windows 8 metro 风格开发（8）-图片压缩
目前win8 的SDK中还没有图片压缩处理的API，只能借助第三方的类库来处理。可惜专门针对win8的图片压缩处理的第三方类库也没有。不过还好，win8的API跟Silverlight的API是差不多的，所以可以直接从Silverlight中移植过来。我找了一个LibJpeg.net的Silverlight版的类库源码，经过简单的修改，改为win8版的图片压缩处理类库。这个类库可以对图片进行按质量百分比的压缩。
下面贴出部分代码。
protected override async void OnNavigatedTo(NavigationEventArgs e)
{
string str = "http://gimg.vancl.com/img/02/8705542.jpg";
var storageFile = await Windows.Storage.StorageFile.CreateStreamedFileFromUriAsync("temp.jpg", new Uri(str, UriKind.Absolute), null);
var file = await storageFile.OpenAsync(Windows.Storage.FileAccessMode.Read);
//原图
BitmapImage bitImage1 = new BitmapImage();
bitImage1.SetSource(file);
img.Source = bitImage1;
txt.Text = "原图大小：" + file.Size;
//原图压缩处理
var jpegimage = new JpegImage(file.AsStream());
System.IO.MemoryStream stream = new MemoryStream();
jpegimage.WriteJpeg(stream, new CompressionParameters() { Quality = 20 });//压缩质量为20%
byte[] buffer = new byte;
stream.Seek(0, SeekOrigin.Begin);
stream.Read(buffer, 0, buffer.Length);
var ibuffer = CryptographicBuffer.CreateFromByteArray(buffer);
InMemoryRandomAccessStream memoryRandomStream = new InMemoryRandomAccessStream();
await memoryRandomStream.WriteAsync(ibuffer);
memoryRandomStream.Seek(0);
BitmapImage bitImage2 = new BitmapImage();
bitImage2.SetSource(memoryRandomStream);
img2.Source = bitImage2;
txt2.Text = "压缩后图片大小：" + memoryRandomStream.Size;
}
完整代码下载
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