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From Stephan Huber, improved performance by using native apple functions for flipping image

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This commit is contained in:
Robert Osfield 2012-11-06 11:18:33 +00:00
parent f09b9576c6
commit 4fa32ee0b8
1 changed files with 12 additions and 38 deletions
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50
src/osgPlugins/imageio/ReaderWriterImageIO.cpp
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@ -376,7 +376,9 @@ osg::Image* CreateOSGImageFromCGImage(CGImageRef image_ref)
color_space,
bitmap_info
);
CGContextTranslateCTM(bitmap_context, 0, the_height);
CGContextScaleCTM(bitmap_context, 1.0, -1.0);
// Draws the image into the context's image_data
CGContextDrawImage(bitmap_context, the_rect, image_ref);
@ -385,42 +387,15 @@ osg::Image* CreateOSGImageFromCGImage(CGImageRef image_ref)
if (!image_data)
return NULL;
//
// Reverse the premultiplied alpha for avoiding unexpected darker edges
// by Tatsuhiro Nishioka (based on SDL's workaround on the similar issue)
// http://bugzilla.libsdl.org/show_bug.cgi?id=868
//
if (bits_per_pixel > 8 && (bitmap_info & kCGBitmapAlphaInfoMask) == kCGImageAlphaPremultipliedFirst) {
int i, j;
GLubyte *pixels = (GLubyte *)image_data;
for (i = the_height * the_width; i--; ) {
#if __BIG_ENDIAN__
// That value is a temporary one and only needed for endianess conversion
GLuint *value = (GLuint *)pixels;
//
// swap endian of each pixel for avoiding weird colors on ppc macs
// by Tatsuhiro Nishioka
// FIXME: I've tried many combinations of pixel_format, internal_format, and data_type
// but none worked well. Therefore I tried endian swapping, which seems working with gif,png,tiff,tga,and psd.
// (for grayscaled tga and non-power-of-two tga, I can't guarantee since test images (made with Gimp)
// get corrupted on Preview.app ...
*value = ((*value) >> 24) | (((*value) << 8) & 0x00FF0000) | (((*value) >> 8) & 0x0000FF00) | ((*value) << 24);
#endif
GLubyte alpha = pixels[3];
if (alpha) {
for (j = 0; j < 3; ++j) {
pixels[j] = (pixels[j] * 255) / alpha;
}
}
pixels += 4;
}
}
//
// Workaround for ignored alpha channel
// by Tatsuhiro Nishioka
// FIXME: specifying GL_UNSIGNED_INT_8_8_8_8_REV or GL_UNSIGNED_INT_8_8_8_8 ignores the alpha channel.
// alpha is premultiplied with rgba, undo it
vImage_Buffer vb;
vb.data = image_data;
vb.height = the_height;
vb.width = the_width;
vb.rowBytes = the_width * 4;
vImageUnpremultiplyData_RGBA8888(&vb, &vb, 0);
// changing it to GL_UNSIGNED_BYTE seems working, but I'm not sure if this is a right way.
//
data_type = GL_UNSIGNED_BYTE;
@ -437,7 +412,6 @@ osg::Image* CreateOSGImageFromCGImage(CGImageRef image_ref)
osg::Image::USE_MALLOC_FREE // Assumption: osg_image takes ownership of image_data and will free
);
osg_image->flipVertical();
return osg_image;