wpf - 如何在 WPF 中裁剪图像并保存到 ImageSource 中？

Question

我是 WPF 的新手。在这里我有一个问题。我有一个图像，宽度：360，高度：360。在这里，我想裁剪此图像，如下所示：

(0,0) 到 (120,120) 保存到第一个 ImageSource 对象，

(120,0) 到 (240,120) 保存到第二个 ImageSource 对象，

(240,0) 到 (360,120) 保存到第三个 ImageSource 对象；，

……</p>

请在下图中查看更多详细信息：

我的代码示例如下：

    private void CutImage(string img)
    {
        int iLeft = 0;
        int iTop = 0;
        int count = 0;

        Image thisImg = new Image();
        BitmapImage src = new BitmapImage();
        src.BeginInit();
        src.UriSource = new Uri(img, UriKind.Relative);
        src.CacheOption = BitmapCacheOption.OnLoad;
        src.EndInit();
        thisImg.Source = src;

        for (int i = 0; i < 3; i++)
        {
            iTop = i * 120;
            for (int j = 0; j < 3; j++)
            {
                iLeft = j * 120;

                Canvas canvas = new Canvas();

                Rectangle destRect = new Rectangle();
                destRect.SetValue(Canvas.LeftProperty, (double)0);
                destRect.SetValue(Canvas.TopProperty,(double)0);
                destRect.Width = destRect.Height = 120;

                Rect srcRect = new Rect();
                srcRect.X = iLeft;
                srcRect.Y = iTop;
                srcRect.Width = srcRect.Height = 120;


                thisImg.Clip = new RectangleGeometry(srcRect);

                thisImg.Clip.SetValue(Canvas.TopProperty, (double)iTop);
                thisImg.Clip.SetValue(Canvas.LeftProperty, (double)iLeft);
                thisImg.Clip.SetValue(Canvas.WidthProperty, (double)120);
                thisImg.Clip.SetValue(Canvas.HeightProperty,(double)120);

                objImg[count++] = (ImageSource)thisImg.GetValue(Image.SourceProperty);
            }
        }
      }

但它不像我预期的那样工作，似乎所有 ImageSource 对象都存储相同的图像，而不是 corping 部分。任何人都可以帮助我吗？谢谢。

Answer 1

使用CroppedBitmap执行此操作：

private void CutImage(string img)
{
    int count = 0;

    BitmapImage src = new BitmapImage();
    src.BeginInit();
    src.UriSource = new Uri(img, UriKind.Relative);
    src.CacheOption = BitmapCacheOption.OnLoad;
    src.EndInit();

    for (int i = 0; i < 3; i++)
        for (int j = 0; j < 3; j++)
            objImg[count++] = new CroppedBitmap(src, new Int32Rect(j * 120, i * 120, 120, 120));
}

Answer 2

做就是了：

private static BitmapSource CaptureScreen(Visual target, double dpiX, double dpiY)
{
    if (target == null)
    {
        return null;
    }
    Rect bounds = VisualTreeHelper.GetDescendantBounds(target);
    RenderTargetBitmap rtb = new RenderTargetBitmap((int)(bounds.Width * dpiX / 96.0),
                                                    (int)(bounds.Height * dpiY / 96.0),
                                                    dpiX,
                                                    dpiY,
                                                    PixelFormats.Pbgra32);
    DrawingVisual dv = new DrawingVisual();
    using (DrawingContext ctx = dv.RenderOpen())
    {
        VisualBrush vb = new VisualBrush(target);
        ctx.DrawRectangle(vb, null, new Rect(new Point(), bounds.Size));
    }
    rtb.Render(dv);
    return rtb;
}

VisualBrush part1 = new VisualBrush(yourVISUAL);
part1.ViewBoxUnits = ..Absolute;
part1.ViewBox = new Rect(x, y, width, height);
BitmapSource bitmapSource = CaptureScreen(part1, 96, 96);
    using (var fileStream = new FileStream(filePath, FileMode.Create))
    {
        BitmapEncoder encoder = new PngBitmapEncoder();
        encoder.Frames.Add(BitmapFrame.Create(bitmapSource));
        encoder.Save(fileStream);
    }