A tile render in progress: advanced in time slices, disposed when done or abandoned.
public interface ITileRender : IDisposable
ISO 32000-2 §10.7.1. Spec #33 viewer capability 2 (time-sliced replay). A backend may leave a finished tile on the device (the WebGL backend keeps it in its canvas) instead of in the target bitmap: ReadBack() brings it into the bitmap, and disposing the render drops it. The session therefore disposes a render after its tile is presented and before the bitmap is released, and reads the tile back first for a surface that reads pixels (AcceptsDevicePixels, #380).
kind:method, kind:property, kind:ctor. Press Esc to clear.ReadBack()Puts the finished tile's pixels into the target bitmap: a backend that left them on the device reads them back. Called once RenderSlice(TimeSpan) has returned true, before the tile goes to a surface that reads its pixels.RenderSlice(TimeSpan)Draws for about budget, at least one operation.