使用C＃将颜色合并到位图中（通用Windows应用程序）

我有一个.png资源，其中包括需要按下表所述进行“着色”的区域（这些是我自己的定义，如果有更好的用语，我可以随时使用它来教育我）。我需要基于ColorBrush（例如BGRA =＃6572D8FF）对图像进行“着色”，以便...

//                        Input            Output
//    Transparent  BGRA=#FFFFFF00 --> #FFFFFF00
//    AlphaOnly    BGRA=#00000000 --> #6572D800   // Colored area
//    Alpha-Shaded BGRA=#000000aa --> #6572D8aa   // Colored area
//    Solid colors BGRA=#bbggrrFF --> #rrggbbFF

需要使用以下XAML显示生成的图像...

    <Viewbox Height="{TemplateBinding Height}" Width="{TemplateBinding Width}">
        <Grid Height="100" Width="100">
            <Image x:Name="currentImage" />
        </Grid>
    </Viewbox>

我希望将控件放置在红色背景上并指定蓝色ColorBrush，希望获得底部图像（我是通过在原始图像后面简单地放置一个蓝色椭圆来创建的）

不幸的是我得到了最高的形象。我的透明度丢失了，我希望达到的Alpha底纹是错误的。任何帮助（包括您的“白痴”，您都应该这样）将不胜感激。

public sealed class MyImage : Control {
    public MyImage() {
        this.DefaultStyleKey = typeof(MyImage);
        Loaded += MyImage_Loaded;
    }
    private async void MyImage_Loaded(object sender, RoutedEventArgs e) {
        ((Image)this.GetTemplateChild("currentImage")).Source = await ColorImage();
    }
    private async Task<WriteableBitmap> ColorImage() {
        // Get the image as a byte array
        StorageFile fileImage = await StorageFile.GetFileFromApplicationUriAsync(new Uri(BaseImageUri, UriKind.Absolute));
        ImageProperties propsImage = await fileImage.Properties.GetImagePropertiesAsync();
        int height = (int)propsImage.Height;
        int width = (int)propsImage.Width;
        byte[] baseImagePixels = await ReadPixels(fileImage);

        // Modify the mask by adding the accent color
        for (int y = 0; y < height; y++) {
            for (int x = 0; x < width; x++) {
                byte B = baseImagePixels[4 * (y * height + x) + 0];
                byte G = baseImagePixels[4 * (y * height + x) + 1];
                byte R = baseImagePixels[4 * (y * height + x) + 2];
                byte A = baseImagePixels[4 * (y * height + x) + 3];
                if (R == 0x00 && G == 0x00 && B == 0x00 && A != 0xFF) {
                    baseImagePixels[4 * (y * height + x) + 0] = ColorBrush.Color.B;
                    baseImagePixels[4 * (y * height + x) + 1] = ColorBrush.Color.G;
                    baseImagePixels[4 * (y * height + x) + 2] = ColorBrush.Color.R;
                }
            }
        }
        WriteableBitmap coloredImage = new WriteableBitmap((int)propsImage.Width, (int)propsImage.Height);
        using (Stream stream = coloredImage.PixelBuffer.AsStream()) {
            await stream.WriteAsync(baseImagePixels, 0, baseImagePixels.Length);
        }
        return coloredImage;
    }
    private async Task<byte[]> ReadPixels(StorageFile file) {
        BitmapDecoder decoder = await BitmapDecoder.CreateAsync(await file.OpenAsync(FileAccessMode.Read));
        BitmapTransform transform = new BitmapTransform();
        PixelDataProvider pixelData = await decoder.GetPixelDataAsync(
            BitmapPixelFormat.Bgra8,
            BitmapAlphaMode.Ignore,
            new BitmapTransform(),
            ExifOrientationMode.IgnoreExifOrientation,
            ColorManagementMode.DoNotColorManage);
        return pixelData.DetachPixelData();
    }
    public String BaseImageUri {
        get { return (String)GetValue(BaseImageUriProperty); }
        set {
            if (value.StartsWith("ms-appx:///")) {
                SetValue(BaseImageUriProperty, value);
            } else {
                SetValue(BaseImageUriProperty, "ms-appx:///" + value);
            }
        }
    }
    public static readonly DependencyProperty BaseImageUriProperty =
        DependencyProperty.Register("BaseImageUri", typeof(String), typeof(MyImage), new PropertyMetadata(0));
    public SolidColorBrush ColorBrush {
        get { return (SolidColorBrush)GetValue(ColorBrushProperty); }
        set { SetValue(ColorBrushProperty, value); }
    }
    public static readonly DependencyProperty ColorBrushProperty =
        DependencyProperty.Register("ColorBrush", typeof(SolidColorBrush), typeof(MyImage), new PropertyMetadata(0));
}