Question

我有一个图像，可以移动并使用捏合手势缩放..所有这些都在onTouch()内完成。我想限制这个并且只有在用户对图像进行了长按之后才使其可移动（并且可伸缩）。我该怎么做？

Answer 1

注册LongCLickListener。如果识别出长按，则将标志设置为true。

在OnTouch方法中，仅当标志设置为true时才允许缩放和移动。移动和缩放后，再次将标志设置为false。

这是一些伪代码：

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;
   }
}

Answer 2

Roflcoptr的主要思想是正确的，但即使你没有长按也移动你的指针，也会调用onLongClick。为避免这种情况，您可以使用以下代码：

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);
}

希望它会帮助某人）

Answer 3

您可以创建两个View.ontouchlistener for one和一个空，并将侦听器设置为仅在onlongpress上查看

    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;
        }
    });

Android：如何在onLongClick之后调用onTouch？

3 个答案: