將DrawingImage轉換爲BitmapImage

Question

我想繪製大量的形狀（線，橢圓和...），然後將它們保存爲位圖或png。我提出的圖紙和問題是：如何在C＃中將DrawingImage轉換爲BitmapImage？的代碼是這樣的：

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成圖像的控制和渲染成，這是一個的BitmapSource，因此可以由一個BitmapEncoder（PngBitmapEncoder在此實例中）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，你實際上並不需要編碼一個BitmapImage的，因爲的BitmapSource（或類似RenderTargetBitmap任何派生類）將被接受作爲參數傳遞給BitmapFrame.Create。

---

稍微不同的解決方案將涉及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); 
    } 
}