Android: custom compass image only partially redraws

Question

I am looking to draw my own compass image on a MapView by subclassing MyLocationOverlay. The custom image needs to be larger than the default image shown by MyLocationOverlay. I override drawCompass and use my own drawables (bitmaps) to draw the compass:

@Override
protected void drawCompass(Canvas canvas, float bearing) {

    Rect bounds = canvas.getClipBounds();
    // usual result: bottom=98, left=10, right=90, top=18

    // draw something custom here...

    // Don't want default compass image:        
    //super.drawCompass(canvas, bearing);

}

How do you set the bounds of the custom imagery so that calls to drawCompass set the required bounds on the canvas object? It seems the bounds I'm getting are those applicable to the default imagery.

(drawCompass appears to be called from MyLocationOverlay.draw() - I can override that, but am still unsure how to change the ClipBounds on the canvas object.)

Answer 1

Your question made me realize the clipping problem you describe was causing the weird way my custom compass was drawing. I found the answer here:

http://jtomlinson.blogspot.com/2008/10/clipping.html

You need to use

   canvas.clipRect(0, 0, newWidth, newHeight, Region.Op.REPLACE);

(To use it you will need to import android.graphics.Region.)