Invalidates specified tile layers.
Assembly: System.Windows (in System.Windows.dll)
protected void InvalidateTileLayer( int level, int tilePositionX, int tilePositionY, int tileLayer )
The method can be used to change the URIs returned for a tile layer. For example, if you have an implementation of a map and you want to zoom straight to street level, normally Deep Zoom would blend all the levels from 0 to 19. Instead, you can implement a MultiScaleTileSource class that returns null for all layers 18 and below. When a user starts to zoom out, you invalidate all the layers through 18, and return the proper URLs for the tiles instead.