[project @ 2006-02-28 00:45:15 by rjw]
Implement bitfield encoding for BMPs. We now correctly decode every image in the BMP test suite at http://pobox.com/~jason1/bmpsuite/ svn path=/import/netsurf/; revision=2099
This commit is contained in:
Richard Wilson
parent
6929d90d41
commit
6f654c6f1e
195
image/bmpread.c
195
image/bmpread.c
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@ -5,7 +5,6 @@
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* Copyright 2006 Richard Wilson <info@tinct.net>
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*/
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#include <assert.h>
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#include <stdbool.h>
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#include <stdio.h>
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@ -20,6 +19,7 @@
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bmp_result bmp_analyse_header(struct bmp_image *bmp, char *data);
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bmp_result bmp_decode_rgb24(struct bmp_image *bmp, char **start, int bytes);
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bmp_result bmp_decode_rgb16(struct bmp_image *bmp, char **start, int bytes);
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bmp_result bmp_decode_rgb(struct bmp_image *bmp, char **start, int bytes);
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bmp_result bmp_decode_mask(struct bmp_image *bmp, char *data, int bytes);
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bmp_result bmp_decode_rle(struct bmp_image *bmp, char *data, int bytes, int size);
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@ -132,7 +132,7 @@ bmp_result ico_analyse(struct ico_collection *ico) {
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bmp_result bmp_analyse_header(struct bmp_image *bmp, char *data) {
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unsigned int header_size;
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unsigned int i;
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int width, height;
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int width, height, j;
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int palette_size;
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unsigned int flags;
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@ -157,8 +157,8 @@ bmp_result bmp_analyse_header(struct bmp_image *bmp, char *data) {
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if (width < 0)
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return BMP_DATA_ERROR;
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if (height < 0) {
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bmp->reversed = true;
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height = -height;
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bmp->reversed = true;
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height = -height;
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}
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bmp->width = width;
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bmp->height = height;
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@ -170,8 +170,8 @@ bmp_result bmp_analyse_header(struct bmp_image *bmp, char *data) {
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} else if (header_size < 40) {
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return BMP_DATA_ERROR;
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} else {
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/* the following header is for windows 3.x and onwards. it is a
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* minimum of 40 bytes and (as of Windows 95) a maximum of 108 bytes.
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/* the following header is for windows 3.x and onwards. it is a
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* minimum of 40 bytes and (as of Windows 95) a maximum of 108 bytes.
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*
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* +0 INT size of this header (in bytes)
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* +4 INT image width (in pixels)
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@ -208,8 +208,8 @@ bmp_result bmp_analyse_header(struct bmp_image *bmp, char *data) {
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if (width < 0)
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return BMP_DATA_ERROR;
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if (height < 0) {
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bmp->reversed = true;
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height = -height;
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bmp->reversed = true;
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height = -height;
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}
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bmp->width = width;
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bmp->height = height;
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@ -220,13 +220,39 @@ bmp_result bmp_analyse_header(struct bmp_image *bmp, char *data) {
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if (bmp->bpp == 0)
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bmp->bpp = 8;
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bmp->encoding = READ_INT(data, 16);
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if (bmp->encoding >= BMP_ENCODING_BITFIELDS) /* unsupported so far */
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if (bmp->encoding > BMP_ENCODING_BITFIELDS)
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return BMP_DATA_ERROR;
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if (bmp->encoding == BMP_ENCODING_BITFIELDS) {
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if ((bmp->bpp != 16) && (bmp->bpp != 32))
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return BMP_DATA_ERROR;
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if (header_size == 40) {
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header_size += 12;
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if (bmp->buffer_size < (14 + header_size))
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return BMP_INSUFFICIENT_DATA;
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for (i = 0; i < 3; i++)
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bmp->mask[i] = READ_INT(data, 40 + (i << 2));
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} else {
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for (i = 0; i < 4; i++)
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bmp->mask[i] = READ_INT(data, 40 + (i << 2));
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}
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for (i = 0; i < 4; i++) {
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if (bmp->mask[i] == 0)
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break;
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for (j = 31; j > 0; j--)
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if (bmp->mask[i] & (1 << j)) {
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if ((j - 7) > 0)
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bmp->mask[i] &= 0xff << (j - 7);
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else
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bmp->mask[i] &= 0xff >> (-(j - 7));
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bmp->shift[i] = (i << 3) - (j - 7);
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break;
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}
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}
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}
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bmp->colours = READ_INT(data, 32);
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if (bmp->colours == 0)
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bmp->colours = (1 << bmp->bpp);
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palette_size = 4;
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/* we don't understand the rest of the data yet */
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}
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data += header_size;
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@ -256,7 +282,7 @@ bmp_result bmp_analyse_header(struct bmp_image *bmp, char *data) {
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/* create our bitmap */
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flags = BITMAP_NEW | BITMAP_CLEAR_MEMORY;
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if (!bmp->ico)
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if ((!bmp->ico) || (bmp->mask[3] == 0))
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flags |= BITMAP_OPAQUE;
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bmp->bitmap = bitmap_create(bmp->width, bmp->height, flags);
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if (!bmp->bitmap) {
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@ -278,7 +304,7 @@ bmp_result bmp_analyse_header(struct bmp_image *bmp, char *data) {
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* as possible from the images in the collection.
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*
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* \param ico the ICO collection to examine
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* \param width the preferred width
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* \param width the preferred width
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* \param height the preferred height
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*/
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struct bmp_image *ico_find(struct ico_collection *ico, int width, int height) {
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@ -341,7 +367,7 @@ bmp_result bmp_decode(struct bmp_image *bmp) {
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if (bmp->bpp >= 24)
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result = bmp_decode_rgb24(bmp, &data, bytes);
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else if (bmp->bpp > 8)
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return BMP_DATA_ERROR;
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result = bmp_decode_rgb16(bmp, &data, bytes);
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else
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result = bmp_decode_rgb(bmp, &data, bytes);
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break;
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@ -352,7 +378,12 @@ bmp_result bmp_decode(struct bmp_image *bmp) {
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result = bmp_decode_rle(bmp, data, bytes, 4);
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break;
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case BMP_ENCODING_BITFIELDS:
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return BMP_DATA_ERROR;
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if (bmp->bpp == 32)
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result = bmp_decode_rgb24(bmp, &data, bytes);
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else if (bmp->bpp == 16)
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result = bmp_decode_rgb16(bmp, &data, bytes);
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else
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return BMP_DATA_ERROR;
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}
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if ((!bmp->ico) || (result != BMP_OK))
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@ -376,6 +407,7 @@ bmp_result bmp_decode_rgb24(struct bmp_image *bmp, char **start, int bytes) {
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unsigned int *scanline;
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unsigned int x, y, swidth, skip;
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unsigned int addr;
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unsigned int i, word;
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data = *start;
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swidth = bitmap_get_rowstride(bmp->bitmap);
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@ -395,9 +427,86 @@ bmp_result bmp_decode_rgb24(struct bmp_image *bmp, char **start, int bytes) {
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scanline = (unsigned int *)(top + (y * swidth));
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else
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scanline = (unsigned int *)(bottom - (y * swidth));
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for (x = 0; x < bmp->width; x++) {
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scanline[x] = data[2] | (data[1] << 8) | (data[0] << 16);
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data += skip;
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if (bmp->encoding == BMP_ENCODING_BITFIELDS) {
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for (x = 0; x < bmp->width; x++) {
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word = data[0] | (data[1] << 8) | (data[2] << 16) |
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(data[3] << 24);
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scanline[x] = 0;
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for (i = 0; i < 4; i++)
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if (bmp->shift[i] > 0)
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scanline[x] |= ((word & bmp->mask[i]) <<
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bmp->shift[i]);
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else
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scanline[x] |= ((word & bmp->mask[i]) >>
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(-bmp->shift[i]));
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data += 4;
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}
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} else {
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for (x = 0; x < bmp->width; x++) {
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scanline[x] = data[2] | (data[1] << 8) | (data[0] << 16) |
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(data[3] << 24);
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data += skip;
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}
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}
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}
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*start = data;
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return BMP_OK;
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}
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/**
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* Decode BMP data stored in 16bpp colour.
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*
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* \param bmp the BMP image to decode
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* \param start the data to decode, updated to last byte read on success
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* \param bytes the number of bytes of data available
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* \return BMP_OK on success
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*/
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bmp_result bmp_decode_rgb16(struct bmp_image *bmp, char **start, int bytes) {
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char *top, *bottom, *end, *data;
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unsigned int *scanline;
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unsigned int x, y, swidth;
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unsigned int addr;
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unsigned int word, i;
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data = *start;
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swidth = bitmap_get_rowstride(bmp->bitmap);
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top = bitmap_get_buffer(bmp->bitmap);
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bottom = top + swidth * (bmp->height - 1);
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end = data + bytes;
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addr = ((unsigned int)data) & 3;
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bmp->decoded = true;
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for (y = 0; y < bmp->height; y++) {
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if (addr != (((unsigned int)data) & 3))
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data += 2;
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if ((data + (2 * bmp->width)) > end)
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return BMP_INSUFFICIENT_DATA;
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if (bmp->reversed)
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scanline = (unsigned int *)(top + (y * swidth));
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else
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scanline = (unsigned int *)(bottom - (y * swidth));
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if (bmp->encoding == BMP_ENCODING_BITFIELDS) {
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for (x = 0; x < bmp->width; x++) {
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word = data[0] | (data[1] << 8);
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scanline[x] = 0;
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for (i = 0; i < 4; i++)
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if (bmp->shift[i] > 0)
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scanline[x] |= ((word & bmp->mask[i]) <<
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bmp->shift[i]);
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else
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scanline[x] |= ((word & bmp->mask[i]) >>
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(-bmp->shift[i]));
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data += 2;
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}
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} else {
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for (x = 0; x < bmp->width; x++) {
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word = data[0] | (data[1] << 8);
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scanline[x] = ((word & (31 << 0)) << 19) |
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((word & (31 << 5)) << 6) |
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((word & (31 << 10)) >> 7);
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data += 2;
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}
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}
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}
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*start = data;
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@ -487,7 +596,7 @@ bmp_result bmp_decode_mask(struct bmp_image *bmp, char *data, int bytes) {
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return BMP_INSUFFICIENT_DATA;
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scanline = (unsigned int *)(bottom - (y * swidth));
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for (x = 0; x < bmp->width; x++) {
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if ((x & 7) == 0)
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if ((x & 7) == 0)
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cur_byte = *data++;
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if ((cur_byte & 128) == 0)
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scanline[x] |= (0xff << 24);
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@ -525,13 +634,13 @@ bmp_result bmp_decode_rle(struct bmp_image *bmp, char *data, int bytes, int size
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bmp->decoded = true;
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do {
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if (data + 2 > end)
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return BMP_INSUFFICIENT_DATA;
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if (data + 2 > end)
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return BMP_INSUFFICIENT_DATA;
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length = *data++;
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if (length == 0) {
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length = *data++;
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if (length == 0) {
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/* 00 - 00 means end of scanline */
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/* 00 - 00 means end of scanline */
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x = 0;
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if (last_y == y) {
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if (++y > bmp->height)
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@ -539,12 +648,12 @@ bmp_result bmp_decode_rle(struct bmp_image *bmp, char *data, int bytes, int size
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}
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last_y = y;
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} else if (length == 1) {
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/* 00 - 01 means end of RLE data */
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/* 00 - 01 means end of RLE data */
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return BMP_OK;
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} else if (length == 2) {
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/* 00 - 02 - XX - YY means move cursor */
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if (data + 2 > end)
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return BMP_INSUFFICIENT_DATA;
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/* 00 - 02 - XX - YY means move cursor */
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if (data + 2 > end)
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return BMP_INSUFFICIENT_DATA;
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x += *data++;
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if (x >= bmp->width)
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return BMP_DATA_ERROR;
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@ -552,7 +661,7 @@ bmp_result bmp_decode_rle(struct bmp_image *bmp, char *data, int bytes, int size
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if (y >= bmp->height)
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return BMP_DATA_ERROR;
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} else {
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/* 00 - NN means escape pixels */
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/* 00 - NN means escape NN pixels */
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if (bmp->reversed) {
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pixels_left = (y + 1) * bmp->width - x;
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scanline = (unsigned int *)(top + (y * swidth));
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@ -560,14 +669,14 @@ bmp_result bmp_decode_rle(struct bmp_image *bmp, char *data, int bytes, int size
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pixels_left = (bmp->height - y + 1) * bmp->width - x;
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scanline = (unsigned int *)(bottom - (y * swidth));
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}
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if (length > pixels_left)
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length = pixels_left;
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if (data + length > end)
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return BMP_INSUFFICIENT_DATA;
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if (length > pixels_left)
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length = pixels_left;
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if (data + length > end)
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return BMP_INSUFFICIENT_DATA;
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/* the following code could be easily optimised by simply
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* checking the bounds on entry and using some simply copying
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* routines if so */
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/* the following code could be easily optimised by simply
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* checking the bounds on entry and using some simply copying
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* routines if so */
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if (size == 8) {
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for (i = 0; i < length; i++) {
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if (x >= bmp->width) {
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@ -586,7 +695,7 @@ bmp_result bmp_decode_rle(struct bmp_image *bmp, char *data, int bytes, int size
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return BMP_DATA_ERROR;
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scanline -= bmp->width;
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}
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if ((i & 1) == 0) {
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if ((i & 1) == 0) {
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pixel = *data++;
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scanline[x++] = bmp->colour_table
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[pixel >> 4];
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@ -602,7 +711,7 @@ bmp_result bmp_decode_rle(struct bmp_image *bmp, char *data, int bytes, int size
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}
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} else {
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/* NN means perform RLE for NN pixels */
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/* NN means perform RLE for NN pixels */
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if (bmp->reversed) {
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pixels_left = (y + 1) * bmp->width - x;
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scanline = (unsigned int *)(top + (y * swidth));
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@ -610,12 +719,12 @@ bmp_result bmp_decode_rle(struct bmp_image *bmp, char *data, int bytes, int size
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pixels_left = (bmp->height - y + 1) * bmp->width - x;
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scanline = (unsigned int *)(bottom - (y * swidth));
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}
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if (length > pixels_left)
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length = pixels_left;
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if (length > pixels_left)
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length = pixels_left;
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/* the following code could be easily optimised by simply
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* checking the bounds on entry and using some simply copying
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* routines if so */
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/* the following code could be easily optimised by simply
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* checking the bounds on entry and using some simply copying
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* routines if so */
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if (size == 8) {
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pixel = bmp->colour_table[(int)*data++];
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for (i = 0; i < length; i++) {
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@ -676,8 +785,8 @@ void ico_finalise(struct ico_collection *ico) {
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for (image = ico->first; image; image = image->next)
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bmp_finalise(&image->bmp);
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while (ico->first) {
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image = ico->first;
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ico->first = image->next;
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free(image);
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image = ico->first;
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ico->first = image->next;
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free(image);
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}
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}
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@ -31,7 +31,6 @@ typedef enum {
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BMP_ENCODING_BITFIELDS = 3
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} bmp_encoding;
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struct bmp_image {
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unsigned char *bmp_data; /** pointer to BMP data */
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unsigned int buffer_size; /** total number of bytes of BMP data available */
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@ -45,6 +44,8 @@ struct bmp_image {
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bool reversed; /** scanlines are top to bottom */
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bool decoded; /** whether the image has been decoded */
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bool ico; /** image is part of an ICO, mask follows */
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unsigned int mask[4]; /** four bitwise mask */
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int shift[4]; /** four bitwise shifts */
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struct bitmap *bitmap; /** decoded image */
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};
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