title: Dynamically draw arc
body: <p>I draw an arc using <code>onDraw(canvas)</code>:</p>
  
  <pre><code>@Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(new MyView(this));
  }
  
  public class MyView extends View {
  
      public MyView(Context context) {
          super(context);
      }
  
      @Override
      public void onDraw(Сanvas canvas) {
          super.onDraw(canvas);
          float width = (float) getWidth();
          float height = (float) getHeight();
          float radius;
          if (width &gt; height) {
              radius = height / 4;
          } else {
              radius = width / 4;
          }
  
          final Paint paint = new Paint();
          paint.setColor(Color.WHITE);
          paint.setStrokeWidth(50);
          paint.setStyle(Paint.Style.STROKE);
  
          float center_x, center_y;
          center_x = width / 2;
          center_y = height / 4;
          final RectF oval = new RectF();
          oval.set(center_x - radius, center_y - radius, center_x + radius,
                  center_y + radius);
  
          paint.setStyle(Paint.Style.STROKE);
          center_x = width / 2;
          center_y = height * 3 / 4;
          oval.set(center_x - radius, center_y - radius, center_x + radius,
                  center_y + radius);
  
          canvas.drawArc(oval, -90, 45, false, paint);
      }
  }
  </code></pre>
  
  <p>Tell me, how to dynamically change the value of <a href="http://developer.android.com/reference/android/graphics/Canvas.html#drawArc%28android.graphics.RectF,%20float,%20float,%20boolean,%20android.graphics.Paint%29" rel="nofollow">sweepAngle()</a> == 45 in line 
  <code>canvas.drawArc(oval, -90, 45, false, paint)</code>?</p>