在位图图像中设置背景颜色

我想将canvas保存为图像。 它有效，但背景颜色为黑色。 如何添加以改变颜色？

我用这个代码：

Size size = new Size(surface.Width, surface.Height); surface.Measure(size); surface.Arrange(new Rect(size)); // Create a render bitmap and push the surface to it RenderTargetBitmap renderBitmap = new RenderTargetBitmap((int)size.Width, (int)size.Height, 96d, 96d, PixelFormats.Pbgra32); renderBitmap.Render(surface); // Create a file stream for saving image using (FileStream outStream = new FileStream(filename, FileMode.Create)) { BmpBitmapEncoder encoder = new BmpBitmapEncoder(); // push the rendered bitmap to it encoder.Frames.Add(BitmapFrame.Create(renderBitmap)); // save the data to the stream encoder.Save(outStream); } 

Answer 1

尝试使用PixelFormats.Default或PixelFormats.Bgra32或PixelFormats.Rgb24而不是PixelFormats.Pbgra32 。

P代表预乘 – 假设每个通道预先乘以alpha。

MSDN参考

Answer 2

试试这个

 Size size = new Size(surface.Width, surface.Height); surface.Measure(size); surface.Arrange(new Rect(size)); // Create a render bitmap and push the surface to it RenderTargetBitmap renderBitmap = new RenderTargetBitmap((int)size.Width, (int)size.Height, 96d, 96d, PixelFormats.Pbgra32); DrawingVisual drawingVisual = new DrawingVisual(); using (DrawingContext drawingContext = drawingVisual.RenderOpen()) { VisualBrush visualBrush = new VisualBrush(surface); drawingContext.DrawRectangle(visualBrush, null, new Rect(new Point(), new Size(size.Width, size.Height))); } renderBitmap.Render(drawingVisual); // Create a file stream for saving image using (FileStream outStream = new FileStream(filename, FileMode.Create)) { BmpBitmapEncoder encoder = new BmpBitmapEncoder(); // push the rendered bitmap to it encoder.Frames.Add(BitmapFrame.Create(renderBitmap)); // save the data to the stream encoder.Save(outStream); }