Allow PPMs to be read from a string. [FRQ 540375]

2 files changed, 327 insertions, 8 deletions

diff --git a/ChangeLog b/ChangeLog
index fd8993b..fc5539e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2004-03-26  Donal K. Fellows  <donal.k.fellows@man.ac.uk>
+
+	* generic/tkImgPPM.c (ReadPPMStringHeader): Code to read PPM/PGM data
+	(StringReadPPM, StringMatchPPM): from strings/bytearrays. [FRQ 540375]
+
 2004-03-26  Don Porter  <dgp@users.sourceforge.net>
 
 	* unix/tcl.m4:	Replaced -Wno-strict-alias with more portable
diff --git a/generic/tkImgPPM.c b/generic/tkImgPPM.c
index 1f3585e..ac989db 100644
--- a/generic/tkImgPPM.c
+++ b/generic/tkImgPPM.c
@@ -13,7 +13,7 @@
  *	   Department of Computer Science,
  *	   Australian National University.
  *
- * RCS: @(#) $Id: tkImgPPM.c,v 1.13 2004/03/26 19:49:40 dgp Exp $
+ * RCS: @(#) $Id: tkImgPPM.c,v 1.14 2004/03/27 00:12:22 dkf Exp $
  */
 
 #include "tkInt.h"
@@ -51,13 +51,21 @@ static int		FileWritePPM _ANSI_ARGS_((Tcl_Interp *interp,
 			    Tk_PhotoImageBlock *blockPtr));
 static int		StringWritePPM _ANSI_ARGS_((Tcl_Interp *interp,
 			    Tcl_Obj *format, Tk_PhotoImageBlock *blockPtr));
+static int		StringMatchPPM _ANSI_ARGS_((Tcl_Obj *dataObj,
+			    Tcl_Obj *format, int *widthPtr, int *heightPtr,
+			    Tcl_Interp *interp));
+static int		StringReadPPM _ANSI_ARGS_((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 */
-    NULL,			/* stringMatchProc */
+    StringMatchPPM,		/* stringMatchProc */
     FileReadPPM,		/* fileReadProc */
-    NULL,			/* stringReadProc */
+    StringReadPPM,		/* stringReadProc */
     FileWritePPM,		/* fileWriteProc */
     StringWritePPM,		/* stringWriteProc */
 };
@@ -69,6 +77,10 @@ Tk_PhotoImageFormat tkImgFmtPPM = {
 static int		ReadPPMFileHeader _ANSI_ARGS_((Tcl_Channel chan,
 			    int *widthPtr, int *heightPtr,
 			    int *maxIntensityPtr));
+static int		ReadPPMStringHeader _ANSI_ARGS_((Tcl_Obj *dataObj,
+			    int *widthPtr, int *heightPtr,
+			    int *maxIntensityPtr,
+			    unsigned char **dataBufferPtr, int *dataSizePtr));
 
 /*
  *----------------------------------------------------------------------
@@ -151,7 +163,7 @@ FileReadPPM(interp, chan, fileName, format, imageHandle, destX, destY,
     }
     if ((fileWidth <= 0) || (fileHeight <= 0)) {
 	Tcl_AppendResult(interp, "PPM image file \"", fileName,
-		"\" has dimension(s) <= 0", (char *) NULL);
+		"\" has dimension(s) <= 0", NULL);
 	return TCL_ERROR;
     }
     if ((maxIntensity <= 0) || (maxIntensity >= 256)) {
@@ -159,8 +171,7 @@ FileReadPPM(interp, chan, fileName, format, imageHandle, destX, destY,
 
 	sprintf(buffer, "%d", maxIntensity);
 	Tcl_AppendResult(interp, "PPM image file \"", fileName,
-		"\" has bad maximum intensity value ", buffer,
-		(char *) NULL);
+		"\" has bad maximum intensity value ", buffer, NULL);
 	return TCL_ERROR;
     }
 
@@ -221,7 +232,7 @@ FileReadPPM(interp, chan, fileName, format, imageHandle, destX, destY,
 	    Tcl_AppendResult(interp, "error reading PPM image file \"",
 		    fileName, "\": ",
 		    Tcl_Eof(chan) ? "not enough data" : Tcl_PosixError(interp),
-		    (char *) NULL);
+		    NULL);
 	    ckfree((char *) pixelPtr);
 	    return TCL_ERROR;
 	}
@@ -327,7 +338,7 @@ FileWritePPM(interp, fileName, format, blockPtr)
 
  writeerror:
     Tcl_AppendResult(interp, "error writing \"", fileName, "\": ",
-	    Tcl_PosixError(interp), (char *) NULL);
+	    Tcl_PosixError(interp), NULL);
     if (chan != NULL) {
 	Tcl_Close(NULL, chan);
     }
@@ -409,6 +420,190 @@ StringWritePPM(interp, format, blockPtr)
 /*
  *----------------------------------------------------------------------
  *
+ * StringMatchPPM --
+ *
+ *	This procedure 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(dataObj, format, widthPtr, heightPtr, interp)
+    Tcl_Obj *dataObj;		/* The image data. */
+    Tcl_Obj *format;		/* User-specified format string, or NULL. */
+    int *widthPtr, *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 procedure 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(interp, dataObj, format, imageHandle, destX, destY,
+	width, height, srcX, srcY)
+    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, destY;		/* Coordinates of top-left pixel in
+				 * photo image to be written to. */
+    int width, height;		/* Dimensions of block of photo image to
+				 * be written to. */
+    int srcX, srcY;		/* Coordinates of top-left pixel to be used
+				 * in image being read. */
+{
+    int fileWidth, fileHeight, maxIntensity;
+    int nLines, nBytes, h, type, count, dataSize;
+    unsigned char *pixelPtr, *dataBuffer;
+    Tk_PhotoImageBlock block;
+
+    type = ReadPPMStringHeader(dataObj, &fileWidth, &fileHeight,
+	    &maxIntensity, &dataBuffer, &dataSize);
+    if (type == 0) {
+	Tcl_AppendResult(interp, "couldn't read raw PPM header from string",
+		NULL);
+	return TCL_ERROR;
+    }
+    if ((fileWidth <= 0) || (fileHeight <= 0)) {
+	Tcl_AppendResult(interp, "PPM image data has dimension(s) <= 0",
+		NULL);
+	return TCL_ERROR;
+    }
+    if ((maxIntensity <= 0) || (maxIntensity >= 256)) {
+	char buffer[TCL_INTEGER_SPACE];
+
+	sprintf(buffer, "%d", maxIntensity);
+	Tcl_AppendResult(interp,
+		"PPM image data has bad maximum intensity value ", buffer,
+		NULL);
+	return TCL_ERROR;
+    }
+
+    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;
+        block.offset[0] = 0;
+	block.offset[1] = 0;
+	block.offset[2] = 0;
+    } else {
+        block.pixelSize = 3;
+        block.offset[0] = 0;
+	block.offset[1] = 1;
+	block.offset[2] = 2;
+    }
+    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 == 255) {
+	/*
+	 * We have all the data in memory, so write everything in one
+	 * go.
+	 */
+	if (block.pitch*height < dataSize) {
+	    Tcl_AppendResult(interp, "truncated PPM data", 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((unsigned) 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((char *) pixelPtr);
+	    Tcl_AppendResult(interp, "truncated PPM data", NULL);
+	    return TCL_ERROR;
+	}
+	for (p=pixelPtr,count=nBytes ; count>0 ; count--,p++,dataBuffer++) {
+	    *p = (((int) *dataBuffer) * 255)/maxIntensity;
+	}
+	dataSize -= nBytes;
+	block.height = nLines;
+	if (Tk_PhotoPutBlock(interp, imageHandle, &block, destX, destY,
+		width, nLines, TK_PHOTO_COMPOSITE_SET) != TCL_OK) {
+	    ckfree((char *) pixelPtr);
+	    return TCL_ERROR;
+	}
+	destY += nLines;
+    }
+
+    ckfree((char *) pixelPtr);
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * ReadPPMFileHeader --
  *
  *	This procedure reads the PPM header from the beginning of a
@@ -510,3 +705,122 @@ ReadPPMFileHeader(chan, widthPtr, heightPtr, maxIntensityPtr)
     }
     return type;
 }
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ReadPPMStringHeader --
+ *
+ *	This procedure 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(dataPtr, widthPtr, heightPtr, maxIntensityPtr,
+	dataBufferPtr, dataSizePtr)
+    Tcl_Obj *dataPtr;		/* Object to read the header from. */
+    int *widthPtr, *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];
+    int i, numFields, dataSize;
+    int type = 0;
+    char c;
+    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;
+}