854 lines
23 KiB
C
854 lines
23 KiB
C
/*
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* tkImgPPM.c --
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*
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* A photo image file handler for PPM (Portable PixMap) files.
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*
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* Copyright (c) 1994 The Australian National University.
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* Copyright (c) 1994-1997 Sun Microsystems, Inc.
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*
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* See the file "license.terms" for information on usage and redistribution of
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* this file, and for a DISCLAIMER OF ALL WARRANTIES.
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*
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* Author: Paul Mackerras (paulus@cs.anu.edu.au),
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* Department of Computer Science,
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* Australian National University.
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*/
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#include "tkInt.h"
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/*
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* The maximum amount of memory to allocate for data read from the file. If we
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* need more than this, we do it in pieces.
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*/
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#define MAX_MEMORY 10000 /* don't allocate > 10KB */
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/*
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* Define PGM and PPM, i.e. gray images and color images.
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*/
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#define PGM 1
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#define PPM 2
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/*
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* The format record for the PPM file format:
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*/
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static int FileMatchPPM(Tcl_Channel chan, const char *fileName,
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Tcl_Obj *format, int *widthPtr, int *heightPtr,
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Tcl_Interp *interp);
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static int FileReadPPM(Tcl_Interp *interp, Tcl_Channel chan,
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const char *fileName, Tcl_Obj *format,
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Tk_PhotoHandle imageHandle, int destX, int destY,
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int width, int height, int srcX, int srcY);
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static int FileWritePPM(Tcl_Interp *interp, const char *fileName,
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Tcl_Obj *format, Tk_PhotoImageBlock *blockPtr);
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static int StringWritePPM(Tcl_Interp *interp, Tcl_Obj *format,
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Tk_PhotoImageBlock *blockPtr);
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static int StringMatchPPM(Tcl_Obj *dataObj, Tcl_Obj *format,
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int *widthPtr, int *heightPtr, Tcl_Interp *interp);
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static int StringReadPPM(Tcl_Interp *interp, Tcl_Obj *dataObj,
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Tcl_Obj *format, Tk_PhotoHandle imageHandle,
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int destX, int destY, int width, int height,
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int srcX, int srcY);
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Tk_PhotoImageFormat tkImgFmtPPM = {
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"ppm", /* name */
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FileMatchPPM, /* fileMatchProc */
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StringMatchPPM, /* stringMatchProc */
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FileReadPPM, /* fileReadProc */
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StringReadPPM, /* stringReadProc */
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FileWritePPM, /* fileWriteProc */
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StringWritePPM, /* stringWriteProc */
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NULL
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};
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/*
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* Prototypes for local functions defined in this file:
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*/
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static int ReadPPMFileHeader(Tcl_Channel chan, int *widthPtr,
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int *heightPtr, int *maxIntensityPtr);
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static int ReadPPMStringHeader(Tcl_Obj *dataObj, int *widthPtr,
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int *heightPtr, int *maxIntensityPtr,
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unsigned char **dataBufferPtr, int *dataSizePtr);
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/*
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*----------------------------------------------------------------------
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*
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* FileMatchPPM --
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*
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* This function is invoked by the photo image type to see if a file
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* contains image data in PPM format.
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*
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* Results:
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* The return value is >0 if the first characters in file "f" look like
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* PPM data, and 0 otherwise.
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*
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* Side effects:
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* The access position in f may change.
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*
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*----------------------------------------------------------------------
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*/
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static int
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FileMatchPPM(
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Tcl_Channel chan, /* The image file, open for reading. */
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TCL_UNUSED(const char *), /* The name of the image file. */
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TCL_UNUSED(Tcl_Obj *), /* User-specified format string, or NULL. */
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int *widthPtr, int *heightPtr,
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/* The dimensions of the image are returned
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* here if the file is a valid raw PPM
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* file. */
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TCL_UNUSED(Tcl_Interp *)) /* unused */
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{
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int dummy;
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return ReadPPMFileHeader(chan, widthPtr, heightPtr, &dummy);
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}
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/*
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*----------------------------------------------------------------------
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*
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* FileReadPPM --
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*
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* This function is called by the photo image type to read PPM format
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* data from a file and write it into a given photo image.
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*
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* Results:
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* A standard TCL completion code. If TCL_ERROR is returned then an error
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* message is left in the interp's result.
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*
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* Side effects:
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* The access position in file f is changed, and new data is added to the
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* image given by imageHandle.
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*
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*----------------------------------------------------------------------
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*/
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static int
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FileReadPPM(
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Tcl_Interp *interp, /* Interpreter to use for reporting errors. */
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Tcl_Channel chan, /* The image file, open for reading. */
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const char *fileName, /* The name of the image file. */
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TCL_UNUSED(Tcl_Obj *), /* User-specified format string, or NULL. */
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Tk_PhotoHandle imageHandle, /* The photo image to write into. */
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int destX, int destY, /* Coordinates of top-left pixel in photo
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* image to be written to. */
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int width, int height, /* Dimensions of block of photo image to be
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* written to. */
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int srcX, int srcY) /* Coordinates of top-left pixel to be used in
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* image being read. */
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{
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int fileWidth, fileHeight, maxIntensity;
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int nLines, nBytes, h, type, count, bytesPerChannel = 1;
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unsigned char *pixelPtr;
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Tk_PhotoImageBlock block;
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type = ReadPPMFileHeader(chan, &fileWidth, &fileHeight, &maxIntensity);
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if (type == 0) {
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Tcl_SetObjResult(interp, Tcl_ObjPrintf(
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"couldn't read raw PPM header from file \"%s\"", fileName));
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Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "NO_HEADER", NULL);
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return TCL_ERROR;
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}
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if ((fileWidth <= 0) || (fileHeight <= 0)) {
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Tcl_SetObjResult(interp, Tcl_ObjPrintf(
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"PPM image file \"%s\" has dimension(s) <= 0", fileName));
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Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "DIMENSIONS", NULL);
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return TCL_ERROR;
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}
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if ((maxIntensity <= 0) || (maxIntensity > 0xffff)) {
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Tcl_SetObjResult(interp, Tcl_ObjPrintf(
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"PPM image file \"%s\" has bad maximum intensity value %d",
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fileName, maxIntensity));
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Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "INTENSITY", NULL);
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return TCL_ERROR;
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} else if (maxIntensity > 0x00ff) {
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bytesPerChannel = 2;
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}
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if ((srcX + width) > fileWidth) {
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width = fileWidth - srcX;
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}
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if ((srcY + height) > fileHeight) {
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height = fileHeight - srcY;
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}
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if ((width <= 0) || (height <= 0)
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|| (srcX >= fileWidth) || (srcY >= fileHeight)) {
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return TCL_OK;
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}
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if (type == PGM) {
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block.pixelSize = 1 * bytesPerChannel;
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block.offset[0] = 0;
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block.offset[1] = 0;
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block.offset[2] = 0;
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} else {
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block.pixelSize = 3 * bytesPerChannel;
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block.offset[0] = 0;
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block.offset[1] = 1 * bytesPerChannel;
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block.offset[2] = 2 * bytesPerChannel;
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}
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block.offset[3] = 0;
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block.width = width;
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block.pitch = block.pixelSize * fileWidth;
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if (Tk_PhotoExpand(interp, imageHandle,
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destX + width, destY + height) != TCL_OK) {
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return TCL_ERROR;
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}
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if (srcY > 0) {
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Tcl_Seek(chan, (Tcl_WideInt)(srcY * block.pitch), SEEK_CUR);
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}
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nLines = (MAX_MEMORY + block.pitch - 1) / block.pitch;
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if (nLines > height) {
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nLines = height;
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}
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if (nLines <= 0) {
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nLines = 1;
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}
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nBytes = nLines * block.pitch;
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pixelPtr = (unsigned char *)ckalloc(nBytes);
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block.pixelPtr = pixelPtr + srcX * block.pixelSize;
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for (h = height; h > 0; h -= nLines) {
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if (nLines > h) {
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nLines = h;
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nBytes = nLines * block.pitch;
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}
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count = Tcl_Read(chan, (char *) pixelPtr, nBytes);
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if (count != nBytes) {
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Tcl_SetObjResult(interp, Tcl_ObjPrintf(
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"error reading PPM image file \"%s\": %s", fileName,
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Tcl_Eof(chan)?"not enough data":Tcl_PosixError(interp)));
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if (Tcl_Eof(chan)) {
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Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "EOF", NULL);
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}
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ckfree(pixelPtr);
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return TCL_ERROR;
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}
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if (maxIntensity < 0x00ff) {
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unsigned char *p;
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for (p = pixelPtr; count > 0; count--, p++) {
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*p = (((int) *p) * 255)/maxIntensity;
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}
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} else if (maxIntensity > 0x00ff) {
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unsigned char *p;
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unsigned int value;
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for (p = pixelPtr; count > 0; count--, p += 2) {
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value = ((unsigned int) p[0]) * 256 + ((unsigned int) p[1]);
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value = value * 255 / maxIntensity;
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p[0] = p[1] = (unsigned char) value;
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}
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}
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block.height = nLines;
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if (Tk_PhotoPutBlock(interp, imageHandle, &block, destX, destY,
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width, nLines, TK_PHOTO_COMPOSITE_SET) != TCL_OK) {
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ckfree(pixelPtr);
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return TCL_ERROR;
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}
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destY += nLines;
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}
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ckfree(pixelPtr);
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return TCL_OK;
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}
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/*
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*----------------------------------------------------------------------
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*
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* FileWritePPM --
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*
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* This function is invoked to write image data to a file in PPM format
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* (although we can read PGM files, we never write them).
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*
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* Results:
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* A standard TCL completion code. If TCL_ERROR is returned then an error
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* message is left in the interp's result.
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*
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* Side effects:
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* Data is written to the file given by "fileName".
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*
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*----------------------------------------------------------------------
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*/
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static int
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FileWritePPM(
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Tcl_Interp *interp,
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const char *fileName,
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TCL_UNUSED(Tcl_Obj *),
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Tk_PhotoImageBlock *blockPtr)
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{
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Tcl_Channel chan;
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int w, h, greenOffset, blueOffset, nBytes;
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unsigned char *pixelPtr, *pixLinePtr;
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char header[16 + TCL_INTEGER_SPACE * 2];
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chan = Tcl_OpenFileChannel(interp, fileName, "w", 0666);
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if (chan == NULL) {
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return TCL_ERROR;
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}
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if (Tcl_SetChannelOption(interp, chan, "-translation", "binary")
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!= TCL_OK) {
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Tcl_Close(NULL, chan);
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return TCL_ERROR;
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}
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if (Tcl_SetChannelOption(interp, chan, "-encoding", "binary")
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!= TCL_OK) {
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Tcl_Close(NULL, chan);
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return TCL_ERROR;
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}
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sprintf(header, "P6\n%d %d\n255\n", blockPtr->width, blockPtr->height);
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Tcl_Write(chan, header, -1);
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pixLinePtr = blockPtr->pixelPtr + blockPtr->offset[0];
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greenOffset = blockPtr->offset[1] - blockPtr->offset[0];
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blueOffset = blockPtr->offset[2] - blockPtr->offset[0];
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if ((greenOffset == 1) && (blueOffset == 2) && (blockPtr->pixelSize == 3)
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&& (blockPtr->pitch == (blockPtr->width * 3))) {
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nBytes = blockPtr->height * blockPtr->pitch;
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if (Tcl_Write(chan, (char *) pixLinePtr, nBytes) != nBytes) {
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goto writeerror;
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}
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} else {
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for (h = blockPtr->height; h > 0; h--) {
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pixelPtr = pixLinePtr;
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for (w = blockPtr->width; w > 0; w--) {
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if ( Tcl_Write(chan,(char *)&pixelPtr[0], 1) == -1 ||
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Tcl_Write(chan,(char *)&pixelPtr[greenOffset],1) == -1 ||
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Tcl_Write(chan,(char *)&pixelPtr[blueOffset],1) == -1) {
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goto writeerror;
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}
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pixelPtr += blockPtr->pixelSize;
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}
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pixLinePtr += blockPtr->pitch;
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}
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}
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if (Tcl_Close(NULL, chan) == 0) {
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return TCL_OK;
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}
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chan = NULL;
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writeerror:
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Tcl_SetObjResult(interp, Tcl_ObjPrintf("error writing \"%s\": %s",
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fileName, Tcl_PosixError(interp)));
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if (chan != NULL) {
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Tcl_Close(NULL, chan);
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}
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return TCL_ERROR;
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}
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/*
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*----------------------------------------------------------------------
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*
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* StringWritePPM --
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*
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* This function is invoked to write image data to a string in PPM
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* format.
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*
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* Results:
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* A standard TCL completion code. If TCL_ERROR is returned then an error
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* message is left in the interp's result.
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*
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* Side effects:
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* None.
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*
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*----------------------------------------------------------------------
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*/
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static int
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StringWritePPM(
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Tcl_Interp *interp,
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TCL_UNUSED(Tcl_Obj *),
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Tk_PhotoImageBlock *blockPtr)
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{
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int w, h, size, greenOffset, blueOffset;
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unsigned char *pixLinePtr, *byteArray;
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char header[16 + TCL_INTEGER_SPACE * 2];
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Tcl_Obj *byteArrayObj;
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sprintf(header, "P6\n%d %d\n255\n", blockPtr->width, blockPtr->height);
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/*
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* Construct a byte array of the right size with the header and
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* get a pointer to the data part of it.
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*/
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size = strlen(header);
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byteArrayObj = Tcl_NewByteArrayObj((unsigned char *)header, size);
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byteArray = Tcl_SetByteArrayLength(byteArrayObj,
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size + 3*blockPtr->width*blockPtr->height);
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byteArray += size;
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pixLinePtr = blockPtr->pixelPtr + blockPtr->offset[0];
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greenOffset = blockPtr->offset[1] - blockPtr->offset[0];
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blueOffset = blockPtr->offset[2] - blockPtr->offset[0];
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/*
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* Check if we can do the data move in single action.
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*/
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if ((greenOffset == 1) && (blueOffset == 2) && (blockPtr->pixelSize == 3)
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&& (blockPtr->pitch == (blockPtr->width * 3))) {
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memcpy(byteArray, pixLinePtr,
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(unsigned)blockPtr->height * blockPtr->pitch);
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} else {
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for (h = blockPtr->height; h > 0; h--) {
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unsigned char *pixelPtr = pixLinePtr;
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for (w = blockPtr->width; w > 0; w--) {
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*byteArray++ = pixelPtr[0];
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*byteArray++ = pixelPtr[greenOffset];
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*byteArray++ = pixelPtr[blueOffset];
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pixelPtr += blockPtr->pixelSize;
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}
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pixLinePtr += blockPtr->pitch;
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}
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}
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/*
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* Return the object in the interpreter result.
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*/
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Tcl_SetObjResult(interp, byteArrayObj);
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return TCL_OK;
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}
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/*
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*----------------------------------------------------------------------
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*
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* StringMatchPPM --
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*
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* This function is invoked by the photo image type to see if a string
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* contains image data in PPM format.
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*
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* Results:
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* The return value is >0 if the first characters in file "f" look like
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* PPM data, and 0 otherwise.
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*
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* Side effects:
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* The access position in f may change.
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*
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*----------------------------------------------------------------------
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*/
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static int
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StringMatchPPM(
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Tcl_Obj *dataObj, /* The image data. */
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TCL_UNUSED(Tcl_Obj *), /* User-specified format string, or NULL. */
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int *widthPtr, int *heightPtr,
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/* The dimensions of the image are returned
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* here if the file is a valid raw PPM
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* file. */
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TCL_UNUSED(Tcl_Interp *)) /* unused */
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{
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int dummy;
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return ReadPPMStringHeader(dataObj, widthPtr, heightPtr,
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&dummy, NULL, NULL);
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}
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/*
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*----------------------------------------------------------------------
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*
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* StringReadPPM --
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*
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* This function is called by the photo image type to read PPM format
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* data from a string and write it into a given photo image.
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*
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* Results:
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* A standard TCL completion code. If TCL_ERROR is returned then an error
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* message is left in the interp's result.
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*
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* Side effects:
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* New data is added to the image given by imageHandle.
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*
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*----------------------------------------------------------------------
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*/
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static int
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StringReadPPM(
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Tcl_Interp *interp, /* Interpreter to use for reporting errors. */
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Tcl_Obj *dataObj, /* The image data. */
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TCL_UNUSED(Tcl_Obj *), /* User-specified format string, or NULL. */
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Tk_PhotoHandle imageHandle, /* The photo image to write into. */
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int destX, int destY, /* Coordinates of top-left pixel in photo
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* image to be written to. */
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int width, int height, /* Dimensions of block of photo image to be
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* written to. */
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int srcX, int srcY) /* Coordinates of top-left pixel to be used in
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* image being read. */
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{
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int fileWidth, fileHeight, maxIntensity;
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int nLines, nBytes, h, type, count, dataSize, bytesPerChannel = 1;
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unsigned char *pixelPtr, *dataBuffer;
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Tk_PhotoImageBlock block;
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type = ReadPPMStringHeader(dataObj, &fileWidth, &fileHeight,
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&maxIntensity, &dataBuffer, &dataSize);
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if (type == 0) {
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Tcl_SetObjResult(interp, Tcl_NewStringObj(
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"couldn't read raw PPM header from string", -1));
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Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "NO_HEADER", NULL);
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return TCL_ERROR;
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}
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if ((fileWidth <= 0) || (fileHeight <= 0)) {
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Tcl_SetObjResult(interp, Tcl_NewStringObj(
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"PPM image data has dimension(s) <= 0", -1));
|
||
Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "DIMENSIONS", NULL);
|
||
return TCL_ERROR;
|
||
}
|
||
if ((maxIntensity <= 0) || (maxIntensity > 0xffff)) {
|
||
Tcl_SetObjResult(interp, Tcl_ObjPrintf(
|
||
"PPM image data has bad maximum intensity value %d",
|
||
maxIntensity));
|
||
Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "INTENSITY", NULL);
|
||
return TCL_ERROR;
|
||
} else if (maxIntensity > 0x00ff) {
|
||
bytesPerChannel = 2;
|
||
}
|
||
|
||
if ((srcX + width) > fileWidth) {
|
||
width = fileWidth - srcX;
|
||
}
|
||
if ((srcY + height) > fileHeight) {
|
||
height = fileHeight - srcY;
|
||
}
|
||
if ((width <= 0) || (height <= 0)
|
||
|| (srcX >= fileWidth) || (srcY >= fileHeight)) {
|
||
return TCL_OK;
|
||
}
|
||
|
||
if (type == PGM) {
|
||
block.pixelSize = 1 * bytesPerChannel;
|
||
block.offset[0] = 0;
|
||
block.offset[1] = 0;
|
||
block.offset[2] = 0;
|
||
} else {
|
||
block.pixelSize = 3 * bytesPerChannel;
|
||
block.offset[0] = 0;
|
||
block.offset[1] = 1 * bytesPerChannel;
|
||
block.offset[2] = 2 * bytesPerChannel;
|
||
}
|
||
block.offset[3] = 0;
|
||
block.width = width;
|
||
block.pitch = block.pixelSize * fileWidth;
|
||
|
||
if (srcY > 0) {
|
||
dataBuffer += srcY * block.pitch;
|
||
dataSize -= srcY * block.pitch;
|
||
}
|
||
|
||
if (maxIntensity == 0x00ff) {
|
||
/*
|
||
* We have all the data in memory, so write everything in one go.
|
||
*/
|
||
|
||
if (block.pitch*height > dataSize) {
|
||
Tcl_SetObjResult(interp, Tcl_NewStringObj(
|
||
"truncated PPM data", -1));
|
||
Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "TRUNCATED", NULL);
|
||
return TCL_ERROR;
|
||
}
|
||
block.pixelPtr = dataBuffer + srcX * block.pixelSize;
|
||
block.height = height;
|
||
return Tk_PhotoPutBlock(interp, imageHandle, &block, destX, destY,
|
||
width, height, TK_PHOTO_COMPOSITE_SET);
|
||
}
|
||
|
||
if (Tk_PhotoExpand(interp, imageHandle,
|
||
destX + width, destY + height) != TCL_OK) {
|
||
return TCL_ERROR;
|
||
}
|
||
|
||
nLines = (MAX_MEMORY + block.pitch - 1) / block.pitch;
|
||
if (nLines > height) {
|
||
nLines = height;
|
||
}
|
||
if (nLines <= 0) {
|
||
nLines = 1;
|
||
}
|
||
nBytes = nLines * block.pitch;
|
||
pixelPtr = (unsigned char *)ckalloc(nBytes);
|
||
block.pixelPtr = pixelPtr + srcX * block.pixelSize;
|
||
|
||
for (h = height; h > 0; h -= nLines) {
|
||
unsigned char *p;
|
||
|
||
if (nLines > h) {
|
||
nLines = h;
|
||
nBytes = nLines * block.pitch;
|
||
}
|
||
if (dataSize < nBytes) {
|
||
ckfree(pixelPtr);
|
||
Tcl_SetObjResult(interp, Tcl_NewStringObj(
|
||
"truncated PPM data", -1));
|
||
Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "TRUNCATED", NULL);
|
||
return TCL_ERROR;
|
||
}
|
||
if (maxIntensity < 0x00ff) {
|
||
for (p=pixelPtr,count=nBytes ; count>0 ; count--,p++,dataBuffer++) {
|
||
*p = (((int) *dataBuffer) * 255)/maxIntensity;
|
||
}
|
||
} else {
|
||
unsigned int value;
|
||
|
||
for (p = pixelPtr,count=nBytes; count > 1; count-=2, p += 2) {
|
||
value = ((unsigned int) p[0]) * 256 + ((unsigned int) p[1]);
|
||
value = value * 255 / maxIntensity;
|
||
p[0] = p[1] = (unsigned char) value;
|
||
}
|
||
}
|
||
dataSize -= nBytes;
|
||
block.height = nLines;
|
||
if (Tk_PhotoPutBlock(interp, imageHandle, &block, destX, destY,
|
||
width, nLines, TK_PHOTO_COMPOSITE_SET) != TCL_OK) {
|
||
ckfree(pixelPtr);
|
||
return TCL_ERROR;
|
||
}
|
||
destY += nLines;
|
||
}
|
||
|
||
ckfree(pixelPtr);
|
||
return TCL_OK;
|
||
}
|
||
|
||
/*
|
||
*----------------------------------------------------------------------
|
||
*
|
||
* ReadPPMFileHeader --
|
||
*
|
||
* This function reads the PPM header from the beginning of a PPM file
|
||
* and returns information from the header.
|
||
*
|
||
* Results:
|
||
* The return value is PGM if file "f" appears to start with a valid PGM
|
||
* header, PPM if "f" appears to start with a valid PPM header, and 0
|
||
* otherwise. If the header is valid, then *widthPtr and *heightPtr are
|
||
* modified to hold the dimensions of the image and *maxIntensityPtr is
|
||
* modified to hold the value of a "fully on" intensity value.
|
||
*
|
||
* Side effects:
|
||
* The access position in f advances.
|
||
*
|
||
*----------------------------------------------------------------------
|
||
*/
|
||
|
||
static int
|
||
ReadPPMFileHeader(
|
||
Tcl_Channel chan, /* Image file to read the header from. */
|
||
int *widthPtr, int *heightPtr,
|
||
/* The dimensions of the image are returned
|
||
* here. */
|
||
int *maxIntensityPtr) /* The maximum intensity value for the image
|
||
* is stored here. */
|
||
{
|
||
#define BUFFER_SIZE 1000
|
||
char buffer[BUFFER_SIZE], c;
|
||
int i, numFields, type = 0;
|
||
|
||
/*
|
||
* Read 4 space-separated fields from the file, ignoring comments (any
|
||
* line that starts with "#").
|
||
*/
|
||
|
||
if (Tcl_Read(chan, &c, 1) != 1) {
|
||
return 0;
|
||
}
|
||
i = 0;
|
||
for (numFields = 0; numFields < 4; numFields++) {
|
||
/*
|
||
* Skip comments and white space.
|
||
*/
|
||
|
||
while (1) {
|
||
while (isspace(UCHAR(c))) {
|
||
if (Tcl_Read(chan, &c, 1) != 1) {
|
||
return 0;
|
||
}
|
||
}
|
||
if (c != '#') {
|
||
break;
|
||
}
|
||
do {
|
||
if (Tcl_Read(chan, &c, 1) != 1) {
|
||
return 0;
|
||
}
|
||
} while (c != '\n');
|
||
}
|
||
|
||
/*
|
||
* Read a field (everything up to the next white space).
|
||
*/
|
||
|
||
while (!isspace(UCHAR(c))) {
|
||
if (i < (BUFFER_SIZE-2)) {
|
||
buffer[i] = c;
|
||
i++;
|
||
}
|
||
if (Tcl_Read(chan, &c, 1) != 1) {
|
||
goto done;
|
||
}
|
||
}
|
||
if (i < (BUFFER_SIZE-1)) {
|
||
buffer[i] = ' ';
|
||
i++;
|
||
}
|
||
}
|
||
|
||
done:
|
||
buffer[i] = 0;
|
||
|
||
/*
|
||
* Parse the fields, which are: id, width, height, maxIntensity.
|
||
*/
|
||
|
||
if (strncmp(buffer, "P6 ", 3) == 0) {
|
||
type = PPM;
|
||
} else if (strncmp(buffer, "P5 ", 3) == 0) {
|
||
type = PGM;
|
||
} else {
|
||
return 0;
|
||
}
|
||
if (sscanf(buffer+3, "%d %d %d", widthPtr, heightPtr, maxIntensityPtr)
|
||
!= 3) {
|
||
return 0;
|
||
}
|
||
return type;
|
||
}
|
||
|
||
/*
|
||
*----------------------------------------------------------------------
|
||
*
|
||
* ReadPPMStringHeader --
|
||
*
|
||
* This function reads the PPM header from the beginning of a PPM-format
|
||
* string and returns information from the header.
|
||
*
|
||
* Results:
|
||
* The return value is PGM if the string appears to start with a valid
|
||
* PGM header, PPM if the string appears to start with a valid PPM
|
||
* header, and 0 otherwise. If the header is valid, then *widthPtr and
|
||
* *heightPtr are modified to hold the dimensions of the image and
|
||
* *maxIntensityPtr is modified to hold the value of a "fully on"
|
||
* intensity value.
|
||
*
|
||
* Side effects:
|
||
* None
|
||
*
|
||
*----------------------------------------------------------------------
|
||
*/
|
||
|
||
static int
|
||
ReadPPMStringHeader(
|
||
Tcl_Obj *dataPtr, /* Object to read the header from. */
|
||
int *widthPtr, int *heightPtr,
|
||
/* The dimensions of the image are returned
|
||
* here. */
|
||
int *maxIntensityPtr, /* The maximum intensity value for the image
|
||
* is stored here. */
|
||
unsigned char **dataBufferPtr,
|
||
int *dataSizePtr)
|
||
{
|
||
#define BUFFER_SIZE 1000
|
||
char buffer[BUFFER_SIZE], c;
|
||
int i, numFields, dataSize, type = 0;
|
||
unsigned char *dataBuffer;
|
||
|
||
dataBuffer = Tcl_GetByteArrayFromObj(dataPtr, &dataSize);
|
||
|
||
/*
|
||
* Read 4 space-separated fields from the string, ignoring comments (any
|
||
* line that starts with "#").
|
||
*/
|
||
|
||
if (dataSize-- < 1) {
|
||
return 0;
|
||
}
|
||
c = (char) (*dataBuffer++);
|
||
i = 0;
|
||
for (numFields = 0; numFields < 4; numFields++) {
|
||
/*
|
||
* Skip comments and white space.
|
||
*/
|
||
|
||
while (1) {
|
||
while (isspace(UCHAR(c))) {
|
||
if (dataSize-- < 1) {
|
||
return 0;
|
||
}
|
||
c = (char) (*dataBuffer++);
|
||
}
|
||
if (c != '#') {
|
||
break;
|
||
}
|
||
do {
|
||
if (dataSize-- < 1) {
|
||
return 0;
|
||
}
|
||
c = (char) (*dataBuffer++);
|
||
} while (c != '\n');
|
||
}
|
||
|
||
/*
|
||
* Read a field (everything up to the next white space).
|
||
*/
|
||
|
||
while (!isspace(UCHAR(c))) {
|
||
if (i < (BUFFER_SIZE-2)) {
|
||
buffer[i] = c;
|
||
i++;
|
||
}
|
||
if (dataSize-- < 1) {
|
||
goto done;
|
||
}
|
||
c = (char) (*dataBuffer++);
|
||
}
|
||
if (i < (BUFFER_SIZE-1)) {
|
||
buffer[i] = ' ';
|
||
i++;
|
||
}
|
||
}
|
||
|
||
done:
|
||
buffer[i] = 0;
|
||
|
||
/*
|
||
* Parse the fields, which are: id, width, height, maxIntensity.
|
||
*/
|
||
|
||
if (strncmp(buffer, "P6 ", 3) == 0) {
|
||
type = PPM;
|
||
} else if (strncmp(buffer, "P5 ", 3) == 0) {
|
||
type = PGM;
|
||
} else {
|
||
return 0;
|
||
}
|
||
if (sscanf(buffer+3, "%d %d %d", widthPtr, heightPtr, maxIntensityPtr)
|
||
!= 3) {
|
||
return 0;
|
||
}
|
||
if (dataBufferPtr != NULL) {
|
||
*dataBufferPtr = dataBuffer;
|
||
*dataSizePtr = dataSize;
|
||
}
|
||
return type;
|
||
}
|
||
|
||
/*
|
||
* Local Variables:
|
||
* mode: c
|
||
* c-basic-offset: 4
|
||
* fill-column: 78
|
||
* End:
|
||
*/
|