies either an id that selects a single +item or a tag that selects zero or more items. +Some widget commands only operate on a single item at a +time; if \fItagOrId\fR is specified in a way that +names multiple items, then the normal behavior is for +the command to use the first (lowest) of these items in +the display list that is suitable for the command. +Exceptions are noted in the widget command descriptions +below. + +.SH "COORDINATES" +.PP +All coordinates related to canvases are stored as floating-point +numbers. +Coordinates and distances are specified in screen units, +which are floating-point numbers optionally followed +by one of several letters. +If no letter is supplied then the distance is in pixels. +If the letter is \fBm\fR then the distance is in millimeters on +the screen; if it is \fBc\fR then the distance is in centimeters; +\fBi\fR means inches, and \fBp\fR means printers points (1/72 inch). +Larger y-coordinates refer to points lower on the screen; larger +x-coordinates refer to points farther to the right. + +.SH TRANSFORMATIONS +.PP +Normally the origin of the canvas coordinate system is at the +upper-left corner of the window containing the canvas. +It is possible to adjust the origin of the canvas +coordinate system relative to the origin of the window using the +\fBxview\fR and \fByview\fR widget commands; this is typically used +for scrolling. +Canvases do not support scaling or rotation of the canvas coordinate +system relative to the window coordinate system. +.PP +Individual items may be moved or scaled using widget commands +described below, but they may not be rotated. + +.SH "INDICES" +.PP +Text items support the notion of an \fIindex\fR for identifying +particular positions within the item. +Indices are used for commands such as inserting text, deleting +a range of characters, and setting the insertion cursor position. +An index may be specified in any of a number of ways, and +different types of items may support different forms for +specifying indices. +Text items support the following forms for an index; if you +define new types of text-like items, it would be advisable to +support as many of these forms as practical. +Note that it is possible to refer to the character just after +the last one in the text item; this is necessary for such +tasks as inserting new text at the end of the item. +.TP 10 +\fInumber\fR +A decimal number giving the position of the desired character +within the text item. +0 refers to the first character, 1 to the next character, and +so on. +A number less than 0 is treated as if it were zero, and a +number greater than the length of the text item is treated +as if it were equal to the length of the text item. +.TP 10 +\fBend\fR +Refers to the character just after the last one in the item +(same as the number of characters in the item). +.TP 10 +\fBinsert\fR +Refers to the character just before which the insertion cursor +is drawn in this item. +.TP 10 +\fBsel.first\fR +Refers to the first selected character in the item. +If the selection isn't in this item then this form is illegal. +.TP 10 +\fBsel.last\fR +Refers to the last selected character in the item. +If the selection isn't in this item then this form is illegal. +.TP 10 +\fB@\fIx,y\fR +Refers to the character at the point given by \fIx\fR and +\fIy\fR, where \fIx\fR and \fIy\fR are specified in the coordinate +system of the canvas. +If \fIx\fR and \fIy\fR lie outside the coordinates covered by the +text item, then they refer to the first or last character in the +line that is closest to the given point. + +.SH "WIDGET COMMAND" +.PP +The \fBcanvas\fR command creates a new Tcl command whose +name is \fIpathName\fR. This +command may be used to invoke various +operations on the widget. It has the following general form: +.CS +\fIpathName option \fR?\fIarg arg ...\fR? +.CE +\fIOption\fR and the \fIarg\fRs +determine the exact behavior of the command. +The following widget commands are possible for canvas widgets: +.TP +\fIpathName \fBaddtag \fItag searchSpec \fR?\fIarg arg ...\fR? +For each item that meets the constraints specified by +\fIsearchSpec\fR and the \fIarg\fRs, add +\fItag\fR to the list of tags associated with the item if it +isn't already present on that list. +It is possible that no items will satisfy the constraints +given by \fIsearchSpec\fR and \fIarg\fRs, in which case the +command has no effect. +This command returns an empty string as result. +\fISearchSpec\fR and \fIarg\fR's may take any of the following +forms: +.RS +.TP +\fBabove \fItagOrId\fR +Selects the item just after (above) the one given by \fItagOrId\fR +in the display list. +If \fItagOrId\fR denotes more than one item, then the last (topmost) +of these items in the display list is used. +.TP +\fBall\fR +Selects all the items in the canvas. +.TP +\fBbelow \fItagOrId\fR +Selects the item just before (below) the one given by \fItagOrId\fR +in the display list. +If \fItagOrId\fR denotes more than one item, then the first (lowest) +of these items in the display list is used. +.TP +\fBclosest \fIx y \fR?\fIhalo\fR? ?\fIstart\fR? +Selects the item closest to the point given by \fIx\fR and \fIy\fR. +If more than one item is at the same closest distance (e.g. two +items overlap the point), then the top-most of these items (the +last one in the display list) is used. +If \fIhalo\fR is specified, then it must be a non-negative +value. +Any item closer than \fIhalo\fR to the point is considered to +overlap it. +The \fIstart\fR argument may be used to step circularly through +all the closest items. +If \fIstart\fR is specified, it names an item using a tag or id +(if by tag, it selects the first item in the display list with +the given tag). +Instead of selecting the topmost closest item, this form will +select the topmost closest item that is below \fIstart\fR in +the display list; if no such item exists, then the selection +behaves as if the \fIstart\fR argument had not been specified. +.TP +\fBenclosed\fR \fIx1\fR \fIy1\fR \fIx2\fR \fIy2\fR +Selects all the items completely enclosed within the rectangular +region given by \fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR. +\fIX1\fR must be no greater then \fIx2\fR and \fIy1\fR must be +no greater than \fIy2\fR. +.TP +\fBoverlapping\fR \fIx1\fR \fIy1\fR \fIx2\fR \fIy2\fR +Selects all the items that overlap or are enclosed within the +rectangular region given by \fIx1\fR, \fIy1\fR, \fIx2\fR, +and \fIy2\fR. +\fIX1\fR must be no greater then \fIx2\fR and \fIy1\fR must be +no greater than \fIy2\fR. +.TP +\fBwithtag \fItagOrId\fR +Selects all the items given by \fItagOrId\fR. +.RE +.TP +\fIpathName \fBbbox \fItagOrId\fR ?\fItagOrId tagOrId ...\fR? +Returns a list with four elements giving an approximate bounding box +for all the items named by the \fItagOrId\fR arguments. +The list has the form ``\fIx1 y1 x2 y2\fR'' such that the drawn +areas of all the named elements are within the region bounded by +\fIx1\fR on the left, \fIx2\fR on the right, \fIy1\fR on the top, +and \fIy2\fR on the bottom. +The return value may overestimate the actual bounding box by +a few pixels. +If no items match any of the \fItagOrId\fR arguments or if the +matching items have empty bounding boxes (i.e. they have nothing +to display) +then an empty string is returned. +.TP +\fIpathName \fBbind \fItagOrId\fR ?\fIsequence\fR? ?\fIcommand\fR? +This command associates \fIcommand\fR with all the items given by +\fItagOrId\fR such that whenever the event sequence given by +\fIsequence\fR occurs for one of the items the command will +be invoked. +This widget command is similar to the \fBbind\fR command except that +it operates on items in a canvas rather than entire widgets. +See the \fBbind\fR manual entry for complete details +on the syntax of \fIsequence\fR and the substitutions performed +on \fIcommand\fR before invoking it. +If all arguments are specified then a new binding is created, replacing +any existing binding for the same \fIsequence\fR and \fItagOrId\fR +(if the first character of \fIcommand\fR is ``+'' then \fIcommand\fR +augments an existing binding rather than replacing it). +In this case the return value is an empty string. +If \fIcommand\fR is omitted then the command returns the \fIcommand\fR +associated with \fItagOrId\fR and \fIsequence\fR (an error occurs +if there is no such binding). +If both \fIcommand\fR and \fIsequence\fR are omitted then the command +returns a list of all the sequences for which bindings have been +defined for \fItagOrId\fR. +.RS +.PP +.VS +The only events for which bindings may be specified are those related to +the mouse and keyboard (such as \fBEnter\fR, \fBLeave\fR, +\fBButtonPress\fR, \fBMotion\fR, and \fBKeyPress\fR) or virtual events. +The handling of events in canvases uses the current item defined in ITEM +IDS AND TAGS above. \fBEnter\fR and \fBLeave\fR events trigger for an +item when it becomes the current item or ceases to be the current item; +note that these events are different than \fBEnter\fR and \fBLeave\fR +events for windows. Mouse-related events are directed to the current +item, if any. Keyboard-related events are directed to the focus item, if +any (see the \fBfocus\fR widget command below for more on this). If a +virtual event is used in a binding, that binding can trigger only if the +virtual event is defined by an underlying mouse-related or +keyboard-related event. +.VE +.PP +It is possible for multiple bindings to match a particular event. +This could occur, for example, if one binding is associated with the +item's id and another is associated with one of the item's tags. +When this occurs, all of the matching bindings are invoked. +A binding associated with the \fBall\fR tag is invoked first, +followed by one binding for each of the item's tags (in order), +followed by a binding associated with the item's id. +If there are multiple matching bindings for a single tag, +then only the most specific binding is invoked. +A \fBcontinue\fR command in a binding script terminates that +script, and a \fBbreak\fR command terminates that script +and skips any remaining scripts for the event, just as for the +\fBbind\fR command. +.PP +If bindings have been created for a canvas window using the \fBbind\fR +command, then they are invoked in addition to bindings created for +the canvas's items using the \fBbind\fR widget command. +The bindings for items will be invoked before any of the bindings +for the window as a whole. +.RE +.TP +\fIpathName \fBcanvasx \fIscreenx\fR ?\fIgridspacing\fR? +Given a window x-coordinate in the canvas \fIscreenx\fR, this command returns +the canvas x-coordinate that is displayed at that location. +If \fIgridspacing\fR is specified, then the canvas coordinate is +rounded to the nearest multiple of \fIgridspacing\fR units. +.TP +\fIpathName \fBcanvasy \fIscreeny\fR ?\fIgridspacing\fR? +Given a window y-coordinate in the canvas \fIscreeny\fR this command returns +the canvas y-coordinate that is displayed at that location. +If \fIgridspacing\fR is specified, then the canvas coordinate is +rounded to the nearest multiple of \fIgridspacing\fR units. +.TP +\fIpathName \fBcget\fR \fIoption\fR +Returns the current value of the configuration option given +by \fIoption\fR. +\fIOption\fR may have any of the values accepted by the \fBcanvas\fR +command. +.TP +\fIpathName \fBconfigure ?\fIoption\fR? ?\fIvalue\fR? ?\fIoption value ...\fR? +Query or modify the configuration options of the widget. +If no \fIoption\fR is specified, returns a list describing all of +the available options for \fIpathName\fR (see \fBTk_ConfigureInfo\fR for +information on the format of this list). If \fIoption\fR is specified +with no \fIvalue\fR, then the command returns a list describing the +one named option (this list will be identical to the corresponding +sublist of the value returned if no \fIoption\fR is specified). If +one or more \fIoption\-value\fR pairs are specified, then the command +modifies the given widget option(s) to have the given value(s); in +this case the command returns an empty string. +\fIOption\fR may have any of the values accepted by the \fBcanvas\fR +command. +.TP +\fIpathName\fR \fBcoords \fItagOrId \fR?\fIx0 y0 ...\fR? +Query or modify the coordinates that define an item. +If no coordinates are specified, this command returns a list +whose elements are the coordinates of the item named by +\fItagOrId\fR. +If coordinates are specified, then they replace the current +coordinates for the named item. +If \fItagOrId\fR refers to multiple items, then +the first one in the display list is used. +.TP +\fIpathName \fBcreate \fItype x y \fR?\fIx y ...\fR? ?\fIoption value ...\fR? +Create a new item in \fIpathName\fR of type \fItype\fR. +The exact format of the arguments after \fBtype\fR depends +on \fBtype\fR, but usually they consist of the coordinates for +one or more points, followed by specifications for zero or +more item options. +See the subsections on individual item types below for more +on the syntax of this command. +This command returns the id for the new item. +.TP +\fIpathName \fBdchars \fItagOrId first \fR?\fIlast\fR? +For each item given by \fItagOrId\fR, delete the characters +in the range given by \fIfirst\fR and \fIlast\fR, +inclusive. +If some of the items given by \fItagOrId\fR don't support +text operations, then they are ignored. +\fIFirst\fR and \fIlast\fR are indices of characters +within the item(s) as described in INDICES above. +If \fIlast\fR is omitted, it defaults to \fIfirst\fR. +This command returns an empty string. +.TP +\fIpathName \fBdelete \fR?\fItagOrId tagOrId ...\fR? +Delete each of the items given by each \fItagOrId\fR, and return +an empty string. +.TP +\fIpathName \fBdtag \fItagOrId \fR?\fItagToDelete\fR? +For each of the items given by \fItagOrId\fR, delete the +tag given by \fItagToDelete\fR from the list of those +associated with the item. +If an item doesn't have the tag \fItagToDelete\fR then +the item is unaffected by the command. +If \fItagToDelete\fR is omitted then it defaults to \fItagOrId\fR. +This command returns an empty string. +.TP +\fIpathName \fBfind \fIsearchCommand \fR?\fIarg arg ...\fR? +This command returns a list consisting of all the items that +meet the constraints specified by \fIsearchCommand\fR and +\fIarg\fR's. +\fISearchCommand\fR and \fIargs\fR have any of the forms +accepted by the \fBaddtag\fR command. +The items are returned in stacking order, with the lowest item first. +.TP +\fIpathName \fBfocus \fR?\fItagOrId\fR? +Set the keyboard focus for the canvas widget to the item given by +\fItagOrId\fR. +If \fItagOrId\fR refers to several items, then the focus is set +to the first such item in the display list that supports the +insertion cursor. +If \fItagOrId\fR doesn't refer to any items, or if none of them +support the insertion cursor, then the focus isn't changed. +If \fItagOrId\fR is an empty +string, then the focus item is reset so that no item has the focus. +If \fItagOrId\fR is not specified then the command returns the +id for the item that currently has the focus, or an empty string +if no item has the focus. +.RS +.PP +Once the focus has been set to an item, the item will display +the insertion cursor and all keyboard events will be directed +to that item. +The focus item within a canvas and the focus window on the +screen (set with the \fBfocus\fR command) are totally independent: +a given item doesn't actually have the input focus unless (a) +its canvas is the focus window and (b) the item is the focus item +within the canvas. +In most cases it is advisable to follow the \fBfocus\fR widget +command with the \fBfocus\fR command to set the focus window to +the canvas (if it wasn't there already). +.RE +.TP +\fIpathName \fBgettags\fR \fItagOrId\fR +Return a list whose elements are the tags associated with the +item given by \fItagOrId\fR. +If \fItagOrId\fR refers to more than one item, then the tags +are returned from the first such item in the display list. +If \fItagOrId\fR doesn't refer to any items, or if the item +contains no tags, then an empty string is returned. +.TP +\fIpathName \fBicursor \fItagOrId index\fR +Set the position of the insertion cursor for the item(s) +given by \fItagOrId\fR +to just before the character whose position is given by \fIindex\fR. +If some or all of the items given by \fItagOrId\fR don't support +an insertion cursor then this command has no effect on them. +See INDICES above for a description of the +legal forms for \fIindex\fR. +Note: the insertion cursor is only displayed in an item if +that item currently has the keyboard focus (see the widget +command \fBfocus\fR, below), but the cursor position may +be set even when the item doesn't have the focus. +This command returns an empty string. +.TP +\fIpathName \fBindex \fItagOrId index\fR +This command returns a decimal string giving the numerical index +within \fItagOrId\fR corresponding to \fIindex\fR. +\fIIndex\fR gives a textual description of the desired position +as described in INDICES above. +The return value is guaranteed to lie between 0 and the number +of characters within the item, inclusive. +If \fItagOrId\fR refers to multiple items, then the index +is processed in the first of these items that supports indexing +operations (in display list order). +.TP +\fIpathName \fBinsert \fItagOrId beforeThis string\fR +For each of the items given by \fItagOrId\fR, if the item supports +text insertion then \fIstring\fR is inserted into the item's +text just before the character whose index is \fIbeforeThis\fR. +See INDICES above for information about the forms allowed +for \fIbeforeThis\fR. +This command returns an empty string. +.TP +\fIpathName \fBitemcget\fR \fItagOrId\fR \fIoption\fR +Returns the current value of the configuration option for the +item given by \fItagOrId\fR whose name is \fIoption\fR. +This command is similar to the \fBcget\fR widget command except that +it applies to a particular item rather than the widget as a whole. +\fIOption\fR may have any of the values accepted by the \fBcreate\fR +widget command when the item was created. +If \fItagOrId\fR is a tag that refers to more than one item, +the first (lowest) such item is used. +.TP +\fIpathName \fBitemconfigure \fItagOrId\fR ?\fIoption\fR? ?\fIvalue\fR? ?\fIoption value ...\fR? +This command is similar to the \fBconfigure\fR widget command except +that it modifies item-specific options for the items given by +\fItagOrId\fR instead of modifying options for the overall +canvas widget. +If no \fIoption\fR is specified, returns a list describing all of +the available options for the first item given by \fItagOrId\fR +(see \fBTk_ConfigureInfo\fR for +information on the format of this list). If \fIoption\fR is specified +with no \fIvalue\fR, then the command returns a list describing the +one named option (this list will be identical to the corresponding +sublist of the value returned if no \fIoption\fR is specified). If +one or more \fIoption\-value\fR pairs are specified, then the command +modifies the given widget option(s) to have the given value(s) in +each of the items given by \fItagOrId\fR; in +this case the command returns an empty string. +The \fIoption\fRs and \fIvalue\fRs are the same as those permissible +in the \fBcreate\fR widget command when the item(s) were created; +see the sections describing individual item types below for details +on the legal options. +.TP +\fIpathName \fBlower \fItagOrId \fR?\fIbelowThis\fR? +Move all of the items given by \fItagOrId\fR to a new position +in the display list just before the item given by \fIbelowThis\fR. +If \fItagOrId\fR refers to more than one item then all are moved +but the relative order of the moved items will not be changed. +\fIBelowThis\fR is a tag or id; if it refers to more than one +item then the first (lowest) of these items in the display list is used +as the destination location for the moved items. +Note: this command has no effect on window items. Window items always +obscure other item types, and the stacking order of window items is +determined by the \fBraise\fR and \fBlower\fR commands, not the +\fBraise\fR and \fBlower\fR widget commands for canvases. +This command returns an empty string. +.TP +\fIpathName \fBmove \fItagOrId xAmount yAmount\fR +Move each of the items given by \fItagOrId\fR in the canvas coordinate +space by adding \fIxAmount\fR to the x-coordinate of each point +associated with the item and \fIyAmount\fR to the y-coordinate of +each point associated with the item. +This command returns an empty string. +.TP +\fIpathName \fBpostscript \fR?\fIoption value option value ...\fR? +Generate a Postscript representation for part or all of the canvas. +If the \fB\-file\fR option is specified then the Postscript is written +to a file and an empty string is returned; otherwise the Postscript +is returned as the result of the command. +.VS +If the interpreter that owns the canvas is marked as safe, the operation +will fail because safe interpreters are not allowed to write files. +If the \fB\-channel\fR option is specified, the argument denotes the name +of a channel already opened for writing. The Postscript is written to +that channel, and the channel is left open for further writing at the end +of the operation. +.VE +The Postscript is created in Encapsulated Postscript form using +version 3.0 of the Document Structuring Conventions. +Note: by default Postscript is only generated for information that +appears in the canvas's window on the screen. If the canvas is +freshly created it may still have its initial size of 1x1 pixel +so nothing will appear in the Postscript. To get around this problem +either invoke the "update" command to wait for the canvas window +to reach its final size, or else use the \fB\-width\fR and \fB\-height\fR +options to specify the area of the canvas to print. +The \fIoption\fR\-\fIvalue\fR argument pairs provide additional +information to control the generation of Postscript. The following +options are supported: +.RS +.TP +\fB\-colormap \fIvarName\fR +\fIVarName\fR must be the name of an array variable +that specifies a color mapping to use in the Postscript. +Each element of \fIvarName\fR must consist of Postscript +code to set a particular color value (e.g. ``\fB1.0 1.0 0.0 setrgbcolor\fR''). +When outputting color information in the Postscript, Tk checks +to see if there is an element of \fIvarName\fR with the same +name as the color. +If so, Tk uses the value of the element as the Postscript command +to set the color. +If this option hasn't been specified, or if there isn't an entry +in \fIvarName\fR for a given color, then Tk uses the red, green, +and blue intensities from the X color. +.TP +\fB\-colormode \fImode\fR +Specifies how to output color information. \fIMode\fR must be either +\fBcolor\fR (for full color output), \fBgray\fR (convert all colors +to their gray-scale equivalents) or \fBmono\fR (convert all colors +to black or white). +.TP +\fB\-file \fIfileName\fR +Specifies the name of the file in which to write the Postscript. +If this option isn't specified then the Postscript is returned as the +result of the command instead of being written to a file. +.TP +\fB\-fontmap \fIvarName\fR +\fIVarName\fR must be the name of an array variable +that specifies a font mapping to use in the Postscript. +Each element of \fIvarName\fR must consist of a Tcl list with +two elements, which are the name and point size of a Postscript font. +When outputting Postscript commands for a particular font, Tk +checks to see if \fIvarName\fR contains an element with the same +name as the font. +If there is such an element, then the font information contained in +that element is used in the Postscript. +Otherwise Tk attempts to guess what Postscript font to use. +Tk's guesses generally only work for well-known fonts such as +Times and Helvetica and Courier, and only if the X font name does not +omit any dashes up through the point size. +For example, \fB\-*\-Courier\-Bold\-R\-Normal\-\-*\-120\-*\fR will work but +\fB*Courier\-Bold\-R\-Normal*120*\fR will not; Tk needs the dashes to +parse the font name). +.TP +\fB\-height \fIsize\fR +Specifies the height of the area of the canvas to print. +Defaults to the height of the canvas window. +.TP +\fB\-pageanchor \fIanchor\fR +Specifies which point of the printed area of the canvas should appear over +the positioning point on the page (which is given by the \fB\-pagex\fR +and \fB\-pagey\fR options). +For example, \fB\-pageanchor n\fR means that the top center of the +area of the canvas being printed (as it appears in the canvas window) +should be over the positioning point. Defaults to \fBcenter\fR. +.TP +\fB\-pageheight \fIsize\fR +Specifies that the Postscript should be scaled in both x and y so +that the printed area is \fIsize\fR high on the Postscript page. +\fISize\fR consists of a floating-point number followed by +\fBc\fR for centimeters, \fBi\fR for inches, \fBm\fR for millimeters, +or \fBp\fR or nothing for printer's points (1/72 inch). +Defaults to the height of the printed area on the screen. +If both \fB\-pageheight\fR and \fB\-pagewidth\fR are specified then +the scale factor from \fB\-pagewidth\fR is used (non-uniform scaling +is not implemented). +.TP +\fB\-pagewidth \fIsize\fR +Specifies that the Postscript should be scaled in both x and y so +that the printed area is \fIsize\fR wide on the Postscript page. +\fISize\fR has the same form as for \fB\-pageheight\fR. +Defaults to the width of the printed area on the screen. +If both \fB\-pageheight\fR and \fB\-pagewidth\fR are specified then +the scale factor from \fB\-pagewidth\fR is used (non-uniform scaling +is not implemented). +.TP +\fB\-pagex \fIposition\fR +\fIPosition\fR gives the x-coordinate of the positioning point on +the Postscript page, using any of the forms allowed for \fB\-pageheight\fR. +Used in conjunction with the \fB\-pagey\fR and \fB\-pageanchor\fR options +to determine where the printed area appears on the Postscript page. +Defaults to the center of the page. +.TP +\fB\-pagey \fIposition\fR +\fIPosition\fR gives the y-coordinate of the positioning point on +the Postscript page, using any of the forms allowed for \fB\-pageheight\fR. +Used in conjunction with the \fB\-pagex\fR and \fB\-pageanchor\fR options +to determine where the printed area appears on the Postscript page. +Defaults to the center of the page. +.TP +\fB\-rotate \fIboolean\fR +\fIBoolean\fR specifies whether the printed area is to be rotated 90 +degrees. +In non-rotated output the x-axis of the printed area runs along +the short dimension of the page (``portrait'' orientation); +in rotated output the x-axis runs along the long dimension of the +page (``landscape'' orientation). +Defaults to non-rotated. +.TP +\fB\-width \fIsize\fR +Specifies the width of the area of the canvas to print. +Defaults to the width of the canvas window. +.TP +\fB\-x \fIposition\fR +Specifies the x-coordinate of the left edge of the area of the +canvas that is to be printed, in canvas coordinates, not window +coordinates. +Defaults to the coordinate of the left edge of the window. +.TP +\fB\-y \fIposition\fR +Specifies the y-coordinate of the top edge of the area of the +canvas that is to be printed, in canvas coordinates, not window +coordinates. +Defaults to the coordinate of the top edge of the window. +.RE +.TP +\fIpathName \fBraise \fItagOrId \fR?\fIaboveThis\fR? +Move all of the items given by \fItagOrId\fR to a new position +in the display list just after the item given by \fIaboveThis\fR. +If \fItagOrId\fR refers to more than one item then all are moved +but the relative order of the moved items will not be changed. +\fIAboveThis\fR is a tag or id; if it refers to more than one +item then the last (topmost) of these items in the display list is used +as the destination location for the moved items. +Note: this command has no effect on window items. Window items always +obscure other item types, and the stacking order of window items is +determined by the \fBraise\fR and \fBlower\fR commands, not the +\fBraise\fR and \fBlower\fR widget commands for canvases. +This command returns an empty string. +.TP +\fIpathName \fBscale \fItagOrId xOrigin yOrigin xScale yScale\fR +Rescale all of the items given by \fItagOrId\fR in canvas coordinate +space. +\fIXOrigin\fR and \fIyOrigin\fR identify the origin for the scaling +operation and \fIxScale\fR and \fIyScale\fR identify the scale +factors for x- and y-coordinates, respectively (a scale factor of +1.0 implies no change to that coordinate). +For each of the points defining each item, the x-coordinate is +adjusted to change the distance from \fIxOrigin\fR by a factor +of \fIxScale\fR. +Similarly, each y-coordinate is adjusted to change the distance +from \fIyOrigin\fR by a factor of \fIyScale\fR. +This command returns an empty string. +.TP +\fIpathName \fBscan\fR \fIoption args\fR +This command is used to implement scanning on canvases. It has +two forms, depending on \fIoption\fR: +.RS +.TP +\fIpathName \fBscan mark \fIx y\fR +Records \fIx\fR and \fIy\fR and the canvas's current view; used +in conjunction with later \fBscan dragto\fR commands. +Typically this command is associated with a mouse button press in +the widget and \fIx\fR and \fIy\fR are the coordinates of the +mouse. It returns an empty string. +.TP +\fIpathName \fBscan dragto \fIx y\fR. +This command computes the difference between its \fIx\fR and \fIy\fR +arguments (which are typically mouse coordinates) and the \fIx\fR and +\fIy\fR arguments to the last \fBscan mark\fR command for the widget. +It then adjusts the view by 10 times the +difference in coordinates. This command is typically associated +with mouse motion events in the widget, to produce the effect of +dragging the canvas at high speed through its window. The return +value is an empty string. +.RE +.TP +\fIpathName \fBselect \fIoption\fR ?\fItagOrId arg\fR? +Manipulates the selection in one of several ways, depending on +\fIoption\fR. +The command may take any of the forms described below. +In all of the descriptions below, \fItagOrId\fR must refer to +an item that supports indexing and selection; if it refers to +multiple items then the first of +these that supports indexing and the selection is used. +\fIIndex\fR gives a textual description of a position +within \fItagOrId\fR, as described in INDICES above. +.RS +.TP +\fIpathName \fBselect adjust \fItagOrId index\fR +Locate the end of the selection in \fItagOrId\fR nearest +to the character given by \fIindex\fR, and adjust that +end of the selection to be at \fIindex\fR (i.e. including +but not going beyond \fIindex\fR). +The other end of the selection is made the anchor point +for future \fBselect to\fR commands. +If the selection isn't currently in \fItagOrId\fR then +this command behaves the same as the \fBselect to\fR widget +command. +Returns an empty string. +.TP +\fIpathName \fBselect clear\fR +Clear the selection if it is in this widget. +If the selection isn't in this widget then the command +has no effect. +Returns an empty string. +.TP +\fIpathName \fBselect from \fItagOrId index\fR +Set the selection anchor point for the widget to be just +before the character +given by \fIindex\fR in the item given by \fItagOrId\fR. +This command doesn't change the selection; it just sets +the fixed end of the selection for future \fBselect to\fR +commands. +Returns an empty string. +.TP +\fIpathName \fBselect item\fR +Returns the id of the selected item, if the selection is in an +item in this canvas. +If the selection is not in this canvas then an empty string +is returned. +.TP +\fIpathName \fBselect to \fItagOrId index\fR +Set the selection to consist of those characters of \fItagOrId\fR +between the selection anchor point and +\fIindex\fR. +The new selection will include the character given by \fIindex\fR; +it will include the character given by the anchor point only if +\fIindex\fR is greater than or equal to the anchor point. +The anchor point is determined by the most recent \fBselect adjust\fR +or \fBselect from\fR command for this widget. +If the selection anchor point for the widget isn't currently in +\fItagOrId\fR, then it is set to the same character given +by \fIindex\fR. +Returns an empty string. +.RE +.TP +\fIpathName \fBtype\fI tagOrId\fR +Returns the type of the item given by \fItagOrId\fR, such as +\fBrectangle\fR or \fBtext\fR. +If \fItagOrId\fR refers to more than one item, then the type +of the first item in the display list is returned. +If \fItagOrId\fR doesn't refer to any items at all then +an empty string is returned. +.TP +\fIpathName \fBxview \fR?\fIargs\fR? +This command is used to query and change the horizontal position of the +information displayed in the canvas's window. +It can take any of the following forms: +.RS +.TP +\fIpathName \fBxview\fR +Returns a list containing two elements. +Each element is a real fraction between 0 and 1; together they describe +the horizontal span that is visible in the window. +For example, if the first element is .2 and the second element is .6, +20% of the canvas's area (as defined by the \fB\-scrollregion\fR option) +is off-screen to the left, the middle 40% is visible +in the window, and 40% of the canvas is off-screen to the right. +These are the same values passed to scrollbars via the \fB\-xscrollcommand\fR +option. +.TP +\fIpathName \fBxview moveto\fI fraction\fR +Adjusts the view in the window so that \fIfraction\fR of the +total width of the canvas is off-screen to the left. +\fIFraction\fR must be a fraction between 0 and 1. +.TP +\fIpathName \fBxview scroll \fInumber what\fR +This command shifts the view in the window left or right according to +\fInumber\fR and \fIwhat\fR. +\fINumber\fR must be an integer. +\fIWhat\fR must be either \fBunits\fR or \fBpages\fR or an abbreviation +of one of these. +If \fIwhat\fR is \fBunits\fR, the view adjusts left or right in units +of the \fBxScrollIncrement\fR option, if it is greater than zero, +or in units of one-tenth the window's width otherwise. +If \fIwhat is \fBpages\fR then the view +adjusts in units of nine-tenths the window's width. +If \fInumber\fR is negative then information farther to the left +becomes visible; if it is positive then information farther to the right +becomes visible. +.RE +.TP +\fIpathName \fByview \fI?args\fR? +This command is used to query and change the vertical position of the +information displayed in the canvas's window. +It can take any of the following forms: +.RS +.TP +\fIpathName \fByview\fR +Returns a list containing two elements. +Each element is a real fraction between 0 and 1; together they describe +the vertical span that is visible in the window. +For example, if the first element is .6 and the second element is 1.0, +the lowest 40% of the canvas's area (as defined by the \fB\-scrollregion\fR +option) is visible in the window. +These are the same values passed to scrollbars via the \fB\-yscrollcommand\fR +option. +.TP +\fIpathName \fByview moveto\fI fraction\fR +Adjusts the view in the window so that \fIfraction\fR of the canvas's +area is off-screen to the top. +\fIFraction\fR is a fraction between 0 and 1. +.TP +\fIpathName \fByview scroll \fInumber what\fR +This command adjusts the view in the window up or down according to +\fInumber\fR and \fIwhat\fR. +\fINumber\fR must be an integer. +\fIWhat\fR must be either \fBunits\fR or \fBpages\fR. +If \fIwhat\fR is \fBunits\fR, the view adjusts up or down in units +of the \fByScrollIncrement\fR option, if it is greater than zero, +or in units of one-tenth the window's height otherwise. +If \fIwhat\fR is \fBpages\fR then +the view adjusts in units of nine-tenths the window's height. +If \fInumber\fR is negative then higher information becomes +visible; if it is positive then lower information +becomes visible. +.RE + +.SH "OVERVIEW OF ITEM TYPES" +.PP +The sections below describe the various types of items supported +by canvas widgets. Each item type is characterized by two things: +first, the form of the \fBcreate\fR command used to create +instances of the type; and second, a set of configuration options +for items of that type, which may be used in the +\fBcreate\fR and \fBitemconfigure\fR widget commands. +Most items don't support indexing or selection or the commands +related to them, such as \fBindex\fR and \fBinsert\fR. +Where items do support these facilities, it is noted explicitly +in the descriptions below (at present, only text items provide +this support). + +.SH "ARC ITEMS" +.PP +Items of type \fBarc\fR appear on the display as arc-shaped regions. +An arc is a section of an oval delimited by two angles (specified +by the \fB\-start\fR and \fB\-extent\fR options) and displayed in +one of several ways (specified by the \fB\-style\fR option). +Arcs are created with widget commands of the following form: +.CS +\fIpathName \fBcreate arc \fIx1 y1 x2 y2 \fR?\fIoption value option value ...\fR? +.CE +The arguments \fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR give +the coordinates of two diagonally opposite corners of a +rectangular region enclosing the oval that defines the arc. +After the coordinates there may be any number of \fIoption\fR\-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR\-\fIvalue\fR pairs may be +used in \fBitemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for arcs: +.TP +\fB\-extent \fIdegrees\fR +Specifies the size of the angular range occupied by the arc. +The arc's range extends for \fIdegrees\fR degrees counter-clockwise +from the starting angle given by the \fB\-start\fR option. +\fIDegrees\fR may be negative. +If it is greater than 360 or less than -360, then \fIdegrees\fR +modulo 360 is used as the extent. +.TP +\fB\-fill \fIcolor\fR +Fill the region of the arc with \fIcolor\fR. +\fIColor\fR may have any of the forms accepted by \fBTk_GetColor\fR. +If \fIcolor\fR is an empty string (the default), then +then the arc will not be filled. +.TP +\fB\-outline \fIcolor\fR +\fIColor\fR specifies a color to use for drawing the arc's +outline; it may have any of the forms accepted by \fBTk_GetColor\fR. +This option defaults to \fBblack\fR. If \fIcolor\fR is specified +as an empty string then no outline is drawn for the arc. +.TP +\fB\-outlinestipple \fIbitmap\fR +Indicates that the outline for the arc should be drawn with a stipple pattern; +\fIbitmap\fR specifies the stipple pattern to use, in any of the +forms accepted by \fBTk_GetBitmap\fR. +If the \fB\-outline\fR option hasn't been specified then this option +has no effect. +If \fIbitmap\fR is an empty string (the default), then the outline is drawn +in a solid fashion. +.TP +\fB\-start \fIdegrees\fR +Specifies the beginning of the angular range occupied by the +arc. +\fIDegrees\fR is given in units of degrees measured counter-clockwise +from the 3-o'clock position; it may be either positive or negative. +.TP +\fB\-stipple \fIbitmap\fR +Indicates that the arc should be filled in a stipple pattern; +\fIbitmap\fR specifies the stipple pattern to use, in any of the +forms accepted by \fBTk_GetBitmap\fR. +If the \fB\-fill\fR option hasn't been specified then this option +has no effect. +If \fIbitmap\fR is an empty string (the default), then filling is done +in a solid fashion. +.TP +\fB\-style \fItype\fR +Specifies how to draw the arc. If \fItype\fR is \fBpieslice\fR +(the default) then the arc's region is defined by a section +of the oval's perimeter plus two line segments, one between the center +of the oval and each end of the perimeter section. +If \fItype\fR is \fBchord\fR then the arc's region is defined +by a section of the oval's perimeter plus a single line segment +connecting the two end points of the perimeter section. +If \fItype\fR is \fBarc\fR then the arc's region consists of +a section of the perimeter alone. +In this last case the \fB\-fill\fR option is ignored. +.TP +\fB\-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\fB\-width \fIoutlineWidth\fR +Specifies the width of the outline to be drawn around +the arc's region, in any of the forms described in the COORDINATES +section above. +If the \fB\-outline\fR option has been specified as an empty string +then this option has no effect. +Wide outlines will be drawn centered on the edges of the arc's region. +This option defaults to 1.0. + +.SH "BITMAP ITEMS" +.PP +Items of type \fBbitmap\fR appear on the display as images with +two colors, foreground and background. +Bitmaps are created with widget commands of the following form: +.CS +\fIpathName \fBcreate bitmap \fIx y \fR?\fIoption value option value ...\fR? +.CE +The arguments \fIx\fR and \fIy\fR specify the coordinates of a +point used to position the bitmap on the display (see the \fB\-anchor\fR +option below for more information on how bitmaps are displayed). +After the coordinates there may be any number of \fIoption\fR\-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR\-\fIvalue\fR pairs may be +used in \fBitemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for bitmaps: +.TP +\fB\-anchor \fIanchorPos\fR +\fIAnchorPos\fR tells how to position the bitmap relative to the +positioning point for the item; it may have any of the forms +accepted by \fBTk_GetAnchor\fR. For example, if \fIanchorPos\fR +is \fBcenter\fR then the bitmap is centered on the point; if +\fIanchorPos\fR is \fBn\fR then the bitmap will be drawn so that +its top center point is at the positioning point. +This option defaults to \fBcenter\fR. +.TP +\fB\-background \fIcolor\fR +Specifies a color to use for each of the bitmap pixels +whose value is 0. +\fIColor\fR may have any of the forms accepted by \fBTk_GetColor\fR. +If this option isn't specified, or if it is specified as an empty +string, then nothing is displayed where the bitmap pixels are 0; this +produces a transparent effect. +.TP +\fB\-bitmap \fIbitmap\fR +Specifies the bitmap to display in the item. +\fIBitmap\fR may have any of the forms accepted by \fBTk_GetBitmap\fR. +.TP +\fB\-foreground \fIcolor\fR +Specifies a color to use for each of the bitmap pixels +whose value is 1. +\fIColor\fR may have any of the forms accepted by \fBTk_GetColor\fR and +defaults to \fBblack\fR. +.TP +\fB\-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. + +.SH "IMAGE ITEMS" +.PP +Items of type \fBimage\fR are used to display images on a +canvas. +Images are created with widget commands of the following form: +.CS +\fIpathName \fBcreate image \fIx y \fR?\fIoption value option value ...\fR? +.CE +The arguments \fIx\fR and \fIy\fR specify the coordinates of a +point used to position the image on the display (see the \fB\-anchor\fR +option below for more information). +After the coordinates there may be any number of \fIoption\fR\-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR\-\fIvalue\fR pairs may be +used in \fBitemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for images: +.TP +\fB\-anchor \fIanchorPos\fR +\fIAnchorPos\fR tells how to position the image relative to the +positioning point for the item; it may have any of the forms +accepted by \fBTk_GetAnchor\fR. For example, if \fIanchorPos\fR +is \fBcenter\fR then the image is centered on the point; if +\fIanchorPos\fR is \fBn\fR then the image will be drawn so that +its top center point is at the positioning point. +This option defaults to \fBcenter\fR. +.TP +\fB\-image \fIname\fR +Specifies the name of the image to display in the item. +This image must have been created previously with the +\fBimage create\fR command. +.TP +\fB\-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item; it may be an empty list. + +.SH "LINE ITEMS" +.PP +Items of type \fBline\fR appear on the display as one or more connected +line segments or curves. +Lines are created with widget commands of the following form: +.CS +\fIpathName \fBcreate line \fIx1 y1... xn yn \fR?\fIoption value option value ...\fR? +.CE +The arguments \fIx1\fR through \fIyn\fR give +the coordinates for a series of two or more points that describe +a series of connected line segments. +After the coordinates there may be any number of \fIoption\fR\-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR\-\fIvalue\fR pairs may be +used in \fBitemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for lines: +.TP +\fB\-arrow \fIwhere\fR +Indicates whether or not arrowheads are to be drawn at one or both +ends of the line. +\fIWhere\fR must have one of the values \fBnone\fR (for no arrowheads), +\fBfirst\fR (for an arrowhead at the first point of the line), +\fBlast\fR (for an arrowhead at the last point of the line), or +\fBboth\fR (for arrowheads at both ends). +This option defaults to \fBnone\fR. +.TP +\fB\-arrowshape \fIshape\fR +This option indicates how to draw arrowheads. +The \fIshape\fR argument must be a list with three elements, each +specifying a distance in any of the forms described in +the COORDINATES section above. +The first element of the list gives the distance along the line +from the neck of the arrowhead to its tip. +The second element gives the distance along the line from the +trailing points of the arrowhead to the tip, and the third +element gives the distance from the outside edge of the line to the +trailing points. +If this option isn't specified then Tk picks a ``reasonable'' shape. +.TP +\fB\-capstyle \fIstyle\fR +Specifies the ways in which caps are to be drawn at the endpoints +of the line. +\fIStyle\fR may have any of the forms accepted by \fBTk_GetCapStyle\fR +(\fBbutt\fR, \fBprojecting\fR, or \fBround\fR). +If this option isn't specified then it defaults to \fBbutt\fR. +Where arrowheads are drawn the cap style is ignored. +.TP +\fB\-fill \fIcolor\fR +\fIColor\fR specifies a color to use for drawing the line; it may have +any of the forms acceptable to \fBTk_GetColor\fR. It may also be an +empty string, in which case the line will be transparent. +This option defaults to \fBblack\fR. +.TP +\fB\-joinstyle \fIstyle\fR +Specifies the ways in which joints are to be drawn at the vertices +of the line. +\fIStyle\fR may have any of the forms accepted by \fBTk_GetCapStyle\fR +(\fBbevel\fR, \fBmiter\fR, or \fBround\fR). +If this option isn't specified then it defaults to \fBmiter\fR. +If the line only contains two points then this option is +irrelevant. +.TP +\fB\-smooth \fIboolean\fR +\fIBoolean\fR must have one of the forms accepted by \fBTk_GetBoolean\fR. +It indicates whether or not the line should be drawn as a curve. +If so, the line is rendered as a set of parabolic splines: one spline +is drawn for the first and second line segments, one for the second +and third, and so on. Straight-line segments can be generated within +a curve by duplicating the end-points of the desired line segment. +.TP +\fB\-splinesteps \fInumber\fR +Specifies the degree of smoothness desired for curves: each spline +will be approximated with \fInumber\fR line segments. This +option is ignored unless the \fB\-smooth\fR option is true. +.TP +\fB\-stipple \fIbitmap\fR +Indicates that the line should be filled in a stipple pattern; +\fIbitmap\fR specifies the stipple pattern to use, in any of the +forms accepted by \fBTk_GetBitmap\fR. +If \fIbitmap\fR is an empty string (the default), then filling is +done in a solid fashion. +.TP +\fB\-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\fB\-width \fIlineWidth\fR +\fILineWidth\fR specifies the width of the line, in any of the forms +described in the COORDINATES section above. +Wide lines will be drawn centered on the path specified by the +points. +If this option isn't specified then it defaults to 1.0. + +.SH "OVAL ITEMS" +.PP +Items of type \fBoval\fR appear as circular or oval regions on +the display. Each oval may have an outline, a fill, or +both. Ovals are created with widget commands of the +following form: +.CS +\fIpathName \fBcreate oval \fIx1 y1 x2 y2 \fR?\fIoption value option value ...\fR? +.CE +The arguments \fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR give +the coordinates of two diagonally opposite corners of a +rectangular region enclosing the oval. +The oval will include the top and left edges of the rectangle +not the lower or right edges. +If the region is square then the resulting oval is circular; +otherwise it is elongated in shape. +After the coordinates there may be any number of \fIoption\fR\-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR\-\fIvalue\fR pairs may be +used in \fBitemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for ovals: +.TP +\fB\-fill \fIcolor\fR +Fill the area of the oval with \fIcolor\fR. +\fIColor\fR may have any of the forms accepted by \fBTk_GetColor\fR. +If \fIcolor\fR is an empty string (the default), then +then the oval will not be filled. +.TP +\fB\-outline \fIcolor\fR +\fIColor\fR specifies a color to use for drawing the oval's +outline; it may have any of the forms accepted by \fBTk_GetColor\fR. +This option defaults to \fBblack\fR. +If \fIcolor\fR is an empty string then no outline will be +drawn for the oval. +.TP +\fB\-stipple \fIbitmap\fR +Indicates that the oval should be filled in a stipple pattern; +\fIbitmap\fR specifies the stipple pattern to use, in any of the +forms accepted by \fBTk_GetBitmap\fR. +If the \fB\-fill\fR option hasn't been specified then this option +has no effect. +If \fIbitmap\fR is an empty string (the default), then filling is done +in a solid fashion. +.TP +\fB\-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\fB\-width \fIoutlineWidth\fR +\fIoutlineWidth\fR specifies the width of the outline to be drawn around +the oval, in any of the forms described in the COORDINATES section above. +If the \fB\-outline\fR option hasn't been specified then this option +has no effect. +Wide outlines are drawn centered on the oval path defined by +\fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR. +This option defaults to 1.0. + +.SH "POLYGON ITEMS" +.PP +Items of type \fBpolygon\fR appear as polygonal or curved filled regions +on the display. +Polygons are created with widget commands of the following form: +.CS +\fIpathName \fBcreate polygon \fIx1 y1 ... xn yn \fR?\fIoption value option value ...\fR? +.CE +The arguments \fIx1\fR through \fIyn\fR specify the coordinates for +three or more points that define a closed polygon. +The first and last points may be the same; whether they are or not, +Tk will draw the polygon as a closed polygon. +After the coordinates there may be any number of \fIoption\fR\-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR\-\fIvalue\fR pairs may be +used in \fBitemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for polygons: +.TP +\fB\-fill \fIcolor\fR +\fIColor\fR specifies a color to use for filling the area of the +polygon; it may have any of the forms acceptable to \fBTk_GetColor\fR. +If \fIcolor\fR is an empty string then the polygon will be +transparent. +This option defaults to \fBblack\fR. +.TP +\fB\-outline \fIcolor\fR +\fIColor\fR specifies a color to use for drawing the polygon's +outline; it may have any of the forms accepted by \fBTk_GetColor\fR. +If \fIcolor\fR is an empty string then no outline will be +drawn for the polygon. +This option defaults to empty (no outline). +.TP +\fB\-smooth \fIboolean\fR +\fIBoolean\fR must have one of the forms accepted by \fBTk_GetBoolean\fR +It indicates whether or not the polygon should be drawn with a +curved perimeter. +If so, the outline of the polygon becomes a set of parabolic splines, +one spline for the first and second line segments, one for the second +and third, and so on. Straight-line segments can be generated in a +smoothed polygon by duplicating the end-points of the desired line segment. +.TP +\fB\-splinesteps \fInumber\fR +Specifies the degree of smoothness desired for curves: each spline +will be approximated with \fInumber\fR line segments. This +option is ignored unless the \fB\-smooth\fR option is true. +.TP +\fB\-stipple \fIbitmap\fR +Indicates that the polygon should be filled in a stipple pattern; +\fIbitmap\fR specifies the stipple pattern to use, in any of the +forms accepted by \fBTk_GetBitmap\fR. +If \fIbitmap\fR is an empty string (the default), then filling is +done in a solid fashion. +.TP +\fB\-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\fB\-width \fIoutlineWidth\fR +\fIOutlineWidth\fR specifies the width of the outline to be drawn around +the polygon, in any of the forms described in the COORDINATES section above. +If the \fB\-outline\fR option hasn't been specified then this option +has no effect. This option defaults to 1.0. +.PP +Polygon items are different from other items such as rectangles, ovals +and arcs in that interior points are considered to be ``inside'' a +polygon (e.g. for purposes of the \fBfind closest\fR and +\fBfind overlapping\fR widget commands) even if it is not filled. +For most other item types, an +interior point is considered to be inside the item only if the item +is filled or if it has neither a fill nor an outline. If you would +like an unfilled polygon whose interior points are not considered +to be inside the polygon, use a line item instead. + +.SH "RECTANGLE ITEMS" +.PP +Items of type \fBrectangle\fR appear as rectangular regions on +the display. Each rectangle may have an outline, a fill, or +both. Rectangles are created with widget commands of the +following form: +.CS +\fIpathName \fBcreate rectangle \fIx1 y1 x2 y2 \fR?\fIoption value option value ...\fR? +.CE +The arguments \fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR give +the coordinates of two diagonally opposite corners of the rectangle +(the rectangle will include its upper and left edges but not +its lower or right edges). +After the coordinates there may be any number of \fIoption\fR\-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR\-\fIvalue\fR pairs may be +used in \fBitemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for rectangles: +.TP +\fB\-fill \fIcolor\fR +Fill the area of the rectangle with \fIcolor\fR, which may be +specified in any of the forms accepted by \fBTk_GetColor\fR. +If \fIcolor\fR is an empty string (the default), +then the rectangle will not be filled. +.TP +\fB\-outline \fIcolor\fR +Draw an outline around the edge of the rectangle in \fIcolor\fR. +\fIColor\fR may have any of the forms accepted by \fBTk_GetColor\fR. +This option defaults to \fBblack\fR. +If \fIcolor\fR is an empty string then no outline will be +drawn for the rectangle. +.TP +\fB\-stipple \fIbitmap\fR +Indicates that the rectangle should be filled in a stipple pattern; +\fIbitmap\fR specifies the stipple pattern to use, in any of the +forms accepted by \fBTk_GetBitmap\fR. +If the \fB\-fill\fR option hasn't been specified then this option +has no effect. +If \fIbitmap\fR is an empty string (the default), then filling +is done in a solid fashion. +.TP +\fB\-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\fB\-width \fIoutlineWidth\fR +\fIOutlineWidth\fR specifies the width of the outline to be drawn around +the rectangle, in any of the forms described in the COORDINATES section above. +If the \fB\-outline\fR option hasn't been specified then this option +has no effect. +Wide outlines are drawn centered on the rectangular path +defined by \fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR. +This option defaults to 1.0. + +.SH "TEXT ITEMS" +.PP +A text item displays a string of characters on the screen in one +or more lines. +Text items support indexing and selection, along with the +following text-related canvas widget commands: \fBdchars\fR, +\fBfocus\fR, \fBicursor\fR, \fBindex\fR, \fBinsert\fR, +\fBselect\fR. +Text items are created with widget commands of the following +form: +.CS +\fIpathName \fBcreate text \fIx y \fR?\fIoption value option value ...\fR? +.CE +The arguments \fIx\fR and \fIy\fR specify the coordinates of a +point used to position the text on the display (see the options +below for more information on how text is displayed). +After the coordinates there may be any number of \fIoption\fR\-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR\-\fIvalue\fR pairs may be +used in \fBitemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for text items: +.TP +\fB\-anchor \fIanchorPos\fR +\fIAnchorPos\fR tells how to position the text relative to the +positioning point for the text; it may have any of the forms +accepted by \fBTk_GetAnchor\fR. For example, if \fIanchorPos\fR +is \fBcenter\fR then the text is centered on the point; if +\fIanchorPos\fR is \fBn\fR then the text will be drawn such that +the top center point of the rectangular region occupied by the +text will be at the positioning point. +This option defaults to \fBcenter\fR. +.TP +\fB\-fill \fIcolor\fR +\fIColor\fR specifies a color to use for filling the text characters; +it may have any of the forms accepted by \fBTk_GetColor\fR. +If this option isn't specified then it defaults to \fBblack\fR. +.TP +\fB\-font \fIfontName\fR +Specifies the font to use for the text item. +\fIFontName\fR may be any string acceptable to \fBTk_GetFontStruct\fR. +If this option isn't specified, it defaults to a system-dependent +font. +.TP +\fB\-justify \fIhow\fR +Specifies how to justify the text within its bounding region. +\fIHow\fR must be one of the values \fBleft\fR, \fBright\fR, +or \fBcenter\fR. +This option will only matter if the text is displayed as multiple +lines. +If the option is omitted, it defaults to \fBleft\fR. +.TP +\fB\-stipple \fIbitmap\fR +Indicates that the text should be drawn in a stippled pattern +rather than solid; +\fIbitmap\fR specifies the stipple pattern to use, in any of the +forms accepted by \fBTk_GetBitmap\fR. +If \fIbitmap\fR is an empty string (the default) then the text +is drawn in a solid fashion. +.TP +\fB\-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\fB\-text \fIstring\fR +\fIString\fR specifies the characters to be displayed in the text item. +Newline characters cause line breaks. +The characters in the item may also be changed with the +\fBinsert\fR and \fBdelete\fR widget commands. +This option defaults to an empty string. +.TP +\fB\-width \fIlineLength\fR +Specifies a maximum line length for the text, in any of the forms +described in the COORDINATES section above. +If this option is zero (the default) the text is broken into +lines only at newline characters. +However, if this option is non-zero then any line that would +be longer than \fIlineLength\fR is broken just before a space +character to make the line shorter than \fIlineLength\fR; the +space character is treated as if it were a newline +character. + +.SH "WINDOW ITEMS" +.PP +Items of type \fBwindow\fR cause a particular window to be displayed +at a given position on the canvas. +Window items are created with widget commands of the following form: +.CS +\fIpathName \fBcreate window \fIx y \fR?\fIoption value option value ...\fR? +.CE +The arguments \fIx\fR and \fIy\fR specify the coordinates of a +point used to position the window on the display (see the \fB\-anchor\fR +option below for more information on how bitmaps are displayed). +After the coordinates there may be any number of \fIoption\fR\-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR\-\fIvalue\fR pairs may be +used in \fBitemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for window items: +.TP +\fB\-anchor \fIanchorPos\fR +\fIAnchorPos\fR tells how to position the window relative to the +positioning point for the item; it may have any of the forms +accepted by \fBTk_GetAnchor\fR. For example, if \fIanchorPos\fR +is \fBcenter\fR then the window is centered on the point; if +\fIanchorPos\fR is \fBn\fR then the window will be drawn so that +its top center point is at the positioning point. +This option defaults to \fBcenter\fR. +.TP +\fB\-height \fIpixels\fR +Specifies the height to assign to the item's window. +\fIPixels\fR may have any of the +forms described in the COORDINATES section above. +If this option isn't specified, or if it is specified as an empty +string, then the window is given whatever height it requests internally. +.TP +\fB\-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\fB\-width \fIpixels\fR +Specifies the width to assign to the item's window. +\fIPixels\fR may have any of the +forms described in the COORDINATES section above. +If this option isn't specified, or if it is specified as an empty +string, then the window is given whatever width it requests internally. +.TP +\fB\-window \fIpathName\fR +Specifies the window to associate with this item. +The window specified by \fIpathName\fR must either be a child of +the canvas widget or a child of some ancestor of the canvas widget. +\fIPathName\fR may not refer to a top-level window. +.PP +Note: due to restrictions in the ways that windows are managed, it is not +possible to draw other graphical items (such as lines and images) on top +of window items. A window item always obscures any graphics that +overlap it, regardless of their order in the display list. + +.SH "APPLICATION-DEFINED ITEM TYPES" +.PP +It is possible for individual applications to define new item +types for canvas widgets using C code. +See the documentation for \fBTk_CreateItemType\fR. + +.SH BINDINGS +.PP +In the current implementation, new canvases are not given any +default behavior: you'll have to execute explicit Tcl commands +to give the canvas its behavior. + +.SH CREDITS +.PP +Tk's canvas widget is a blatant ripoff of ideas from Joel Bartlett's +\fIezd\fR program. \fIEzd\fR provides structured graphics in a Scheme +environment and preceded canvases by a year or two. Its simple +mechanisms for placing and animating graphical objects inspired the +functions of canvases. + +.SH KEYWORDS +canvas, widget |