Android™ How to Program, Second Edition

Anonymous Inner Class That Implements Interface OnSeekBarChangeListener to Respond to the Events of the widthSeekBar

Lines 93–127 define the lineWidthChanged OnSeekBarChangeListener that responds to events when the user adjusts the SeekBar in the Choose Line Width dialog. Lines 96–97 create a Bitmap on which to display a sample line representing the selected line thickness. Line 98 creates a Canvas for drawing on the Bitmap. Method onProgressChanged (lines 100–116) draws the sample line based on the current drawing color and the SeekBar’s value. First, lines 105–109 configure a Paint object for drawing the sample line. Class Paint’s setStrokeCap method (line 108) specifies the appearance of the line ends—in this case, they’re rounded (Paint.Cap.ROUND ...