Android™ How to Program, Second Edition

Overridden View Method onDraw

When a View needs to be redrawn, its onDraw method is called. Figure 7.25 overrides onDraw to display bitmap (the Bitmap that contains the drawing) on the DoodleView by calling the Canvas argument’s drawBitmap method. The first argument is the Bitmap to draw, the next two arguments are the x-y coordinates where the upper-left corner of the Bitmap should be placed on the View and the last argument is the Paint object that specifies the drawing characteristics. Lines 115–116 then loop through and display the Paths that are currently being drawn. For each Integer key in the pathMap, we pass the corresponding Path to Canvas’s drawPath method to draw the Path using the paintLine object, which defines the line width and ...