Use StbSharp for all Texture2D.FromStream #6008
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Also, all images will be converted to 32-bit on loading as Stb is called with Imaging.STBI_rgb_alpha. It could be avoided by using Imaging.STBI__default, then images will be loaded with their original channels per pixel. But then a conversion code will be required to convert image to the corresponding SurfaceType. |
That should be correct. If i remember correctly XNA only returned |
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That is correct. I tested XNA with 1-, 8-, 24- and 32-bit PNGs and it
returns each with a texture with SurfaceFormat.Color, so the current
behaviour is correct. I added the optimisation that it checks for zero
alpha only on images that had less than four channels in the source image.
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I see. Thanks for the explanation. |
| using (var bitmap = LoadBitmap(stream, out decoder)) | ||
| using (decoder) | ||
| // XNA blacks out any pixels with an alpha of zero. | ||
| if (channels == 4) |
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This should be unnecessary as we always read 4 channels?
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Oh wait... is this the original number for channels before conversion to RGBA? If so i see this is just here to avoid doing the black out if the data was 24bit and didn't have alpha to begin with.
| b[i + 0] = 0; | ||
| b[i + 1] = 0; | ||
| b[i + 2] = 0; | ||
| } |
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Do we know if this is necessary with STB? We should determine if it internally does this already to avoid the extra work.
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XNA was unique in this regard by partially premultiplying alpha (only where A = 0). STB returns the data as in the original PNG. In my test case, this was RGB = 0xFFFFFF and A = 0.
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Agree, why adding extra dependency if we can use WIC on windows and the corresponding platform code? |
That's what we are trying to avoid. We want one managed codebase that works on all platforms. |
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Would love to see this merged! Most of our textures are loaded via FromStream directly from PNGs, but it seems some driver vendors do not support this and crash instead. The less we can depend on driver vendors the better, IMO. |
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Sorry, my PR #6131 created conflict with this one. |
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@KonajuGames can you rebase this? |
StbSharp is now used for all implementations of Texture2D.FromStream(GraphicsDevice, Stream), avoiding discrepancies with OS-provided image loading routines. As a result of this, DirectX platforms no longer support TIF or DDS through FromStream(). Added unit tests for loading 1-, 8-, 24- and 32-bit PNGs. Fixes MonoGame#6001
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This PR is now rebased and passing again. |
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looks good, @tomspilman |
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Thanks @KonajuGames ! |
StbSharp is now used for all implementations of Texture2D.FromStream(GraphicsDevice, Stream), avoiding discrepancies with OS-provided image loading routines.
As a result of this, DirectX platforms no longer support TIF or DDS through FromStream().
Added unit tests for loading 1-, 8-, 24- and 32-bit PNGs.
Fixes #6001