internal SavableBitDepths ChooseBitDepth(
Set <SavableBitDepths> allowedBitDepths,
Set <SavableBitDepths> losslessBitDepths,
bool allOpaque,
bool all0Or255Alpha,
int uniqueColorCount)
{
if (allowedBitDepths.Count == 0)
{
throw new ArgumentException("Count must be 1 or more", "allowedBitDepths");
}
Tracing.Ping("allowedBitDepths = " + PrintSet(allowedBitDepths));
Tracing.Ping("losslessBitDepths = " + PrintSet(losslessBitDepths));
if (allowedBitDepths.Count == 1)
{
return(allowedBitDepths.ToArray()[0]);
}
// allowedBitDepths.Count >= 2
Set <SavableBitDepths> bestBitDepths = Set <SavableBitDepths> .Intersect(allowedBitDepths, losslessBitDepths);
if (bestBitDepths.Count == 1)
{
return(bestBitDepths.ToArray()[0]);
}
Set <SavableBitDepths> candidates;
if (bestBitDepths.Count == 0)
{
candidates = allowedBitDepths;
}
else
{
candidates = bestBitDepths;
}
// candidates.Count >= 2
// lossless choices
if (candidates.Contains(SavableBitDepths.Rgba8) && all0Or255Alpha && uniqueColorCount <= 255)
{
return(SavableBitDepths.Rgba8);
}
if (candidates.Contains(SavableBitDepths.Rgb8) && allOpaque && uniqueColorCount <= 256)
{
return(SavableBitDepths.Rgb8);
}
if (candidates.Contains(SavableBitDepths.Rgb24) && allOpaque)
{
return(SavableBitDepths.Rgb24);
}
if (candidates.Contains(SavableBitDepths.Rgba32))
{
return(SavableBitDepths.Rgba32);
}
// forced choices -- we wanted Rgba32 but it was not allowed
if (candidates.IsEqualTo(Set.Create(SavableBitDepths.Rgb8, SavableBitDepths.Rgb24)))
{
return(SavableBitDepths.Rgb24);
}
if (candidates.IsEqualTo(Set.Create(SavableBitDepths.Rgb8, SavableBitDepths.Rgba8)))
{
return(SavableBitDepths.Rgba8);
}
if (candidates.IsEqualTo(Set.Create(SavableBitDepths.Rgba8, SavableBitDepths.Rgb24)))
{
return(SavableBitDepths.Rgb24);
}
throw new ArgumentException("Could not accomodate input values -- internal error?");
}
protected unsafe override sealed void OnSaveT(
Document input,
Stream output,
PropertyBasedSaveConfigToken token,
Surface scratchSurface,
ProgressEventHandler progressCallback)
{
// flatten the document -- render w/ transparent background
scratchSurface.Clear(ColorBgra.Transparent);
using (RenderArgs ra = new RenderArgs(scratchSurface))
{
input.Render(ra, false);
}
// load properties from token
int thresholdFromToken = GetThresholdFromToken(token);
int ditherLevel = GetDitherLevelFromToken(token);
Set <SavableBitDepths> allowedBitDepths = CreateAllowedBitDepthListFromToken(token);
if (allowedBitDepths.Count == 0)
{
throw new ArgumentException("there must be at least 1 element returned from CreateAllowedBitDepthListFromToken()");
}
// allowedBitDepths.Count >= 1
// set to 1 unless allowedBitDepths contains only Rgb8 and Rgba8
int threshold;
if (allowedBitDepths.IsSubsetOf(Set.Create(SavableBitDepths.Rgb8, SavableBitDepths.Rgba8)))
{
threshold = thresholdFromToken;
}
else
{
threshold = 1;
}
// Analyze image, try to detect what bit-depth or whatever to use, based on allowedBitDepths
bool allOpaque;
bool all0or255Alpha;
int uniqueColorCount;
Analyze(scratchSurface, out allOpaque, out all0or255Alpha, out uniqueColorCount);
Set <SavableBitDepths> losslessBitDepths = new Set <SavableBitDepths>();
losslessBitDepths.Add(SavableBitDepths.Rgba32);
if (allOpaque)
{
losslessBitDepths.Add(SavableBitDepths.Rgb24);
if (uniqueColorCount <= 256)
{
losslessBitDepths.Add(SavableBitDepths.Rgb8);
}
}
else if (all0or255Alpha && uniqueColorCount < 256)
{
losslessBitDepths.Add(SavableBitDepths.Rgba8);
}
SavableBitDepths bitDepth = ChooseBitDepth(allowedBitDepths, losslessBitDepths, allOpaque, all0or255Alpha, uniqueColorCount);
if (bitDepth == SavableBitDepths.Rgba8 && threshold == 0 && allowedBitDepths.Contains(SavableBitDepths.Rgba8) && allowedBitDepths.Contains(SavableBitDepths.Rgb8))
{
// threshold of 0 should effectively force full 256 color palette, instead of 255+1 transparent
bitDepth = SavableBitDepths.Rgb8;
}
// if bit depth is 24 or 8, then we have to do away with the alpha channel
// for 8-bit, we must have pixels that have either 0 or 255 alpha
if (bitDepth == SavableBitDepths.Rgb8 ||
bitDepth == SavableBitDepths.Rgba8 ||
bitDepth == SavableBitDepths.Rgb24)
{
UserBlendOps.NormalBlendOp blendOp = new UserBlendOps.NormalBlendOp();
for (int y = 0; y < scratchSurface.Height; ++y)
{
for (int x = 0; x < scratchSurface.Width; ++x)
{
ColorBgra p = scratchSurface[x, y];
if (p.A < threshold && bitDepth == SavableBitDepths.Rgba8)
{
p = ColorBgra.FromBgra(0, 0, 0, 0);
}
else
{
p = blendOp.Apply(ColorBgra.White, p);
}
scratchSurface[x, y] = p;
}
}
}
Tracing.Ping("Chose " + bitDepth + ", ditherLevel=" + ditherLevel + ", threshold=" + threshold);
// finally, do the save.
FinalSave(input, output, scratchSurface, ditherLevel, bitDepth, token, progressCallback);
}