Question

为什么以下代码为btmSrc返回null？

DrawingImage drawingElement =(DrawingImage)System.Windows.Application.Current.TryFindResource(name);
 System.Windows.Controls.Image image = new System.Windows.Controls.Image();
 image.Source = drawingElement as ImageSource;

BitmapSource btmSrc = image.Source as BitmapSource;

Answer 1

简化您的代码：

DrawingImage drawingElement = (DrawingImage)System.Windows.Application.Current.TryFindResource(name);
BitmapSource btmSrc = drawingElement as BitmapSource;

由于DrawingImage不从BitmapSource继承，结果将为null。

我没有DrawingImage进行测试（因此将其视为伪代码而不是复制粘贴解决方案），但转换代码应如下所示：

// Create a visual from a drawing
DrawingVisual drawingVisual = new DrawingVisual();
drawingVisual.Drawing.Children.Add(drawingImage.Drawing);

// Render it to a WPF bitmap
var renderTargetBitmap = new RenderTargetBitmap(
    drawingVisual.Drawing.Bounds.Right,
    drawingVisual.Drawing.Bounds.Bottom, 96, 96, PixelFormats.Pbgra32);
renderTargetBitmap.Render(drawingVisual);

// Create a bitmap with the correct size
Bitmap bmp = new Bitmap(renderTargetBitmap.PixelWidth,
    renderTargetBitmap.PixelHeight,  PixelFormat.Format32bppPArgb);
BitmapData data = bmp.LockBits(new Rectangle(Point.Empty, bmp.Size),
    ImageLockMode.WriteOnly, PixelFormat.Format32bppPArgb);
renderTargetBitmap.CopyPixels(Int32Rect.Empty, data.Scan0,
    data.Height * data.Stride, data.Stride);
bmp.UnlockBits(data);

最后一部分取自Is there a good way to convert between BitmapSource and Bitmap?

从图像控件获取BitmapSource

1 个答案: