Android: How to call onTouch only after an onLongClick?

问题

I have an image, which can be moved around and scaled with pinch gesture.. All this is done inside onTouch(). I want to restrict this and make it movable(and scalable) only after the user has done a longclick on the image.. How do I do this?

回答1:

In the OnTouch method allow scaling and moving only if the flag is set to true. After the moving and scaling set the flag to false again.

Here is some pseudocode:

public class MyActivity extends Activity {

   private boolean longClick = false;

   public boolean onTouch(View v, MotionEvent event) {
      if (longClick) {
         // do scaling and moving ...
         longClick = false;
      }
      return false;
   }

   public boolean onLongClick(View v) {
      longClick = true;
      return false;
   }
}

回答2:

You can create two View.ontouchlistener one for work and one empty, and set the listener to view only on onlongpress

    LinearLayout.LayoutParams longpressLP = new LinearLayout.LayoutParams(100,100);
    LinearLayout longpress = new LinearLayout(this);
    longpress.setBackgroundColor(Color.GREEN);
    mainlayout.addView(longpress,longpressLP);



    final View.OnTouchListener buttontouch=new View.OnTouchListener() {

        public boolean onTouch(View v, MotionEvent event) {
            // TODO Auto-generated method stub
            if(event.getAction()==MotionEvent.ACTION_DOWN)
                v.setOnTouchListener(buttontouchnone);
            else
                Toast.makeText(getApplicationContext(), "Touched", Toast.LENGTH_SHORT).show();
            return false;
        }
    };
    final View.OnTouchListener buttontouchnone=new View.OnTouchListener() {

        public boolean onTouch(View v, MotionEvent event) {
            // TODO Auto-generated method stub
            Toast.makeText(getApplicationContext(), "None Touch", Toast.LENGTH_SHORT).show();
            return false;
        }
    };
    longpress.setOnTouchListener(buttontouch);
    longpress.setOnLongClickListener(new View.OnLongClickListener() {

        public boolean onLongClick(View v) {
            // TODO Auto-generated method stub
            Toast.makeText(getApplicationContext(), "LongClick", Toast.LENGTH_SHORT).show();
            v.setOnTouchListener(buttontouch);
            return true;
        }
    });

回答3:

Main idea of Roflcoptr is right, but even if you'll move your pointer without long click, onLongClick will be called. To avoid this, you can use this code:

final int NONE=0;
final int DRAG=1;
final int LONG_PRESS=2;
int mode=NONE;

PointF start=new PointF();

public boolean onLongClick(View v) {
    if(mode==NONE) mode=LONG_PRESS; //it helps to avoid unwanted onLongClick
    return false;
}

public boolean onTouch(View v, MotionEvent event){
    switch(event.getAction() & MotionEvent.ACTION_MASK){
        case MotionEvent.ACTION_DOWN:
            start.set(event.getX(),event.getY()); //point where we started from
            break;
        case MotionEvent.ACTION_UP:
            mode=NONE;
            break;
        case MotionEvent.ACTION_MOVE:
            if(mode==NONE && getDistance(event.getX(),event.getY(),start.x,start.y)>30d) mode=DRAG; //if we really move our pointer, then start the drag mode.
            //it helps to avoid unwanted moving

            if(mode==DRAG){
            //do your stuff
            }
            if(mode==LONG_PRESS){
            //do your stuff
            }
            break;
    }
}

//returns distance between 2 points
private double getDistance(float x1,float y1,float x2,float y2){
    float dx=Math.abs(x1-x2);
    float dy=Math.abs(y1-y2);
    return Math.sqrt(dx*dx+dy*dy);
}

Hope it will help someone )

来源：https://stackoverflow.com/questions/5471959/android-how-to-call-ontouch-only-after-an-onlongclick

标签

android

image

onclick