Question

In my application, I have a chart (WPF Toolkit) in normal resolution/size (for example 640×480). I want to export this chart to an image in different resolutions (for example 800×600 or greater).

Currently, I use these lines of codes:

var path = String.Format(@"C:\Temp\chart-{0}.bmp", DateTime.Now.Ticks);
var renderBitmap = new RenderTargetBitmap((int)xamChart.ActualWidth,
                                          (int)xamChart.ActualHeight,
                                          96d,
                                          96d,
                                          PixelFormats.Pbgra32);
renderBitmap.Render(xamChart);

// Create a file stream for saving image
using (var outStream = new FileStream(path, FileMode.Create))
{
   // Use png encoder for our data
   var encoder = new BmpBitmapEncoder();

   // push the rendered bitmap to it
   encoder.Frames.Add(BitmapFrame.Create(renderBitmap));

   // save the data to the stream
   encoder.Save(outStream);
}

It works very well, but if I want to save in greater resolution, I need to change size of the chart. These changes of sizes are visible on my form and are not acceptable. Is there a way to keep the original size of the element and save it as an image in different sizes?

PS. I don’t want save the chart to an image in its original size and in then change the image size, because I lose image quality.

PPS. Second solution: Maybe someone knows how to export a WPF element to vector graphics?

Answer 1

I have not tried it at all but it might be possible to do what you ask by increasing the DPI(the forth and fifth argument to RenderTargetBitmap)