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+'\"
+'\" 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