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Add support for 8-bit transparent PNG sprites (fixed issue #5).

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This commit is contained in:
David Capello 2011-01-05 00:16:39 -03:00
parent 85e75122b5
commit 6a216ad6a8
1 changed files with 36 additions and 2 deletions
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38
src/file/png_format.cpp
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@ -184,8 +184,10 @@ static bool load_PNG(FileOp *fop)
return false;
}
/* read palette */
// Transparent palette entries
std::vector<bool> trans_entries(256, false);
// Read the palette
if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette)) {
int c;
@ -199,6 +201,20 @@ static bool load_PNG(FileOp *fop)
for (; c < 256; c++) {
fop_sequence_set_color(fop, c, 0, 0, 0);
}
// Read transparent entries
png_bytep trans = NULL; // Transparent palette entries
int num_trans = 0;
png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans, NULL);
for (int i = 0; i < num_trans; ++i) {
int j = trans[i];
if (j >= 0 && j < (int)trans_entries.size()) {
trans_entries[j] = true;
fop->seq.has_alpha = true; // Is a transparent sprite
}
}
}
/* Allocate the memory to hold the image using the fields of info_ptr. */
@ -268,7 +284,15 @@ static bool load_PNG(FileOp *fop)
for (x=0; x<width; x++) {
c = *(src_address++);
*(dst_address++) = c;
// All transparent values are converted to entry 0.
// TODO Add support for multiple transparent palette entries in Indexed sprites.
if (!trans_entries.empty() && trans_entries[c]) {
*(dst_address++) = 0;
}
else {
*(dst_address++) = c;
}
}
}
@ -390,6 +414,16 @@ static bool save_PNG(FileOp *fop)
}
png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH);
// Index 0 will be the transparent color in the PNG file (only if
// the sprite does not have a background layer).
if (fop->sprite->getBackgroundLayer() == NULL) {
png_bytep trans = (png_bytep)png_malloc(png_ptr, 1);
trans[0] = 0; // Entry 0 is transparent
png_set_tRNS(png_ptr, info_ptr, trans, 1, NULL);
png_free(png_ptr, trans);
}
}
/* Write the file header information. */