如何在WPF中保存清晰无模糊的高质量控件图像？

DevOps 小满

2026-7-13

问题：RenderTargetBitmap导出大尺寸图像模糊

我正在使用DrawingContext绘制图像，随后将结果渲染至RenderTargetBitmap。图像在屏幕上显示清晰锐利，但保存后会变得模糊，即使在100%缩放比例下该问题仍然存在。有趣的是，当图像宽度小于2000px时导出正常，但宽度越大，导出的图像模糊程度越高。

代码示例

private void Window_Loaded(object sender, RoutedEventArgs e)
{
    BitmapImage bitmap = new BitmapImage();
    bitmap.BeginInit();
    bitmap.UriSource = new Uri(@"image-full-hd.png");
    bitmap.EndInit();
    img1.Source = bitmap;

    img1.Width = bitmap.Width;
    img1.Height= bitmap.Height;
}

private void btnExport_Click(object sender, RoutedEventArgs e)
{
    var result = CaptureSnapshot(img1);
    Clipboard.SetImage(result);
}

public BitmapSource CaptureSnapshot(UIElement source)
{
    var dpi = VisualTreeHelper.GetDpi(source);
    double dpiX = dpi.DpiScaleX, dpiY = dpi.DpiScaleY;

    double newImageWidth = source.RenderSize.Width * dpiX;
    double newImageHeight = source.RenderSize.Height * dpiY;

    RenderTargetBitmap renderTarget = new RenderTargetBitmap((int)newImageWidth, (int)newImageHeight, 96, 96, PixelFormats.Pbgra32);

    DrawingVisual visual = new DrawingVisual();

    using (DrawingContext context = visual.RenderOpen())
    {
        VisualBrush sourceBrush1 = new VisualBrush(source)
        {
            Stretch = Stretch.None
        };

        context.DrawRectangle(sourceBrush1, null, new Rect(source.RenderSize));
    }

    System.Windows.Size s1size = new System.Windows.Size(newImageWidth, newImageHeight);
    source.Measure(s1size); 
    source.Arrange(new Rect(s1size));

    RenderOptions.SetEdgeMode(renderTarget, EdgeMode.Unspecified);
    RenderOptions.SetBitmapScalingMode(renderTarget, BitmapScalingMode.HighQuality);
    renderTarget.Render(visual);

    return renderTarget;
}