從Silverlight中的Image中呈現WriteableBitmap問題

Question

我有下一個問題，我需要使用調整大小將字節數組轉換爲WriteableBitmap。我寫下一個代碼。

private byte[] ResizeImage(byte[] array, double maxWidth, double maxHeight) 
{ 
    WriteableBitmap wb = null; 

    var stream = new MemoryStream(array); 
    stream.Seek(0, SeekOrigin.Begin); 
    var bmp = new WriteableBitmap(0, 0); 
    bmp.SetSource(stream); 
    stream.Close(); 
    var img = new Image(); 
    img.Source = bmp; 
    double scaleX = 1; 
    double scaleY = 1; 
    if (bmp.PixelHeight > maxHeight) 
    { 
     scaleY = maxHeight/bmp.PixelHeight; 
    } 
    if (bmp.PixelWidth > maxWidth) 
    { 
     scaleX = maxWidth/bmp.PixelWidth; 
    } 
    wb = new WriteableBitmap(0, 0); 
    var scale = Math.Min(scaleY, scaleX); 
    wb.Render(img, new ScaleTransform() { ScaleX = scale, ScaleY = scale }); 
    wb.Invalidate(); 
    return Utils.Encode(wb); 

} 

通話wb.Render(img, new ScaleTransform() { ScaleX = scale, ScaleY = scale });後，wb具有零個像素。

請幫忙。

Answer 1

嘗試改變：

wb = new WriteableBitmap(0, 0); 

要：

wb = new WriteableBitmap(maxWidth, maxHeight); 

Answer 2

private byte[] ResizeImage(byte[] array, int maxWidth, int maxHeight) 
{ 
    var stream = new MemoryStream(array); 
    stream.Seek(0, SeekOrigin.Begin); 

    var bmp = new BitmapImage(); 
    bmp.SetSource(stream); 
    stream.Close(); 
    var img = new Image(); 
    img.Source = new BitmapImage(); 

    double scaleX = 1; 
    double scaleY = 1; 
    if (bmp.PixelHeight > maxHeight) 
    { 
     scaleY = maxHeight/bmp.PixelHeight; 
    } 
    if (bmp.PixelWidth > maxWidth) 
    { 
     scaleX = maxWidth/bmp.PixelWidth; 
    } 

    WriteableBitmap wb = new WriteableBitmap(maxWidth, maxHeight); 
    var scale = Math.Min(scaleY, scaleX); 
    wb.Render(img, new ScaleTransform() { ScaleX = scale, ScaleY = scale }); 
    wb.Invalidate(); 

    return Utils.Encode(wb); 
}