internal static async Task <GifDataStream> ReadAsync(Stream stream)
{
var file = new GifDataStream();
await file.ReadInternalAsync(stream).ConfigureAwait(false);
return(file);
}
private Animator(Stream sourceStream, Uri sourceUri, GifDataStream metadata, RepeatBehavior repeatBehavior, Image image)
{
_sourceStream = sourceStream;
_sourceUri = sourceUri;
_metadata = metadata;
_image = image;
_palettes = CreatePalettes(metadata);
_bitmap = CreateBitmap(metadata);
var desc = metadata.Header.LogicalScreenDescriptor;
_stride = 4 * ((desc.Width * 32 + 31) / 32);
_previousBackBuffer = new byte[desc.Height * _stride];
_indexStreamBuffer = CreateIndexStreamBuffer(metadata, _sourceStream);
_timingManager = CreateTimingManager(metadata, repeatBehavior);
}
private static RepeatBehavior GetRepeatBehavior(GifDataStream metadata)
{
if (metadata.RepeatCount == 0)
return RepeatBehavior.Forever;
return new RepeatBehavior(metadata.RepeatCount);
}
private static byte[] CreateIndexStreamBuffer(GifDataStream metadata, Stream stream)
{
// Find the size of the largest frame pixel data
// (ignoring the fact that we include the next frame's header)
long lastSize = stream.Length - metadata.Frames.Last().ImageData.CompressedDataStartOffset;
long maxSize = lastSize;
if (metadata.Frames.Count > 1)
{
var sizes = metadata.Frames.Zip(metadata.Frames.Skip(1),
(f1, f2) => f2.ImageData.CompressedDataStartOffset - f1.ImageData.CompressedDataStartOffset);
maxSize = Math.Max(sizes.Max(), lastSize);
}
// Need 4 extra bytes so that BitReader doesn't need to check the size for every read
return new byte[maxSize + 4];
}
private static Dictionary<int, GifPalette> CreatePalettes(GifDataStream metadata)
{
var palettes = new Dictionary<int, GifPalette>();
Color[] globalColorTable = null;
if (metadata.Header.LogicalScreenDescriptor.HasGlobalColorTable)
{
globalColorTable =
metadata.GlobalColorTable
.Select(gc => Color.FromArgb(0xFF, gc.R, gc.G, gc.B))
.ToArray();
}
for (int i = 0; i < metadata.Frames.Count; i++)
{
var frame = metadata.Frames[i];
var colorTable = globalColorTable;
if (frame.Descriptor.HasLocalColorTable)
{
colorTable =
frame.LocalColorTable
.Select(gc => Color.FromArgb(0xFF, gc.R, gc.G, gc.B))
.ToArray();
}
int? transparencyIndex = null;
var gce = frame.GraphicControl;
if (gce != null && gce.HasTransparency)
{
transparencyIndex = gce.TransparencyIndex;
}
palettes[i] = new GifPalette(transparencyIndex, colorTable);
}
return palettes;
}
private static WriteableBitmap CreateBitmap(GifDataStream metadata)
{
var desc = metadata.Header.LogicalScreenDescriptor;
#if WPF
var bitmap = new WriteableBitmap(desc.Width, desc.Height, 96, 96, PixelFormats.Bgra32, null);
#elif WINRT
var bitmap = new WriteableBitmap(desc.Width, desc.Height);
#else
#error Not implemented
#endif
return bitmap;
}
private TimingManager CreateTimingManager(GifDataStream metadata, RepeatBehavior repeatBehavior)
{
var actualRepeatBehavior =
repeatBehavior == default(RepeatBehavior)
? GetRepeatBehavior(metadata)
: repeatBehavior;
var manager = new TimingManager(actualRepeatBehavior);
foreach (var frame in metadata.Frames)
{
manager.Add(GetFrameDelay(frame));
}
manager.Completed += TimingManagerCompleted;
return manager;
}
public ImageAnimator(Stream sourceStream, Uri sourceUri, GifDataStream metadata, RepeatBehavior repeatBehavior, Image image) : base(sourceStream, sourceUri, metadata, repeatBehavior)
{
ErrorSource = image;
}
private BrushAnimator(Stream sourceStream, Uri sourceUri, GifDataStream metadata, RepeatBehavior repeatBehavior) : base(sourceStream, sourceUri, metadata, repeatBehavior)
{
Brush = new ImageBrush {ImageSource = Bitmap};
}
internal static async Task<GifDataStream> ReadAsync(Stream stream)
{
var file = new GifDataStream();
await file.ReadInternalAsync(stream).ConfigureAwait(false);
return file;
}
public ImageAnimator(Stream sourceStream, Uri sourceUri, GifDataStream metadata, RepeatBehavior repeatBehavior, Image image) : base(sourceStream, sourceUri, metadata, repeatBehavior)
{
_image = image;
OnRepeatBehaviorChanged(); // in case the value has changed during creation
}
