- 最近在研究robotium的方法,在Scroller.java中有一个drag方法,如下:
- /**
- * Simulate touching a specific location and dragging to a new location.
- *
- * This method was copied from {@code TouchUtils.java} in the Android Open Source Project, and modified here.
- *
- * @param fromX X coordinate of the initial touch, in screen coordinates
- * @param toX Xcoordinate of the drag destination, in screen coordinates
- * @param fromY X coordinate of the initial touch, in screen coordinates
- * @param toY Y coordinate of the drag destination, in screen coordinates
- * @param stepCount How many move steps to include in the drag
- */
- public void drag(float fromX, float toX, float fromY, float toY,
- int stepCount) {
- long downTime = SystemClock.uptimeMillis();
- long eventTime = SystemClock.uptimeMillis();
- float y = fromY;
- float x = fromX;
- float yStep = (toY - fromY) / stepCount;
- float xStep = (toX - fromX) / stepCount;
- <strong><span style="color:#ff6666;">MotionEvent event = MotionEvent.obtain(downTime, eventTime,MotionEvent.ACTION_DOWN, fromX, fromY, 0);</span></strong>
- try {
- inst.sendPointerSync(event);
- } catch (SecurityException ignored) {}
- for (int i = 0; i < stepCount; ++i) {
- y += yStep;
- x += xStep;
- eventTime = SystemClock.uptimeMillis();
- event = MotionEvent.obtain(downTime, eventTime,MotionEvent.ACTION_MOVE, x, y, 0);
- try {
- inst.sendPointerSync(event);
- } catch (SecurityException ignored) {}
- }
- eventTime = SystemClock.uptimeMillis();
- event = MotionEvent.obtain(downTime, eventTime, MotionEvent.ACTION_UP,toX, toY, 0);
- try {
- inst.sendPointerSync(event);
- } catch (SecurityException ignored) {}
- }
里面有个MotionEvent的类,下面摘自网上的一篇博客,写的很好;
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android中的事件类型分为按键事件和屏幕触摸事件,Touch事件是屏幕触摸事件的基础事件,有必要对它进行深入的了解。
一个最简单的屏幕触摸动作触发了一系列Touch事件:ACTION_DOWN->ACTION_MOVE->ACTION_MOVE->ACTION_MOVE...->ACTION_MOVE->ACTION_UP
当屏幕中包含一个ViewGroup,而这个ViewGroup又包含一个子view,这个时候android系统如何处理Touch事件呢?到底是ViewGroup来处理Touch事件,还是子view来处理Touch事件呢?我只能很肯定的对你说不一定。呵呵,为什么呢?看看下面我的调查结果你就明白了。
android系统中的每个View的子类都具有下面三个和TouchEvent处理密切相关的方法:
1)public boolean dispatchTouchEvent(MotionEvent ev) 这个方法用来分发TouchEvent
2)public boolean onInterceptTouchEvent(MotionEvent ev) 这个方法用来拦截TouchEvent
3)public boolean onTouchEvent(MotionEvent ev) 这个方法用来处理TouchEvent
当TouchEvent发生时,首先Activity将TouchEvent传递给最顶层的View, TouchEvent最先到达最顶层 view 的 dispatchTouchEvent ,然后由 dispatchTouchEvent 方法进行分发,如果dispatchTouchEvent返回true ,则交给这个view的onTouchEvent处理,如果dispatchTouchEvent返回 false ,则交给这个 view 的 interceptTouchEvent 方法来决定是否要拦截这个事件,如果 interceptTouchEvent 返回 true ,也就是拦截掉了,则交给它的 onTouchEvent 来处理,如果 interceptTouchEvent 返回 false ,那么就传递给子 view ,由子 view 的 dispatchTouchEvent 再来开始这个事件的分发。如果事件传递到某一层的子 view 的 onTouchEvent 上了,这个方法返回了 false ,那么这个事件会从这个 view 往上传递,都是 onTouchEvent 来接收。而如果传递到最上面的 onTouchEvent 也返回 false 的话,这个事件就会“消失”,而且接收不到下一次事件。
通过语言描述这个处理逻辑很抽象,下面我就用代码来具体说明一下。
layout配置文件 main.xml
- <?xml version="1.0" encoding="utf-8"?>
- <test.lzqdiy.MyLinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
- android:layout_width="fill_parent"
- android:layout_height="fill_parent"
- android:gravity="center"
- android:orientation="vertical" >
- <test.lzqdiy.MyTextView
- android:id="@+id/tv"
- android:layout_width="200px"
- android:layout_height="200px"
- android:background="#FFFFFF"
- android:text="lzqdiy"
- android:textColor="#0000FF"
- android:textSize="40sp"
- android:textStyle="bold" />
- </test.lzqdiy.MyLinearLayout>
三个java文件:
- package test.lzqdiy;
- import android.os.Bundle;
- import android.app.Activity;
- import android.view.Menu;
- public class MainActivity extends Activity
- {
- @Override
- protected void onCreate(Bundle savedInstanceState)
- {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_main);
- }
- @Override
- public boolean onCreateOptionsMenu(Menu menu)
- {
- // Inflate the menu; this adds items to the action bar if it is present.
- getMenuInflater().inflate(R.menu.main, menu);
- return true;
- }
- }
- package test.lzqdiy;
- import android.content.Context;
- import android.util.AttributeSet;
- import android.util.Log;
- import android.view.MotionEvent;
- import android.widget.LinearLayout;
- public class MyLinearLayout extends LinearLayout {
- private final String TAG = "MyLinearLayout";
- public MyLinearLayout(Context context, AttributeSet attrs) {
- super(context, attrs);
- Log.d(TAG, TAG);
- }
- @Override
- public boolean dispatchTouchEvent(MotionEvent ev) {
- int action = ev.getAction();
- switch (action) {
- case MotionEvent.ACTION_DOWN:
- Log.d(TAG, "dispatchTouchEvent action:ACTION_DOWN");
- break;
- case MotionEvent.ACTION_MOVE:
- Log.d(TAG, "dispatchTouchEvent action:ACTION_MOVE");
- break;
- case MotionEvent.ACTION_UP:
- Log.d(TAG, "dispatchTouchEvent action:ACTION_UP");
- break;
- case MotionEvent.ACTION_CANCEL:
- Log.d(TAG, "dispatchTouchEvent action:ACTION_CANCEL");
- break;
- }
- return super.dispatchTouchEvent(ev);
- }
- @Override
- public boolean onInterceptTouchEvent(MotionEvent ev) {
- int action = ev.getAction();
- switch (action) {
- case MotionEvent.ACTION_DOWN:
- Log.d(TAG, "onInterceptTouchEvent action:ACTION_DOWN");
- break;
- case MotionEvent.ACTION_MOVE:
- Log.d(TAG, "onInterceptTouchEvent action:ACTION_MOVE");
- break;
- case MotionEvent.ACTION_UP:
- Log.d(TAG, "onInterceptTouchEvent action:ACTION_UP");
- break;
- case MotionEvent.ACTION_CANCEL:
- Log.d(TAG, "onInterceptTouchEvent action:ACTION_CANCEL");
- break;
- }
- return false;
- }
- @Override
- public boolean onTouchEvent(MotionEvent ev) {
- int action = ev.getAction();
- switch (action) {
- case MotionEvent.ACTION_DOWN:
- Log.d(TAG, "---onTouchEvent action:ACTION_DOWN");
- break;
- case MotionEvent.ACTION_MOVE:
- Log.d(TAG, "---onTouchEvent action:ACTION_MOVE");
- break;
- case MotionEvent.ACTION_UP:
- Log.d(TAG, "---onTouchEvent action:ACTION_UP");
- break;
- case MotionEvent.ACTION_CANCEL:
- Log.d(TAG, "---onTouchEvent action:ACTION_CANCEL");
- break;
- }
- return true;
- }
- }
- package test.lzqdiy;
- import android.content.Context;
- import android.util.AttributeSet;
- import android.util.Log;
- import android.view.MotionEvent;
- import android.widget.TextView;
- public class MyTextView extends TextView
- {
- private final String TAG = "MyTextView";
- public MyTextView(Context context, AttributeSet attrs)
- {
- super(context, attrs);
- }
- @Override
- public boolean dispatchTouchEvent(MotionEvent ev)
- {
- int action = ev.getAction();
- switch (action)
- {
- case MotionEvent.ACTION_DOWN:
- Log.d(TAG, "dispatchTouchEvent action:ACTION_DOWN");
- break;
- case MotionEvent.ACTION_MOVE:
- Log.d(TAG, "dispatchTouchEvent action:ACTION_MOVE");
- break;
- case MotionEvent.ACTION_UP:
- Log.d(TAG, "dispatchTouchEvent action:ACTION_UP");
- break;
- case MotionEvent.ACTION_CANCEL:
- Log.d(TAG, "onTouchEvent action:ACTION_CANCEL");
- break;
- }
- return super.dispatchTouchEvent(ev);
- }
- @Override
- public boolean onTouchEvent(MotionEvent ev)
- {
- int action = ev.getAction();
- switch (action)
- {
- case MotionEvent.ACTION_DOWN:
- Log.d(TAG, "---onTouchEvent action:ACTION_DOWN");
- break;
- case MotionEvent.ACTION_MOVE:
- Log.d(TAG, "---onTouchEvent action:ACTION_MOVE");
- break;
- case MotionEvent.ACTION_UP:
- Log.d(TAG, "---onTouchEvent action:ACTION_UP");
- break;
- case MotionEvent.ACTION_CANCEL:
- Log.d(TAG, "---onTouchEvent action:ACTION_CANCEL");
- break;
- }
- return true;
- }
- }
为了指代方便,下面将MyLinearLayout简称为L,将MyTextView简称为T,L.onInterceptTouchEvent=true 表示的含义为MyLinearLayout中的onInterceptTouchEvent方法返回值为true,通过程序运行时输出的Log来说明调用时序。
第1种情况 L.onInterceptTouchEvent=false&& L.onTouchEvent=true &&T.onTouchEvent=true 输出下面的Log:
D/MyLinearLayout(11865): dispatchTouchEvent action:ACTION_DOWN
D/MyLinearLayout(11865): onInterceptTouchEvent action:ACTION_DOWN
D/MyTextView(11865): dispatchTouchEvent action:ACTION_DOWN
D/MyTextView(11865): ---onTouchEvent action:ACTION_DOWN
D/MyLinearLayout(11865): dispatchTouchEvent action:ACTION_MOVE
D/MyLinearLayout(11865): onInterceptTouchEvent action:ACTION_MOVE
D/MyTextView(11865): dispatchTouchEvent action:ACTION_MOVE
D/MyTextView(11865): ---onTouchEvent action:ACTION_MOVE
...........省略其他的ACTION_MOVE事件Log
D/MyLinearLayout(11865): dispatchTouchEvent action:ACTION_UP
D/MyLinearLayout(11865): onInterceptTouchEvent action:ACTION_UP
D/MyTextView(11865): dispatchTouchEvent action:ACTION_UP
D/MyTextView(11865): ---onTouchEvent action:ACTION_UP
结论:TouchEvent完全由TextView处理。
第2种情况 L.onInterceptTouchEvent=false&& L.onTouchEvent=true &&T.onTouchEvent=false 输出下面的Log:
D/MyLinearLayout(13101): dispatchTouchEvent action:ACTION_DOWN
D/MyLinearLayout(13101): onInterceptTouchEvent action:ACTION_DOWN
D/MyTextView(13101): dispatchTouchEvent action:ACTION_DOWN
D/MyTextView(13101): ---onTouchEvent action:ACTION_DOWN
D/MyLinearLayout(13101): ---onTouchEvent action:ACTION_DOWN
D/MyLinearLayout(13101): dispatchTouchEvent action:ACTION_MOVE
D/MyLinearLayout(13101): ---onTouchEvent action:ACTION_MOVE
...........省略其他的ACTION_MOVE事件Log
D/MyLinearLayout(13101): dispatchTouchEvent action:ACTION_UP
D/MyLinearLayout(13101): ---onTouchEvent action:ACTION_UP
结论:TextView只处理了ACTION_DOWN事件,LinearLayout处理了所有的TouchEvent。
第3种情况 L.onInterceptTouchEvent=true&& L.onTouchEvent=true 输出下面的Log:
D/MyLinearLayout(13334): dispatchTouchEvent action:ACTION_DOWN
D/MyLinearLayout(13334): onInterceptTouchEvent action:ACTION_DOWN
D/MyLinearLayout(13334): ---onTouchEvent action:ACTION_DOWN
D/MyLinearLayout(13334): dispatchTouchEvent action:ACTION_MOVE
D/MyLinearLayout(13334): ---onTouchEvent action:ACTION_MOVE
...........省略其他的ACTION_MOVE事件Log
D/MyLinearLayout(13334): dispatchTouchEvent action:ACTION_UP
D/MyLinearLayout(13334): ---onTouchEvent action:ACTION_UP
结论:LinearLayout处理了所有的TouchEvent。
第4种情况 L.onInterceptTouchEvent=true&& L.onTouchEvent=false 输出下面的Log:
D/MyLinearLayout(13452): dispatchTouchEvent action:ACTION_DOWN
D/MyLinearLayout(13452): onInterceptTouchEvent action:ACTION_DOWN
D/MyLinearLayout(13452): ---onTouchEvent action:ACTION_DOWN
结论:LinearLayout只处理了ACTION_DOWN事件,那么其他的TouchEvent被谁处理了呢?答案是LinearLayout最外层的Activity处理了TouchEvent。
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