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Android 触屏事件 OnTouch onClick onTouchEvent对于触屏事件的处理和分发

时间:2015-05-06 18:03:54      阅读:285      评论:0      收藏:0      [点我收藏+]

标签:android   ontouch   ontouchevent   onclick   

Android 触屏事件 OnTouch onClick onTouchEvent对于触屏事件的处理和分发 


           做项目的时候经常遇到需要事件分发,很多时候我们发现当我们触发了onTouch却触发不了onClick。或者触发了View的事件却触发不了ViewGroup的事件。那么他们之间到底是什么关系呢,其实最终他们涉及的只是两个问题

         OnTouch 、onClick 、onTouchEvent 之间的关系
         OnTouch 、onClick 、onTouchEvent 之间的处理顺序

这里,我做了简单的例子来看看他们之间的关系。
技术分享
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFFFFF">
    <com.example.empty.MyFrameLayout
        android:id="@+id/mFrame"
        android:layout_width="300dp"
        android:layout_gravity="center"
        android:layout_height="300dp"
        android:background="#00FFFF" >

        <com.example.empty.MyImageView
            android:id="@+id/mImage"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/image_128"
            android:background="#00FF00"
            android:layout_gravity="center" />
    </com.example.empty.MyFrameLayout>

</FrameLayout>

package com.example.empty;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.view.MotionEvent;
import android.widget.FrameLayout;

public class MyFrameLayout extends FrameLayout implements OnClickListener,OnTouchListener{

    private static final String TAG = "Event";
    public MyFrameLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        Log.d(TAG,"MyFrameLayout init");
        setOnClickListener(this);
        setOnTouchListener(this);
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        Log.d(TAG,"MyFrameLayout dispatchTouchEvent");
        return super.dispatchTouchEvent(event);
    }
    
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        Log.d(TAG,"MyFrameLayout onTouchEvent");
        return super.onTouchEvent(event);
    }

    @Override
    public void onClick(View view) {
        // TODO Auto-generated method stub
        Log.d(TAG,"MyFrameLayout onClick");
    }

    @Override
    public boolean onTouch(View view, MotionEvent event) {
        // TODO Auto-generated method stub
        Log.d(TAG,"MyFrameLayout onTouch");
        return false;
    }
}

package com.example.empty;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.ImageView;

public class MyImageView extends ImageView implements OnClickListener,OnTouchListener{
    private static final String TAG = "Event";
    public MyImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        Log.d(TAG,"MyImageView init");
        setOnClickListener(this);
        setOnTouchListener(this);
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        Log.d(TAG,"MyImageView dispatchTouchEvent");
        return super.dispatchTouchEvent(event);
    }
    
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        Log.d(TAG,"MyImageView onTouchEvent");
        return super.onTouchEvent(event);
    }
    
    @Override
    public boolean onTouch(View arg0, MotionEvent arg1) {
        // TODO Auto-generated method stub
        Log.d(TAG,"MyImageView onTouch");
        return false;
    }

    @Override
    public void onClick(View arg0) {
        // TODO Auto-generated method stub
        Log.d(TAG,"MyImageView onClick");
    }

}


例子很简单,下面我们让Log来告诉我们一些东西
当我们点击我们ImageView时
技术分享
当我们再点击我们FrameLayout
技术分享
从这个Log 我们可以得出2点结论
一、执行顺序来讲
dispatchTouchEvent > onTouch > onTouchEvent > onClick
二、事件分发顺序
点击图片时  我们触发了而且还是首先触发了FrameLayout的dispatchTouchEvent 

这里我们知道在Android中我们所有的控件都源自View甚至
public abstract class ViewGroup extends View

所以从底层来看我们的所有事件最终都是交给我们的View
目录(源码目录/frameworks/base\core\java\android\view/View.java)
public class View implements Drawable.Callback, KeyEvent.Callback,
        AccessibilityEventSource {
        ......
     public interface OnClickListener {
        /**
         * Called when a view has been clicked.
         *
         * @param v The view that was clicked.
         */
        void onClick(View v);
    }
    
    ......
    public interface OnTouchListener {
        /**
         * Called when a touch event is dispatched to a view. This allows listeners to
         * get a chance to respond before the target view.
         *
         * @param v The view the touch event has been dispatched to.
         * @param event The MotionEvent object containing full information about
         *        the event.
         * @return True if the listener has consumed the event, false otherwise.
         */
        boolean onTouch(View v, MotionEvent event);
    }
    ......
    public boolean dispatchTouchEvent(MotionEvent event) {
        if (mInputEventConsistencyVerifier != null) {
            mInputEventConsistencyVerifier.onTouchEvent(event, 0);
        }

        if (DBG_MOTION) {
            Xlog.d(VIEW_LOG_TAG, "(View)dispatchTouchEvent: event = " + event + ",this = " + this);
        }

        if (onFilterTouchEventForSecurity(event)) {
            //noinspection SimplifiableIfStatement
            ListenerInfo li = mListenerInfo;
            if (li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED
                    && li.mOnTouchListener.onTouch(this, event)) {
                return true;
            }

            if (onTouchEvent(event)) {
                return true;
            }
        }

        if (mInputEventConsistencyVerifier != null) {
            mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
        }
        return false;
    }

    /**
     * Filter the touch event to apply security policies.
     *
     * @param event The motion event to be filtered.
     * @return True if the event should be dispatched, false if the event should be dropped.
     *
     * @see #getFilterTouchesWhenObscured
     */
    public boolean onFilterTouchEventForSecurity(MotionEvent event) {
        //noinspection RedundantIfStatement
        if ((mViewFlags & FILTER_TOUCHES_WHEN_OBSCURED) != 0
                && (event.getFlags() & MotionEvent.FLAG_WINDOW_IS_OBSCURED) != 0) {
            // Window is obscured, drop this touch.
            return false;
        }
        return true;
    }
    .....
    public boolean onTouchEvent(MotionEvent event) {
        final int viewFlags = mViewFlags;
        if ((viewFlags & ENABLED_MASK) == DISABLED) {
            /// M: we need to reset the pressed state or remove prepressed callback either up or cancel event happens.
            final int action = event.getAction();
            if (action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_CANCEL) {
                if ((mPrivateFlags & PFLAG_PRESSED) != 0) {
                    setPressed(false);
                } else if ((mPrivateFlags & PFLAG_PREPRESSED) != 0) {
                    Xlog.d(VIEW_LOG_TAG, "View onTouch event, if view is DISABLED & PFLAG_PREPRESSED, remove callback mPrivateFlags = "
                                + mPrivateFlags + ", this = " + this);
                    removeTapCallback();
                }
            }
            // A disabled view that is clickable still consumes the touch
            // events, it just doesn't respond to them.
            return (((viewFlags & CLICKABLE) == CLICKABLE ||
                    (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE));
        }

        if (mTouchDelegate != null) {
            if (mTouchDelegate.onTouchEvent(event)) {
                return true;
            }
        }

        if (((viewFlags & CLICKABLE) == CLICKABLE ||
                (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE)) {
            switch (event.getAction()) {
                case MotionEvent.ACTION_UP:
                    boolean prepressed = (mPrivateFlags & PFLAG_PREPRESSED) != 0;
                    if (DBG_MOTION) {
                        Xlog.d(VIEW_LOG_TAG, "(View)Touch up: prepressed = " + prepressed + ",this = " + this);
                    }

                    if ((mPrivateFlags & PFLAG_PRESSED) != 0 || prepressed) {
                        // take focus if we don't have it already and we should in
                        // touch mode.
                        boolean focusTaken = false;
                        if (isFocusable() && isFocusableInTouchMode() && !isFocused()) {
                            focusTaken = requestFocus();
                        }

                        if (prepressed) {
                            // The button is being released before we actually
                            // showed it as pressed.  Make it show the pressed
                            // state now (before scheduling the click) to ensure
                            // the user sees it.
                            setPressed(true);
                       }

                        if (!mHasPerformedLongPress) {
                            // This is a tap, so remove the longpress check
                            removeLongPressCallback();

                            // Only perform take click actions if we were in the pressed state
                            if (!focusTaken) {
                                // Use a Runnable and post this rather than calling
                                // performClick directly. This lets other visual state
                                // of the view update before click actions start.
                                if (mPerformClick == null) {
                                    mPerformClick = new PerformClick();
                                }
                                if (!post(mPerformClick)) {
                                    performClick();
                                }
                            }
                        }

                        if (mUnsetPressedState == null) {
                            mUnsetPressedState = new UnsetPressedState();
                        }

                        if (prepressed) {
                            postDelayed(mUnsetPressedState,
                                    ViewConfiguration.getPressedStateDuration());
                        } else if (!post(mUnsetPressedState)) {
                            // If the post failed, unpress right now
                            mUnsetPressedState.run();
                        }
                        removeTapCallback();
                    }
                    break;

                case MotionEvent.ACTION_DOWN:
                    mHasPerformedLongPress = false;

                    if (performButtonActionOnTouchDown(event)) {
                        break;
                    }

                    // Walk up the hierarchy to determine if we're inside a scrolling container.
                    boolean isInScrollingContainer = isInScrollingContainer();
                    if (DBG_MOTION) {
                        Xlog.d(VIEW_LOG_TAG, "(View)Touch down: isInScrollingContainer = "
                                + isInScrollingContainer + ",this = " + this);
                    }

                    // For views inside a scrolling container, delay the pressed feedback for
                    // a short period in case this is a scroll.
                    if (isInScrollingContainer) {
                        mPrivateFlags |= PFLAG_PREPRESSED;
                        if (mPendingCheckForTap == null) {
                            mPendingCheckForTap = new CheckForTap();
                        }
                        postDelayed(mPendingCheckForTap, ViewConfiguration.getTapTimeout());
                    } else {
                        // Not inside a scrolling container, so show the feedback right away
                        setPressed(true);
                        checkForLongClick(0);
                    }
                    break;

                case MotionEvent.ACTION_CANCEL:
                    if (DBG_MOTION) {
                        Xlog.d(VIEW_LOG_TAG, "(View)Touch cancel: this = " + this);
                    }

                    setPressed(false);
                    removeTapCallback();
                    removeLongPressCallback();
                    break;

                case MotionEvent.ACTION_MOVE:
                    final int x = (int) event.getX();
                    final int y = (int) event.getY();
                    if (DBG_MOTION) {
                        Xlog.d(VIEW_LOG_TAG, "(View)Touch move: x = " + x + ",y = " + y
                                + ",mTouchSlop = " + mTouchSlop + ",this = " + this);
                    }

                    // Be lenient about moving outside of buttons
                    if (!pointInView(x, y, mTouchSlop)) {
                        // Outside button
                        removeTapCallback();
                        if ((mPrivateFlags & PFLAG_PRESSED) != 0) {
                            // Remove any future long press/tap checks
                            removeLongPressCallback();

                            setPressed(false);
                        }
                    }
                    break;
            }
            return true;
        }

        return false;
    }
        
}        

有了源码,其他自然一目了然。在这里我们发现onTouchListener 和onClickListener接口
很明显他们事件确定之后的回调(我自定义的View都实现了这两个接口)。
那么很明显他们和我们dispatchTouchEvent不会具有可比性
那么接下来我们把目光对准dispatchTouchEvent
   public boolean dispatchTouchEvent(MotionEvent event) {
        if (mInputEventConsistencyVerifier != null) {
            mInputEventConsistencyVerifier.onTouchEvent(event, 0);
        }

        if (DBG_MOTION) {
            Xlog.d(VIEW_LOG_TAG, "(View)dispatchTouchEvent: event = " + event + ",this = " + this);
        }

        if (onFilterTouchEventForSecurity(event)) {
            //noinspection SimplifiableIfStatement
            ListenerInfo li = mListenerInfo;
            if (li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED
                    && li.mOnTouchListener.onTouch(this, event)) {
                return true;
            }

            if (onTouchEvent(event)) {
                return true;
            }
        }

        if (mInputEventConsistencyVerifier != null) {
            mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
        }
        return false;
    }

    /**
     * Filter the touch event to apply security policies.
     *
     * @param event The motion event to be filtered.
     * @return True if the event should be dispatched, false if the event should be dropped.
     *
     * @see #getFilterTouchesWhenObscured
     */
    public boolean onFilterTouchEventForSecurity(MotionEvent event) {
        //noinspection RedundantIfStatement
        if ((mViewFlags & FILTER_TOUCHES_WHEN_OBSCURED) != 0
                && (event.getFlags() & MotionEvent.FLAG_WINDOW_IS_OBSCURED) != 0) {
            // Window is obscured, drop this touch.
            return false;
        }
        return true;
    }
这里重点说明一下onFilterTouchEventForSecurity这个函数
它通过判断我们的窗口Window是否被遮蔽来判断是否舍弃本次事件
所以这就是为什么我们点击我们的ImageView时我们的FrameLayout也执行了dispatchTouchEvent但是却没有向下走了
那么我们继续回归dispatchTouchEvent中不是ViewGroup的情形
接下来,系统会自动判断我们是否实现了onTouchListener 这里就开始有分支了
当我们实现了onTouchListener
那么下一步我们的事件叫交给了onTouchListener .onTouch来处理
这里就又开始了分支
如果我们在onTouch中返回了true,那么就表明我们的onTouchListener 已经消化掉了本次的事件,本次事件完结。这就是为什么我们在onTouch中返回去就永运不会执行onClick,onLongClick了
如果我们在onTouch中返回了false,那么很明显了我们的事件就会被onTouchEvent处理
同理,当我们没有实现了onTouchListener,很明显了我们的事件就会被onTouchEvent处理
殊途同归,最终如果我们的事件没有被干掉,最终都交给了onTouchEvent
那么接下来我们继续来看onTouchEvent
那么我们的onTouchEvent又是用来干什么的呢(这里既然已经有onTouchListener了,他们似乎一模一样啊)
其实不然,说白了我们的onTouchEvent最终会用来分发onClick和onLongClick事件
如果你个人在这里还是不能理解onTouchEvent函数
推荐阅读
希望对你有帮助
这里我需要提到的是注意onTouchEvent对于View的State的判断和处理

Android 触屏事件 OnTouch onClick onTouchEvent对于触屏事件的处理和分发

标签:android   ontouch   ontouchevent   onclick   

原文地址:http://blog.csdn.net/jaysong2012/article/details/45535521

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