我正在尝试使用WPF DrawContext.DrawGeometry裁剪图像。在此项目中，首先使用下面的代码选择裁剪区域。在鼠标左键单击获取当前位置并存储在静态列表中。选择路径后，再启用保存按钮。
protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
{
System.Windows.Point currentPoint = e.GetPosition(this);
if (CurrentGeometryGroup == null)
{
CurrentGeometryGroup = new List<System.Windows.Point>();
}
CurrentGeometryGroup.Add(currentPoint);
if (CurrentGeometry == null)
{
_startPoint = currentPoint;
_lastPoint = currentPoint;
CurrentGeometry = new GeometryGroup();
CurrentGeometry.Children.Add(new EllipseGeometry(currentPoint, 3, 3));
GetPixel(currentPoint, _lastPoint);
}
else
{
if (AreClose(_startPoint, currentPoint))
{
CurrentGeometry.Children.Add(new LineGeometry(_lastPoint, _startPoint));
CurrentGeometry.Freeze();
CurrentGeometry = null;
GetPixel(currentPoint, _lastPoint);
System.Windows.Point Defaly = currentPoint;
RaiseEvent(new RoutedEventArgs(this.CropImageEvent, this));
}
else
{
CurrentGeometry.Children.Add(new LineGeometry(_lastPoint, currentPoint));
CurrentGeometry.Children.Add(new EllipseGeometry(currentPoint, 3, 3));
GetPixel(currentPoint, _lastPoint);
_lastPoint = currentPoint;
}
}
}
点击保存按钮后，我在代码下面调用以裁剪图像。在此代码中使用Bitmap获取源图像。然后使用源宽度和高度创建RenderTargetBitmap。一旦完成，然后使用点创建PathGeometry。之后使用DrawingContext.DrawGeometry裁剪图像。
using (System.Drawing.Bitmap source = new System.Drawing.Bitmap(ImgUrl))
{
RenderTargetBitmap bmp = new RenderTargetBitmap(source.Width, source.Height,
source.HorizontalResolution,
source.VerticalResolution,
PixelFormats.Pbgra32);
float hScale = 1.0f / (float)zoomFactor;
PathFigure pathFigure = new PathFigure();
pathFigure.StartPoint = new System.Windows.Point(CurrentGeometryGroup[0].X / zoomFactor, CurrentGeometryGroup[0].Y / zoomFactor);
for (int x = 1; x < CurrentGeometryGroup.Count; x++)
{
LineSegment lineSegment = new LineSegment();
lineSegment.Point = new System.Windows.Point(CurrentGeometryGroup[x].X / zoomFactor, CurrentGeometryGroup[x].Y / zoomFactor);
pathFigure.Segments.Add(lineSegment);
}
pathFigure.IsClosed = true;
PathGeometry pathGeometry = new PathGeometry();
pathGeometry.Figures.Add(pathFigure);
DrawingVisual visual = new DrawingVisual();
using (DrawingContext context = visual.RenderOpen())
{
ImageBrush imgBrush = new ImageBrush();
imgBrush.ImageSource = new BitmapImage(new Uri(ImageUrl, UriKind.RelativeOrAbsolute));
imgBrush.Stretch = Stretch.None;
imgBrush.Freeze();
context.DrawGeometry(imgBrush, new System.Windows.Media.Pen(System.Windows.Media.Brushes.White, 0), pathGeometry);
}
bmp.Render(visual);
MemoryStream stream = new MemoryStream();
BitmapEncoder encoder = new BmpBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(bmp));
encoder.Save(stream);
Bitmap bitmap = new Bitmap(stream);
tempFileName = System.IO.Path.GetDirectoryName(AppDomain.CurrentDomain.BaseDirectory) + @"\assets\";
if (fixedTempIdx > 2)
fixedTempIdx = 0;
else
++fixedTempIdx;
CleanUp(tempFileName, fixedTempName, fixedTempIdx);
tempFileName = tempFileName + fixedTempName + fixedTempIdx.ToString() + ".jpg";
bitmap.Save(tempFileName, System.Drawing.Imaging.ImageFormat.Jpeg);
cmDragCanvas.RemoveHandler(MenuItem.ClickEvent, cmDragCanvasRoutedEventHandler);
dragCanvasForImg.ContextMenu = null;
cmDragCanvas = null;
BitmapImage bmpPopup = new BitmapImage(new Uri(tempFileName));
popUpImage.Source = bmpPopup;
popUpImage.Height = 200;
popUpImage.Width = 200;
grdCroppedImage.Visibility = Visibility.Visible;
}
毕竟裁剪图像与选择图像不同。检查下面的链接图像。请建议避免这个问题。
