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Improves handling of PNG textures based on GdkPixbuf's setup_png_transformations. The PNG decoder should now support grayscale, RGB or indexed color; bit depth up to 16; and interlacing. Fixes #1640, refs #2823, #3082

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This was SVN commit r16439.
This commit is contained in:
historic_bruno 2015-03-16 02:28:00 +00:00
parent b1c4e29ac8
commit 4741e896c4
1 changed files with 48 additions and 12 deletions
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60
source/lib/tex/tex_png.cpp
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@ -125,22 +125,58 @@ static Status png_decode_impl(MemoryStream* stream, png_structp png_ptr, png_inf
// read header and determine format
png_read_info(png_ptr, info_ptr);
png_uint_32 w, h;
int bit_depth, color_type;
png_get_IHDR(png_ptr, info_ptr, &w, &h, &bit_depth, &color_type, 0, 0, 0);
int bit_depth, color_type, interlace_type;
png_get_IHDR(png_ptr, info_ptr, &w, &h, &bit_depth, &color_type, &interlace_type, 0, 0);
// (The following is based on GdkPixbuf's PNG image loader)
// Convert the following images to 8-bit RGB/RGBA:
// * indexed colors
// * grayscale
// * transparency header
// * bit depth of 16 or less than 8
// * interlaced
if (color_type == PNG_COLOR_TYPE_PALETTE && bit_depth <= 8)
png_set_expand(png_ptr);
else if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
png_set_expand(png_ptr);
else if (bit_depth < 8)
png_set_expand(png_ptr);
if (bit_depth == 16)
png_set_strip_16(png_ptr);
if (color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(png_ptr);
if (interlace_type != PNG_INTERLACE_NONE)
png_set_interlace_handling(png_ptr);
// Update info after transformations
png_read_update_info(png_ptr, info_ptr);
png_get_IHDR(png_ptr, info_ptr, &w, &h, &bit_depth, &color_type, &interlace_type, 0, 0);
// make sure format is acceptable:
// * non-zero dimensions
// * 8-bit depth
// * RGB or RGBA
// * 3 or 4 channels
if (w == 0 || h == 0)
WARN_RETURN(ERR::TEX_INVALID_SIZE);
if (bit_depth != 8)
WARN_RETURN(ERR::TEX_NOT_8BIT_PRECISION);
if (color_type != PNG_COLOR_TYPE_RGB && color_type != PNG_COLOR_TYPE_RGB_ALPHA)
WARN_RETURN(ERR::TEX_INVALID_COLOR_TYPE);
const int channels = png_get_channels(png_ptr, info_ptr);
if (channels != 3 && channels != 4)
WARN_RETURN(ERR::TEX_FMT_INVALID);
const size_t pitch = png_get_rowbytes(png_ptr, info_ptr);
const u32 bpp = (u32)(pitch/w * 8);
const u32 bpp = (u32)(pitch / w * 8);
size_t flags = 0;
if(bpp == 32)
if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
flags |= TEX_ALPHA;
if(color_type == PNG_COLOR_TYPE_GRAY)
flags |= TEX_GREY;
// make sure format is acceptable
if(bit_depth != 8)
WARN_RETURN(ERR::TEX_NOT_8BIT_PRECISION);
if(color_type & PNG_COLOR_MASK_PALETTE)
WARN_RETURN(ERR::TEX_INVALID_COLOR_TYPE);
const size_t img_size = pitch * h;
shared_ptr<u8> data;