How do you draw a string to an image in winRT? In WinForms that could be done using drawstring() method inside the system.drawing name
In Windows 8.1 they finally support rendering of XAML controls to bitmap. Now you can use
var renderTargetBitmap = new RenderTargetBitmap();
await renderTargetBitmap.RenderAsync(uiElement, width, height));
var buffer = await renderTargetBitmap.GetPixelsAsync();
var tmpWbm = new WriteableBitmap(renderTargetBitmap.PixelWidth, renderTargetBitmap.PixelHeight);