雨中即景

使用::
            //將列印字串格式化為圖片
            FormattedText text = new FormattedText(
               "文字字串",
               CultureInfo.InvariantCulture,
               FlowDirection.LeftToRight,
               new Typeface("Segeo UI"),
               14,
               Brushes.Black);

            string SourcePath = Directory.GetCurrentDirectory() + "\\Source.jpg";
            string OutFileName = "Output.jpg";
            WriteTextToImage(
                SourcePath,
                OutFileName,
                text,
                new Point(10, 10));

方法::
      public void WriteTextToImage(string inputFile, string outputFile, FormattedText text, Point position)
      {
         BitmapImage bitmap = new BitmapImage(new Uri(inputFile)); // inputFile must be absolute path
         DrawingVisual visual = new DrawingVisual();

         using (DrawingContext dc = visual.RenderOpen())
         {
            dc.DrawImage(bitmap, new Rect(0, 0, bitmap.PixelWidth, bitmap.PixelHeight));
            dc.DrawText(text, position);
         }

         RenderTargetBitmap target = new RenderTargetBitmap(bitmap.PixelWidth, bitmap.PixelHeight,
                                                            bitmap.DpiX, bitmap.DpiY, PixelFormats.Default);
         target.Render(visual);

         BitmapEncoder encoder = null;

         switch (System.IO.Path.GetExtension(outputFile))
         {
            case ".jpg":
               //encoder = new PngBitmapEncoder();
               encoder = new JpegBitmapEncoder();
               break;
            // more encoders here
         }

         if (encoder != null)
         {
            encoder.Frames.Add(BitmapFrame.Create(target));
            using (FileStream outputStream = new FileStream(outputFile, FileMode.Create))
            {
               encoder.Save(outputStream);
            }
         }
      }