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'\"

'\" Copyright (c) 1994 The Australian National University

'\" 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.

'\"

'\" Author: Paul Mackerras (paulus@cs.anu.edu.au),

'\"         Department of Computer Science,

'\"         Australian National University.

'\"

'\" RCS: @(#) $Id: FindPhoto.3,v 1.1.1.1 2002-01-16 10:25:48 markom Exp $

'\"

.so man.macros

.TH Tk_FindPhoto 3 8.0 Tk "Tk Library Procedures"

.BS

.SH NAME

Tk_FindPhoto, Tk_PhotoPutBlock, Tk_PhotoPutZoomedBlock, Tk_PhotoGetImage, Tk_PhotoBlank, Tk_PhotoExpand, Tk_PhotoGetSize, Tk_PhotoSetSize \- manipulate the image data stored in a photo image.

.SH SYNOPSIS

.nf

\fB#include \fR

\fB#include \fR

.sp

Tk_PhotoHandle

.VS 8.0 br

\fBTk_FindPhoto\fR(\fIinterp, imageName\fR)

.VE

.sp

void

\fBTk_PhotoPutBlock\fR(\fIhandle, blockPtr, x, y, width, height\fR)

.sp

void

\fBTk_PhotoPutZoomedBlock\fR(\fIhandle, blockPtr, x, y, width, height,\

zoomX, zoomY, subsampleX, subsampleY\fR)

.sp

int

\fBTk_PhotoGetImage\fR(\fIhandle, blockPtr\fR)

.sp

void

\fBTk_PhotoBlank\fR(\fIhandle\fR)

.sp

void

\fBTk_PhotoExpand\fR(\fIhandle, width, height\fR)

.sp

void

\fBTk_PhotoGetSize\fR(\fIhandle, widthPtr, heightPtr\fR)

.sp

void

\fBTk_PhotoSetSize\fR(\fIhandle, width, height\fR)

.SH ARGUMENTS

.AS Tk_PhotoImageBlock window_path

.AP Tcl_Interp *interp in

.VS

Interpreter in which image was created.

.VE

.AP char *imageName in

Name of the photo image.

.AP Tk_PhotoHandle handle in

Opaque handle identifying the photo image to be affected.

.AP Tk_PhotoImageBlock *blockPtr in

Specifies the address and storage layout of image data.

.AP int x in

Specifies the X coordinate where the top-left corner of the block is

to be placed within the image.

.AP int y in

Specifies the Y coordinate where the top-left corner of the block is

to be placed within the image.

.AP int width in

Specifies the width of the image area to be affected (for

\fBTk_PhotoPutBlock\fR) or the desired image width (for

\fBTk_PhotoExpand\fR and \fBTk_PhotoSetSize\fR).

.AP int height in

Specifies the height of the image area to be affected (for

\fBTk_PhotoPutBlock\fR) or the desired image height (for

\fBTk_PhotoExpand\fR and \fBTk_PhotoSetSize\fR).

.AP int *widthPtr out

Pointer to location in which to store the image width.

.AP int *heightPtr out

Pointer to location in which to store the image height.

.AP int subsampleX in

Specifies the subsampling factor in the X direction for input

image data.

.AP int subsampleY in

Specifies the subsampling factor in the Y direction for input

image data.

.AP int zoomX in

Specifies the zoom factor to be applied in the X direction to pixels

being written to the photo image.

.AP int zoomY in

Specifies the zoom factor to be applied in the Y direction to pixels

being written to the photo image.

.BE

.SH DESCRIPTION

.PP

\fBTk_FindPhoto\fR 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 \fBimage create

photo\fR command, or assigned by that command if no name was specified.

.PP

\fBTk_PhotoPutBlock\fR is used to supply blocks of image data to be

displayed.  The call affects an area of the image of size

\fIwidth\fR x \fIheight\fR pixels, with its top-left corner at

coordinates (\fIx\fR,\fIy\fR).  All of \fIwidth\fR, \fIheight\fR,

\fIx\fR, and \fIy\fR 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

\fB\-width\fR and/or \fB\-height\fR widget configuration options

(see photo(n)); in that

case the area is silently clipped to the image boundaries.

.PP

The \fIblock\fR parameter is a pointer to a

\fBTk_PhotoImageBlock\fR structure, defined as follows:

.CS

typedef struct {

        unsigned char *\fIpixelPtr\fR;

        int \fIwidth\fR;

        int \fIheight\fR;

        int \fIpitch\fR;

        int \fIpixelSize\fR;

        int \fIoffset[3]\fR;

} Tk_PhotoImageBlock;

.CE

The \fIpixelPtr\fR field points to the first pixel, that is, the

top-left pixel in the block.

The \fIwidth\fR and \fIheight\fR fields specify the dimensions of the

block of pixels.  The \fIpixelSize\fR field specifies the address

difference between two horizontally adjacent pixels.  Often it is 3

or 4, but it can have any value.  The \fIpitch\fR field specifies the

address difference between two vertically adjacent pixels.  The

\fIoffset\fR 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.

.PP

The value given for the \fIwidth\fR and \fIheight\fR parameters to

\fBTk_PhotoPutBlock\fR do not have to correspond to the values specified

in \fIblock\fR.  If they are smaller, \fBTk_PhotoPutBlock\fR 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.

.PP

\fBTk_PhotoPutZoomedBlock\fR works like \fBTk_PhotoPutBlock\fR except that

the image can be reduced or enlarged for display.  The

\fIsubsampleX\fR and \fIsubsampleY\fR parameters allow the size of the

image to be reduced by subsampling.

\fBTk_PhotoPutZoomedBlock\fR will use only pixels from the input image

whose X coordinates are multiples of \fIsubsampleX\fR, and whose Y

coordinates are multiples of \fIsubsampleY\fR.  For example, an image

of 512x512 pixels can be reduced to 256x256 by setting

\fIsubsampleX\fR and \fIsubsampleY\fR to 2.

.PP

The \fIzoomX\fR and \fIzoomY\fR parameters allow the image to be

enlarged by pixel replication.  Each pixel of the (possibly subsampled)

input image will be written to a block \fIzoomX\fR pixels wide and

\fIzoomY\fR pixels high of the displayed image.  Subsampling and

zooming can be used together for special effects.

.PP

\fBTk_PhotoGetImage\fR can be used to retrieve image data from a photo

image.  \fBTk_PhotoGetImage\fR fills

in the structure pointed to by the \fIblockPtr\fR 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.

\fBTk_PhotoGetImage\fR returns 1 for compatibility with the

corresponding procedure in the old photo widget.

.PP

\fBTk_PhotoBlank\fR blanks the entire area of the

photo image.  Blank areas of a photo image are transparent.

.PP

\fBTk_PhotoExpand\fR requests that the widget's image be expanded to be

at least \fIwidth\fR x \fIheight\fR pixels in size.  The width and/or

height are unchanged if the user has specified an explicit image width

or height with the \fB\-width\fR and/or \fB\-height\fR configuration

options, respectively.

If the image data

are being supplied in many small blocks, it is more efficient to use

\fBTk_PhotoExpand\fR or \fBTk_PhotoSetSize\fR at the beginning rather than

allowing the image to expand in many small increments as image blocks

are supplied.

.PP

\fBTk_PhotoSetSize\fR specifies the size of the image, as if the user

had specified the given \fIwidth\fR and \fIheight\fR values to the

\fB\-width\fR and \fB\-height\fR configuration options.  A value of

zero for \fIwidth\fR or \fIheight\fR does not change the image's width

or height, but allows the width or height to be changed by subsequent

calls to \fBTk_PhotoPutBlock\fR, \fBTk_PhotoPutZoomedBlock\fR or

\fBTk_PhotoExpand\fR.

.PP

\fBTk_PhotoGetSize\fR returns the dimensions of the image in

*\fIwidthPtr\fR and *\fIheightPtr\fR.

.SH CREDITS

.PP

The code for the photo image type was developed by Paul Mackerras,

based on his earlier photo widget code.

.SH KEYWORDS

photo, image