WPF技术问题：如何将多个RenderTargetBitmap合并为单图并复制到剪贴板

Got it, let's solve this problem together! The core issue here is that you need to merge all your individual RenderTargetBitmap instances into a single composite image before copying to the clipboard—this way you'll get all elements in one paste instead of just the last one. Here's a step-by-step approach and modified code:

Step 1: Calculate the Total Size of the Combined Image #

First, decide how you want to arrange your elements (vertical stack, horizontal row, etc.). For this example, we'll use a vertical stack:

• Total width = maximum width of all elements (so narrower elements are centered)
• Total height = sum of all elements' heights

Step 2: Create a Composite RenderTargetBitmap #

Make a new large bitmap that can hold all your individual images.

Step 3: Draw All Individual Images onto the Composite Bitmap #

Use a DrawingVisual to render each image at the correct position on the large bitmap.

Modified Full Code #

public static void CopyManyUiElementToClipboard(List<FrameworkElement> elements)
{
    var images = new List<RenderTargetBitmap>();

    // First, render each element to its own RenderTargetBitmap (your existing logic)
    elements.ForEach(element =>
    {
        double width = element.ActualWidth;
        double height = element.ActualHeight;
        var size = new Size(width, height);

        var drawingContext = new DrawingVisual();
        using (DrawingContext draw = drawingContext.RenderOpen())
        {
            var visualBrush = new VisualBrush(element);
            draw.DrawRectangle(visualBrush, null, new Rect(new Point(), size));
        }

        var renderBitmap = new RenderTargetBitmap((int)size.Width, (int)size.Height, 96d, 96d, PixelFormats.Pbgra32);
        var vRect = new Rectangle { Width = (int)size.Width, Height = (int)size.Height, Fill = Brushes.White };
        vRect.Arrange(new Rect(size));
        renderBitmap.Render(vRect);
        renderBitmap.Render(drawingContext);

        images.Add(renderBitmap);
    });

    // Now combine all images into one
    if (images.Count == 0) return;

    // Calculate total dimensions (vertical stack example)
    double totalWidth = images.Max(img => img.Width);
    double totalHeight = images.Sum(img => img.Height);

    // Create the combined bitmap
    var combinedBitmap = new RenderTargetBitmap((int)totalWidth, (int)totalHeight, 96d, 96d, PixelFormats.Pbgra32);

    // Draw all individual images onto the combined bitmap
    var compositeVisual = new DrawingVisual();
    using (DrawingContext dc = compositeVisual.RenderOpen())
    {
        double currentYPosition = 0;
        foreach (var img in images)
        {
            // Center narrower elements horizontally
            double horizontalOffset = (totalWidth - img.Width) / 2;
            dc.DrawImage(img, new Rect(horizontalOffset, currentYPosition, img.Width, img.Height));
            currentYPosition += img.Height;
        }
    }

    combinedBitmap.Render(compositeVisual);

    // Copy the combined image to clipboard
    Clipboard.SetImage(combinedBitmap);
}

Customization Tips #

• Horizontal Arrangement: If you want to stack elements side-by-side instead, change the dimension calculations:

  double totalHeight = images.Max(img => img.Height);
  double totalWidth = images.Sum(img => img.Width);
  

  Then track currentXPosition instead of currentYPosition and update the Rect accordingly.
• Add Spacing: To add gaps between elements, just adjust the position increment (e.g., currentYPosition += img.Height + 10; for 10px vertical spacing).
• Custom Background: If you want a non-white background for the composite image, draw a full-size rectangle first in the DrawingContext:

  dc.DrawRectangle(Brushes.LightGray, null, new Rect(0, 0, totalWidth, totalHeight));
  

内容的提问来源于stack exchange，提问作者Wojciech Szabowicz