diff options
Diffstat (limited to 'generic/tkImgGIF.c')
| -rw-r--r-- | generic/tkImgGIF.c | 50 |
1 files changed, 34 insertions, 16 deletions
diff --git a/generic/tkImgGIF.c b/generic/tkImgGIF.c index b6fec53..f1fc25a 100644 --- a/generic/tkImgGIF.c +++ b/generic/tkImgGIF.c @@ -29,7 +29,7 @@ * | provided "as is" without express or implied warranty. | * +-------------------------------------------------------------------+ * - * RCS: @(#) $Id: tkImgGIF.c,v 1.12 2000/02/10 08:52:33 hobbs Exp $ + * RCS: @(#) $Id: tkImgGIF.c,v 1.13 2000/02/26 00:51:17 ericm Exp $ */ /* @@ -63,6 +63,22 @@ typedef struct mFile { #include "tkPort.h" /* + * Non-ASCII encoding support: + * Most data in a GIF image is binary and is treated as such. However, + * a few key bits are stashed in ASCII. If we try to compare those pieces + * to the char they represent, it will fail on any non-ASCII (eg, EBCDIC) + * system. To accomodate these systems, we test against the numeric value + * of the ASCII characters instead of the characters themselves. This is + * encoding independant. + */ + +# define GIF87a "\x47\x49\x46\x38\x37\x61" /* ASCII GIF87a */ +# define GIF89a "\x47\x49\x46\x38\x39\x61" /* ASCII GIF89a */ +# define GIF_TERMINATOR 0x3b /* ASCII ; */ +# define GIF_EXTENSION 0x21 /* ASCII ! */ +# define GIF_START 0x2c /* ASCII , */ + +/* * HACK ALERT!! HACK ALERT!! HACK ALERT!! * This code is hard-wired for reading from files. In order to read * from a data stream, we'll trick fread so we can reuse the same code. @@ -311,7 +327,7 @@ FileReadGIF(interp, chan, fileName, format, imageHandle, destX, destY, break; } - if (buf[0] == ';') { + if (buf[0] == GIF_TERMINATOR) { /* * GIF terminator. */ @@ -321,7 +337,7 @@ FileReadGIF(interp, chan, fileName, format, imageHandle, destX, destY, goto error; } - if (buf[0] == '!') { + if (buf[0] == GIF_EXTENSION) { /* * This is a GIF extension. */ @@ -340,7 +356,7 @@ FileReadGIF(interp, chan, fileName, format, imageHandle, destX, destY, continue; } - if (buf[0] != ',') { + if (buf[0] != GIF_START) { /* * Not a valid start character; ignore it. */ @@ -509,14 +525,14 @@ StringMatchGIF(dataObj, format, widthPtr, heightPtr, interp) /* Check whether the data is Base64 encoded */ - if ((strncmp("\107\111\106\70\67\141", (char *) data, 6) != 0) && - (strncmp("\107\111\106\70\71\141", (char *) data, 6) != 0)) { + if ((strncmp(GIF87a, (char *) data, 6) != 0) && + (strncmp(GIF89a, (char *) data, 6) != 0)) { /* Try interpreting the data as Base64 encoded */ mInit((unsigned char *) data, &handle); got = Mread(header, 10, 1, &handle); if (got != 10 - || ((strncmp("\107\111\106\70\67\141", (char *) header, 6) != 0) - && (strncmp("\107\111\106\70\71\141", (char *) header, 6) != 0))) { + || ((strncmp(GIF87a, (char *) header, 6) != 0) + && (strncmp(GIF89a, (char *) header, 6) != 0))) { return 0; } } else { @@ -570,8 +586,8 @@ StringReadGIF(interp, dataObj, format, imageHandle, * Check whether the data is Base64 encoded */ data = (char *) Tcl_GetByteArrayFromObj(dataObj, NULL); - if ((strncmp("\107\111\106\70\67\141", data, 6) != 0) && - (strncmp("\107\111\106\70\71\141", data, 6) != 0)) { + if ((strncmp(GIF87a, data, 6) != 0) && + (strncmp(GIF89a, data, 6) != 0)) { mInit((unsigned char *)data, &handle); tsdPtr->fromData = 1; dataSrc = (Tcl_Channel) &handle; @@ -615,8 +631,8 @@ ReadGIFHeader(chan, widthPtr, heightPtr) unsigned char buf[7]; if ((Fread(buf, 1, 6, chan) != 6) - || ((strncmp("\107\111\106\70\67\141", (char *) buf, 6) != 0) - && (strncmp("\107\111\106\70\71\141", (char *) buf, 6) != 0))) { + || ((strncmp(GIF87a, (char *) buf, 6) != 0) + && (strncmp(GIF89a, (char *) buf, 6) != 0))) { return 0; } @@ -1381,7 +1397,7 @@ CommonWriteGIF(interp, handle, format, blockPtr) alphaOffset = 0; } - Tcl_Write(handle, (char *) (alphaOffset ? "GIF89a":"GIF87a"), 6); + Tcl_Write(handle, (char *) (alphaOffset ? GIF89a : GIF87a), 6); for (x=0;x<MAXCOLORMAPSIZE;x++) { mapa[x][CM_RED] = 255; @@ -1437,10 +1453,12 @@ CommonWriteGIF(interp, handle, format, blockPtr) */ if (alphaOffset) { - Tcl_Write(handle, "!\371\4\1\0\0\0", 8); + c = GIF_EXTENSION; + Mputc(c, handle); + Tcl_Write(handle, "\371\4\1\0\0\0", 7); } - c = ','; + c = GIF_START; Mputc(c,handle); c=LSB(top); Mputc(c,handle); @@ -1472,7 +1490,7 @@ CommonWriteGIF(interp, handle, format, blockPtr) c = 0; Mputc(c,handle); - c = ';'; + c = GIF_TERMINATOR; Mputc(c,handle); return TCL_OK; |