c#之将 DrawingImage 转换为 BitmapImage

我想绘制大量形状(直线、椭圆和...)，然后将它们保存为位图或 png。我画了图，问题是:如何在 C# 中将 DrawingImage 转换为 BitmapImage？代码是这样的:

DrawingGroup drawingGroup = new DrawingGroup(); 
using(DrawingContext context = drawingGroup.Open()) 
{ 
    //make some drawing  
} 
DrawingImage drawingImage = new DrawingImage(drawingGroup) 
 
// your suggestion? DrawingImage - > BitmapImage 

请您参考如下方法:

您可以将 ImageDrawing 放入 Image 控件中并将其渲染到 RenderTargetBitmap 中，它是一个 BitmapSource，因此可以由 BitmapEncoder 序列化。 (本例中为 PngBitmapEncoder)。

public void SaveDrawingToFile(Drawing drawing, string fileName, double scale) 
{ 
    var drawingImage = new Image { Source = new DrawingImage(drawing) }; 
    var width = drawing.Bounds.Width * scale; 
    var height = drawing.Bounds.Height * scale; 
    drawingImage.Arrange(new Rect(0, 0, width, height)); 
 
    var bitmap = new RenderTargetBitmap((int)width, (int)height, 96, 96, PixelFormats.Pbgra32); 
    bitmap.Render(drawingImage); 
 
    var encoder = new PngBitmapEncoder(); 
    encoder.Frames.Add(BitmapFrame.Create(bitmap)); 
 
    using (var stream = new FileStream(fileName, FileMode.Create)) 
    { 
        encoder.Save(stream); 
    } 
} 

请注意，您实际上不需要 BitmapImage 进行编码，因为 BitmapSource(或任何派生类，如 RenderTargetBitmap)将被接受为 BitmapFrame.Create 的参数。 .

稍微不同的解决方案将涉及 DrawingVisual而不是绘图图像:

public void SaveDrawingToFile(Drawing drawing, string fileName, double scale) 
{ 
    var drawingVisual = new DrawingVisual(); 
 
    using (var drawingContext = drawingVisual.RenderOpen()) 
    { 
        drawingContext.PushTransform(new ScaleTransform(scale, scale)); 
        drawingContext.PushTransform(new TranslateTransform(-drawing.Bounds.X, -drawing.Bounds.Y)); 
        drawingContext.DrawDrawing(drawing); 
    } 
 
    var width = drawing.Bounds.Width * scale; 
    var height = drawing.Bounds.Height * scale; 
    var bitmap = new RenderTargetBitmap((int)width, (int)height, 96, 96, PixelFormats.Pbgra32); 
    bitmap.Render(drawingVisual); 
 
    var encoder = new PngBitmapEncoder(); 
    encoder.Frames.Add(BitmapFrame.Create(bitmap)); 
 
    using (var stream = new FileStream(fileName, FileMode.Create)) 
    { 
        encoder.Save(stream); 
    } 
}