public CanvasDrawingSession CreateDrawingSession()

Return Value

CanvasRenderTarget is useful for offscreen rendering.

Note that drawing work is not usually actually carried out by the GPU until the returned drawing session object is closed. In C# this is typically done with a 'using' statement, or in C++/CX the 'delete' keyword. Be sure to close the drawing session before using the rendertarget as a source for some other operation (for example DrawImage Overload, SaveAsync Overload, or CopyPixelsFromBitmap Overload).

Like CanvasBitmap, CanvasRenderTargets are created against an ICanvasResourceCreator, such as a device or control.

CanvasRenderTarget renderTarget = new CanvasRenderTarget(canvasControl, 100, 150);

using (CanvasDrawingSession drawingSession = renderTarget.CreateDrawingSession())
{
    drawingSession.Clear(Colors.Blue);
}

Or if you are programming in C++/CX:

CanvasRenderTarget^ renderTarget = ref new CanvasRenderTarget(canvasControl, 100, 150);
CanvasDrawingSession^ drawingSession = renderTarget->CreateDrawingSession();

drawingSession->Clear(Colors::Blue);

delete drawingSession;

Reference