如何：对 GIF 图像进行编码和解码
更新：2007 年 11 月
下面的示例演示如何使用特定的 GifBitmapDecoder 和 GifBitmapEncoder 对象来对图形交换格式 (GIF) 图像进行解码和编码。有关完整示例，请参见 GIF 编码器和解码器示例。
示例
下面的示例演示如何从 FileStream 中使用 GifBitmapDecoder 对 GIF 图像进行解码。
' Open a Stream and decode a GIF image
Dim imageStreamSource As New FileStream("tulipfarm.gif", FileMode.Open, FileAccess.Read, FileShare.Read)
Dim decoder As New GifBitmapDecoder(imageStreamSource, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default)
Dim bitmapSource As BitmapSource = decoder.Frames(0)
' Draw the Image
Dim myImage As New Image()
myImage.Source = bitmapSource
myImage.Stretch = Stretch.None
myImage.Margin = New Thickness(20)
// Open a Stream and decode a GIF image
Stream imageStreamSource = new FileStream("tulipfarm.gif", FileMode.Open, FileAccess.Read, FileShare.Read);
GifBitmapDecoder decoder = new GifBitmapDecoder(imageStreamSource, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);
BitmapSource bitmapSource = decoder.Frames[0];
// Draw the Image
Image myImage = new Image();
myImage.Source = bitmapSource;
myImage.Stretch = Stretch.None;
myImage.Margin = new Thickness(20);
下面的示例演示如何使用 GifBitmapEncoder 将 BitmapSource 编码为 GIF 图像。
Dim width As Integer = 128
Dim height As Integer = width
Dim stride As Integer = CType(width / 8, Integer)
Dim pixels(height * stride) As Byte
' Define the image palette
Dim myPalette As BitmapPalette = BitmapPalettes.WebPalette
' Creates a new empty image with the pre-defined palette
Dim image As BitmapSource = System.Windows.Media.Imaging.BitmapSource.Create(width, height, 96, 96, PixelFormats.Indexed1, myPalette, pixels, stride)
Dim stream As New FileStream("new.gif", FileMode.Create)
Dim encoder As New GifBitmapEncoder()
Dim myTextBlock As New TextBlock()
myTextBlock.Text = "Codec Author is: " + encoder.CodecInfo.Author.ToString()
encoder.Frames.Add(BitmapFrame.Create(image))
encoder.Save(stream)
int width = 128;
int height = width;
int stride = width / 8;
byte[] pixels = new byte[height * stride];
// Define the image palette
BitmapPalette myPalette = BitmapPalettes.WebPalette;
// Creates a new empty image with the pre-defined palette
BitmapSource image = BitmapSource.Create(
width,
height,
96,
96,
PixelFormats.Indexed1,
myPalette,
pixels,
stride);
FileStream stream = new FileStream("new.gif", FileMode.Create);
GifBitmapEncoder encoder = new GifBitmapEncoder();
TextBlock myTextBlock = new TextBlock();
myTextBlock.Text = "Codec Author is: " + encoder.CodecInfo.Author.ToString();
encoder.Frames.Add(BitmapFrame.Create(image));
encoder.Save(stream);