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Pierre G. Richard - Fri, 30 Jul 2004 11:13:11 +0000 (UTC)
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 * Added support for RLE encoded BMP files
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@slouken
slouken committed Aug 21, 2004
1 parent f98a1db commit 685630f
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@@ -1,4 +1,6 @@
1.2.4:
Pierre G. Richard - Fri, 30 Jul 2004 11:13:11 +0000 (UTC)
* Added support for RLE encoded BMP files
Marc Le Douarain - Fri, 26 Dec 2003 18:23:42 +0100
* Added EHB and HAM mode support to the ILBM loader
Sam Lantinga - Wed Nov 19 00:23:44 PST 2003
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379 changes: 378 additions & 1 deletion IMG_bmp.c
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Expand Up @@ -46,10 +46,387 @@ int IMG_isBMP(SDL_RWops *src)
return(is_BMP);
}

#include "SDL_error.h"
#include "SDL_video.h"
#include "SDL_endian.h"

/* Compression encodings for BMP files */
#ifndef BI_RGB
#define BI_RGB 0
#define BI_RLE8 1
#define BI_RLE4 2
#define BI_BITFIELDS 3
#endif

static int readRlePixels(SDL_Surface * surface, SDL_RWops * src, int isRle8)
{
/*
| Sets the surface pixels from src. A bmp image is upside down.
*/
int pitch = surface->pitch;
int height = surface->h;
Uint8 * bits = (Uint8 *)surface->pixels + ((height-1) * pitch);
int ofs = 0;
Uint8 ch;
Uint8 needsPad;

for (;;) {
if ( !SDL_RWread(src, &ch, 1, 1) ) return 1;
/*
| encoded mode starts with a run length, and then a byte
| with two colour indexes to alternate between for the run
*/
if ( ch ) {
Uint8 pixel;
if ( !SDL_RWread(src, &pixel, 1, 1) ) return 1;
if ( isRle8 ) { /* 256-color bitmap, compressed */
do {
bits[ofs++] = pixel;
} while (--ch);
}else { /* 16-color bitmap, compressed */
Uint8 pixel0 = pixel >> 4;
Uint8 pixel1 = pixel & 0x0F;
for (;;) {
bits[ofs++] = pixel0; /* even count, high nibble */
if (!--ch) break;
bits[ofs++] = pixel1; /* odd count, low nibble */
if (!--ch) break;
}
}
} else {
/*
| A leading zero is an escape; it may signal the end of the bitmap,
| a cursor move, or some absolute data.
| zero tag may be absolute mode or an escape
*/
if ( !SDL_RWread(src, &ch, 1, 1) ) return 1;
switch (ch) {
case 0: /* end of line */
ofs = 0;
bits -= pitch; /* go to previous */
break;
case 1: /* end of bitmap */
return 0; /* success! */
case 2: /* delta */
if ( !SDL_RWread(src, &ch, 1, 1) ) return 1;
ofs += ch;
if ( !SDL_RWread(src, &ch, 1, 1) ) return 1;
bits -= (ch * pitch);
break;
default: /* no compression */
if (isRle8) {
needsPad = ( ch & 1 );
do {
if ( !SDL_RWread(src, bits + ofs++, 1, 1) ) return 1;
} while (--ch);
} else {
needsPad = ( ((ch+1)>>1) & 1 ); /* (ch+1)>>1: bytes size */
for (;;) {
Uint8 pixel;
if ( !SDL_RWread(src, &pixel, 1, 1) ) return 1;
bits[ofs++] = pixel >> 4;
if (!--ch) break;
bits[ofs++] = pixel & 0x0F;
if (!--ch) break;
}
}
/* pad at even boundary */
if ( needsPad && !SDL_RWread(src, &ch, 1, 1) ) return 1;
break;
}
}
}
}

static SDL_Surface *LoadBMP_RW (SDL_RWops *src, int freesrc)
{
int was_error;
long fp_offset;
int bmpPitch;
int i, pad;
SDL_Surface *surface;
Uint32 Rmask;
Uint32 Gmask;
Uint32 Bmask;
SDL_Palette *palette;
Uint8 *bits;
int ExpandBMP;

/* The Win32 BMP file header (14 bytes) */
char magic[2];
Uint32 bfSize;
Uint16 bfReserved1;
Uint16 bfReserved2;
Uint32 bfOffBits;

/* The Win32 BITMAPINFOHEADER struct (40 bytes) */
Uint32 biSize;
Sint32 biWidth;
Sint32 biHeight;
Uint16 biPlanes;
Uint16 biBitCount;
Uint32 biCompression;
Uint32 biSizeImage;
Sint32 biXPelsPerMeter;
Sint32 biYPelsPerMeter;
Uint32 biClrUsed;
Uint32 biClrImportant;

/* Make sure we are passed a valid data source */
surface = NULL;
was_error = 0;
if ( src == NULL ) {
was_error = 1;
goto done;
}

/* Read in the BMP file header */
fp_offset = SDL_RWtell(src);
SDL_ClearError();
if ( SDL_RWread(src, magic, 1, 2) != 2 ) {
SDL_Error(SDL_EFREAD);
was_error = 1;
goto done;
}
if ( strncmp(magic, "BM", 2) != 0 ) {
SDL_SetError("File is not a Windows BMP file");
was_error = 1;
goto done;
}
bfSize = SDL_ReadLE32(src);
bfReserved1 = SDL_ReadLE16(src);
bfReserved2 = SDL_ReadLE16(src);
bfOffBits = SDL_ReadLE32(src);

/* Read the Win32 BITMAPINFOHEADER */
biSize = SDL_ReadLE32(src);
if ( biSize == 12 ) {
biWidth = (Uint32)SDL_ReadLE16(src);
biHeight = (Uint32)SDL_ReadLE16(src);
biPlanes = SDL_ReadLE16(src);
biBitCount = SDL_ReadLE16(src);
biCompression = BI_RGB;
biSizeImage = 0;
biXPelsPerMeter = 0;
biYPelsPerMeter = 0;
biClrUsed = 0;
biClrImportant = 0;
} else {
biWidth = SDL_ReadLE32(src);
biHeight = SDL_ReadLE32(src);
biPlanes = SDL_ReadLE16(src);
biBitCount = SDL_ReadLE16(src);
biCompression = SDL_ReadLE32(src);
biSizeImage = SDL_ReadLE32(src);
biXPelsPerMeter = SDL_ReadLE32(src);
biYPelsPerMeter = SDL_ReadLE32(src);
biClrUsed = SDL_ReadLE32(src);
biClrImportant = SDL_ReadLE32(src);
}

/* Check for read error */
if ( strcmp(SDL_GetError(), "") != 0 ) {
was_error = 1;
goto done;
}

/* Expand 1 and 4 bit bitmaps to 8 bits per pixel */
switch (biBitCount) {
case 1:
case 4:
ExpandBMP = biBitCount;
biBitCount = 8;
break;
default:
ExpandBMP = 0;
break;
}

/* RLE4 and RLE8 BMP compression is supported */
Rmask = Gmask = Bmask = 0;
switch (biCompression) {
case BI_RGB:
/* If there are no masks, use the defaults */
if ( bfOffBits == (14+biSize) ) {
/* Default values for the BMP format */
switch (biBitCount) {
case 15:
case 16:
Rmask = 0x7C00;
Gmask = 0x03E0;
Bmask = 0x001F;
break;
case 24:
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
Rmask = 0x000000FF;
Gmask = 0x0000FF00;
Bmask = 0x00FF0000;
break;
#endif
case 32:
Rmask = 0x00FF0000;
Gmask = 0x0000FF00;
Bmask = 0x000000FF;
break;
default:
break;
}
break;
}
/* Fall through -- read the RGB masks */

default:
switch (biBitCount) {
case 15:
case 16:
case 32:
Rmask = SDL_ReadLE32(src);
Gmask = SDL_ReadLE32(src);
Bmask = SDL_ReadLE32(src);
break;
default:
break;
}
break;
}

/* Create a compatible surface, note that the colors are RGB ordered */
surface = SDL_CreateRGBSurface(SDL_SWSURFACE,
biWidth, biHeight, biBitCount, Rmask, Gmask, Bmask, 0);
if ( surface == NULL ) {
was_error = 1;
goto done;
}

/* Load the palette, if any */
palette = (surface->format)->palette;
if ( palette ) {
/*
| guich: always use 1<<bpp b/c some bitmaps can bring wrong information
| for colorsUsed
*/
/* if ( biClrUsed == 0 ) { */
biClrUsed = 1 << biBitCount;
/* } */
if ( biSize == 12 ) {
for ( i = 0; i < (int)biClrUsed; ++i ) {
SDL_RWread(src, &palette->colors[i].b, 1, 1);
SDL_RWread(src, &palette->colors[i].g, 1, 1);
SDL_RWread(src, &palette->colors[i].r, 1, 1);
palette->colors[i].unused = 0;
}
} else {
for ( i = 0; i < (int)biClrUsed; ++i ) {
SDL_RWread(src, &palette->colors[i].b, 1, 1);
SDL_RWread(src, &palette->colors[i].g, 1, 1);
SDL_RWread(src, &palette->colors[i].r, 1, 1);
SDL_RWread(src, &palette->colors[i].unused, 1, 1);
}
}
palette->ncolors = biClrUsed;
}

/* Read the surface pixels. Note that the bmp image is upside down */
if ( SDL_RWseek(src, fp_offset+bfOffBits, SEEK_SET) < 0 ) {
SDL_Error(SDL_EFSEEK);
was_error = 1;
goto done;
}
if ((biCompression == BI_RLE4) || (biCompression == BI_RLE8)) {
was_error = readRlePixels(surface, src, biCompression == BI_RLE8);
if (was_error) SDL_SetError("Error reading from BMP");
goto done;
}
bits = (Uint8 *)surface->pixels+(surface->h*surface->pitch);
switch (ExpandBMP) {
case 1:
bmpPitch = (biWidth + 7) >> 3;
pad = (((bmpPitch)%4) ? (4-((bmpPitch)%4)) : 0);
break;
case 4:
bmpPitch = (biWidth + 1) >> 1;
pad = (((bmpPitch)%4) ? (4-((bmpPitch)%4)) : 0);
break;
default:
pad = ((surface->pitch%4) ?
(4-(surface->pitch%4)) : 0);
break;
}
while ( bits > (Uint8 *)surface->pixels ) {
bits -= surface->pitch;
switch (ExpandBMP) {
case 1:
case 4: {
Uint8 pixel = 0;
int shift = (8-ExpandBMP);
for ( i=0; i<surface->w; ++i ) {
if ( i%(8/ExpandBMP) == 0 ) {
if ( !SDL_RWread(src, &pixel, 1, 1) ) {
SDL_SetError(
"Error reading from BMP");
was_error = 1;
goto done;
}
}
*(bits+i) = (pixel>>shift);
pixel <<= ExpandBMP;
} }
break;

default:
if ( SDL_RWread(src, bits, 1, surface->pitch)
!= surface->pitch ) {
SDL_Error(SDL_EFREAD);
was_error = 1;
goto done;
}
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
/* Byte-swap the pixels if needed. Note that the 24bpp
case has already been taken care of above. */
switch(biBitCount) {
case 15:
case 16: {
Uint16 *pix = (Uint16 *)bits;
for(i = 0; i < surface->w; i++)
pix[i] = SDL_Swap16(pix[i]);
break;
}

case 32: {
Uint32 *pix = (Uint32 *)bits;
for(i = 0; i < surface->w; i++)
pix[i] = SDL_Swap32(pix[i]);
break;
}
}
#endif
break;
}
/* Skip padding bytes, ugh */
if ( pad ) {
Uint8 padbyte;
for ( i=0; i<pad; ++i ) {
SDL_RWread(src, &padbyte, 1, 1);
}
}
}
done:
if ( was_error ) {
if ( surface ) {
SDL_FreeSurface(surface);
}
surface = NULL;
}
if ( freesrc && src ) {
SDL_RWclose(src);
}
return(surface);
}

/* Load a BMP type image from an SDL datasource */
SDL_Surface *IMG_LoadBMP_RW(SDL_RWops *src)
{
return(SDL_LoadBMP_RW(src, 0));
return(LoadBMP_RW(src, 0));
}

#else
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