将DrawingImage转换为BitmapImage

Question

我想绘制大量的形状（线，椭圆和...），然后将它们保存为位图或png。我提出的图纸和问题是：如何在C＃中将DrawingImage转换为BitmapImage？的代码是这样的：

DrawingGroup drawingGroup = new DrawingGroup(); 
using(DrawingContext context = drawingGroup.Open()) 
{ 
    //make some drawing 
} 
DrawingImage drawingImage = new DrawingImage(drawingGroup) 

// your suggestion? DrawingImage - > BitmapImage 

Answer 1

您可能把ImageDrawing成图像的控制和渲染成，这是一个的BitmapSource，因此可以由一个BitmapEncoder（PngBitmapEncoder在此实例中）被序列化。

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); 
    } 
} 

注意，你实际上并不需要编码一个BitmapImage的，因为的BitmapSource（或类似RenderTargetBitmap任何派生类）将被接受作为参数传递给BitmapFrame.Create。

---

稍微不同的解决方案将涉及DrawingVisual代替DrawingImage：

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); 
    } 
}