WP7学习笔记（一）BitmapImage转化为WriteableBitmap

今天写代码的时候，遇到需要将BitmapImage转化为WriteableBitmap,自己果断写下如下代码。结果调试的时候每次都报错。

BitmapImage bitmapImage = new BitmapImage(new Uri("/images/test.png",UriKind.Relative));
WriteableBitmap writeableBitmap = new WriteableBitmap(bitmapImage);

自己尝试设置图片的属性，无论是resource还是content也都不行，地址也是绝对相对都换过，还是不行。

最后google到发现bitmapImage原来是异步加载图片，也就说我创建writeablebitmap的时候bitmapimage还没有加载完成，所以报错。

于是就有了

            ///do something...
            Uri url = new Uri("/Img/1.png", UriKind.Relative);
            BitmapImage bitmapImage = new BitmapImage();
            bitmapImage.CreateOptions = BitmapCreateOptions.None;
            bitmapImage.ImageOpened += bitmapImage_ImageOpened;
            bitmapImage.UriSource = url;
            bitmapImage.ImageFailed += bitmapImage_ImageFailed;
}

 void bitmapImage_ImageOpened(object sender, RoutedEventArgs e)
        {
            WriteableBitmap wb = new WriteableBitmap(sender as BitmapImage);
            ///do something...
        }

当然也可以这么写：

Uri url = new Uri("/Img/1.png", UriKind.Relative);
BitmapImage bitmapImage = new BitmapImage();
bitmapImage.CreateOptions = BitmapCreateOptions.None;
bitmapImage.ImageOpened +=(o,args)=>
    {
        WriteableBitmap wb = new WriteableBitmap(o as BitmapImage);
        ///do something ...
    }; 
bitmapImage.UriSource = url;