BitmapImage使用FileStream读取文件

            var bitmapImage = new BitmapImage();
            using (FileStream fs = new FileStream(file.FullName, FileMode.Open))
            {
                bitmapImage.BeginInit();
                bitmapImage.CacheOption = BitmapCacheOption.OnLoad;
                bitmapImage.StreamSource = fs;
                bitmapImage.EndInit();
            }
            bitmapImage.Freeze();

            var img = new Image();
            img.Source = bitmapImage;

第二种方式：

                    byte[] buffer = File.ReadAllBytes(file.FullName);
                    img.Source = new ImageSourceConverter().ConvertFrom(buffer) as BitmapSource;

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