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Diffstat (limited to 'doc/photo.n')
| -rw-r--r-- | doc/photo.n | 122 |
1 files changed, 109 insertions, 13 deletions
diff --git a/doc/photo.n b/doc/photo.n index c14abe3..f54dc2e 100644 --- a/doc/photo.n +++ b/doc/photo.n @@ -16,9 +16,22 @@ .SH NAME photo \- Full-color images .SH SYNOPSIS +.nf \fBimage create photo \fR?\fIname\fR? ?\fIoptions\fR? -.BE +\fIimageName \fBblank\fR +\fIimageName \fBcget \fIoption\fR +\fIimageName \fBconfigure\fR ?\fIoption\fR? ?\fIvalue option value ...\fR? +\fIimageName \fBcopy \fIsourceImage\fR ?\fIoption value(s) ...\fR? +\fIimageName \fBdata\fR ?\fIoption value(s) ...\fR? +\fIimageName \fBget \fIx y\fR +\fIimageName \fBput \fIdata\fR ?\fIoption value(s) ...\fR? +\fIimageName \fBread \fIfilename\fR ?\fIoption value(s) ...\fR? +\fIimageName \fBredither\fR +\fIimageName \fBtransparency \fIsubcommand \fR?\fIarg arg ...\fR? +\fIimageName \fBwrite \fIfilename\fR ?\fIoption value(s) ...\fR? +.fi +.BE .SH DESCRIPTION .PP A photo is an image whose pixels can display any color or be @@ -26,7 +39,11 @@ transparent. A photo image is stored internally in full color (32 bits per pixel), and is displayed using dithering if necessary. Image data for a photo image can be obtained from a file or a string, or it can be supplied from -C code through a procedural interface. At present, only GIF and PPM/PGM +C code through a procedural interface. At present, only +.VS 8.6 +PNG, +.VE 8.6 +GIF and PPM/PGM formats are supported, but an interface exists to allow additional image file formats to be added easily. A photo image is transparent in regions where no image data has been supplied @@ -39,24 +56,29 @@ command. Photos support the following \fIoptions\fR: .TP \fB\-data \fIstring\fR +. Specifies the contents of the image as a string. The string should contain binary data or, for some formats, base64-encoded data (this is -currently guaranteed to be supported for GIF images). The format of the +currently guaranteed to be supported for PNG and GIF images). The +format of the string must be one of those for which there is an image file format handler that will accept string data. If both the \fB\-data\fR and \fB\-file\fR options are specified, the \fB\-file\fR option takes precedence. .TP \fB\-format \fIformat-name\fR +. Specifies the name of the file format for the data specified with the \fB\-data\fR or \fB\-file\fR option. .TP \fB\-file \fIname\fR +. \fIname\fR gives the name of a file that is to be read to supply data for the photo image. The file format must be one of those for which there is an image file format handler that can read data. .TP \fB\-gamma \fIvalue\fR +. Specifies that the colors allocated for displaying this image in a window should be corrected for a non-linear display with the specified gamma exponent value. (The intensity produced by most @@ -68,12 +90,14 @@ will make the image lighter, and values less than one will make it darker. .TP \fB\-height \fInumber\fR +. Specifies the height of the image, in pixels. This option is useful primarily in situations where the user wishes to build up the contents of the image piece by piece. A value of zero (the default) allows the image to expand or shrink vertically to fit the data stored in it. .TP \fB\-palette \fIpalette-spec\fR +. Specifies the resolution of the color cube to be allocated for displaying this image, and thus the number of colors used from the colormaps of the windows where it is displayed. The @@ -85,6 +109,7 @@ number) is used, the image will be displayed in monochrome (i.e., grayscale). .TP \fB\-width \fInumber\fR +. Specifies the width of the image, in pixels. This option is useful primarily in situations where the user wishes to build up the contents of the image piece by piece. A value of zero (the default) allows the @@ -112,17 +137,20 @@ changed. The following commands are possible for photo images: .TP \fIimageName \fBblank\fR +. Blank the image; that is, set the entire image to have no data, so it will be displayed as transparent, and the background of whatever window it is displayed in will show through. .TP \fIimageName \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 -\fBimage create photo\fR command. +\fBimage create\fR \fBphoto\fR command. .TP \fIimageName \fBconfigure\fR ?\fIoption\fR? ?\fIvalue option value ...\fR? +. Query or modify the configuration options for the image. If no \fIoption\fR is specified, returns a list describing all of the available options for \fIimageName\fR (see \fBTk_ConfigureInfo\fR for @@ -134,9 +162,10 @@ one or more \fIoption\-value\fR pairs are specified, then the command modifies the given 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 -\fBimage create photo\fR command. +\fBimage create\fR \fBphoto\fR command. .TP \fIimageName \fBcopy\fR \fIsourceImage\fR ?\fIoption value(s) ...\fR? +. Copies a region from the image called \fIsourceImage\fR (which must be a photo image) to the image called \fIimageName\fR, possibly with pixel zooming and/or subsampling. If no options are specified, this @@ -146,6 +175,7 @@ options may be specified: .RS .TP \fB\-from \fIx1 y1 x2 y2\fR +. Specifies a rectangular sub-region of the source image to be copied. (\fIx1,y1\fR) and (\fIx2,y2\fR) specify diagonally opposite corners of the rectangle. If \fIx2\fR and \fIy2\fR are not specified, the @@ -155,6 +185,7 @@ rectangle but not the bottom or right edges. If the \fB\-from\fR option is not given, the default is the whole source image. .TP \fB\-to \fIx1 y1 x2 y2\fR +. Specifies a rectangular sub-region of the destination image to be affected. (\fIx1,y1\fR) and (\fIx2,y2\fR) specify diagonally opposite corners of the rectangle. If \fIx2\fR and \fIy2\fR are not specified, @@ -164,6 +195,7 @@ region (after subsampling and zooming, if specified). If \fIx2\fR and necessary to fill the destination region in a tiled fashion. .TP \fB\-shrink\fR +. Specifies that the size of the destination image should be reduced, if necessary, so that the region being copied into is at the bottom-right corner of the image. This option will not affect the width or height @@ -171,6 +203,7 @@ of the image if the user has specified a non-zero value for the \fB\-width\fR or \fB\-height\fR configuration option, respectively. .TP \fB\-zoom \fIx y\fR +. Specifies that the source region should be magnified by a factor of \fIx\fR in the X direction and \fIy\fR in the Y direction. If \fIy\fR is not given, the default value is the same as \fIx\fR. With this @@ -179,6 +212,7 @@ of \fIx\fR x \fIy\fR pixels in the destination image, all the same color. \fIx\fR and \fIy\fR must be greater than 0. .TP \fB\-subsample \fIx y\fR +. Specifies that the source image should be reduced in size by using only every \fIx\fRth pixel in the X direction and \fIy\fRth pixel in the Y direction. Negative values will cause the image to be flipped @@ -186,6 +220,7 @@ about the Y or X axes, respectively. If \fIy\fR is not given, the default value is the same as \fIx\fR. .TP \fB\-compositingrule \fIrule\fR +. Specifies how transparent pixels in the source image are combined with the destination image. When a compositing rule of \fIoverlay\fR is set, the old contents of the destination image are visible, as if the @@ -196,17 +231,20 @@ the source image is used as-is. The default compositing rule is \fIoverlay\fR. .RE .TP -\fIimageName \fBdata ?\fIoption value(s) ...\fR? +\fIimageName \fBdata\fR ?\fIoption value(s) ...\fR? +. Returns image data in the form of a string. The following options may be specified: .RS .TP \fB\-background\fI color\fR +. If the color is specified, the data will not contain any transparency information. In all transparent pixels the color will be replaced by the specified color. .TP \fB\-format\fI format-name\fR +. Specifies the name of the image file format handler to be used. Specifically, this subcommand searches for the first handler whose name matches an initial substring of @@ -220,6 +258,7 @@ format (where \fIrr\fR is a pair of hexadecimal digits for the red channel, \fIgg\fR for green, and \fIbb\fR for blue). .TP \fB\-from \fIx1 y1 x2 y2\fR +. Specifies a rectangular region of \fIimageName\fR to be returned. If only \fIx1\fR and \fIy1\fR are specified, the region extends from \fI(x1,y1)\fR to the bottom-right corner of @@ -229,16 +268,19 @@ and excluding x2,y2. The default, if this option is not given, is the whole image. .TP \fB\-grayscale\fR +. If this options is specified, the data will not contain color information. All pixel data will be transformed into grayscale. .RE .TP \fIimageName \fBget\fR \fIx y\fR +. Returns the color of the pixel at coordinates (\fIx\fR,\fIy\fR) in the image as a list of three integers between 0 and 255, representing the red, green and blue components respectively. .TP \fIimageName \fBput\fR \fIdata\fR ?\fIoption value(s) ...\fR? +. Sets pixels in \fI imageName\fR to the data specified in \fIdata\fR. This command first searches the list of image file format handlers for a handler that can interpret the data in \fIdata\fR, and then reads @@ -253,12 +295,14 @@ that color. The following options may be specified: .RS .TP \fB\-format \fIformat-name\fR +. Specifies the format of the image data in \fIdata\fR. Specifically, only image file format handlers whose names begin with \fIformat-name\fR will be used while searching for an image data format handler to read the data. .TP \fB\-to \fIx1 y1\fR ?\fIx2 y2\fR? +. Specifies the coordinates of the top-left corner (\fIx1\fR,\fIy1\fR) of the region of \fIimageName\fR into which the image data will be copied. The default position is (0,0). If \fIx2\fR,\fIy2\fR is given @@ -270,6 +314,7 @@ represented by (\fIx2\fR,\fIy2\fR) will be filled with that color. .RE .TP \fIimageName \fBread\fR \fIfilename\fR ?\fIoption value(s) ...\fR? +. Reads image data from the file named \fIfilename\fR into the image. This command first searches the list of image file format handlers for a handler that can interpret the data @@ -279,12 +324,14 @@ specified: .RS .TP \fB\-format \fIformat-name\fR +. Specifies the format of the image data in \fIfilename\fR. Specifically, only image file format handlers whose names begin with \fIformat-name\fR will be used while searching for an image data format handler to read the data. .TP \fB\-from \fIx1 y1 x2 y2\fR +. Specifies a rectangular sub-region of the image file data to be copied to the destination image. If only \fIx1\fR and \fIy1\fR are specified, the region extends from (\fIx1,y1\fR) to the bottom-right @@ -294,6 +341,7 @@ The default, if this option is not specified, is the whole of the image in the image file. .TP \fB\-shrink\fR +. If this option, the size of \fIimageName\fR will be reduced, if necessary, so that the region into which the image file data are read is at the bottom-right corner of the \fIimageName\fR. This option @@ -302,12 +350,14 @@ specified a non-zero value for the \fB\-width\fR or \fB\-height\fR configuration option, respectively. .TP \fB\-to \fIx y\fR +. Specifies the coordinates of the top-left corner of the region of \fIimageName\fR into which data from \fIfilename\fR are to be read. The default is (0,0). .RE .TP \fIimageName \fBredither\fR +. The dithering algorithm used in displaying photo images propagates quantization errors from one pixel to its neighbors. If the image data for \fIimageName\fR is supplied in pieces, the @@ -316,39 +366,47 @@ not noticeable, but if it is a problem, this command can be used to recalculate the dithered image in each window where the image is displayed. .TP -\fIimageName \fBtransparency \fIsubcommand ?arg arg ...?\fR +\fIimageName \fBtransparency \fIsubcommand \fR?\fIarg arg ...\fR? +. Allows examination and manipulation of the transparency information in the photo image. Several subcommands are available: .RS .TP \fIimageName \fBtransparency get \fIx y\fR +. Returns a boolean indicating if the pixel at (\fIx\fR,\fIy\fR) is transparent. .TP \fIimageName \fBtransparency set \fIx y boolean\fR +. Makes the pixel at (\fIx\fR,\fIy\fR) transparent if \fIboolean\fR is true, and makes that pixel opaque otherwise. .RE .TP \fIimageName \fBwrite \fIfilename\fR ?\fIoption value(s) ...\fR? +. Writes image data from \fIimageName\fR to a file named \fIfilename\fR. The following options may be specified: .RS .TP \fB\-background\fI color\fR +. If the color is specified, the data will not contain any transparency information. In all transparent pixels the color will be replaced by the specified color. .TP \fB\-format\fI format-name\fR +. Specifies the name of the image file format handler to be used to write the data to the file. Specifically, this subcommand searches for the first handler whose name matches an initial substring of \fIformat-name\fR and which has the capability to write an image -file. If this option is not given, this subcommand uses the first -handler that has the capability to write an image file. +file. If this option is not given, the format is guessed from +the file extension. If that cannot be determined, this subcommand +uses the first handler that has the capability to write an image file. .TP \fB\-from \fIx1 y1 x2 y2\fR +. Specifies a rectangular region of \fIimageName\fR to be written to the image file. If only \fIx1\fR and \fIy1\fR are specified, the region extends from \fI(x1,y1)\fR to the bottom-right corner of @@ -357,6 +415,7 @@ diagonally opposite corners of the rectangular region. The default, if this option is not given, is the whole image. .TP \fB\-grayscale\fR +. If this options is specified, the data will not contain color information. All pixel data will be transformed into grayscale. .RE @@ -366,8 +425,8 @@ The photo image code is structured to allow handlers for additional image file formats to be added easily. The photo image code maintains a list of these handlers. Handlers are added to the list by registering them with a call to \fBTk_CreatePhotoImageFormat\fR. The -standard Tk distribution comes with handlers for PPM/PGM and GIF formats, -which are automatically registered on initialization. +standard Tk distribution comes with handlers for PPM/PGM, PNG and GIF +formats, which are automatically registered on initialization. .PP When reading an image file or processing string data specified with the \fB\-data\fR configuration option, the @@ -391,6 +450,27 @@ that, which the handler can use, for example, to specify which variant to use of the formats supported by the handler. Note that not all image handlers may support writing transparency data to a file, even where the target image format does. +.SS "FORMAT SUBOPTIONS" +.PP +.VS 8.6 +Some image formats support sub-options, which are specified at the time that +the image is loaded using additional words in the \fB\-format\fR option. At +the time of writing, the following are supported: +.TP +\fBgif \-index\fI indexValue\fR +. +When parsing a multi-part GIF image, Tk normally only accesses the first +image. By giving the \fB\-index\fR sub-option, the \fIindexValue\fR'th value +may be used instead. The \fIindexValue\fR must be an integer from 0 up to the +number of image parts in the GIF data. +.TP +\fBpng \-alpha\fI alphaValue\fR +. +An additional alpha filtering for the overall image, which allows the +background on which the image is displayed to show through. This usually also +has the effect of desaturating the image. The \fIalphaValue\fR must be between +0.0 and 1.0. +.VE 8.6 .SH "COLOR ALLOCATION" .PP When a photo image is displayed in a window, the photo image code @@ -426,8 +506,10 @@ The photo image type was designed and implemented by Paul Mackerras, based on his earlier photo widget and some suggestions from John Ousterhout. .SH EXAMPLE +.PP Load an image from a file and tile it to the size of a window, which is useful for producing a tiled background: +.PP .CS # These lines should be called once \fBimage create photo\fR untiled \-file "theFile.ppm" @@ -439,9 +521,23 @@ set width [winfo width .someWidget] set height [winfo height .someWidget] tiled \fBcopy\fR untiled \-to 0 0 $width $height \-shrink .CE - +.PP +.VS 8.6 +The PNG image loader allows the application of an additional alpha factor +during loading, which is useful for generating images suitable for disabled +buttons: +.PP +.CS +\fBimage create photo\fR icon \-file "icon.png" +\fBimage create photo\fR iconDisabled \-file "icon.png" \e + \-format "png \-alpha 0.5" +button .b \-image icon \-disabledimage iconDisabled +.CE +.VE 8.6 .SH "SEE ALSO" image(n) - .SH KEYWORDS photo, image, color +'\" Local Variables: +'\" mode: nroff +'\" End: |