Can't resize an animated GIF when using streams instead of directory paths

Hello,

Can't resize an animated GIF when using streams instead of directory paths... The stream has 0 length... Could you help me with this?

Code snippet:

private static byte[] ResizeAnimatedGif(byte[] media, int Width, int height)
{
	using (var exportedImageStream = new MemoryStream())
	using (var imageReader = new GifReader(new MemoryStream(media)))
	using (var imageWriter = new GifWriter(exportedImageStream))
	{
   
		var kX = (float)Width / (float)imageReader.Width;
		var kY = (float)height / (float)imageReader.Height;

		imageWriter.BackgroundIndex = imageReader.BackgroundEntryIndex;
		imageWriter.Palette = imageReader.Palette;
		imageWriter.PlaybackCount = imageReader.PlaybackCount;

		for (var i = 0; i < imageReader.Frames.Count; i++)
		{
			using (var frame = imageReader.Frames[i])
			using (var bitmap = frame.GetBitmap())
			{
				var palette = bitmap.Palette;
				var pixelFormat = bitmap.PixelFormat;

				// Convert the bitmap to a non-indexed format
				bitmap.ColorManagement.Convert(ColorSpace.Rgb, true, false);

				var newWidth = Math.Max(1, (int)(bitmap.Width * kX));
				var newHeight = Math.Max(1, (int)(bitmap.Height * kY));

				//Use ResizeInterpolationMode.Low to prevent noise
				bitmap.Transforms.Resize(newWidth, newHeight, ResizeInterpolationMode.Low);

				bitmap.Palette = palette;
				bitmap.ColorManagement.Convert(pixelFormat);

				imageWriter.FrameOptions.Left = (ushort)(frame.Left * kX);
				imageWriter.FrameOptions.Top = (ushort)(frame.Top * kY);
				imageWriter.FrameOptions.Delay = frame.Delay;
				imageWriter.FrameOptions.DisposalMethod = frame.DisposalMethod;

				Pipeline.Run(bitmap + imageWriter);
			}
		}

		return exportedImageStream.GetBuffer();
	}

}

I'm using Graphics Mill v9.0.21

Thank you,
Bruno

attach #1307

We confirm the problem (Aurigma Bug #0022949). It seems GifWriter doesn't work correctly with MemoryStream.

We will fix it shortly. I will keep you informed of the status.

To fix the problem you should:

1. Сlose GifWriter before getting a byte array.
2. Use the MemoryStream.ToArray method instead of MemoryStream.GetBuffer.

private static byte[] ResizeAnimatedGif(byte[] media, int Width, int height)
{
	using (var exportedImageStream = new MemoryStream())
	using (var imageReader = new GifReader(new MemoryStream(media)))
	using (var imageWriter = new GifWriter(exportedImageStream))
	{
		var kX = (float)Width / (float)imageReader.Width;
		var kY = (float)height / (float)imageReader.Height;

		imageWriter.BackgroundIndex = imageReader.BackgroundEntryIndex;
		imageWriter.Palette = imageReader.Palette;
		imageWriter.PlaybackCount = imageReader.PlaybackCount;

		for (var i = 0; i < imageReader.Frames.Count; i++)
		{
			using (var frame = imageReader.Frames[i])
			using (var bitmap = frame.GetBitmap())
			{
				var palette = bitmap.Palette;
				var pixelFormat = bitmap.PixelFormat;

				// Convert the bitmap to a non-indexed format
				bitmap.ColorManagement.Convert(ColorSpace.Rgb, true, false);

				var newWidth = Math.Max(1, (int)(bitmap.Width * kX));
				var newHeight = Math.Max(1, (int)(bitmap.Height * kY));

				//Use ResizeInterpolationMode.Low to prevent noise
				bitmap.Transforms.Resize(newWidth, newHeight, ResizeInterpolationMode.Low);

				bitmap.Palette = palette;
				bitmap.ColorManagement.Convert(pixelFormat);

				imageWriter.FrameOptions.Left = (ushort)(frame.Left * kX);
				imageWriter.FrameOptions.Top = (ushort)(frame.Top * kY);
				imageWriter.FrameOptions.Delay = frame.Delay;
				imageWriter.FrameOptions.DisposalMethod = frame.DisposalMethod;

				Pipeline.Run(bitmap + imageWriter);
			}
		}

		exportedImageStream.Position = 0;

		imageWriter.Close();
		return exportedImageStream.ToArray();
	}
}