Tk_FindPhoto (3)

SYNOPSIS

#include <tk.h>
#include <tkPhoto.h>
Tk_PhotoHandle
8.0 br
Tk_FindPhoto(interp, imageName)

void
Tk_PhotoPutBlock(handle, blockPtr, x, y, width, height)
void
Tk_PhotoPutZoomedBlock(handle, blockPtr, x, y, width, height,\
zoomX, zoomY, subsampleX, subsampleY)
int
Tk_PhotoGetImage(handle, blockPtr)
void
Tk_PhotoBlank(handle)
void
Tk_PhotoExpand(handle, width, height)
void
Tk_PhotoGetSize(handle, widthPtr, heightPtr)
void
Tk_PhotoSetSize(handle, width, height)

ARGUMENTS

Tk_PhotoImageBlock window_path Tcl_Interp *interp in Interpreter in which image was created. char *imageName in Name of the photo image. Tk_PhotoHandle handle in Opaque handle identifying the photo image to be affected. Tk_PhotoImageBlock *blockPtr in Specifies the address and storage layout of image data. int x in Specifies the X coordinate where the top-left corner of the block is to be placed within the image. int y in Specifies the Y coordinate where the top-left corner of the block is to be placed within the image. int width in Specifies the width of the image area to be affected (for Tk_PhotoPutBlock) or the desired image width (for Tk_PhotoExpand and Tk_PhotoSetSize). int height in Specifies the height of the image area to be affected (for Tk_PhotoPutBlock) or the desired image height (for Tk_PhotoExpand and Tk_PhotoSetSize). int *widthPtr out Pointer to location in which to store the image width. int *heightPtr out Pointer to location in which to store the image height. int subsampleX in Specifies the subsampling factor in the X direction for input image data. int subsampleY in Specifies the subsampling factor in the Y direction for input image data. int zoomX in Specifies the zoom factor to be applied in the X direction to pixels being written to the photo image. int zoomY in Specifies the zoom factor to be applied in the Y direction to pixels being written to the photo image.

DESCRIPTION

Tk_FindPhoto returns an opaque handle that is used to identify a particular photo image to the other procedures. The parameter is the name of the image, that is, the name specified to the image create photo command, or assigned by that command if no name was specified.

Tk_PhotoPutBlock is used to supply blocks of image data to be displayed. The call affects an area of the image of size width x height pixels, with its top-left corner at coordinates (x,y). All of width, height, x, and y must be non-negative. If part of this area lies outside the current bounds of the image, the image will be expanded to include the area, unless the user has specified an explicit image size with the -width and/or -height widget configuration options (see photo(n)); in that case the area is silently clipped to the image boundaries.

The block parameter is a pointer to a Tk_PhotoImageBlock structure, defined as follows: typedef struct { unsigned char *pixelPtr; int width; int height; int pitch; int pixelSize; int offset[3]; } Tk_PhotoImageBlock; The pixelPtr field points to the first pixel, that is, the top-left pixel in the block. The width and height fields specify the dimensions of the block of pixels. The pixelSize field specifies the address difference between two horizontally adjacent pixels. Often it is 3 or 4, but it can have any value. The pitch field specifies the address difference between two vertically adjacent pixels. The offset array contains the offsets from the address of a pixel to the addresses of the bytes containing the red, green and blue components. These are normally 0, 1 and 2, but can have other values, e.g., for images that are stored as separate red, green and blue planes.

The value given for the width and height parameters to Tk_PhotoPutBlock do not have to correspond to the values specified in block. If they are smaller, Tk_PhotoPutBlock extracts a sub-block from the image data supplied. If they are larger, the data given are replicated (in a tiled fashion) to fill the specified area. These rules operate independently in the horizontal and vertical directions.

Tk_PhotoPutZoomedBlock works like Tk_PhotoPutBlock except that the image can be reduced or enlarged for display. The subsampleX and subsampleY parameters allow the size of the image to be reduced by subsampling. Tk_PhotoPutZoomedBlock will use only pixels from the input image whose X coordinates are multiples of subsampleX, and whose Y coordinates are multiples of subsampleY. For example, an image of 512x512 pixels can be reduced to 256x256 by setting subsampleX and subsampleY to 2.

The zoomX and zoomY parameters allow the image to be enlarged by pixel replication. Each pixel of the (possibly subsampled) input image will be written to a block zoomX pixels wide and zoomY pixels high of the displayed image. Subsampling and zooming can be used together for special effects.

Tk_PhotoGetImage can be used to retrieve image data from a photo image. Tk_PhotoGetImage fills in the structure pointed to by the blockPtr parameter with values that describe the address and layout of the image data that the photo image has stored internally. The values are valid until the image is destroyed or its size is changed. Tk_PhotoGetImage returns 1 for compatibility with the corresponding procedure in the old photo widget.

Tk_PhotoBlank blanks the entire area of the photo image. Blank areas of a photo image are transparent.

Tk_PhotoExpand requests that the widget's image be expanded to be at least width x height pixels in size. The width and/or height are unchanged if the user has specified an explicit image width or height with the -width and/or -height configuration options, respectively. If the image data are being supplied in many small blocks, it is more efficient to use Tk_PhotoExpand or Tk_PhotoSetSize at the beginning rather than allowing the image to expand in many small increments as image blocks are supplied.

Tk_PhotoSetSize specifies the size of the image, as if the user had specified the given width and height values to the -width and -height configuration options. A value of zero for width or height does not change the image's width or height, but allows the width or height to be changed by subsequent calls to Tk_PhotoPutBlock, Tk_PhotoPutZoomedBlock or Tk_PhotoExpand.

Tk_PhotoGetSize returns the dimensions of the image in *widthPtr and *heightPtr.

CREDITS

The code for the photo image type was developed by Paul Mackerras, based on his earlier photo widget code.

KEYWORDS

photo, image '\" '\" Copyright (c) 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. '\" '\" RCS: @(#) $Id: TextLayout.3,v 1.2 1998/09/14 18:22:54 stanton Exp $ '\" '\" The definitions below are for supplemental macros used in Tcl/Tk '\" manual entries. '\" '\" .AP type name in/out ?indent? '\" Start paragraph describing an argument to a library procedure. '\" type is type of argument (int, etc.), in/out is either "in", "out", '\" or "in/out" to describe whether procedure reads or modifies arg, '\" and indent is equivalent to second arg of .IP (shouldn't ever be '\" needed; use .AS below instead) '\" '\" .AS ?type? ?name? '\" Give maximum sizes of arguments for setting tab stops. Type and '\" name are examples of largest possible arguments that will be passed '\" to .AP later. If args are omitted, default tab stops are used. '\" '\" .BS '\" Start box enclosure. From here until next .BE, everything will be '\" enclosed in one large box. '\" '\" .BE '\" End of box enclosure. '\" '\" .CS '\" Begin code excerpt. '\" '\" .CE '\" End code excerpt. '\" '\" .VS ?version? ?br? '\" Begin vertical sidebar, for use in marking newly-changed parts '\" of man pages. The first argument is ignored and used for recording '\" the version when the .VS was added, so that the sidebars can be '\" found and removed when they reach a certain age. If another argument '\" is present, then a line break is forced before starting the sidebar. '\" '\" .VE '\" End of vertical sidebar. '\" '\" .DS '\" Begin an indented unfilled display. '\" '\" .DE '\" End of indented unfilled display. '\" '\" .SO '\" Start of list of standard options for a Tk widget. The '\" options follow on successive lines, in four columns separated '\" by tabs. '\" '\" .SE '\" End of list of standard options for a Tk widget. '\" '\" .OP cmdName dbName dbClass '\" Start of description of a specific option. cmdName gives the '\" option's name as specified in the class command, dbName gives '\" the option's name in the option database, and dbClass gives '\" the option's class in the option database. '\" '\" .UL arg1 arg2 '\" Print arg1 underlined, then print arg2 normally. '\" '\" RCS: @(#) $Id: man.macros,v 1.2 1998/09/14 18:39:54 stanton Exp $ '\" '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. t .wh -1.3i ^B ^l \n(.l b '\" # Start an argument description AP !"\\$4"" .TP \\$4 \{\ !"\\$2"" .TP \\n()Cu .TP 15