将DrawingImage转换为BitmapImage

Question

我想绘制大量的形状(线条,椭圆和......),然后将它们保存为位图或png.我制作了图纸,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

Answer 1

您可以将ImageDrawing放入Image控件并将其渲染为RenderTargetBitmap,这是一个BitmapSource,因此可以通过BitmapEncoder(本例中为PngBitmapEncoder)进行序列化.

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);
    }
}

请注意,实际上并不需要BitmapImage进行编码,因为BitmapSource(或RenderTargetBitmap等任何派生类)将被接受为BitmapFrame.Create的参数.

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);
    }
}