c# - BitmapImage 构造函数（Uri）在 Windows Phone 7 上不起作用

Question

BitmapImage tempBitmap = new BitmapImage(onlineImageLocation);

相当简单的代码。OnlineImageLocation 指的是http://dantonybrown.com/brownsoft/SweepyCleaner.png

但在构建位图图像后不包含填充字段。甚至 PixelWidth 和 PixelHeight 都是 0。

有任何想法吗？

丹尼

Answer 1

For instance like this?

    BitmapImage bmpImage = new BitmapImage(new Uri("http://dantonybrown.com/brownsoft/SweepyCleaner.png"));
    MessageBox.Show(bmpImage.PixelWidth.ToString());

That makes perfect sense. The image is loaded on demand, and on the background. You have multiple options here:

1. Assign the BitmapImage to an Image control. You can access the properties after the ImageLoaded event occured:

       BitmapImage bmpImage = new BitmapImage(new Uri("http://dantonybrown.com/brownsoft/SweepyCleaner.png"));
       bmpImage.ImageOpened += (sender, args) => Dispatcher.BeginInvoke(() => MessageBox.Show(
           bmpImage.PixelWidth.ToString(CultureInfo.InvariantCulture)));
       imageCtrl.Source = bmpImage;
   

2. Load the BitmapImage with CreateOptions.None. This will still load the image in the background, but you don't have to assign the image to a control before it starts loading:

       BitmapImage bmpImage = new BitmapImage(new Uri("http://dantonybrown.com/brownsoft/SweepyCleaner.png"))
                                  {CreateOptions = BitmapCreateOptions.None};
       bmpImage.ImageOpened += (sender, args) => Dispatcher.BeginInvoke(() => MessageBox.Show(
           bmpImage.PixelWidth.ToString(CultureInfo.InvariantCulture)));