Reduces size used for png files from 13,366,660 bytes to 13,055,285 bytes in total. Changes size used for oramap files from 2,601,027 bytes to 2,605,779 bytes in total (contained PNGs are smaller, but the oramap zip wrapper didn't compress as well). This slight filesize improvement doesn't noticeably impact loading times.
zopfilpng is used for compression with the following command line:
'zopflipng.exe -y -m image.png image.png'
This follows on from 78bef8a98f and bc5e7d1497. Except now that the PNG decoder supports bit depths of 1, 2 or 4 we don't have to preserve the original bit depth of the image, allowing for more compression.
The oramap files were updated by:
- Running utility command "<mod> --unpack-map unpack" for each mod.
- Compressing the png files using the command above.
- Running utility command "<mod> --unpack-map repack" for each mod, except in Map.Save the line `if (!LockPreview) { var previewData = ...` is replaced with `if (false) { var previewData = ...` to save the existing optimized image on disk rather than generating a fresh preview.
Reduces size used for png files from 19,034,446 bytes to 13,305,798 bytes in total. The smaller files also improve loading times as the zlib decoder has less bytes to schlep through.
The PNG decoder shipped with OpenRA only supports a bit depth of 8 for images with a palette, so must must ensure that other depths (1,2 or 4) are not used.
zopfilpng is used for compression with the following command line:
'zopflipng.exe --keepcolortype -y -m image.png image.png'
The keepcolortype flag ensures the bit depth is not changed.
