GIF animation in WPF

Zolador

Rate me:

3.41/5 (9 votes)

14 Feb 2008CPOL

124.7K

4.7K

Animation of a transparent GIF image in WPF.

Download source code - 60 KB

Introduction

I have found a solution for GIF animation by only using Windows Forms. Based on this, I have solved this problem in WPF (.NET 3.5).

Using the Code

I have created my own class:

public class AnimatedImageControl : UserControl {...}

and overridden the OnRender function:

protected override void OnRender(DrawingContext p_drawingContext)
{ 
   //Get the next frame ready for rendering.
   ImageAnimator.UpdateFrames(m_animatedImage);

   //Draw the next frame in the animation.
   Graphics gr = Graphics.FromHwnd(m_hwnd.Handle);
   gr.FillRectangle(m_brush, m_rectangle);
   gr.DrawImage(m_animatedImage, m_rectangle);
}

Points of Interest

The main trick is using Graphics instead of DrawingContext.

It works properly only if the background is a solid color brush, because calling FillRectangle() is necessary.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Written By

Zolador

Hungary

This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

protected override void OnRender(DrawingContext p_drawingContext) { //Get the next frame ready for rendering. ImageAnimator.UpdateFrames(m_animatedImage); //Draw the next frame in the animation. Bitmap drawableBMP = new Bitmap(m_animatedImage.Width, m_animatedImage.Height); Graphics gdc = Graphics.FromImage(drawableBMP); gdc.DrawImage(m_animatedImage, new System.Drawing.Rectangle(0, 0, m_rectangle.Width, m_rectangle.Height)); MemoryStream outStream = TransparentGif.DrawTransparentGif(drawableBMP, m_animatedImage.Width, m_animatedImage.Height); System.Windows.Media.Imaging.BitmapImage bmpImage = new System.Windows.Media.Imaging.BitmapImage(); bmpImage.BeginInit(); bmpImage.StreamSource = outStream; bmpImage.EndInit(); System.Windows.Controls.Image image = new System.Windows.Controls.Image(); image.Source = bmpImage; p_drawingContext.DrawImage(image.Source, new Rect(m_rectangle.X, m_rectangle.Y, m_rectangle.Width, m_rectangle.Height)); gdc.Dispose(); }

public class TransparentGif { public static MemoryStream DrawTransparentGif(Bitmap drawableBMP, Int32 width, Int32 height) { try { MemoryStream memStream = new MemoryStream(); drawableBMP.Save(memStream, ImageFormat.Gif); memStream.Seek(0, SeekOrigin.Begin); System.Drawing.Image gifed = System.Drawing.Image.FromStream(memStream, true, true); ColorPalette cp = gifed.Palette; Int32 alpha = 0; for (Int32 c = 0; c < cp.Entries.Length; c++) { if (cp.Entries[c].A == 0) { alpha = c; break; } } BitmapData data = ((Bitmap)gifed).LockBits( new System.Drawing.Rectangle(0, 0, width, height), ImageLockMode.ReadWrite, gifed.PixelFormat); long length = data.Stride * height; Byte[] buffer = new Byte[length]; Marshal.Copy(data.Scan0, buffer, 0, (int)length); for (Int32 c = 0; c < buffer.Length; c++) { if (cp.Entries[buffer[c]].ToArgb() == System.Drawing.Color.Black.ToArgb()) { buffer[c] = (Byte)alpha; } } Marshal.Copy(buffer, 0, data.Scan0, buffer.Length); ((Bitmap)gifed).UnlockBits(data); MemoryStream outStream = new MemoryStream(); gifed.Save(outStream, ImageFormat.Gif); outStream.Seek(0, SeekOrigin.Begin); return outStream; } catch { return null; }; } }

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

GIF animation in WPF

Introduction

Using the Code

Points of Interest

License

Comments and Discussions