如何通过从源BitmapImage的中心裁剪来停止呈现为DrawingImage的椭圆裁剪 [英] How do I stop an elliptical crop rendered as a DrawingImage from cropping from the centre of the source BitmapImage

问题描述

我的代码适用于WPF .Net 4.5 Virtual Studio 2012 ：

//在图像上绘制了一个圆圈，裁剪的细节在theCropRect中





< pre lang =cs> internal void GetOvalCrop（BitmapImage bi，Rect theCropRect）
{

// 创建图片
图片img = new Image（）;
img.Horizo​​ntalAlignment = Horizo​​ntalAlignment.Left;
img.Source = bi;

// 定义剪辑的轮廓

img.Clip = new EllipseGeometry（theCropRect）;
GeometryDrawing gd = 新 GeometryDrawing（）;
gd.Geometry = img.Clip;

// 将剪辑的内容定义为ImageBrush
ImageBrush imb = new ImageBrush（img.Source）;
imb.Stretch = Stretch.None;
gd.Brush = imb;

// 尝试将剪辑内容转换为DrawingImage
DrawingImage gImg = new DrawingImage（gd）;
gImg.Freeze（）;

将Drawingimage转换为RenderTargetBitmap
RenderTargetBitmap rtb = DrawingImageExtensions.ToBitmapSource（gImg）;

// 化妆名称
string name = Oval _ + ovalClip.ToString（）+ 。png;
ovalClip ++;


// 保存结果
SaveRtbAsPng（ rtb，姓名）;
}

 内部 静态  void  SaveRtbAsPng（RenderTargetBitmap rtb， string  name）
 {
 PngBitmapEncoder ping =  new  PngBitmapEncoder（）; 
 
 尝试 
 {
 使用（FileStream文件=  new  FileStream（name，FileMode.Create，FileAccess.Write））
 {
 ping.Frames.Add（BitmapFrame.Create（rtb） ）; 
 
 
 ping.Save（file）; 
 
  if （file！=  null ）
 file.Close （）; 
 
} 
 
} 
  catch  {} 
} 

  public   static   class  DrawingImageExtensions 
 {
  public   static  RenderTargetBitmap ToBitmapSource（ this  DrawingImage source）
 {
 DrawingVisual drawingVisual =  new  DrawingVisual（）; 
 DrawingContext drawingContext = drawingVisual.RenderOpen（）; 
 drawingContext.DrawImage（source， new  Rect（ 0 ， 0 ，（ int ）source.Width，（ int ）source.Height ））; 
 drawingContext.Close（）; 
 
 RenderTargetBitmap bmp =  new  RenderTargetBitmap（（ int ）source.Width，（  int ）source.Height， 96 ， 96 ，PixelFormats.Pbgra32）; 
 bmp.Render（drawingVisual）; 
  return  bmp; 
} 
  public   static  DrawingImage ToDrawingImage（这个 BitmapSource源代码）
 {
 Rect imageRect =  new  Rect（ 0 ， 0 ，source.PixelWidth，source.PixelHeight）; 
 ImageDrawing drawing =  new  ImageDrawing（source，imageRect）; 
  return   new  DrawingImage（drawing）; 
} 
} 

结果对于高度和宽度是正确的，但椭圆的中心始终是保存裁剪的中心。



从图像左侧裁剪的圆圈最终是矩形图像中心的裁剪。



有什么想法吗？

解决方案

My Code is for WPF .Net 4.5 Virtual Studio 2012:
// a circle has been drawn on an image and the cropping details are in "theCropRect"

internal void GetOvalCrop(BitmapImage bi, Rect theCropRect)
        {

// create an image
            Image img = new Image();
            img.HorizontalAlignment = HorizontalAlignment.Left;
            img.Source = bi;

//define the outline of the clip

            img.Clip = new EllipseGeometry(theCropRect);           
            GeometryDrawing gd = new GeometryDrawing();
            gd.Geometry = img.Clip;

// define the contents of the clip as an ImageBrush
            ImageBrush imb = new ImageBrush(img.Source);
            imb.Stretch = Stretch.None;
            gd.Brush = imb;

// try to convert clip contents to a DrawingImage
            DrawingImage gImg = new DrawingImage(gd);
            gImg.Freeze();

            convert the Drawingimage to a RenderTargetBitmap
            RenderTargetBitmap rtb = DrawingImageExtensions.ToBitmapSource(gImg);
           
// makeup a name
 string name = "Oval_" + ovalClip.ToString() + ".png";
             ovalClip++;


            // save results
            SaveRtbAsPng(rtb, name);
}

internal static void SaveRtbAsPng(RenderTargetBitmap rtb, string name)
       {
           PngBitmapEncoder ping = new PngBitmapEncoder();

           try
           {
               using (FileStream file = new FileStream(name, FileMode.Create, FileAccess.Write))
               {
                   ping.Frames.Add(BitmapFrame.Create(rtb));


                       ping.Save(file);

                       if (file != null)
                           file.Close();

               }

           }
           catch { }
       }

public static class DrawingImageExtensions
    {
        public static RenderTargetBitmap ToBitmapSource(this DrawingImage source)
        {
            DrawingVisual drawingVisual = new DrawingVisual();
            DrawingContext drawingContext = drawingVisual.RenderOpen();
            drawingContext.DrawImage(source, new Rect(0, 0, (int)source.Width, (int)source.Height));
            drawingContext.Close();

            RenderTargetBitmap bmp = new RenderTargetBitmap((int)source.Width, (int)source.Height, 96, 96, PixelFormats.Pbgra32);
            bmp.Render(drawingVisual);
            return bmp;
        }
        public static DrawingImage ToDrawingImage(this BitmapSource source)
        {
            Rect imageRect = new Rect(0, 0, source.PixelWidth, source.PixelHeight);
            ImageDrawing drawing = new ImageDrawing(source, imageRect);
            return new DrawingImage(drawing);
        }
    }

The result is correct for Height and Width but the centre of the ellipse is always the center of saved crop.

A Circle cropped from the left of the image ends up being a crop of the center of the rectangular image.

Any thoughts?

解决方案

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