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-rw-r--r--tk8.6/generic/tkImgPPM.c854
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diff --git a/tk8.6/generic/tkImgPPM.c b/tk8.6/generic/tkImgPPM.c
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+++ b/tk8.6/generic/tkImgPPM.c
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+/*
+ * tkImgPPM.c --
+ *
+ * A photo image file handler for PPM (Portable PixMap) files.
+ *
+ * Copyright (c) 1994 The Australian National University.
+ * Copyright (c) 1994-1997 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.
+ */
+
+#include "tkInt.h"
+
+/*
+ * The maximum amount of memory to allocate for data read from the file. If we
+ * need more than this, we do it in pieces.
+ */
+
+#define MAX_MEMORY 10000 /* don't allocate > 10KB */
+
+/*
+ * Define PGM and PPM, i.e. gray images and color images.
+ */
+
+#define PGM 1
+#define PPM 2
+
+/*
+ * The format record for the PPM file format:
+ */
+
+static int FileMatchPPM(Tcl_Channel chan, const char *fileName,
+ Tcl_Obj *format, int *widthPtr, int *heightPtr,
+ Tcl_Interp *interp);
+static int FileReadPPM(Tcl_Interp *interp, Tcl_Channel chan,
+ const char *fileName, Tcl_Obj *format,
+ Tk_PhotoHandle imageHandle, int destX, int destY,
+ int width, int height, int srcX, int srcY);
+static int FileWritePPM(Tcl_Interp *interp, const char *fileName,
+ Tcl_Obj *format, Tk_PhotoImageBlock *blockPtr);
+static int StringWritePPM(Tcl_Interp *interp, Tcl_Obj *format,
+ Tk_PhotoImageBlock *blockPtr);
+static int StringMatchPPM(Tcl_Obj *dataObj, Tcl_Obj *format,
+ int *widthPtr, int *heightPtr, Tcl_Interp *interp);
+static int StringReadPPM(Tcl_Interp *interp, Tcl_Obj *dataObj,
+ Tcl_Obj *format, Tk_PhotoHandle imageHandle,
+ int destX, int destY, int width, int height,
+ int srcX, int srcY);
+
+Tk_PhotoImageFormat tkImgFmtPPM = {
+ "ppm", /* name */
+ FileMatchPPM, /* fileMatchProc */
+ StringMatchPPM, /* stringMatchProc */
+ FileReadPPM, /* fileReadProc */
+ StringReadPPM, /* stringReadProc */
+ FileWritePPM, /* fileWriteProc */
+ StringWritePPM, /* stringWriteProc */
+ NULL
+};
+
+/*
+ * Prototypes for local functions defined in this file:
+ */
+
+static int ReadPPMFileHeader(Tcl_Channel chan, int *widthPtr,
+ int *heightPtr, int *maxIntensityPtr);
+static int ReadPPMStringHeader(Tcl_Obj *dataObj, int *widthPtr,
+ int *heightPtr, int *maxIntensityPtr,
+ unsigned char **dataBufferPtr, int *dataSizePtr);
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileMatchPPM --
+ *
+ * This function is invoked by the photo image type to see if a file
+ * contains image data in PPM format.
+ *
+ * Results:
+ * The return value is >0 if the first characters in file "f" look like
+ * PPM data, and 0 otherwise.
+ *
+ * Side effects:
+ * The access position in f may change.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+FileMatchPPM(
+ Tcl_Channel chan, /* The image file, open for reading. */
+ const char *fileName, /* The name of the image file. */
+ Tcl_Obj *format, /* User-specified format string, or NULL. */
+ int *widthPtr, int *heightPtr,
+ /* The dimensions of the image are returned
+ * here if the file is a valid raw PPM
+ * file. */
+ Tcl_Interp *interp) /* unused */
+{
+ int dummy;
+
+ return ReadPPMFileHeader(chan, widthPtr, heightPtr, &dummy);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileReadPPM --
+ *
+ * This function is called by the photo image type to read PPM format
+ * data from a file and write it into a given photo image.
+ *
+ * Results:
+ * A standard TCL completion code. If TCL_ERROR is returned then an error
+ * message is left in the interp's result.
+ *
+ * Side effects:
+ * The access position in file f is changed, and new data is added to the
+ * image given by imageHandle.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+FileReadPPM(
+ Tcl_Interp *interp, /* Interpreter to use for reporting errors. */
+ Tcl_Channel chan, /* The image file, open for reading. */
+ const char *fileName, /* The name of the image file. */
+ Tcl_Obj *format, /* User-specified format string, or NULL. */
+ Tk_PhotoHandle imageHandle, /* The photo image to write into. */
+ int destX, int destY, /* Coordinates of top-left pixel in photo
+ * image to be written to. */
+ int width, int height, /* Dimensions of block of photo image to be
+ * written to. */
+ int srcX, int srcY) /* Coordinates of top-left pixel to be used in
+ * image being read. */
+{
+ int fileWidth, fileHeight, maxIntensity;
+ int nLines, nBytes, h, type, count, bytesPerChannel = 1;
+ unsigned char *pixelPtr;
+ Tk_PhotoImageBlock block;
+
+ type = ReadPPMFileHeader(chan, &fileWidth, &fileHeight, &maxIntensity);
+ if (type == 0) {
+ Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+ "couldn't read raw PPM header from file \"%s\"", fileName));
+ Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "NO_HEADER", NULL);
+ return TCL_ERROR;
+ }
+ if ((fileWidth <= 0) || (fileHeight <= 0)) {
+ Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+ "PPM image file \"%s\" has dimension(s) <= 0", fileName));
+ Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "DIMENSIONS", NULL);
+ return TCL_ERROR;
+ }
+ if ((maxIntensity <= 0) || (maxIntensity > 0xffff)) {
+ Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+ "PPM image file \"%s\" has bad maximum intensity value %d",
+ fileName, 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 (Tk_PhotoExpand(interp, imageHandle,
+ destX + width, destY + height) != TCL_OK) {
+ return TCL_ERROR;
+ }
+
+ if (srcY > 0) {
+ Tcl_Seek(chan, (Tcl_WideInt)(srcY * block.pitch), SEEK_CUR);
+ }
+
+ nLines = (MAX_MEMORY + block.pitch - 1) / block.pitch;
+ if (nLines > height) {
+ nLines = height;
+ }
+ if (nLines <= 0) {
+ nLines = 1;
+ }
+ nBytes = nLines * block.pitch;
+ pixelPtr = ckalloc(nBytes);
+ block.pixelPtr = pixelPtr + srcX * block.pixelSize;
+
+ for (h = height; h > 0; h -= nLines) {
+ if (nLines > h) {
+ nLines = h;
+ nBytes = nLines * block.pitch;
+ }
+ count = Tcl_Read(chan, (char *) pixelPtr, nBytes);
+ if (count != nBytes) {
+ Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+ "error reading PPM image file \"%s\": %s", fileName,
+ Tcl_Eof(chan)?"not enough data":Tcl_PosixError(interp)));
+ if (Tcl_Eof(chan)) {
+ Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "EOF", NULL);
+ }
+ ckfree(pixelPtr);
+ return TCL_ERROR;
+ }
+ if (maxIntensity < 0x00ff) {
+ unsigned char *p;
+
+ for (p = pixelPtr; count > 0; count--, p++) {
+ *p = (((int) *p) * 255)/maxIntensity;
+ }
+ } else if (maxIntensity > 0x00ff) {
+ unsigned char *p;
+ unsigned int value;
+
+ for (p = pixelPtr; count > 0; count--, p += 2) {
+ value = ((unsigned int) p[0]) * 256 + ((unsigned int) p[1]);
+ value = value * 255 / maxIntensity;
+ p[0] = p[1] = (unsigned char) value;
+ }
+ }
+ 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;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileWritePPM --
+ *
+ * This function is invoked to write image data to a file in PPM format
+ * (although we can read PGM files, we never write them).
+ *
+ * Results:
+ * A standard TCL completion code. If TCL_ERROR is returned then an error
+ * message is left in the interp's result.
+ *
+ * Side effects:
+ * Data is written to the file given by "fileName".
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+FileWritePPM(
+ Tcl_Interp *interp,
+ const char *fileName,
+ Tcl_Obj *format,
+ Tk_PhotoImageBlock *blockPtr)
+{
+ Tcl_Channel chan;
+ int w, h, greenOffset, blueOffset, nBytes;
+ unsigned char *pixelPtr, *pixLinePtr;
+ char header[16 + TCL_INTEGER_SPACE * 2];
+
+ chan = Tcl_OpenFileChannel(interp, fileName, "w", 0666);
+ if (chan == NULL) {
+ return TCL_ERROR;
+ }
+
+ if (Tcl_SetChannelOption(interp, chan, "-translation", "binary")
+ != TCL_OK) {
+ Tcl_Close(NULL, chan);
+ return TCL_ERROR;
+ }
+ if (Tcl_SetChannelOption(interp, chan, "-encoding", "binary")
+ != TCL_OK) {
+ Tcl_Close(NULL, chan);
+ return TCL_ERROR;
+ }
+
+ sprintf(header, "P6\n%d %d\n255\n", blockPtr->width, blockPtr->height);
+ Tcl_Write(chan, header, -1);
+
+ pixLinePtr = blockPtr->pixelPtr + blockPtr->offset[0];
+ greenOffset = blockPtr->offset[1] - blockPtr->offset[0];
+ blueOffset = blockPtr->offset[2] - blockPtr->offset[0];
+
+ if ((greenOffset == 1) && (blueOffset == 2) && (blockPtr->pixelSize == 3)
+ && (blockPtr->pitch == (blockPtr->width * 3))) {
+ nBytes = blockPtr->height * blockPtr->pitch;
+ if (Tcl_Write(chan, (char *) pixLinePtr, nBytes) != nBytes) {
+ goto writeerror;
+ }
+ } else {
+ for (h = blockPtr->height; h > 0; h--) {
+ pixelPtr = pixLinePtr;
+ for (w = blockPtr->width; w > 0; w--) {
+ if ( Tcl_Write(chan,(char *)&pixelPtr[0], 1) == -1 ||
+ Tcl_Write(chan,(char *)&pixelPtr[greenOffset],1)==-1 ||
+ Tcl_Write(chan,(char *)&pixelPtr[blueOffset],1) ==-1) {
+ goto writeerror;
+ }
+ pixelPtr += blockPtr->pixelSize;
+ }
+ pixLinePtr += blockPtr->pitch;
+ }
+ }
+
+ if (Tcl_Close(NULL, chan) == 0) {
+ return TCL_OK;
+ }
+ chan = NULL;
+
+ writeerror:
+ Tcl_SetObjResult(interp, Tcl_ObjPrintf("error writing \"%s\": %s",
+ fileName, Tcl_PosixError(interp)));
+ if (chan != NULL) {
+ Tcl_Close(NULL, chan);
+ }
+ return TCL_ERROR;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * StringWritePPM --
+ *
+ * This function is invoked to write image data to a string in PPM
+ * format.
+ *
+ * Results:
+ * A standard TCL completion code. If TCL_ERROR is returned then an error
+ * message is left in the interp's result.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+StringWritePPM(
+ Tcl_Interp *interp,
+ Tcl_Obj *format,
+ Tk_PhotoImageBlock *blockPtr)
+{
+ int w, h, size, greenOffset, blueOffset;
+ unsigned char *pixLinePtr, *byteArray;
+ char header[16 + TCL_INTEGER_SPACE * 2];
+ Tcl_Obj *byteArrayObj;
+
+ sprintf(header, "P6\n%d %d\n255\n", blockPtr->width, blockPtr->height);
+
+ /*
+ * Construct a byte array of the right size with the header and
+ * get a pointer to the data part of it.
+ */
+
+ size = strlen(header);
+ byteArrayObj = Tcl_NewByteArrayObj((unsigned char *)header, size);
+ byteArray = Tcl_SetByteArrayLength(byteArrayObj,
+ size + 3*blockPtr->width*blockPtr->height);
+ byteArray += size;
+
+ pixLinePtr = blockPtr->pixelPtr + blockPtr->offset[0];
+ greenOffset = blockPtr->offset[1] - blockPtr->offset[0];
+ blueOffset = blockPtr->offset[2] - blockPtr->offset[0];
+
+ /*
+ * Check if we can do the data move in single action.
+ */
+
+ if ((greenOffset == 1) && (blueOffset == 2) && (blockPtr->pixelSize == 3)
+ && (blockPtr->pitch == (blockPtr->width * 3))) {
+ memcpy(byteArray, pixLinePtr,
+ (unsigned)blockPtr->height * blockPtr->pitch);
+ } else {
+ for (h = blockPtr->height; h > 0; h--) {
+ unsigned char *pixelPtr = pixLinePtr;
+
+ for (w = blockPtr->width; w > 0; w--) {
+ *byteArray++ = pixelPtr[0];
+ *byteArray++ = pixelPtr[greenOffset];
+ *byteArray++ = pixelPtr[blueOffset];
+ pixelPtr += blockPtr->pixelSize;
+ }
+ pixLinePtr += blockPtr->pitch;
+ }
+ }
+
+ /*
+ * Return the object in the interpreter result.
+ */
+
+ Tcl_SetObjResult(interp, byteArrayObj);
+ return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * StringMatchPPM --
+ *
+ * This function is invoked by the photo image type to see if a string
+ * contains image data in PPM format.
+ *
+ * Results:
+ * The return value is >0 if the first characters in file "f" look like
+ * PPM data, and 0 otherwise.
+ *
+ * Side effects:
+ * The access position in f may change.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+StringMatchPPM(
+ Tcl_Obj *dataObj, /* The image data. */
+ Tcl_Obj *format, /* User-specified format string, or NULL. */
+ int *widthPtr, int *heightPtr,
+ /* The dimensions of the image are returned
+ * here if the file is a valid raw PPM
+ * file. */
+ Tcl_Interp *interp) /* unused */
+{
+ int dummy;
+
+ return ReadPPMStringHeader(dataObj, widthPtr, heightPtr,
+ &dummy, NULL, NULL);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * StringReadPPM --
+ *
+ * This function is called by the photo image type to read PPM format
+ * data from a string and write it into a given photo image.
+ *
+ * Results:
+ * A standard TCL completion code. If TCL_ERROR is returned then an error
+ * message is left in the interp's result.
+ *
+ * Side effects:
+ * New data is added to the image given by imageHandle.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+StringReadPPM(
+ Tcl_Interp *interp, /* Interpreter to use for reporting errors. */
+ Tcl_Obj *dataObj, /* The image data. */
+ Tcl_Obj *format, /* User-specified format string, or NULL. */
+ Tk_PhotoHandle imageHandle, /* The photo image to write into. */
+ int destX, int destY, /* Coordinates of top-left pixel in photo
+ * image to be written to. */
+ int width, int height, /* Dimensions of block of photo image to be
+ * written to. */
+ int srcX, int srcY) /* Coordinates of top-left pixel to be used in
+ * image being read. */
+{
+ int fileWidth, fileHeight, maxIntensity;
+ int nLines, nBytes, h, type, count, dataSize, bytesPerChannel = 1;
+ unsigned char *pixelPtr, *dataBuffer;
+ Tk_PhotoImageBlock block;
+
+ type = ReadPPMStringHeader(dataObj, &fileWidth, &fileHeight,
+ &maxIntensity, &dataBuffer, &dataSize);
+ if (type == 0) {
+ Tcl_SetObjResult(interp, Tcl_NewStringObj(
+ "couldn't read raw PPM header from string", -1));
+ Tcl_SetErrorCode(interp, "TK", "IMAGE", "PPM", "NO_HEADER", NULL);
+ return TCL_ERROR;
+ }
+ if ((fileWidth <= 0) || (fileHeight <= 0)) {
+ Tcl_SetObjResult(interp, Tcl_NewStringObj(
+ "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 = 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 char *p;
+ 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:
+ */
generated by cgit v0.12 at 2024-08-29 21:44:22 (GMT)