android - 使用双击和捏合放大 android 时如何使谷歌居中？

Question

我在使用双击和双指缩放进行缩放时搜索了谷歌地图中心。我为 Here 找到了一个解决方案, 这仅适用于双击缩放解决方案。

TouchableWrapper

 public class TouchableWrapper extends FrameLayout {

    GestureDetectorCompat mGestureDetector;


    public TouchableWrapper(Context context) {
        super(context);
        mGestureDetector = new GestureDetectorCompat(context, mGestureListener);
    }


    private final GestureDetector.SimpleOnGestureListener mGestureListener
            = new GestureDetector.SimpleOnGestureListener() {
        @Override
        public boolean onDoubleTap(MotionEvent e) {
            Log.e("GestureDetector", "Executed");
            //Notify the event bus (I am using Otto eventbus of course) that you have just received a double-tap event on the map, inside the event bus event listener
            EventBus_Singleton.getInstance().post(new EventBus_Poster("double_tapped_map"));

            return true;
        }
    };

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        mGestureDetector.onTouchEvent(ev);
        return super.onInterceptTouchEvent(ev);
    }


}

我用过Otto用于事件触发器。

public class EventBus_Singleton {

    private static final Bus BUS = new Bus();

    public static Bus getInstance() {
        return BUS;
    }

    public EventBus_Singleton() {
    }

    public void post(String s) {
        BUS.post(s);
    }
}

EventBus_Poster

public class EventBus_Poster {
    public final String string;

    EventBus_Poster(String string) {
        this.string = string;
    }
}

在我的 map Activity 中，我使用事件接收方法在同一位置缩放 map 。

 @Subscribe
    public void EventBus_singleton(EventBus_Poster event) {
        Log.e("EventBus_singleton", "Executed");
        if (event != null && event.string.equals("double_tapped_map")) {
            if (mapFragment != null) {
                mapFragment.getMap().getUiSettings().setZoomGesturesEnabled(false);
                mapFragment.getMap().getUiSettings().setRotateGesturesEnabled(false);

                mapFragment.getMap().setOnCameraChangeListener(new GoogleMap.OnCameraChangeListener() {
                    @Override
                    public void onCameraChange(CameraPosition cameraPosition) {
                        LatLng lng = cameraPosition.target;
                        Log.e("LatLng", "" + lng);
                    }
                });
                mapFragment.getMap().animateCamera(CameraUpdateFactory.zoomIn(), 400, null);
            }

        }
    }

我曾尝试使用 ScaleGestureDetector.SimpleOnScaleGestureListener 进行捏合缩放，但它没有用，而且有时它会滞后。谁能帮我在谷歌地图中进行缩放？

Answer 1

好吧，我发现在尝试执行此操作时，成功的双指缩放涉及速度 和比例 条件。测量速度以确定你是否真的想要缩放，这取决于你将两根手指移开或靠近的速度，你可以在谷歌地图和 Uber 的应用程序中尝试这个，你实际上可以保持手指远离或靠近彼此靠近但速度很慢，以至于您不会触发 map 上的放大/缩小事件!

因此，在尝试确定完整的捏合手势时肯定涉及速度。第二，当然你也需要比例，我已经打印出比例值，它总是小于正好1.0当你开始捏缩小并且总是大于1.0，当您开始捏合以放大时。

这两者的结合肯定会给你带来更好的结果，我会说先看速度

private final ScaleGestureDetector.OnScaleGestureListener mScaleGestureListener
        = new ScaleGestureDetector.SimpleOnScaleGestureListener() {
    /**
     * This is the active focal point in terms of the viewport. Could be a local
     * variable but kept here to minimize per-frame allocations.
     */

    float startingSpan;
    float startFocusX;
    float startFocusY;

    @Override
    public boolean onScaleBegin(ScaleGestureDetector scaleGestureDetector) {
        startingSpan = scaleGestureDetector.getCurrentSpan();
        startFocusX = scaleGestureDetector.getFocusX();
        startFocusY = scaleGestureDetector.getFocusY();

        return true;
    }

    @Override
    public boolean onScale(ScaleGestureDetector scaleGestureDetector) {
        float scale = scaleGestureDetector.getCurrentSpan() / startingSpan;

        mVelocityTracker.computeCurrentVelocity(1000);

        Log.d("VELOCITY", "X vel : " + mVelocityTracker.getXVelocity());
        Log.d("VELOCITY", "Y vel : " + mVelocityTracker.getYVelocity());

        if (scale <= 1.0) {
            EventBus_Singleton.getInstance().post(new EventBus_Poster("pinched_map", "out"));
        } else {
            EventBus_Singleton.getInstance().post(new EventBus_Poster("pinched_map", "in"));
        }

        return true;
    }
};