gtk2/gdk-pixbuf/io-bmp.c

/* GdkPixbuf library - Windows Bitmap image loader
 *
 * Copyright (C) 1999 The Free Software Foundation
 *
 * Authors: Arjan van de Ven <arjan@fenrus.demon.nl>
 *          Federico Mena-Quintero <federico@gimp.org>
 *
 * Based on io-ras.c
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <config.h>
#include <stdio.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#include "gdk-pixbuf-private.h"
#include "gdk-pixbuf-io.h"



/* 

These structures are actually dummies. These are according to
the "Windows API reference guide volume II" as written by 
Borland International, but GCC fiddles with the alignment of 
the internal members, so these aren't actually usable.

*/

struct BitmapFileHeader {
	gushort bfType;
	guint bfSize;
	guint reserverd;
	guint bfOffbits;
};

struct BitmapInfoHeader {
	guint biSize;
	guint biWidth;
	guint biHeight;
	gushort biPlanes;
	gushort biBitCount;
	guint biCompression;
	guint biSizeImage;
	guint biXPelsPerMeter;
	guint biYPelsPerMeter;
	guint biClrUsed;
	guint biClrImportant;
};

/* biCompression values */

#define BI_RGB 0
#define BI_RLE8 1
#define BI_RLE4 2
#define BI_BITFIELDS 3
#define BI_JPEG 4
#define BI_PNG 5

/* 

DumpBIH printf's the values in a BitmapInfoHeader to the screen, for 
debugging purposes.

*/
#if DUMPBIH
static void DumpBIH(unsigned char *BIH)
{
	printf("biSize      = %i \n",
	       (int) (BIH[3] << 24) + (BIH[2] << 16) + (BIH[1] << 8) +
	       (BIH[0]));
	printf("biWidth     = %i \n",
	       (int) (BIH[7] << 24) + (BIH[6] << 16) + (BIH[5] << 8) +
	       (BIH[4]));
	printf("biHeight    = %i \n",
	       (int) (BIH[11] << 24) + (BIH[10] << 16) + (BIH[9] << 8) +
	       (BIH[8]));
	printf("biPlanes    = %i \n", (int) (BIH[13] << 8) + (BIH[12]));
	printf("biBitCount  = %i \n", (int) (BIH[15] << 8) + (BIH[14]));
	printf("biCompress  = %i \n",
	       (int) (BIH[19] << 24) + (BIH[18] << 16) + (BIH[17] << 8) +
	       (BIH[16]));
	printf("biSizeImage = %i \n",
	       (int) (BIH[23] << 24) + (BIH[22] << 16) + (BIH[21] << 8) +
	       (BIH[20]));
	printf("biXPels     = %i \n",
	       (int) (BIH[27] << 24) + (BIH[26] << 16) + (BIH[25] << 8) +
	       (BIH[24]));
	printf("biYPels     = %i \n",
	       (int) (BIH[31] << 24) + (BIH[30] << 16) + (BIH[29] << 8) +
	       (BIH[28]));
	printf("biClrUsed   = %i \n",
	       (int) (BIH[35] << 24) + (BIH[34] << 16) + (BIH[33] << 8) +
	       (BIH[32]));
	printf("biClrImprtnt= %i \n",
	       (int) (BIH[39] << 24) + (BIH[38] << 16) + (BIH[37] << 8) +
	       (BIH[36]));
}
#endif
/* struct headerpair contains the decoded width/height/depth info for
   the current bitmap */

struct headerpair {
	guint32 size;
	gint32 width;
	gint32 height;
	guint depth;
	guint Negative;		/* Negative = 1 -> top down BMP,  
				   Negative = 0 -> bottom up BMP */
};

/* Data needed for the "state" during decompression */
struct bmp_compression_state {
	gint phase; 
	gint RunCount;

	guchar *linebuff;
	gint linebuffsize;	/* these two counts in nibbles */
	gint linebuffdone;
};

/* Progressive loading */

struct bmp_progressive_state {
	ModulePreparedNotifyFunc prepared_func;
	ModuleUpdatedNotifyFunc updated_func;
	gpointer user_data;

	guint LineWidth;
	guint Lines;		/* # of finished lines */

	guchar *buff;
	gint BufferSize;
	gint BufferDone;

	guchar (*Colormap)[3];

	gint Type;		/*  
				   32 = RGB + alpha
				   24 = RGB
				   16 = RGB
				   4  = 4 bpp colormapped
				   8  = 8 bpp colormapped
				   1  = 1 bit bitonal 
				 */
	gint Compressed;
	struct bmp_compression_state compr;


	struct headerpair Header;	/* Decoded (BE->CPU) header */


	GdkPixbuf *pixbuf;	/* Our "target" */
};

static gpointer
gdk_pixbuf__bmp_image_begin_load(ModulePreparedNotifyFunc prepared_func,
				 ModuleUpdatedNotifyFunc updated_func,
                                 gpointer user_data,
                                 GError **error);

static gboolean gdk_pixbuf__bmp_image_stop_load(gpointer data, GError **error);
static gboolean gdk_pixbuf__bmp_image_load_increment(gpointer data,
                                                     const guchar * buf,
                                                     guint size,
                                                     GError **error);



/* Shared library entry point --> This should be removed when
   generic_image_load enters gdk-pixbuf-io. */
static GdkPixbuf *gdk_pixbuf__bmp_image_load(FILE * f, GError **error)
{
	guchar membuf[4096];
	size_t length;
	struct bmp_progressive_state *State;

	GdkPixbuf *pb;

	State =
	    gdk_pixbuf__bmp_image_begin_load(NULL, NULL, NULL,
                                             error);

        if (State == NULL)
          return NULL;
        
	while (feof(f) == 0) {
		length = fread(membuf, 1, 4096, f);
		if (length > 0)
                  if (!gdk_pixbuf__bmp_image_load_increment(State,
                                                            membuf,
                                                            length,
                                                            error)) {
                          gdk_pixbuf__bmp_image_stop_load (State, NULL);
                          return NULL;
                  }

	}
	if (State->pixbuf != NULL)
		gdk_pixbuf_ref(State->pixbuf);

	pb = State->pixbuf;

	gdk_pixbuf__bmp_image_stop_load(State, NULL);
	return pb;
}

static gboolean DecodeHeader(unsigned char *BFH, unsigned char *BIH,
                             struct bmp_progressive_state *State,
                             GError **error)
{
        /* FIXME this is totally unrobust against bogus image data. */
        
	if (State->BufferSize < GUINT32_FROM_LE (* (guint32 *) &BIH[0]) + 14) {
		State->BufferSize = GUINT32_FROM_LE (* (guint32 *) &BIH[0]) + 14;
		State->buff = g_realloc (State->buff, State->BufferSize);
		return TRUE;
	}

#if DUMPBIH
	DumpBIH(BIH);
#endif

	State->Header.size = GUINT32_FROM_LE (* (guint32 *) &BIH[0]);
	if (State->Header.size == 40) {
		State->Header.width = GINT32_FROM_LE (* (gint32 *) &BIH[4]);
		State->Header.height = GINT32_FROM_LE (* (gint32 *) &BIH[8]);
		State->Header.depth = GUINT16_FROM_LE (* (guint16 *) &BIH[14]);
		State->Compressed = GUINT32_FROM_LE (* (guint32 *) &BIH[16]);
	} else if (State->Header.size == 12) {
		State->Header.width = GUINT16_FROM_LE (* (guint16 *) &BIH[4]);
		State->Header.height = GUINT16_FROM_LE (* (guint16 *) &BIH[6]);
		State->Header.depth = GUINT16_FROM_LE (* (guint16 *) &BIH[10]);
		State->Compressed = 0;
	} else {
		g_set_error (error,
			     GDK_PIXBUF_ERROR,
			     GDK_PIXBUF_ERROR_CORRUPT_IMAGE,
			     _("BMP image has unsupported header size"));
		return FALSE;
	}

	State->Type = State->Header.depth;	/* This may be less trivial someday */

	/* Negative heights indicates bottom-down pixelorder */
	if (State->Header.height < 0) {
		State->Header.height = -State->Header.height;
		State->Header.Negative = 1;
	}
	if (State->Header.width < 0) {
		State->Header.width = -State->Header.width;
		State->Header.Negative = 0;
	}

	if (State->Header.width == 0 || State->Header.height == 0 ||
	    (State->Compressed == BI_RLE4 && State->Type != 4)    ||
	    (State->Compressed == BI_RLE8 && State->Type != 8)	  ||
	    State->Compressed > BI_RLE4) {
		g_set_error (error,
			     GDK_PIXBUF_ERROR,
			     GDK_PIXBUF_ERROR_CORRUPT_IMAGE,
			     _("BMP image has bogus header data"));
		return FALSE;
	}

	if (State->Type == 32)
		State->LineWidth = State->Header.width * 4;
	else if (State->Type == 24)
		State->LineWidth = State->Header.width * 3;
	else if (State->Type == 16)
		State->LineWidth = State->Header.width * 2;
	else if (State->Type == 8)
		State->LineWidth = State->Header.width * 1;
	else if (State->Type == 4)
		State->LineWidth = (State->Header.width + 1) / 2;
	else if (State->Type == 1) {
		State->LineWidth = State->Header.width / 8;
		if ((State->Header.width & 7) != 0)
			State->LineWidth++;
	} else {
		g_set_error (error,
			     GDK_PIXBUF_ERROR,
			     GDK_PIXBUF_ERROR_CORRUPT_IMAGE,
			     _("BMP image has bogus header data"));
		return FALSE;
	}

	/* Pad to a 32 bit boundary */
	if (((State->LineWidth % 4) > 0) && (State->Compressed == BI_RGB))
		State->LineWidth = (State->LineWidth / 4) * 4 + 4;


	if (State->pixbuf == NULL) {
		if (State->Type == 32)
			State->pixbuf =
			    gdk_pixbuf_new(GDK_COLORSPACE_RGB, TRUE, 8,
					   (gint) State->Header.width,
					   (gint) State->Header.height);
		else
			State->pixbuf =
			    gdk_pixbuf_new(GDK_COLORSPACE_RGB, FALSE, 8,
					   (gint) State->Header.width,
					   (gint) State->Header.height);

                if (State->pixbuf == NULL) {
                        g_set_error (error,
                                     GDK_PIXBUF_ERROR,
                                     GDK_PIXBUF_ERROR_INSUFFICIENT_MEMORY,
                                     _("Not enough memory to load bitmap image"));
                        return FALSE;
                }
                
		if (State->prepared_func != NULL)
			/* Notify the client that we are ready to go */
			(*State->prepared_func) (State->pixbuf, NULL, State->user_data);

	}

	if (State->Compressed != BI_RGB) {
		State->compr.linebuffdone = 0;
		State->compr.linebuffsize = State->Header.width;
		if (State->Type == 8)
			State->compr.linebuffsize *= 2;
		State->compr.linebuff = g_malloc ((State->compr.linebuffsize + 1) / 2);
	}

	State->BufferDone = 0;
	if (State->Type <= 8)
		State->BufferSize = GUINT32_FROM_LE (* (guint32 *) &BFH[10]) - 14 - State->Header.size;
	else if (State->Compressed != BI_RGB)
		State->BufferSize = 2;
	else
		State->BufferSize = State->LineWidth;
	State->buff = g_realloc (State->buff, State->BufferSize);

        return TRUE;
}

static void DecodeColormap (guchar *buff,
			    struct bmp_progressive_state *State,
			    GError **error)
{
	gint i;

	State->Colormap = g_malloc ((1 << State->Header.depth) * sizeof (*State->Colormap));

	for (i = 0; i < (1 << State->Header.depth); i++)
	{
		State->Colormap[i][0] = buff[i * (State->Header.size == 12 ? 3 : 4)];
		State->Colormap[i][1] = buff[i * (State->Header.size == 12 ? 3 : 4) + 1];
		State->Colormap[i][2] = buff[i * (State->Header.size == 12 ? 3 : 4) + 2];
	}

	State->BufferDone = 0;
	if (State->Compressed != BI_RGB)
		State->BufferSize = 2;
	else
		State->BufferSize = State->LineWidth;
	State->buff = g_realloc (State->buff, State->BufferSize);
}

/* 
 * func - called when we have pixmap created (but no image data)
 * user_data - passed as arg 1 to func
 * return context (opaque to user)
 */

static gpointer
gdk_pixbuf__bmp_image_begin_load(ModulePreparedNotifyFunc prepared_func,
				 ModuleUpdatedNotifyFunc updated_func,
                                 gpointer user_data,
                                 GError **error)
{
	struct bmp_progressive_state *context;

	context = g_new0(struct bmp_progressive_state, 1);
	context->prepared_func = prepared_func;
	context->updated_func = updated_func;
	context->user_data = user_data;

	context->BufferSize = 26;
	context->buff = g_malloc(26);
	context->BufferDone = 0;
	/* 14 for the BitmapFileHeader, 12 for the BitmapImageHeader */ 

	context->Colormap = NULL;

	context->Lines = 0;

	context->Type = 0;

	memset(&context->Header, 0, sizeof(struct headerpair));
	memset(&context->compr, 0, sizeof(struct bmp_compression_state));


	context->pixbuf = NULL;


	return (gpointer) context;
}

/*
 * context - returned from image_begin_load
 *
 * free context, unref gdk_pixbuf
 */
static gboolean gdk_pixbuf__bmp_image_stop_load(gpointer data, GError **error)
{
	struct bmp_progressive_state *context =
	    (struct bmp_progressive_state *) data;

        /* FIXME this thing needs to report errors if
         * we have unused image data
         */        

	g_return_val_if_fail(context != NULL, TRUE);

	if (context->compr.linebuff != NULL)
		g_free(context->compr.linebuff);

	if (context->Colormap != NULL)
		g_free(context->Colormap);

	if (context->pixbuf)
		gdk_pixbuf_unref(context->pixbuf);

	g_free(context->buff);
	g_free(context);

        return TRUE;
}


/*
The OneLineXX functions are called when 1 line worth of data is present.
OneLine24 is the 24 bpp-version.
*/
static void OneLine32(struct bmp_progressive_state *context)
{
	gint X;
	guchar *Pixels;

	X = 0;
	if (context->Header.Negative == 0)
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  (context->Header.height - context->Lines - 1));
	else
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  context->Lines);
	while (X < context->Header.width) {
		Pixels[X * 4 + 0] = context->buff[X * 4 + 2];
		Pixels[X * 4 + 1] = context->buff[X * 4 + 1];
		Pixels[X * 4 + 2] = context->buff[X * 4 + 0];
		Pixels[X * 4 + 3] = context->buff[X * 4 + 3];
		X++;
	}

}

static void OneLine24(struct bmp_progressive_state *context)
{
	gint X;
	guchar *Pixels;

	X = 0;
	if (context->Header.Negative == 0)
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  (context->Header.height - context->Lines - 1));
	else
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  context->Lines);
	while (X < context->Header.width) {
		Pixels[X * 3 + 0] = context->buff[X * 3 + 2];
		Pixels[X * 3 + 1] = context->buff[X * 3 + 1];
		Pixels[X * 3 + 2] = context->buff[X * 3 + 0];
		X++;
	}

}

static void OneLine16(struct bmp_progressive_state *context)
{
	gint X;
	guchar *Pixels;

	X = 0;
	if (context->Header.Negative == 0)
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  (context->Header.height - context->Lines - 1));
	else
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  context->Lines);
	while (X < context->Header.width) {
		Pixels[X * 3 + 0] = (GUINT16_FROM_LE (* (guint16 *) &context->buff[X * 2]) & 0x7C00) >> 7;
		Pixels[X * 3 + 1] = (GUINT16_FROM_LE (* (guint16 *) &context->buff[X * 2]) & 0x03E0) >> 2;
		Pixels[X * 3 + 2] = (GUINT16_FROM_LE (* (guint16 *) &context->buff[X * 2]) & 0x001F) << 3;
		X++;
	}
}

static void OneLine8(struct bmp_progressive_state *context)
{
	gint X;
	guchar *Pixels;

	X = 0;
	if (context->Header.Negative == 0)
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  (context->Header.height - context->Lines - 1));
	else
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  context->Lines);
	while (X < context->Header.width) {
		Pixels[X * 3 + 0] =
		    context->Colormap[context->buff[X]][2];
		Pixels[X * 3 + 1] =
		    context->Colormap[context->buff[X]][1];
		Pixels[X * 3 + 2] =
		    context->Colormap[context->buff[X]][0];
		X++;
	}
}

static void OneLine4(struct bmp_progressive_state *context)
{
	gint X;
	guchar *Pixels;

	X = 0;
	if (context->Header.Negative == 0)
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  (context->Header.height - context->Lines - 1));
	else
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  context->Lines);

	while (X < context->Header.width) {
		guchar Pix;

		Pix = context->buff[X / 2];

		Pixels[X * 3 + 0] =
		    context->Colormap[Pix >> 4][2];
		Pixels[X * 3 + 1] =
		    context->Colormap[Pix >> 4][1];
		Pixels[X * 3 + 2] =
		    context->Colormap[Pix >> 4][0];
		X++;
		if (X < context->Header.width) {
			/* Handle the other 4 bit pixel only when there is one */
			Pixels[X * 3 + 0] =
			    context->Colormap[Pix & 15][2];
			Pixels[X * 3 + 1] =
			    context->Colormap[Pix & 15][1];
			Pixels[X * 3 + 2] =
			    context->Colormap[Pix & 15][0];
			X++;
		}
	}

}

static void OneLine1(struct bmp_progressive_state *context)
{
	gint X;
	guchar *Pixels;

	X = 0;
	if (context->Header.Negative == 0)
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  (context->Header.height - context->Lines - 1));
	else
		Pixels = (context->pixbuf->pixels +
			  context->pixbuf->rowstride *
			  context->Lines);
	while (X < context->Header.width) {
		gint Bit;

		Bit = (context->buff[X / 8]) >> (7 - (X & 7));
		Bit = Bit & 1;
		Pixels[X * 3 + 0] = context->Colormap[Bit][2];
		Pixels[X * 3 + 1] = context->Colormap[Bit][1];
		Pixels[X * 3 + 2] = context->Colormap[Bit][0];
		X++;
	}
}


static void OneLine(struct bmp_progressive_state *context)
{
	context->BufferDone = 0;
	if (context->Lines >= context->Header.height)
		return;

	if (context->Type == 32)
		OneLine32(context);
	if (context->Type == 24)
		OneLine24(context);
	if (context->Type == 16)
		OneLine16(context);
	if (context->Type == 8)
		OneLine8(context);
	if (context->Type == 4)
		OneLine4(context);
	if (context->Type == 1)
		OneLine1(context);

	context->Lines++;

	if (context->updated_func != NULL) {
		(*context->updated_func) (context->pixbuf,
					  0,
					  context->Lines,
					  context->Header.width,
					  1,
					  context->user_data);

	}
}

static void
DoCompressed(struct bmp_progressive_state *context)
{
	gint count, pos;
	switch (context->compr.phase) {
	case 0:		/* Neutral state */
		if (context->buff[0] != 0) {	/* run count */
			context->compr.RunCount = context->buff[0];
			if (context->Type == 8)
				context->compr.RunCount *= 2;
			while (context->compr.RunCount > 0) {
				if (context->compr.linebuffdone & 1) {
					guchar *ptr = context->compr.linebuff +
					    context->compr.linebuffdone / 2;

					*ptr = (*ptr & 0xF0) | (context->buff[1] >> 4);
					context->buff[1] = (context->buff[1] << 4) |
							   (context->buff[1] >> 4);
					context->compr.linebuffdone++;
					context->compr.RunCount--;
				}

				if (context->compr.RunCount) {
					count = context->compr.linebuffsize -
					    context->compr.linebuffdone;
					if (count > context->compr.RunCount)
						count = context->compr.RunCount;

					memset (context->compr.linebuff +
						context->compr.linebuffdone / 2,
						context->buff[1],
						(count + 1) / 2);
					context->compr.RunCount -= count;
					context->compr.linebuffdone += count;
				}
				if (context->compr.linebuffdone == context->compr.linebuffsize) {
					guchar *tmp = context->buff;
					context->buff = context->compr.linebuff;
					OneLine (context);
					context->buff = tmp;

					if (context->compr.linebuffdone & 1)
						context->buff[1] = (context->buff[1] << 4) |
								   (context->buff[1] >> 4);
					context->compr.linebuffdone = 0;
				}
			}
		} else {	/* Escape */
			if (context->buff[1] == 0) {	/* End of line */
				if (context->compr.linebuffdone) {
					guchar *tmp = context->buff;
					context->buff = context->compr.linebuff;
					OneLine (context);
					context->buff = tmp;

					context->compr.linebuffdone = 0;
				}
			} else if (context->buff[1] == 1) {	/* End of image */
				if (context->compr.linebuffdone) {
					guchar *tmp = context->buff;
					context->buff = context->compr.linebuff;
					OneLine (context);
					context->buff = tmp;
				}

				context->compr.phase = 2;
			} else if (context->buff[1] == 2)	/* Cursor displacement */
				;	/* not implemented */
			else {
				context->compr.phase = 1;
				context->compr.RunCount = context->buff[1];
				if (context->Type == 8)
					context->compr.RunCount *= 2;
				context->BufferSize = (context->compr.RunCount + 3) / 4 * 2;
				context->buff = g_realloc (context->buff, context->BufferSize);
			}
		}
		context->BufferDone = 0;
		break;
	case 1:
		pos = 0;
		while (pos < context->compr.RunCount) {
			count = context->compr.linebuffsize - context->compr.linebuffdone;
			if (count > context->compr.RunCount)
				count = context->compr.RunCount;

			if ((context->compr.linebuffdone & 1) || (pos & 1)) {
				gint i, newval;
				guchar *ptr;
				for (i = 0; i < count; i++) {
					ptr = context->compr.linebuff + (i +
					      context->compr.linebuffdone) / 2;
					newval = *(context->buff + (pos + i) / 2) & (0xf0 >> (((pos + i) % 2) * 4));
					if (((pos + i) % 2) ^ ((context->compr.linebuffdone + i) % 2)) {
						if ((pos + i) % 2)
							newval <<= 4;
						else
							newval >>= 4;
					}
					*ptr = (*ptr & (0xf << (((i + context->compr.linebuffdone) % 2) * 4))) | newval;
				}
			} else {
				memmove (context->compr.linebuff +
					 context->compr.linebuffdone / 2,
					 context->buff + pos / 2,
					 (count + 1) / 2);
			}
			pos += count;
			context->compr.linebuffdone += count;
			if (context->compr.linebuffdone == context->compr.linebuffsize) {
				guchar *tmp = context->buff;
				context->buff = context->compr.linebuff;
				OneLine (context);
				context->buff = tmp;

				context->compr.linebuffdone = 0;
			}
		}
		context->compr.phase = 0;
		context->BufferSize = 2;
		context->buff = g_realloc (context->buff, context->BufferSize);
		context->BufferDone = 0;
		break;
	case 2:
		context->BufferDone = 0;
		break;
	}
}

/*
 * context - from image_begin_load
 * buf - new image data
 * size - length of new image data
 *
 * append image data onto inrecrementally built output image
 */
static gboolean
gdk_pixbuf__bmp_image_load_increment(gpointer data,
                                     const guchar * buf,
                                     guint size,
                                     GError **error)
{
	struct bmp_progressive_state *context =
	    (struct bmp_progressive_state *) data;

	gint BytesToCopy;

	while (size > 0) {
		if (context->BufferDone < context->BufferSize) {	/* We still 
									   have headerbytes to do */
			BytesToCopy =
			    context->BufferSize - context->BufferDone;
			if (BytesToCopy > size)
				BytesToCopy = size;

			memmove(context->buff + context->BufferDone,
				buf, BytesToCopy);

			size -= BytesToCopy;
			buf += BytesToCopy;
			context->BufferDone += BytesToCopy;

			if (context->BufferDone != context->BufferSize)
				break;
		}

		if (!context->Header.size) {
			if (!DecodeHeader (context->buff,
					   context->buff + 14, context,
					   error))
				return FALSE;
		}
		else if (context->Type <= 8 && context->Colormap == NULL)
			DecodeColormap (context->buff, context, error);
		else if (context->Compressed != BI_RGB)
			DoCompressed(context);
		else
			/* Uncompressed pixeldata */
			OneLine(context);
	}

	return TRUE;
}

void
gdk_pixbuf__bmp_fill_vtable (GdkPixbufModule *module)
{
  module->load = gdk_pixbuf__bmp_image_load;
  module->begin_load = gdk_pixbuf__bmp_image_begin_load;
  module->stop_load = gdk_pixbuf__bmp_image_stop_load;
  module->load_increment = gdk_pixbuf__bmp_image_load_increment;
}