将文本呈现为使用WPF的位图的问题 [英] Problems with rendering text as bitmaps using WPF

问题描述

我正在开发一个应用程序，使用WPF动态呈现内容，包括来自WPF的文本和图像转换为jpg文件。我正在使用 RenderTargetBitmap 类来完成这项工作。一切都按预期工作，但渲染字体的质量是可怕的。我知道 RenderTargetBitmap 不使用ClearType，而是使用GrayScale抗锯齿，这是一种小字体。但是我使用大于30分的大字体，结果是完全不能接受的。有这种问题的解决方法吗？

[更新]

我使用的代码如下所示。如预期的那样，在CompositionTarget的每个Rendering事件上都会调用它。

  void CompositionTarget_Rendering（object sender，EventArgs e）
 {
 prefix =; 
 if（counter <10）
 {
 prefix =000; 
 
 else if（counter< 100）
 {
 prefix =00; 
 
 else if（counter< 1000）
 {
 prefix =0; 
} 
 
 Size size = new Size（MainCanvas.Width，MainCanvas.Height）; 
 MainCanvas.Measure（size）; 
 MainCanvas.Arrange（new Rect（size））; 
 
 
 RenderTargetBitmap bmp = new RenderTargetBitmap（imgWidth，imgHeight，96d，96d，PixelFormats.Default）; 
 bmp.Render（MainCanvas）; 
 
 JpegBitmapEncoder encoder = new JpegBitmapEncoder（）; 
 encoder.QualityLevel = 90; 
 encoder.Frames.Add（BitmapFrame.Create（bmp））; 
 string file = basePath + prefix + counter.ToString（）+_testpic.jpg; 
 using（Stream stm = File.Create（file））
 {
 encoder.Save（stm）; 
} 
 counter ++; 
 
 
 
 $ b $ p 
 $ b 
下面是一些结果图像的例子：
 替代文字http://www.randomnoise.org/temp/testpic_v1.jpg  
 替代文字http://www.randomnoise.org/temp/testpic_v2.jpg  
 
 
 
在此先感谢。
 
解决方案
好的，我终于找到了一个解决方案。 Gustavo你在正确的轨道上。问题是，我试图呈现为位图的主容器被其父容器扭曲。解决方案是将主容器添加到画布上，但没有布局引擎来扭曲孩子。我仍然需要做更多的尝试，但看起来很有希望。显然RenderTargetBitmap根本不喜欢扭曲的字体。
 
I am developing an application using WPF to dynamically render content, including text and images from WPF into jpg files. I am currently using the RenderTargetBitmap class to do the job. Everything works as expected but the quality of the rendered fonts is terrible. I understand that the RenderTargetBitmap doesn’t use the ClearType but a GrayScale antialias, which is kind of blury with small fonts. But I am using large fonts, larger than 30 pts, and the results are totally unacceptable. Is there some kind of workaround for this issue? 

[Update]

The Code I am using is listed below. As expected it is called on each Rendering event of the CompositionTarget.
void CompositionTarget_Rendering(object sender, EventArgs e)
        {
            prefix = "";
            if (counter < 10)
            {
                prefix = "000";
            }
            else if (counter < 100)
            {
                prefix = "00";
            }
            else if (counter < 1000)
            {
                prefix = "0";
            }

            Size size = new Size(MainCanvas.Width, MainCanvas.Height);
            MainCanvas.Measure(size);
            MainCanvas.Arrange(new Rect(size));


            RenderTargetBitmap bmp = new RenderTargetBitmap(imgWidth, imgHeight, 96d, 96d, PixelFormats.Default);
            bmp.Render(MainCanvas);

            JpegBitmapEncoder encoder = new JpegBitmapEncoder();
            encoder.QualityLevel = 90;
            encoder.Frames.Add(BitmapFrame.Create(bmp));
            string file = basePath + prefix + counter.ToString() + "_testpic.jpg";
            using (Stream stm = File.Create(file))
            {
                encoder.Save(stm);
            }
            counter++;
        }
Here are some examples of the resulting images:
alt text http://www.randomnoise.org/temp/testpic_v1.jpg
alt text http://www.randomnoise.org/temp/testpic_v2.jpg

Thanks in advance.
解决方案
Ok, I finally found a solution. Gustavo you were on the right track. The problem was that the main container that I was trying to render as bitmap was being distorted by its parent container. The solution was to add the main container to a canvas, that doesn't have a layout engine that distorts its children. I still need to do some more experimenting but it looks very promising.  Apparently RenderTargetBitmap doesn't like distorted fonts at all.

                        
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