WriteableBitmap与标度因子

Question

由于图像闪烁，我使用了WriteableBitmap。我有三个缩放因子的图像。但是GetFileFromApplicationUriAsync总是以最高的缩放因子读取图像，而且移动设备上的图像太大。这是我的代码：

private async Task<WriteableBitmap> CreateBitmapImage(Uri uri)
    {
        var file = await StorageFile.GetFileFromApplicationUriAsync(uri);
        BitmapImage bitmapImage;
        WriteableBitmap writeableBitmap;
        using (IRandomAccessStream fileStream = await file.OpenAsync(FileAccessMode.Read))
        {
            bitmapImage = new BitmapImage();
            await bitmapImage.SetSourceAsync(fileStream);
            writeableBitmap = new WriteableBitmap(bitmapImage.PixelHeight, bitmapImage.PixelWidth);
            fileStream.Seek(0);
            await writeableBitmap.SetSourceAsync(fileStream);
        }
        return writeableBitmap;
    }

我使用BitmapImage是因为WriteableBitmap需要像素高度和宽度作为构造函数中的输入参数。Uri例如:ms-appx://Image/contact.png

Answer 1

我已经解决了这个问题：

<Image Grid.Column="0" x:Name="StatusImage" Margin="0,8,12,8" Source="{x:Bind ImageStatusUri, Mode=OneWay}">
                    <interactivity:Interaction.Behaviors>
                        <core:EventTriggerBehavior EventName="ImageOpened">
                            <core:ChangePropertyAction PropertyName="Source" Value="{Binding ElementName=StatusImage, Path=Source}" TargetObject="{Binding ElementName=CopyOfStatusImage}"/>
                        </core:EventTriggerBehavior>
                    </interactivity:Interaction.Behaviors>
                </Image>
<Image Grid.Column="0" Margin="0,8,12,8" x:Name="CopyOfStatusImage"/>

所以我不需要使用WriteableBitmap和GetFileFromApplicationUriAsync