动态绘制弧形

Question

我使用onDraw(canvas)绘制弧线：

@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 > 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);
    }
}

告诉我，如何动态更改sweepAngle() == 45的值 canvas.drawArc(oval, -90, 45, false, paint)？

Answer 1

一种解决方案是在您的类中使用sweepAngle字段，并在绘制弧时使用该字段而不是45。然后有一个定时添加到sweepAngle并重绘画布的计时器。