public void DecodeImageScanlines()
{
var path = Path.Combine(PathToImages, "CMYK.jpg");
var imageHeight = 516;
var fileData = File.ReadAllBytes(path);
var correctBitmap = SKBitmap.Decode(path);
var stream = new SKFileStream(path);
using (var codec = SKCodec.Create(stream)) {
var info = new SKImageInfo(codec.Info.Width, codec.Info.Height);
using (var scanlineBitmap = new SKBitmap(info)) {
scanlineBitmap.Erase(SKColors.Fuchsia);
var result = codec.StartScanlineDecode(info);
Assert.Equal(SKCodecResult.Success, result);
Assert.Equal(SKCodecScanlineOrder.TopDown, codec.ScanlineOrder);
Assert.Equal(0, codec.NextScanline);
// only decode every second line
for (int y = 0; y < info.Height; y += 2)
{
Assert.Equal(1, codec.GetScanlines(scanlineBitmap.GetAddress(0, y), 1, info.RowBytes));
Assert.Equal(y + 1, codec.NextScanline);
if (codec.SkipScanlines(1))
{
Assert.Equal(y + 2, codec.NextScanline);
}
else
{
Assert.Equal(imageHeight, codec.NextScanline); // reached the end
}
}
Assert.False(codec.SkipScanlines(1));
Assert.Equal(imageHeight, codec.NextScanline);
for (var x = 0; x < info.Width; x++)
{
for (var y = 0; y < info.Height; y++)
{
if (y % 2 == 0)
{
Assert.Equal(correctBitmap.GetPixel(x, y), scanlineBitmap.GetPixel(x, y));
}
else
{
Assert.Equal(SKColors.Fuchsia, scanlineBitmap.GetPixel(x, y));
}
}
}
}
}
}