Basic rendering

So far we've only been drawing a solid background or a linear gradient. That's neither exciting nor really useful. Let's see how we can draw more interesting shapes and primitives. We'll do so by creating an example of a circular activity indicator that we'll be adding more and more features to in the following chapters.

Creating the basic circular activity indicator

The Canvas class provides us with many drawing functions; for example:

• drawArc()
• drawBitmap()
• drawOval()
• drawPath()

To draw a circular activity indicator, we can use the drawArc() method. Let's create the basic class and draw an arc:

public class CircularActivityIndicator extends View { 
    private static final int DEFAULT_FG_COLOR = 0xffff0000; 
    private static final int DEFAULT_BG_COLOR = 0xffa0a0a0; 
    private Paint foregroundPaint; 
    private int selectedAngle; 
 
    public CircularActivityIndicator(Context context, AttributeSet
    attributeSet) { 
        super(context, attributeSet); 
 
        foregroundPaint...