Question

我有两个位图图像，我想合并在一起。我发现我可以用writeablebitmap做到这一点，但我该如何将这些图像转换为writeablebitmaps？

UPDATE：我找不到直接将位图转换为可写位图的方法，所以我所做的就是将我的位图写入隔离存储并在流对象中再次读取它。之后，Xyroid下面给出的代码可用于合并图像并将合并后的图像转换为位图。

Answer 1

我在这里给你合并两张图片的代码。 WinRT的WriteableBitmap是不同的，它的构造函数将高度和宽度作为参数。我已经使用WriteableBitmapEx来执行某些功能。

XAML

<Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
    <Grid.ColumnDefinitions>
        <ColumnDefinition />
        <ColumnDefinition />
    </Grid.ColumnDefinitions>
    <Canvas x:Name="BaseCanvas" Width="683" Height="768">
        <Image Source="Assets/img1.png" />
        <Image Source="Assets/img2.png" Canvas.Top="308" />
    </Canvas>
    <Image x:Name="imgTarget" Grid.Column="1" Stretch="None"/>
</Grid>

C＃

protected async override void OnNavigatedTo(NavigationEventArgs e)
{
    StorageFile destiFile = await ApplicationData.Current.TemporaryFolder.CreateFileAsync("Merged.png", CreationCollisionOption.ReplaceExisting);

    WriteableBitmap wb;

    wb = await Render();

    using (IRandomAccessStream stream = await destiFile.OpenAsync(FileAccessMode.ReadWrite))
    {
        BitmapEncoder encoder = await BitmapEncoder.CreateAsync(
            BitmapEncoder.PngEncoderId, stream);
        Stream pixelStream = wb.PixelBuffer.AsStream();
        byte[] pixels = new byte[pixelStream.Length];
        await pixelStream.ReadAsync(pixels, 0, pixels.Length);

        encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore,
            (uint)wb.PixelWidth, (uint)wb.PixelHeight, 96.0, 96.0, pixels);
        await encoder.FlushAsync();
    }

    var bitmp = new BitmapImage();
    using (var strm = await destiFile.OpenReadAsync())
    {
        bitmp.SetSource(strm);
        imgTarget.Source = bitmp;
    }
}

private async Task<WriteableBitmap> Render()
{
    var Assets = await Windows.ApplicationModel.Package.Current.InstalledLocation.GetFolderAsync("Assets");

    StorageFile file1 = await Assets.GetFileAsync("img1.png");
    StorageFile file2 = await Assets.GetFileAsync("img2.png");

    BitmapImage i1 = new BitmapImage();
    BitmapImage i2 = new BitmapImage();

    using (IRandomAccessStream strm = await file1.OpenReadAsync())
    {
        i1.SetSource(strm);
    }

    using (IRandomAccessStream strm = await file2.OpenReadAsync())
    {
        i2.SetSource(strm);
    }

    WriteableBitmap img1 = new WriteableBitmap(i1.PixelWidth, i1.PixelHeight);
    WriteableBitmap img2 = new WriteableBitmap(i2.PixelWidth, i2.PixelHeight);
    using (IRandomAccessStream strm = await file1.OpenReadAsync())
    {
        img1.SetSource(strm);
    }

    using (IRandomAccessStream strm = await file2.OpenReadAsync())
    {
        img2.SetSource(strm);
    }


    WriteableBitmap destination = new WriteableBitmap((int)(img1.PixelWidth > img2.PixelWidth ? img1.PixelWidth : img2.PixelWidth), (int)(img1.PixelHeight + img1.PixelHeight));
    destination.Clear(Colors.White);
    destination.Blit(new Rect(0, 0, (int)img1.PixelWidth, (int)img1.PixelHeight),img1,new Rect(0, 0, (int)img1.PixelWidth, (int)img1.PixelHeight));
    destination.Blit(new Rect(0, (int)img1.PixelHeight, (int)img2.PixelWidth, (int)img2.PixelHeight), img2, new Rect(0, 0, (int)img2.PixelWidth, (int)img2.PixelHeight));
    return destination;
}

请注意，您必须添加System.Runtime.InteropServices.WindowsRuntime命名空间。

更新1

假设您已经有两个BitmapImage img1和img2，那么就这样做

protected async override void OnNavigatedTo(NavigationEventArgs e)
{
    StorageFile destiFile = await ApplicationData.Current.TemporaryFolder.CreateFileAsync("Merged.png", CreationCollisionOption.ReplaceExisting);

    WriteableBitmap wb;

    wb = await Render();

    using (IRandomAccessStream stream = await destiFile.OpenAsync(FileAccessMode.ReadWrite))
    {
        BitmapEncoder encoder = await BitmapEncoder.CreateAsync(
            BitmapEncoder.PngEncoderId, stream);
        Stream pixelStream = wb.PixelBuffer.AsStream();
        byte[] pixels = new byte[pixelStream.Length];
        await pixelStream.ReadAsync(pixels, 0, pixels.Length);

        encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore,
            (uint)wb.PixelWidth, (uint)wb.PixelHeight, 96.0, 96.0, pixels);
        await encoder.FlushAsync();
    }

    var bitmp = new BitmapImage();
    using (var strm = await destiFile.OpenReadAsync())
    {
        bitmp.SetSource(strm);
        imgTarget.Source = bitmp;
    }
}

private async Task<WriteableBitmap> Render()
{  
    WriteableBitmap destination = new WriteableBitmap((int)(img1.PixelWidth > img2.PixelWidth ? img1.PixelWidth : img2.PixelWidth), (int)(img1.PixelHeight + img1.PixelHeight));
    destination.Clear(Colors.White);
    destination.Blit(new Rect(0, 0, (int)img1.PixelWidth, (int)img1.PixelHeight),img1,new Rect(0, 0, (int)img1.PixelWidth, (int)img1.PixelHeight));
    destination.Blit(new Rect(0, (int)img1.PixelHeight, (int)img2.PixelWidth, (int)img2.PixelHeight), img2, new Rect(0, 0, (int)img2.PixelWidth, (int)img2.PixelHeight));
    return destination;
}

Answer 2

我在Silverlight上做了很多工作，我相信商店应用在很多方面都很相似。

考虑这个构造函数：

WriteableBitmap(BitmapSource)
- Initializes a new instance of the WriteableBitmap class using the
  provided BitmapSource.

接下来的问题是，如何从图像中获取“BitmapSource”？你可以这样做：

(BitmapSource)MyImage.Source

虽然这假设源（类型为'ImageSource'）实际上是'BitmapSource'实例。也就是说，从Silverlight 5.0开始，Silverlight中从ImageSource派生的唯一类是BitmapSource，所以我怀疑这是一个问题。

所以这样的事情可能有用：

WriteableBitmap((BitmapSource)MyImage.Source)

最后，这里有一个开源项目可能会有所帮助：http://writeablebitmapex.codeplex.com/

我可以将图像/位图转换为writeablebitmap吗？

2 个答案: