I've been playing around with NGif Animator for resizing animated gifs and it does resize but parts in many animated gifs I've tried get erased. I looked through the comments on that page and didn't see anyone else mention it.
To eliminate resizing as the cause I simply loop through the frames and save each one. Each frame is a System.Drawing.Image. Transparency is set to none (Color.Empty).
This is my test method currently:
GifDecoder gifDecoder = new GifDecoder();
MemoryStream memoryStream = new MemoryStream();
new BinaryWriter((Stream)memoryStream).Write(imageToResize); // byte array
memoryStream.Position = 0L;
gifDecoder.Read((Stream)memoryStream);
memoryStream.Dispose();
string filename = Guid.NewGuid().ToString().Replace("-", String.Empty) + ".gif";
string output = path + @"\" + filename;
AnimatedGifEncoder animatedGifEncoder = new AnimatedGifEncoder();
animatedGifEncoder.Start(output);
animatedGifEncoder.SetRepeat(gifDecoder.GetLoopCount());
animatedGifEncoder.SetQuality(10); // They say 20 is max quality will get, I've tried higher. Makes it a little bit better but black areas instead of gray. 10 is their default.
animatedGifEncoder.SetTransparent(Color.Empty); // This is default either way
int frameCount = gifDecoder.GetFrameCount();
int num = 0;
Image frame;
Image image = null;
for (int index = frameCount; num < index; ++num)
{
frame = gifDecoder.GetFrame(num);
animatedGifEncoder.SetDelay(gifDecoder.GetDelay(num));
string fname = @"C:\Development\images\frame_" + num.ToString() + ".gif";
if (File.Exists(fname)) { File.Delete(fname); }
frame.Save(fname);
animatedGifEncoder.AddFrame(image);
}
animatedGifEncoder.Finish();
Here's an example of what's happening:
The background is gone and it's gray.
It's supposed to look like:
Anyone have experience with NGif and know what would cause this? The first frame is always fine. It's the others after that have a problem so I'm guessing something isn't being reset from frame to frame (or re-read). I've been adding more things to their reset frame method but so far it hasn't helped. That now looks like:
protected void ResetFrame()
{
lastDispose = dispose;
lastRect = new Rectangle(ix, iy, iw, ih);
lastImage = image;
lastBgColor = bgColor;
delay = 0;
transparency = false; // I don't want transparency
lct = null;
act = null;
transIndex = -1;
}
