javascript - 为 Android 应用程序创建动态雷达

Question

我想在 android studio 中为 android 应用程序创建一个动态雷达，如下所示:

http://jsbin.com/AMag/2/edit?html,css,output

我怎样才能做到这一点？

Answer 1

这是一个起点。创建一个像这样的自定义 View 并将其添加到 LinearLayout。

class RadarBlip {
    float x;
    float y;

    public void setX (float x) {
        this.x = x;
    }

    public Float getX() {
        return x;
    }
    ....
}

private class RadarView extends View {

    List<RadarBlip> mRadarBlips;

    public TimerViewContentView(Context context, List<RadarBlip> radarBlips, currentRadarAngle) {
        super(context);
        setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
        mRadarBlips = radarBlips;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        for(int i = 0; i < mRadarBlips.size(); i++) {
            blipPaint.setAlpha(...do geometry...);
            canvas.drawCircle(mRadarBlips.get(i).getX(), mRadarBlips.get(i).getY(), radius, blipPaint);
        }
        canvas.drawArc(oval, currentRadarAngle, currentRadarAngle - 10, false, radarPaint);
    }
}

然后您想在计时器中调用 View 。类似于:

    new CountDownTimer(timeRemaining, 15) {
        public void onTick(long millisUntilFinished) {
            float radarAngle = ((long)millisUntilFinished)%((long)timeForRevolution) * 360f;
            RadarView mRadarView = new RadarView(MyActivity.this,radarPointsArray,radarAngle);
            radarLayout.removeAllViewsInLayout();
            radarTimerLayout.addView(mRadarView);
            timeRemaining = millisUntilFinished;
        }
        public void onFinish() {
        }
    }.start();

考虑一下使用 NineOldAndroids 的 ObjectAnimator 而不是 Timer 可能会更好。尽管 ObjectAnimator 倾向于永远不会停止并耗尽电池，除非您添加一个函数来停止它。