实现自定义view(2)：仿Android QQ多屏幕显示ListView的效果

转载请注明出处。博客地址：http://blog.csdn.net/mylzc

本文在《仿 UC,墨迹天气左右拖动 多屏幕显示效果》的基础上对代码进行修改，模仿Android QQ主界面的分屏ListView滑动效果。

当进行横向滑动时，会切换屏幕，当纵向滑动时，ListView会滚动。

效果图如下：

代码如下：

工程文件下载

FlingGallery.java

package com.droidful.flinggallery;import android.content.Context;import android.util.Log;import android.view.GestureDetector;import android.view.KeyEvent;import android.view.MotionEvent;import android.view.View;import android.view.animation.Animation;import android.view.animation.AnimationUtils;import android.view.animation.Interpolator;import android.view.animation.Transformation;import android.widget.Adapter;import android.widget.FrameLayout;import android.widget.LinearLayout;// TODO:// 1. In order to improve performance Cache screen bitmap and use for animation// 2. Establish superfluous memory allocations and delay or replace with reused objects//  Probably need to make sure we are not allocating objects (strings, etc.) in loopspublic class FlingGallery extends FrameLayout{// Constantsprivate final int swipe_min_distance = 120;    private final int swipe_max_off_path = 250;    private final int swipe_threshold_veloicty = 400;    // Properties    private int mViewPaddingWidth = 0;    private int mAnimationDuration = 250;    private float mSnapBorderRatio = 0.5f;    private boolean mIsGalleryCircular = true;    private int mDetectScrollX = 50;    // Members    private int mGalleryWidth = 0;    private boolean mIsTouched = false;    private boolean mIsDragging = false;    private float mCurrentOffset = 0.0f;    private long mScrollTimestamp = 0;    private int mFlingDirection = 0;    private int mCurrentPosition = 0;    private int mCurrentViewNumber = 0;    private Context mContext;    private Adapter mAdapter;    private FlingGalleryView[] mViews;    private FlingGalleryAnimation mAnimation;    private GestureDetector mGestureDetector;    private FlingGestureDetectorListener mGestureDetectorListener;    private GestureDetector mInterruptDetector;    private Interpolator mDecelerateInterpolater;    public FlingGallery(Context context){super(context);mContext = context;mAdapter = null;        mViews = new FlingGalleryView[3];        mViews[0] = new FlingGalleryView(0, this);        mViews[1] = new FlingGalleryView(1, this);        mViews[2] = new FlingGalleryView(2, this);mAnimation = new FlingGalleryAnimation();mGestureDetectorListener = new FlingGestureDetectorListener();mGestureDetector = new GestureDetector(mGestureDetectorListener);mInterruptDetector = new GestureDetector(new InterruptGestureDetectorListener());mDecelerateInterpolater = AnimationUtils.loadInterpolator(mContext, android.R.anim.decelerate_interpolator);}public void setPaddingWidth(int viewPaddingWidth){mViewPaddingWidth = viewPaddingWidth;}public void setAnimationDuration(int animationDuration){mAnimationDuration = animationDuration;}public void setSnapBorderRatio(float snapBorderRatio){mSnapBorderRatio = snapBorderRatio;}public void setIsGalleryCircular(boolean isGalleryCircular) {if (mIsGalleryCircular != isGalleryCircular){mIsGalleryCircular = isGalleryCircular;if (mCurrentPosition == getFirstPosition()){// We need to reload the view immediately to the left to change it to circular view or blank    mViews[getPrevViewNumber(mCurrentViewNumber)].recycleView(getPrevPosition(mCurrentPosition));}if (mCurrentPosition == getLastPosition()){// We need to reload the view immediately to the right to change it to circular view or blank    mViews[getNextViewNumber(mCurrentViewNumber)].recycleView(getNextPosition(mCurrentPosition));}}}public int getGalleryCount(){return (mAdapter == null) ? 0 : mAdapter.getCount();}public int getFirstPosition(){return 0;}@Overridepublic boolean onInterceptTouchEvent (MotionEvent ev) {return mInterruptDetector.onTouchEvent(ev);}@Overridepublic boolean onTouchEvent (MotionEvent ev) {Log.d("Test", "test" );boolean value = onGalleryTouchEvent(ev);Log.d("Test", "" + value);return true;}public int getLastPosition(){return (getGalleryCount() == 0) ? 0 : getGalleryCount() - 1;}private int getPrevPosition(int relativePosition){int prevPosition = relativePosition - 1;if (prevPosition < getFirstPosition()){prevPosition = getFirstPosition() - 1;if (mIsGalleryCircular == true){prevPosition = getLastPosition();}}return prevPosition;}private int getNextPosition(int relativePosition){int nextPosition = relativePosition + 1;if (nextPosition > getLastPosition()){nextPosition = getLastPosition() + 1;if (mIsGalleryCircular == true){nextPosition = getFirstPosition();}}return nextPosition;}private int getPrevViewNumber(int relativeViewNumber){return (relativeViewNumber == 0) ? 2 : relativeViewNumber - 1;}private int getNextViewNumber(int relativeViewNumber){return (relativeViewNumber == 2) ? 0 : relativeViewNumber + 1;}@Overrideprotected void onLayout(boolean changed, int left, int top, int right, int bottom){super.onLayout(changed, left, top, right, bottom);// Calculate our view widthmGalleryWidth = right - left;if (changed == true){    // Position views at correct starting offsets    mViews[0].setOffset(0, 0, mCurrentViewNumber);    mViews[1].setOffset(0, 0, mCurrentViewNumber);    mViews[2].setOffset(0, 0, mCurrentViewNumber);    }}public void setAdapter(Adapter adapter)    {    mAdapter = adapter;    mCurrentPosition = 0;        mCurrentViewNumber = 0;        // Load the initial views from adapter        mViews[0].recycleView(mCurrentPosition);    mViews[1].recycleView(getNextPosition(mCurrentPosition));    mViews[2].recycleView(getPrevPosition(mCurrentPosition));    // Position views at correct starting offsets    mViews[0].setOffset(0, 0, mCurrentViewNumber);    mViews[1].setOffset(0, 0, mCurrentViewNumber);    mViews[2].setOffset(0, 0, mCurrentViewNumber);    }private int getViewOffset(int viewNumber, int relativeViewNumber){// Determine width including configured padding widthint offsetWidth = mGalleryWidth + mViewPaddingWidth;// Position the previous view one measured width to leftif (viewNumber == getPrevViewNumber(relativeViewNumber)){return offsetWidth;}// Position the next view one measured width to the rightif (viewNumber == getNextViewNumber(relativeViewNumber)){return offsetWidth * -1;}return 0;}void movePrevious(){// Slide to previous viewmFlingDirection = 1;processGesture();}void moveNext(){// Slide to next viewmFlingDirection = -1;processGesture();} @Override public boolean onKeyDown(int keyCode, KeyEvent event) {    switch (keyCode)    {    case KeyEvent.KEYCODE_DPAD_LEFT:        movePrevious();        return true;    case KeyEvent.KEYCODE_DPAD_RIGHT:        moveNext();        return true;    case KeyEvent.KEYCODE_DPAD_CENTER:    case KeyEvent.KEYCODE_ENTER:    }    return super.onKeyDown(keyCode, event);} public boolean onGalleryTouchEvent(MotionEvent event){boolean consumed = mGestureDetector.onTouchEvent(event);if (event.getAction() == MotionEvent.ACTION_UP){if (mIsTouched || mIsDragging){processScrollSnap();processGesture();}}        return consumed;    }void processGesture(){int newViewNumber = mCurrentViewNumber;int reloadViewNumber = 0;int reloadPosition = 0;mIsTouched = false;mIsDragging = false;if (mFlingDirection > 0){if (mCurrentPosition > getFirstPosition() || mIsGalleryCircular == true){// Determine previous view and outgoing view to recyclenewViewNumber = getPrevViewNumber(mCurrentViewNumber);mCurrentPosition = getPrevPosition(mCurrentPosition);reloadViewNumber = getNextViewNumber(mCurrentViewNumber); reloadPosition = getPrevPosition(mCurrentPosition);}}if (mFlingDirection < 0){if (mCurrentPosition < getLastPosition() || mIsGalleryCircular == true){// Determine the next view and outgoing view to recyclenewViewNumber = getNextViewNumber(mCurrentViewNumber);mCurrentPosition = getNextPosition(mCurrentPosition);reloadViewNumber = getPrevViewNumber(mCurrentViewNumber);reloadPosition = getNextPosition(mCurrentPosition);}}if (newViewNumber != mCurrentViewNumber){mCurrentViewNumber = newViewNumber; // Reload outgoing view from adapter in new positionmViews[reloadViewNumber].recycleView(reloadPosition);}// Ensure input focus on the current viewmViews[mCurrentViewNumber].requestFocus();// Run the slide animations for view transitionsmAnimation.prepareAnimation(mCurrentViewNumber);this.startAnimation(mAnimation);// Reset fling statemFlingDirection = 0;}void processScrollSnap(){// Snap to next view if scrolled passed snap positionfloat rollEdgeWidth = mGalleryWidth * mSnapBorderRatio;int rollOffset = mGalleryWidth - (int) rollEdgeWidth;int currentOffset = mViews[mCurrentViewNumber].getCurrentOffset();if (currentOffset <= rollOffset * -1){// Snap to previous viewmFlingDirection = 1;}if (currentOffset >= rollOffset){// Snap to next viewmFlingDirection = -1;}}private class FlingGalleryView{private int mViewNumber;private FrameLayout mParentLayout;private FrameLayout mInvalidLayout = null;private LinearLayout mInternalLayout = null;private View mExternalView = null;public FlingGalleryView(int viewNumber, FrameLayout parentLayout){mViewNumber = viewNumber;mParentLayout = parentLayout;// Invalid layout is used when outside gallerymInvalidLayout = new FrameLayout(mContext);mInvalidLayout.setLayoutParams(new LinearLayout.LayoutParams(                 LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));// Internal layout is permanent for durationmInternalLayout = new LinearLayout(mContext);mInternalLayout.setLayoutParams(new LinearLayout.LayoutParams(                 LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));mParentLayout.addView(mInternalLayout);}public void recycleView(int newPosition){if (mExternalView != null){mInternalLayout.removeView(mExternalView);}if (mAdapter != null){if (newPosition >= getFirstPosition() && newPosition <= getLastPosition()){mExternalView = mAdapter.getView(newPosition, mExternalView, mInternalLayout);}else{mExternalView = mInvalidLayout;}}if (mExternalView != null){mInternalLayout.addView(mExternalView, new LinearLayout.LayoutParams(                 LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));}}public void setOffset(int xOffset, int yOffset, int relativeViewNumber){// Scroll the target view relative to its own position relative to currently displayed viewmInternalLayout.scrollTo(getViewOffset(mViewNumber, relativeViewNumber) + xOffset, yOffset);}public int getCurrentOffset(){// Return the current scroll positionreturn mInternalLayout.getScrollX();}public void requestFocus(){mInternalLayout.requestFocus();}}    private class FlingGalleryAnimation extends Animation    {    private boolean mIsAnimationInProgres;    private int mRelativeViewNumber;    private int mInitialOffset;    private int mTargetOffset;    private int mTargetDistance;        public FlingGalleryAnimation()    {    mIsAnimationInProgres = false;    mRelativeViewNumber = 0;        mInitialOffset = 0;        mTargetOffset = 0;        mTargetDistance = 0;    }     public void prepareAnimation(int relativeViewNumber)    {    // If we are animating relative to a new view    if (mRelativeViewNumber != relativeViewNumber)    {if (mIsAnimationInProgres == true){// We only have three views so if requested again to animate in same direction we must snap int newDirection = (relativeViewNumber == getPrevViewNumber(mRelativeViewNumber)) ? 1 : -1;    int animDirection = (mTargetDistance < 0) ? 1 : -1;     // If animation in same direction    if (animDirection == newDirection)    {        // Ran out of time to animate so snap to the target offset        mViews[0].setOffset(mTargetOffset, 0, mRelativeViewNumber);mViews[1].setOffset(mTargetOffset, 0, mRelativeViewNumber);mViews[2].setOffset(mTargetOffset, 0, mRelativeViewNumber);    }}// Set relative view number for animation    mRelativeViewNumber = relativeViewNumber;    }// Note: In this implementation the targetOffset will always be zero    // as we are centering the view; but we include the calculations of// targetOffset and targetDistance for use in future implementationsmInitialOffset = mViews[mRelativeViewNumber].getCurrentOffset();mTargetOffset = getViewOffset(mRelativeViewNumber, mRelativeViewNumber);mTargetDistance = mTargetOffset - mInitialOffset;// Configure base animation propertiesthis.setDuration(mAnimationDuration);this.setInterpolator(mDecelerateInterpolater);// Start/continued animationmIsAnimationInProgres = true;}        @Override        protected void applyTransformation(float interpolatedTime, Transformation transformation)        {        // Ensure interpolatedTime does not over-shoot then calculate new offset        interpolatedTime = (interpolatedTime > 1.0f) ? 1.0f : interpolatedTime;int offset = mInitialOffset + (int) (mTargetDistance * interpolatedTime);for (int viewNumber = 0; viewNumber < 3; viewNumber++){// Only need to animate the visible views as the other view will always be off-screenif ((mTargetDistance > 0 && viewNumber != getNextViewNumber(mRelativeViewNumber)) ||(mTargetDistance < 0 && viewNumber != getPrevViewNumber(mRelativeViewNumber))){mViews[viewNumber].setOffset(offset, 0, mRelativeViewNumber);}}        }        @Override        public boolean getTransformation(long currentTime, Transformation outTransformation)        {        if (super.getTransformation(currentTime, outTransformation) == false)        {        // Perform final adjustment to offsets to cleanup animation        mViews[0].setOffset(mTargetOffset, 0, mRelativeViewNumber);mViews[1].setOffset(mTargetOffset, 0, mRelativeViewNumber);mViews[2].setOffset(mTargetOffset, 0, mRelativeViewNumber);// Reached the animation targetmIsAnimationInProgres = false;return false;        }         // Cancel if the screen touched        if (mIsTouched || mIsDragging)        {        // Note that at this point we still consider ourselves to be animating        // because we have not yet reached the target offset; its just that the        // user has temporarily interrupted the animation with a touch gesture        return false;        }        return true;        }    }        private class InterruptGestureDetectorListener extends GestureDetector.SimpleOnGestureListener {            @Override    public boolean onDown(MotionEvent e)    {    // Stop animation    mIsTouched = true;    // Reset fling state    mFlingDirection = 0;            return false;    }            //返回true由FlingGallery的onTouchEvent(MotionEvent)来处理触摸消息，返回false则先由子view(listview)来处理触摸消息    @Override    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)    {    if (e2.getAction() == MotionEvent.ACTION_MOVE)        {            float maxVelocity = mGalleryWidth / (mAnimationDuration / 1000.0f);        long timestampDelta = System.currentTimeMillis() - mScrollTimestamp;        float maxScrollDelta = maxVelocity * (timestampDelta / 1000.0f);         float currentScrollDelta = e1.getX() - e2.getX();        if (currentScrollDelta < maxScrollDelta * -1) currentScrollDelta = maxScrollDelta * -1;        if (currentScrollDelta > maxScrollDelta) currentScrollDelta = maxScrollDelta;        if(Math.abs(currentScrollDelta) > mDetectScrollX){//如果当前x方向滚动的距离大于50，则由FlingGallery的onTouchEvent(MotionEvent)来处理触摸消息        mGestureDetectorListener.setDownEvent(e1);//重新设置mGestureDetectorListener的down消息        return true;        }        }            return false;//不打断，交给子view来处理触摸消息    }    }private class FlingGestureDetectorListener extends GestureDetector.SimpleOnGestureListener    {private MotionEvent mDownEvent;public void setDownEvent(MotionEvent downEvent) {//复原丢失的Down触摸消息mDownEvent = downEvent;}    @Override    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)    {    if (e2.getAction() == MotionEvent.ACTION_MOVE)        {    if (mIsDragging == false)    {        // Stop animation    mIsTouched = true;     // Reconfigure scroll    mIsDragging = true;    mFlingDirection = 0;    mScrollTimestamp = System.currentTimeMillis();    mCurrentOffset = mViews[mCurrentViewNumber].getCurrentOffset();    }            float maxVelocity = mGalleryWidth / (mAnimationDuration / 1000.0f);        long timestampDelta = System.currentTimeMillis() - mScrollTimestamp;        float maxScrollDelta = maxVelocity * (timestampDelta / 1000.0f);         float currentScrollDelta = mDownEvent.getX() - e2.getX();        if (currentScrollDelta < maxScrollDelta * -1) currentScrollDelta = maxScrollDelta * -1;        if (currentScrollDelta > maxScrollDelta) currentScrollDelta = maxScrollDelta;        int scrollOffset = Math.round(mCurrentOffset + currentScrollDelta);        // We can't scroll more than the width of our own frame layout        if (scrollOffset >= mGalleryWidth) scrollOffset = mGalleryWidth;        if (scrollOffset <= mGalleryWidth * -1) scrollOffset = mGalleryWidth * -1;                mViews[0].setOffset(scrollOffset, 0, mCurrentViewNumber);    mViews[1].setOffset(scrollOffset, 0, mCurrentViewNumber);    mViews[2].setOffset(scrollOffset, 0, mCurrentViewNumber);        }            return false;    }    @Override    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)    {            if (Math.abs(mDownEvent.getY() - e2.getY()) <= swipe_max_off_path)            {                if (e2.getX() - mDownEvent.getX() > swipe_min_distance && Math.abs(velocityX) > swipe_threshold_veloicty)                {                movePrevious();                }                if(mDownEvent.getX() - e2.getX() > swipe_min_distance && Math.abs(velocityX) > swipe_threshold_veloicty)                {                moveNext();                }            }            return false;    }    @Override    public void onLongPress(MotionEvent e)    {    // Finalise scrolling    mFlingDirection = 0;            processGesture();    }    @Override    public void onShowPress(MotionEvent e)    {    }    @Override    public boolean onSingleTapUp(MotionEvent e)    {    // Reset fling state    mFlingDirection = 0;            return false;    }    }}

FlingGalleryActivity.java

package com.droidful.flinggallery;import android.app.Activity;import android.os.Bundle;import android.content.Context;import android.graphics.Color;import android.util.Log;import android.view.Gravity;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.view.View.OnClickListener;import android.widget.ArrayAdapter;import android.widget.Button;import android.widget.CheckBox;import android.widget.EditText;import android.widget.LinearLayout;import android.widget.ListView;import android.widget.TableLayout;import android.widget.TextView;public class FlingGalleryActivity extends Activity{    private final String[] mLabelArray = {"View1", "View2", "View3"};    private String[] mAStrings = {            "Abbaye de Belloc", "Abbaye du Mont des Cats", "Abertam", "Abondance", "Ackawi",            "Acorn", "Adelost", "Affidelice au Chablis", "Afuega'l Pitu", "Airag", "Airedale",            "Aisy Cendre", "Allgauer Emmentaler", "Alverca", "Ambert", "American Cheese",            "Ami du Chambertin", "Anejo Enchilado", "Anneau du Vic-Bilh", "Anthoriro", "Appenzell",            "Aragon", "Ardi Gasna", "Ardrahan", "Armenian String", "Aromes au Gene de Marc",            "Asadero", "Asiago", "Aubisque Pyrenees", "Autun", "Avaxtskyr"};private String[] mBStrings = {"Baby Swiss",            "Babybel", "Baguette Laonnaise", "Bakers", "Baladi", "Balaton", "Bandal", "Banon",            "Barry's Bay Cheddar", "Basing", "Basket Cheese", "Bath Cheese", "Bavarian Bergkase",            "Baylough", "Beaufort", "Beauvoorde", "Beenleigh Blue", "Beer Cheese", "Bel Paese",            "Bergader", "Bergere Bleue", "Berkswell", "Beyaz Peynir", "Bierkase", "Bishop Kennedy",            "Blarney", "Bleu d'Auvergne", "Bleu de Gex", "Bleu de Laqueuille",            "Bleu de Septmoncel", "Bleu Des Causses", "Blue", "Blue Castello", "Blue Rathgore",            "Blue Vein (Australian)", "Blue Vein Cheeses", "Bocconcini", "Bocconcini (Australian)",            "Boeren Leidenkaas", "Bonchester", "Bosworth", "Bougon", "Boule Du Roves",            "Boulette d'Avesnes", "Boursault", "Boursin", "Bouyssou", "Bra", "Braudostur",            "Breakfast Cheese", "Brebis du Lavort", "Brebis du Lochois", "Brebis du Puyfaucon",            "Bresse Bleu", "Brick", "Brie", "Brie de Meaux", "Brie de Melun", "Brillat-Savarin",            "Brin", "Brin d' Amour", "Brin d'Amour", "Brinza (Burduf Brinza)",            "Briquette de Brebis", "Briquette du Forez", "Broccio", "Broccio Demi-Affine",            "Brousse du Rove", "Bruder Basil", "Brusselae Kaas (Fromage de Bruxelles)", "Bryndza",            "Buchette d'Anjou", "Buffalo", "Burgos", "Butte", "Butterkase", "Button (Innes)",            "Buxton Blue", };private String[] mCStrings = {"Cabecou", "Caboc", "Cabrales", "Cachaille", "Caciocavallo", "Caciotta",            "Caerphilly", "Cairnsmore", "Calenzana", "Cambazola", "Camembert de Normandie",            "Canadian Cheddar", "Canestrato", "Cantal", "Caprice des Dieux", "Capricorn Goat",            "Capriole Banon", "Carre de l'Est", "Casciotta di Urbino", "Cashel Blue", "Castellano",            "Castelleno", "Castelmagno", "Castelo Branco", "Castigliano", "Cathelain",            "Celtic Promise", "Cendre d'Olivet", "Cerney", "Chabichou", "Chabichou du Poitou",            "Chabis de Gatine", "Chaource", "Charolais", "Chaumes", "Cheddar",            "Cheddar Clothbound", "Cheshire", "Chevres", "Chevrotin des Aravis", "Chontaleno",            "Civray", "Coeur de Camembert au Calvados", "Coeur de Chevre", "Colby", "Cold Pack",            "Comte", "Coolea", "Cooleney", "Coquetdale", "Corleggy", "Cornish Pepper",            "Cotherstone", "Cotija", "Cottage Cheese", "Cottage Cheese (Australian)",            "Cougar Gold", "Coulommiers", "Coverdale", "Crayeux de Roncq", "Cream Cheese",            "Cream Havarti", "Crema Agria", "Crema Mexicana", "Creme Fraiche", "Crescenza",            "Croghan", "Crottin de Chavignol", "Crottin du Chavignol", "Crowdie", "Crowley",            "Cuajada", "Curd", "Cure Nantais", "Curworthy", "Cwmtawe Pecorino",            "Cypress Grove Chevre"};        private String[][] strings = {mAStrings,mBStrings,mCStrings};    private FlingGallery mGallery;private CheckBox mCheckBox;    public void onCreate(Bundle savedInstanceState)    {        super.onCreate(savedInstanceState);        mGallery = new FlingGallery(this);        mGallery.setPaddingWidth(5);        mGallery.setAdapter(new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, mLabelArray)        {        @Override        public View getView(int position, View convertView, ViewGroup parent)        {            ListView lv = new ListView(getApplicationContext());            lv.setAdapter(new ArrayAdapter<String>(getApplicationContext(),                        android.R.layout.simple_list_item_1, strings[position]));            return lv;//返回position位置的listview        }        });        LinearLayout layout = new LinearLayout(getApplicationContext());        layout.setOrientation(LinearLayout.VERTICAL);LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,LinearLayout.LayoutParams.MATCH_PARENT);layoutParams.setMargins(10, 10, 10, 10);layoutParams.weight = 1.0f;          layout.addView(mGallery, layoutParams);            mCheckBox = new CheckBox(getApplicationContext());        mCheckBox.setText("Gallery is Circular");        mCheckBox.setPadding(50, 10, 0, 10);        mCheckBox.setTextSize(30);        mCheckBox.setChecked(false);        mGallery.setIsGalleryCircular(mCheckBox.isChecked());        mCheckBox.setOnClickListener(new OnClickListener()        {@Overridepublic void onClick(View view){mGallery.setIsGalleryCircular(mCheckBox.isChecked());}        });        layout.addView(mCheckBox, new LinearLayout.LayoutParams(    LinearLayout.LayoutParams.MATCH_PARENT,    LinearLayout.LayoutParams.WRAP_CONTENT));            setContentView(layout);    }        }

代码解析：

这里不详细解析分屏效果的实现，只说明ViewGroup对触摸消息的分发规则。

FlingGallery继承FrameLayout，FrameLayout的父类是ViewGroup，因此FlingGallery是ViewGroup的派生类。

默认规则下，当触摸消息(MotionEvent)到达ViewGroup时，ViewGroup会先把消息发给子View的onTouchEvent(MotionEvent)方法进行处理，如果子View消耗了消息，那么ViewGroup的onTouchEvent(MotionEvent)将不会接收到消息。

这个例子我们重载了ViewGroup的onInterceptTouchEvent (MotionEvent ev)方法，如果方法返回true则表示交由ViewGroup的onTouchEvent(MotionEvent)来处理触摸消息，false则按默认规则交由子view处理。我们在此方法中检测是否横向滚动，如果是横向滚动，则返回true，消息传递给ViewGroup的onTouchEvent(MotionEvent)，如果不是横向滑动则有子view处理消息。

希望觉得有用的同学都顶一下，写博客不容易！