MapView 中的 OnTouch 仅在第一次触发

问题描述

我正在尝试在我的 MapView 中实现双击缩放功能.该事件总是第一次触发，但以后不会触发.下面是我的代码.我感觉这与第一次触发事件后地图控制器丢失有关.

I'm trying to implement a double-tap zoom like function in my MapView. The event always fires the first time, but never subsequent times. Below is my code. I have a feeling it has something to do with the map controller getting lost after the first time the event is fired.

import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;

public class mainmap extends MapActivity implements OnTouchListener{

    long lasttime = -1;
    MapController mapc;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        MapView mapView = (MapView) findViewById(R.id.mapview);
        mapView.setBuiltInZoomControls(true);
        mapc = mapView.getController();
        mapView.setOnTouchListener(this);       
    }

    @Override
    protected boolean isRouteDisplayed() {
        // TODO Auto-generated method stub
        return false;
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN){

            if(event.getEventTime()-lasttime<2000){
                mapc.zoomInFixing((int)event.getX(),(int)event.getY());             
            }
        }       
        lasttime=event.getEventTime();
        return true;
    }

  }

我还尝试编辑 OnTouch 方法以将传入的 View 转换为 MapView，在触发事件时获取控制器.但是，在触发第一个事件而不是后续事件的情况下，我得到了相同的结果.

I have also tried editing the OnTouch method to cast the incoming View to a MapView, getting the controller while the event is fired. However, I get the same results where the first event is fired but not subsequent ones.

public boolean onTouch(View v, MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN){

            if(event.getEventTime()-lasttime<2000){
                ((MapView)v).getController().zoomInFixing((int)event.getX(), (int)event.getY());                
            }
        }       
        lasttime=event.getEventTime();
        return true;
    }

为了尽可能简单，我删除了 OnTouch 方法中的所有代码，并将其编程为简单地显示一条小的 toast 消息.

Being as basic as possible, I cut out all of the code in the OnTouch method and programmed it to simply display a small toast message.

public boolean onTouch(View v, MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN){

               Toast.makeText(this,"Down!",Toast.LENGTH_SHORT).show();

        }       

        return true;
}

这按预期工作，每次触摸 MapView 时都会显示 Toast.

This works as expected, displaying the Toast each time the MapView is touched.

我不明白为什么在这种情况下事件会正确触发，但在我之前的实现中却不会.

I don't understand why the event will fire properly in this case but not in my previous implementation.

推荐答案

如果你使用这个方法 "mapView.setBuiltInZoomControls(true);" 那么你的 touch 是立即工作.

If you are using this method "mapView.setBuiltInZoomControls(true);" then your touch is working at once .

请删除该行并检查我确定它会起作用..

Please remove that that line and check I am sure it will work..

在某些情况下，如果您想要 BuiltInZoomControls，那么您可以使用 OnTouch 的 Overlay 方法，如下所示..

In some case if you want BuiltInZoomControls then you can you OnTouch method of Overlay like as below..

public class MapOverlay extends Overlay {

    public MapOverlay(Context ctx) {super(ctx);}

    @Override
    protected void draw(Canvas c, MapView osmv, boolean shadow) { }

    @Override
    public boolean onTouchEvent(MotionEvent e, MapView mapView) {
        //Write yout touch code here..
        return false;
    }
}

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