android 的事件机制

原文在这 http://blog.csdn.net/morgan_xww/article/details/9372285/

 

自己写的touch

package com.weidingqiang.testviewb;

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

/**
 * Created by weidingqiang on 15/11/20.
 */
public class TouchView extends View {

    private static final String TAG = TouchView.class.getSimpleName();

    public TouchView(Context context) {
        super(context);
    }

    public TouchView(Context context, AttributeSet attrs) {
        super(context, attrs);

    }

    public TouchView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    private int oldx,oldy;


    @Override
    public boolean onTouchEvent(MotionEvent event) {

        //以父类为0，0 点
        int in_parentx = (int)event.getX();
        int in_parenty = (int) event.getY();
        //以 屏幕为 0，0
        int in_screen_x = (int) event.getRawX();
        int in_screen_y = (int) event.getRawY();

        switch (event.getAction()){
            case MotionEvent.ACTION_DOWN:
                oldx = in_parentx;
                oldy = in_parenty;
                Log.d(TAG,">>>>>>ACTION_DOWN>>>>>>  x  "+in_parentx+"  y "+in_parenty);
                break;
            case MotionEvent.ACTION_MOVE:
                int dis_x = in_parentx-oldx;
                int dis_y = in_parenty-oldy;
                Log.d(TAG,">>>>>>ACTION_MOVE>>>>>>  x  "+dis_x+"  y  "+dis_y);
                break;
            case MotionEvent.ACTION_UP:
                int dis_x_up = in_parentx-oldx;
                int dis_y_up = in_parenty-oldy;
                Log.d(TAG,">>>>>>ACTION_UP>>>>>>  x  "+dis_x_up+"  y  "+dis_y_up);
                break;
        }

        //需要修改为 true  否则只能监听到 down 事件
        return true;
    }

}

 

跟touch事件相关的3个方法：

public boolean dispatchTouchEvent(MotionEvent ev);    //用来分派event

public boolean onInterceptTouchEvent(MotionEvent ev); //用来拦截event

public boolean onTouchEvent(MotionEvent ev);          //用来处理event

 

流程图