diff options
Diffstat (limited to 'converter/other/bmptopnm.c')
| -rw-r--r-- | converter/other/bmptopnm.c | 114 |
1 files changed, 87 insertions, 27 deletions
diff --git a/converter/other/bmptopnm.c b/converter/other/bmptopnm.c index e1bd1403..9a405d70 100644 --- a/converter/other/bmptopnm.c +++ b/converter/other/bmptopnm.c @@ -17,11 +17,17 @@ in supporting documentation. This software is provided "as is" without express or implied warranty. + Note: From mid-2003 to mid-2007, this program would crash on any 16 + bit BMP without transparency and no one reported it. Before that, it + refused to even try to read a 16 bit BMP. I conclude that essentially + nobody is using 16 bit BMP. + *****************************************************************************/ #include <string.h> #include <limits.h> #include <assert.h> +#include "pm_c_util.h" #include "pnm.h" #include "shhopt.h" #include "nstring.h" @@ -42,6 +48,10 @@ struct bitPosition { Example: if 16 bits are laid out as XRRRRRGGGGGBBBBB then the shift count for the R component is 10 and the mask is 0000000000011111. + + A 'mask' of zero denotes absence of any bits; e.g. in the example + above, the mask for the transparency component is zero because there + is no transparency component . 'shift' is arbitrary in that case. */ unsigned int shift; /* How many bits right you have to shift the value to get the subject @@ -306,6 +316,36 @@ readOs2InfoHeader(FILE * const ifP, static void +validateCompression(unsigned long const compression, + enum rowOrder const rowOrder, + unsigned int const cBitCount) { + + if (compression != COMP_RGB && compression != COMP_BITFIELDS && + compression != COMP_RLE4 && compression != COMP_RLE8 ) + pm_error("Input has unknown encoding. " + "Compression type code = %ld. The only ones we know " + "are RGB (%u), BITFIELDS (%u), " + "RLE4 (%u), and RLE8 (%u)", + compression, COMP_RGB, COMP_BITFIELDS, + COMP_RLE4, COMP_RLE8); + + if ((compression == COMP_RLE4 || compression == COMP_RLE8) && + rowOrder == TOPDOWN ) + pm_error("Invalid BMP header. Claims image is top-down and also " + "compressed, which is an impossible combination."); + + if ( (compression == COMP_RLE4 && cBitCount !=4) || + (compression == COMP_RLE8 && cBitCount !=8) ) + pm_error("Invalid BMP header. " + "Compression type (%s) disagrees with " + "number of bits per pixel (%u).", + compression == COMP_RLE4 ? "RLE4" : "RLE8", + cBitCount); +} + + + +static void readWindowsBasic40ByteInfoHeader(FILE * const ifP, struct bmpInfoHeader * const headerP) { /*---------------------------------------------------------------------------- @@ -340,22 +380,9 @@ readWindowsBasic40ByteInfoHeader(FILE * const ifP, unsigned long int const compression = GetLong(ifP); headerP->bitFields = (compression == COMP_BITFIELDS); - - if (compression != COMP_RGB && compression != COMP_BITFIELDS && - compression != COMP_RLE4 && compression != COMP_RLE8 ) - pm_error("Input is compressed. Unsupported encoding method.\n" - "Compression type code = %ld", compression); - - if ( (compression == COMP_RLE4 || compression == COMP_RLE8) && - headerP->rowOrder == TOPDOWN ) - pm_error("Invalid BMP header. Top-down images cannot be compressed."); - if ( (compression == COMP_RLE4 && headerP->cBitCount !=4) || - (compression == COMP_RLE8 && headerP->cBitCount !=8) ) - pm_error("Invalid BMP header.\n" - "Compression type (%s) disagrees with number of bits per pixel (%u).", - compression == COMP_RLE4 ? "RLE4" : "RLE8", - headerP->cBitCount); + validateCompression(compression, headerP->rowOrder, + headerP->cBitCount); headerP->compression = compression; } @@ -399,7 +426,7 @@ lsbZeroCount(unsigned int const mask) Use GCC built-in when available. -----------------------------------------------------------------------------*/ -#if ( defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 304) ) +#if HAVE_GCC_BITCOUNT { return ( mask==0 ? sizeof(mask)*8 : __builtin_ctz(mask) ); } @@ -463,6 +490,10 @@ defaultPixelformat(unsigned int const bitCount) { switch (bitCount) { case 16: + /* This layout is sometimes called "RGB555". A document from + Microsoft says this is the default (when the "compression" + field of the header says COMP_BITFIELDS). + */ retval.conventionalBgr = FALSE; retval.red.shift = 10; retval.grn.shift = 5; @@ -500,6 +531,11 @@ readV4InfoHeaderExtension(FILE * const ifP, struct bmpInfoHeader * const headerP) { if (headerP->bitFields) { + /* A document from Microsoft says on Windows 95 there is no + transparency plane and (red, green, blue) must be either + (5,5,5) or (5,6,5) for 16 bit and (8,8,8) for 32 bit. + It calls these RGB555, RGB565, RGB888. + */ headerP->pixelformat.red = bitPositionFromMask(GetLong(ifP)); headerP->pixelformat.grn = bitPositionFromMask(GetLong(ifP)); headerP->pixelformat.blu = bitPositionFromMask(GetLong(ifP)); @@ -655,16 +691,16 @@ extractBitFields(unsigned int const rasterval, (rasterval >> pixelformat.blu.shift) & pixelformat.blu.mask; unsigned int const abits = (rasterval >> pixelformat.trn.shift) & pixelformat.trn.mask; - - *rP = pixelformat.red.mask ? - (unsigned int) rbits * maxval / pixelformat.red.mask : 0; - *gP = pixelformat.grn.mask ? - (unsigned int) gbits * maxval / pixelformat.grn.mask : 0; - *bP = pixelformat.blu.mask ? - (unsigned int) bbits * maxval / pixelformat.blu.mask : 0; - *aP = pixelformat.trn.mask ? - (unsigned int) abits * maxval / pixelformat.trn.mask : 0; -} + + *rP = pixelformat.red.mask > 0 ? + (unsigned int) rbits * maxval / pixelformat.red.mask : 0; + *gP = pixelformat.grn.mask > 0 ? + (unsigned int) gbits * maxval / pixelformat.grn.mask : 0; + *bP = pixelformat.blu.mask > 0 ? + (unsigned int) bbits * maxval / pixelformat.blu.mask : 0; + *aP = pixelformat.trn.mask > 0 ? + (unsigned int) abits * maxval / pixelformat.trn.mask : 0; +} @@ -1220,7 +1256,7 @@ readColorMap(FILE * const ifP, bytesRead, BMPlencolormap(BMPheader.class, BMPheader.cBitCount, BMPheader.cmapsize)); -} + } } @@ -1259,6 +1295,25 @@ warnIfBadFileSize(struct bmpInfoHeader const BMPheader, +static bool +isValidBmpBpp(unsigned int const cBitCount) { + + switch (cBitCount) { + case 1: + case 2: + case 4: + case 8: + case 16: + case 24: + case 32: + return true; + default: + return false; + } +} + + + static void readBmp(FILE * const ifP, unsigned char *** const BMPrasterP, @@ -1316,6 +1371,11 @@ readBmp(FILE * const ifP, if (fgetc(ifP) != EOF) pm_message("warning: some image data remains unread."); + if (!isValidBmpBpp(BMPheader.cBitCount)) + pm_error("Invalid BMP image: 'cBitCount' field of header " + "(number of bits for each pixel in raster) is %u", + BMPheader.cBitCount); + *colsP = BMPheader.cols; *rowsP = BMPheader.rows; *cBitCountP = BMPheader.cBitCount; |