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From Eric Sokolowsky, fixed problems in PNG plugin for handling

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paletted images which contain alpha values.
This commit is contained in:
Robert Osfield
2004-05-12 10:45:36 +00:00
parent f66599e00c
commit 82562e5bdd
1 changed files with 28 additions and 6 deletions
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34
src/osgPlugins/png/ReaderWriterPNG.cpp
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@@ -108,12 +108,26 @@ class ReaderWriterPNG : public osgDB::ReaderWriter
// if (!(PalettedTextures && mipmap >= 0 && trans == PNG_SOLID))
// if (!(PalettedTextures && mipmap >= 0 && trans == PNG_SOLID))
//if (color == PNG_COLOR_TYPE_PALETTE)
// png_set_expand(png);
// In addition to expanding the palette, we also need to check
// to expand greyscale and alpha images. See libpng man page.
if (color == PNG_COLOR_TYPE_PALETTE)
png_set_expand(png);
png_set_palette_to_rgb(png);
if (color == PNG_COLOR_TYPE_GRAY && depth < 8)
png_set_gray_1_2_4_to_8(png);
if (png_get_valid(png, info, PNG_INFO_tRNS))
png_set_tRNS_to_alpha(png);
// Make sure that files of small depth are packed properly.
if (depth < 8)
png_set_packing(png);
/*--GAMMA--*/
// checkForGammaEnv();
// checkForGammaEnv();
double screenGamma = 2.2 / 1.0;
if (png_get_gAMA(png, info, &fileGamma))
png_set_gamma(png, screenGamma, fileGamma);
@@ -136,6 +150,7 @@ class ReaderWriterPNG : public osgDB::ReaderWriter
png_read_image(png, row_p);
delete [] row_p;
png_read_end(png, endinfo);
GLenum pixelFormat = 0;
GLenum dataType = depth==8?GL_UNSIGNED_BYTE:GL_UNSIGNED_SHORT;
@@ -150,13 +165,20 @@ class ReaderWriterPNG : public osgDB::ReaderWriter
case(PNG_COLOR_TYPE_RGB_ALPHA): pixelFormat = GL_RGBA; break;
default: break;
}
// Some paletted images contain alpha information. To be
// able to give that back to the calling program, we need to
// check the number of channels in the image. However, the
// call might not return correct information unless
// png_read_end is called first. See libpng man page.
if (pixelFormat == GL_RGB && png_get_channels(png, info) == 4)
pixelFormat = GL_RGBA;
int internalFormat = pixelFormat;
png_read_end(png, endinfo);
png_destroy_read_struct(&png, &info, &endinfo);
// delete [] data;
// delete [] data;
if (fp)
fclose(fp);