C# Programming > Drawing GDI+

C# Displaying Animated GIF

The Code - An Animated GIF Class

Let's apply all of the concepts into one easy-to-use C# class:

public class GifImage
{
     private Image gifImage;
     private FrameDimension dimension;
     private int frameCount;
     private int currentFrame;
     private bool reverse;
     private int step = 1;

     public GifImage(string path)
     {
          gifImage = Image.FromFile(path); //initialize
          dimension = new FrameDimension(gifImage.FrameDimensionsList[0]); //gets the GUID
          frameCount = gifImage.GetFrameCount(dimension); //total frames in the animation
     }

     public bool ReverseAtEnd //whether the gif should play backwards when it reaches the end
     {
          get { return reverse; }
          set { reverse = value; }
     }

     public Image GetNextFrame()
     {

          currentFrame += step;

          //if the animation reaches a boundary...
          if (currentFrame >= frameCount || currentFrame < 1)
          {
               if (reverse)
               {
                    step *= -1; //...reverse the count
                    currentFrame += step; //apply it
               }
               else
                    currentFrame = 0; //...or start over
          }
          return GetFrame(currentFrame);
     }

     public Image GetFrame(int index)
     {
          gifImage.SelectActiveFrame(dimension, index); //find the frame
          return (Image)gifImage.Clone(); //return a copy of it
     }
}

Conclusion

There are a few things to keep in mind. The SelectActivateFrame C# function modifies the same Image object, in which case you need to call the Clone() method before returning the new frame.

The above C# class for displaying animated GIFs also shows a small sample of the possibities of manually extracting frames from a GIF. One being that the frames are displayed backwards when the animation reaches the end. The GetFrame C# function allows direct access to any frame, which opens to door to custom FPS (frames per second) display...

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