public static unsafe Bitmap ExtractThumb(IniFile map) {
var prevSection = map.GetSection("Preview");
var size = prevSection.ReadString("Size").Split(',');
var previewSize = new Rectangle(int.Parse(size[0]), int.Parse(size[1]), int.Parse(size[2]), int.Parse(size[3]));
var preview = new Bitmap(previewSize.Width, previewSize.Height, PixelFormat.Format24bppRgb);
byte[] image = new byte[preview.Width * preview.Height * 3];
var prevDataSection = map.GetSection("PreviewPack");
var image_compressed = Convert.FromBase64String(prevDataSection.ConcatenatedValues());
Format5.DecodeInto(image_compressed, image, 5);
// invert rgb->bgr
BitmapData bmd = preview.LockBits(new Rectangle(0, 0, preview.Width, preview.Height), ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);
int idx = 0;
for (int y = 0; y < bmd.Height; y++) {
byte* row = (byte*)bmd.Scan0 + bmd.Stride * y;
byte* p = row;
for (int x = 0; x < bmd.Width; x++) {
byte b = image[idx++];
byte g = image[idx++];
byte r = image[idx++];
*p++ = r;
*p++ = g;
*p++ = b;
}
}
preview.UnlockBits(bmd);
return preview;
}