public async Task <bool> AddFrame(IRandomAccessStream iRandomAccessStream)
{
if ((iRandomAccessStream == null) || !started || iRandomAccessStream.Size <= 0)
{
return(false);
}
bool ok = true;
try
{
if (!sizeSet)
{
// use first frame's size
Point pointWH = await WriteableBitmapExpansion.GetPixelWidthAndHeight(iRandomAccessStream);
SetSize((int)pointWH.X, (int)pointWH.Y);
}
imageIAStream = iRandomAccessStream;
await GetImagePixels(iRandomAccessStream); // convert to correct format if necessary
AnalyzePixels(); // build color table & map pixels
if (firstFrame)
{
WriteLSD(); // logical screen descriptior
WritePalette(); // global color table
if (repeat >= 0)
{
// use NS app extension to indicate reps
WriteNetscapeExt();
}
}
WriteGraphicCtrlExt(); // write graphic control extension
WriteImageDesc(); // image descriptor
if (!firstFrame)
{
WritePalette(); // local color table
}
WritePixels(); // encode and write pixel data
firstFrame = false;
}
catch (IOException e)
{
ok = false;
}
return(ok);
}
/**
* Extracts image pixels into byte array "pixels"
*/
protected async Task GetImagePixels(IRandomAccessStream iRandomAccessStream)
{
Point pointWH = await WriteableBitmapExpansion.GetPixelWidthAndHeight(iRandomAccessStream);
int w = (int)pointWH.X;
int h = (int)pointWH.Y;
int count = 0;
byte[] tempByte = null;
if ((w != width) ||
(h != height)
)
{
var bytes = await WriteableBitmapExpansion.ResizeBytes(iRandomAccessStream, width, height, BitmapInterpolationMode.Cubic);
//imageIAStream = await WriteableBitmapExpansion.ConvertBytesToIRandomAccessStream(bytes);
pixels = new Byte[3 * width * height];
pointWH = new Point(width, height);
tempByte = bytes;
}
else
{
pointWH = await WriteableBitmapExpansion.GetPixelWidthAndHeight(imageIAStream);
pixels = new Byte[3 * (int)pointWH.X * (int)pointWH.Y];
tempByte = await WriteableBitmapExpansion.WriteableBitmapToBytes(imageIAStream);
}
for (int th = 0; th < pointWH.Y; th++)
{
for (int tw = 0; tw < pointWH.X; tw++)
{
Color color = WriteableBitmapExpansion.GetPixel(tempByte, Convert.ToInt32(pointWH.X), tw, th);
pixels[count] = color.R;
count++;
pixels[count] = color.G;
count++;
pixels[count] = color.B;
count++;
}
}
}