問題描述

我正在嘗試在我的 MapView 中實現雙擊縮放功能.該事件總是第一次觸發，但以后不會觸發.下面是我的代碼.我感覺這與第一次觸發事件后地圖控制器丟失有關.

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;
    }

  }

我還嘗試編輯 OnTouch 方法以將傳入的 View 轉換為 MapView，在觸發事件時獲取控制器.但是，在觸發第一個事件而不是后續事件的情況下，我得到了相同的結果.

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;
    }

為了盡可能簡單，我刪除了 OnTouch 方法中的所有代碼，并將其編程為簡單地顯示一條小的 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;
}

這按預期工作，每次觸摸 MapView 時都會顯示 Toast.

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

我不明白為什么在這種情況下事件會正確觸發，但在我之前的實現中卻不會.

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

推薦答案

如果你使用這個方法 "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 .

請刪除該行并檢查我確定它會起作用..

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

在某些情況下，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;
    }
}

這篇關于MapView 中的 OnTouch 僅在第一次觸發的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！