如何在canvasandroid上绘制带动画的圆形轨迹箭头？

Question

伙计们我尝试实现弧头上的黑色箭头。箭头以弧形动画，并具有圆形轨迹。我已经根据不同的值用动画实现了红色弧线。请参阅附件。如何在红色圆弧上实现黑色箭头？因为如果我按照红色弧形动画的方式进行操作，黑色箭头将打印不需要的轨迹。

提前致谢！里昂

Answer 1

你只需要 Canvas.

这里是例子。

这是你的抽奖class:

public class CircleView   extends View
{
    public CircleView(Context context) {
        super(context);
        path = new Path();
        paint = new Paint();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        float angle = 270;

        float radius = canvas.getWidth()/3;
        float x = canvas.getWidth()/2;
        float y = canvas.getHeight()/2;
        final RectF oval = new RectF();

        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(25);

        oval.set(x - radius, y - radius, x + radius,y + radius);

        // Draw circle
        paint.setColor(Color.RED);
        canvas.drawArc(oval, 135, angle, false, paint);
        paint.setColor(Color.BLUE);
        canvas.drawArc(oval, angle, 405-angle, false, paint);

        paint.setStyle(Paint.Style.FILL);
        paint.setColor(Color.BLACK);

        float l = 1.2f;
        float a = angle*(float)Math.PI/180;
        // Draw arrow
        path.moveTo(x+ (float)Math.cos(a) *radius, y + (float)Math.sin(a) * radius);
        path.lineTo(x+ (float)Math.cos(a+0.1) *radius*l, y + (float)Math.sin(a+0.1) * radius*l);
        path.lineTo(x+ (float)Math.cos(a-0.1) *radius*l, y + (float)Math.sin(a-0.1) * radius*l);
        path.lineTo(x+ (float)Math.cos(a) *radius, y + (float)Math.sin(a) * radius);
        canvas.drawPath(path, paint);
    }
    private Path path;
    private Paint paint;
}

这是 activity 的:

public class MyActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new CircleView(this));
    }
}

对于角度 == 200，您将看到这样的图像：

IntelliJ Idea 的工作副本：https://github.com/weerf/android_circle

如何在canvasandroid上绘制带动画的圆形轨迹箭头？

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