Create an animated bitmap programmatically

Unfortunately, we cannot redistribute neither System.Drawing.Image

, nor System.Drawing.Bitmap

, so overriding image.FrameDimensionsLists

and similar members is out of the question, and Hans Passant's Windows image encoders maintain time measurement on their own. However, I do believe in this specific case based on

I know I can play the animation if I have frames from any source by doing it manually, but I want to do it in a compatible way: If I could create a bitmap like this, I could just use it on a Button, Label, PictureBox or any other existing control and built-in ImageAnimator can handle it automatically as well.

We can get away by injecting a new class that can handle animations and then implicitly cast it into Bitmap. We can use extension methods to automatically activate animations for controls. I know this method is a hack, but I thought it might be worth mentioning this.

Here is a rough implementation and example usage.

AnimatedBitmap: Handles the framework and time-based animation base on the provided sequences:

 public class Sequence
    {
        public Image Image { get; set; }
        public int Delay { get; set; }
    }

    public class AnimatedBitmap:IDisposable
    {
        private readonly Bitmap _buffer;
        private readonly Graphics _g;
        private readonly Sequence[] _sequences;
        private readonly CancellationTokenSource _cancelToken;

        public event EventHandler FrameUpdated;

        protected void OnFrameUpdated()
        {
            if (FrameUpdated != null)
                FrameUpdated(this, EventArgs.Empty);
        }

        public AnimatedBitmap(int width, int height, params Sequence[] sequences)
        {
            _buffer = new Bitmap(width, height, PixelFormat.Format32bppArgb) {Tag = this};

            _sequences = sequences;
            _g=Graphics.FromImage(_buffer);
            _g.CompositingMode=CompositingMode.SourceCopy;

            _cancelToken = new CancellationTokenSource();
            Task.Factory.StartNew(Animate
                , TaskCreationOptions.LongRunning
                , _cancelToken.Token);
        }

        private void Animate(object obj)
        {
            while (!_cancelToken.IsCancellationRequested)
                foreach (var sequence in _sequences)
                {
                    if (_cancelToken.IsCancellationRequested)
                        break;

                    _g.Clear(Color.Transparent);
                    _g.DrawImageUnscaled(sequence.Image,0,0);
                    _g.Flush(FlushIntention.Flush);
                    OnFrameUpdated();
                    Thread.Sleep(sequence.Delay);
                }

            _g.Dispose();
            _buffer.Dispose();
        }

        public AnimatedBitmap(params Sequence[] sequences)
            : this(sequences.Max(s => s.Image.Width), sequences.Max(s => s.Image.Height), sequences)
        {
        }

        public void Dispose()
        {
            _cancelToken.Cancel();
        }

        public static implicit operator Bitmap(AnimatedBitmap animatedBitmap)
        {
            return animatedBitmap._buffer;
        }

        public static explicit operator AnimatedBitmap(Bitmap bitmap)
        {
            var tag = bitmap.Tag as AnimatedBitmap;
            if (tag != null)
                return tag;

            throw new InvalidCastException();
        }

        public static AnimatedBitmap CreateAnimation(Image[] frames, int[] delays)
        {
            var sequences = frames.Select((t, i) => new Sequence {Image = t, Delay = delays[i]}).ToArray();
            var animated=new AnimatedBitmap(sequences);
            return animated;
        }
    }

      

        
        
        
      

    

AnimationController: Handles updating animation controls

public static class AnimationController
{
    private static readonly List<Control> Controls =new List<Control>();
    private static CancellationTokenSource _cancelToken;

    static AnimationController()
    {
        _cancelToken = new CancellationTokenSource();
        _cancelToken.Cancel();
    }

    private static void Animate(object arg)
    {
        while (!_cancelToken.IsCancellationRequested)
        {
            Controls.RemoveAll(c => !(c.BackgroundImage.Tag is AnimatedBitmap));

            foreach (var c in Controls)
            {
                var control = c;
                if (!control.Disposing)
                    control.Invoke(new Action(() => control.Refresh()));
            }

            Thread.Sleep(40);
        }
    }

    public static void StartAnimation(this Control control)
    {
        if (_cancelToken.IsCancellationRequested)
        {
            _cancelToken = new CancellationTokenSource();
            Task.Factory.StartNew(Animate
                , TaskCreationOptions.LongRunning
                , _cancelToken.Token);
        }

        Controls.Add(control);
        control.Disposed += Disposed;
    }

    private static void Disposed(object sender, EventArgs e)
    {
        (sender as Control).StopAnimation();
    }

    public static void StopAnimation(this Control control)
    {
        Controls.Remove(control);
        if(Controls.Count==0)
            _cancelToken.Cancel();
    }

    public static void SetAnimatedBackground(this Control control, AnimatedBitmap bitmap)
    {
        control.BackgroundImage = bitmap;
        control.StartAnimation();
    }
}

      

        
        
        
      

    

and here is a usage example:

    public Form1()
    {
        InitializeComponent();

        var frame1 = Image.FromFile(@"1.png");
        var frame2 = Image.FromFile(@"2.png");

        var animatedBitmap= new AnimatedBitmap(
            new Sequence {Image = frame1, Delay = 33},
            new Sequence {Image = frame2, Delay = 33}
            );

        // or we can do
        //animatedBitmap = AnimatedBitmap.CreateAnimation(new[] {frame1, frame2}, new[] {1000, 2000});

        pictureBox1.SetAnimatedBackground(animatedBitmap);
        button1.SetAnimatedBackground(animatedBitmap);
        label1.SetAnimatedBackground(animatedBitmap);
        checkBox1.SetAnimatedBackground(animatedBitmap);

        //or we can do
        //pictureBox1.BackgroundImage = animatedBitmap;
        //pictureBox1.StartAnimation();
    }