仿ViewPager效果二

1、采用ViewGroup实现

/** * 可以左右滑动切换屏幕的类 * @author libin * */public class ScrollLayout extends ViewGroup {private static final String TAG = "ScrollLayout";private Scroller mScroller;private VelocityTracker mVelocityTracker;private int mCurScreen;private int mDefaultScreen = 0;private static final int TOUCH_STATE_REST = 0;private static final int TOUCH_STATE_SCROLLING = 1;private static final int SNAP_VELOCITY = 600;private int mTouchState = TOUCH_STATE_REST;private int mTouchSlop;private float mLastMotionX;public ScrollLayout(Context context, AttributeSet attrs) {this(context, attrs, 0);}public ScrollLayout(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);// TODO Auto-generated constructor stubmScroller = new Scroller(context);mCurScreen = mDefaultScreen;mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();}@Overrideprotected void onLayout(boolean changed, int l, int t, int r, int b) {if (changed) {int childLeft = 0;final int childCount = getChildCount();for (int i = 0; i < childCount; i++) {final View childView = getChildAt(i);if (childView.getVisibility() != View.GONE) {final int childWidth = childView.getMeasuredWidth();childView.layout(childLeft, 0, childLeft + childWidth,childView.getMeasuredHeight());childLeft += childWidth;}}}}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {Log.e(TAG, "onMeasure");super.onMeasure(widthMeasureSpec, heightMeasureSpec);final int width = MeasureSpec.getSize(widthMeasureSpec);final int widthMode = MeasureSpec.getMode(widthMeasureSpec);if (widthMode != MeasureSpec.EXACTLY) {throw new IllegalStateException("ScrollLayout only canmCurScreen run at EXACTLY mode!");}final int heightMode = MeasureSpec.getMode(heightMeasureSpec);if (heightMode != MeasureSpec.EXACTLY) {throw new IllegalStateException("ScrollLayout only can run at EXACTLY mode!");}final int count = getChildCount();for (int i = 0; i < count; i++) {getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);}scrollTo(mCurScreen * width, 0);}/** * * According to the position of current layout * scroll to the destination * page. */private void snapToDestination() {final int screenWidth = getWidth();final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth;snapToScreen(destScreen);}private void snapToScreen(int whichScreen) { // get the valid layout pagewhichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));if (getScrollX() != (whichScreen * getWidth())) {final int delta = whichScreen * getWidth() - getScrollX();mScroller.startScroll(getScrollX(), 0, delta, 0,Math.abs(delta) * 2);mCurScreen = whichScreen;invalidate();}}public void setToScreen(int whichScreen) {whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));mCurScreen = whichScreen;scrollTo(whichScreen * getWidth(), 0);}public int getCurScreen() {return mCurScreen;}//在执行了invalidate()方法之后，程序便会执行computeScroll()方法@Overridepublic void computeScroll() { // 判断动画是否完成,返回true表示动画没有完成if (mScroller.computeScrollOffset()) {scrollTo(mScroller.getCurrX(), mScroller.getCurrY());postInvalidate();}Log.i(TAG, "computeScroll -- "+mScroller.getCurrX());}@Overridepublic boolean onTouchEvent(MotionEvent event) {if (mVelocityTracker == null) {mVelocityTracker = VelocityTracker.obtain();}mVelocityTracker.addMovement(event);final int action = event.getAction();final float x = event.getX();switch (action) {case MotionEvent.ACTION_DOWN:Log.e(TAG, "event down!");//是否完成if (!mScroller.isFinished()) {mScroller.abortAnimation();}mLastMotionX = x;break;case MotionEvent.ACTION_MOVE:int deltaX = (int) (mLastMotionX - x);mLastMotionX = x;scrollBy(deltaX, 0);break;case MotionEvent.ACTION_UP:Log.e(TAG, "event : up");// if (mTouchState == TOUCH_STATE_SCROLLING) {final VelocityTracker velocityTracker = mVelocityTracker;velocityTracker.computeCurrentVelocity(1000);int velocityX = (int) velocityTracker.getXVelocity();//得到对应的速度值，大于0往做滑动，小于0往右Log.e(TAG, "velocityX:" + velocityX);if (velocityX > SNAP_VELOCITY && mCurScreen > 0) { //向左边Log.e(TAG, "snap left");snapToScreen(mCurScreen - 1);} else if (velocityX < -SNAP_VELOCITY&& mCurScreen < getChildCount() - 1) {// Fling enough to move rightLog.e(TAG, "snap right");snapToScreen(mCurScreen + 1);} else {snapToDestination();}//回收if (mVelocityTracker != null) {mVelocityTracker.recycle();mVelocityTracker = null;}mTouchState = TOUCH_STATE_REST;break;case MotionEvent.ACTION_CANCEL:mTouchState = TOUCH_STATE_REST;break;}return true;}@Overridepublic boolean onInterceptTouchEvent(MotionEvent ev) {Log.e(TAG, "onInterceptTouchEvent-slop:" + mTouchSlop);final int action = ev.getAction();if ((action == MotionEvent.ACTION_MOVE)&& (mTouchState != TOUCH_STATE_REST)) {return true;}final float x = ev.getX();switch (action) {case MotionEvent.ACTION_MOVE:final int xDiff = (int) Math.abs(mLastMotionX - x);if (xDiff > mTouchSlop) {mTouchState = TOUCH_STATE_SCROLLING;}break;case MotionEvent.ACTION_DOWN:mLastMotionX = x;mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST: TOUCH_STATE_SCROLLING;break;case MotionEvent.ACTION_CANCEL:case MotionEvent.ACTION_UP:mTouchState = TOUCH_STATE_REST;break;}return mTouchState != TOUCH_STATE_REST;}}

2、继承HorizontalScrollView

public class MyScrollView extends HorizontalScrollView {private int subChildCount = 0;private ViewGroup firstChild = null;private int downX = 0;private int currentPage = 0;private ArrayList<Integer> pointList = new ArrayList<Integer>();public MyScrollView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);init();}public MyScrollView(Context context, AttributeSet attrs) {super(context, attrs);init();}public MyScrollView(Context context) {super(context);init();}private void init() {setHorizontalScrollBarEnabled(false);}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);receiveChildInfo();}public void receiveChildInfo() {firstChild = (ViewGroup) getChildAt(0);if (firstChild != null) {subChildCount = firstChild.getChildCount();for (int i = 0; i < subChildCount; i++) {if (((View) firstChild.getChildAt(i)).getWidth() > 0) {pointList.add(((View) firstChild.getChildAt(i)).getLeft());}}}}@Overridepublic boolean onTouchEvent(MotionEvent ev) {switch (ev.getAction()) {case MotionEvent.ACTION_DOWN:downX = (int) ev.getX();break;case MotionEvent.ACTION_MOVE: {}break;case MotionEvent.ACTION_UP:case MotionEvent.ACTION_CANCEL: {if (Math.abs((ev.getX() - downX)) > getWidth() / 4) {if (ev.getX() - downX > 0) {smoothScrollToPrePage();} else {smoothScrollToNextPage();}} else {smoothScrollToCurrent();}return true;}}return super.onTouchEvent(ev);}private void smoothScrollToCurrent() {smoothScrollTo(pointList.get(currentPage), 0);}private void smoothScrollToNextPage() {if (currentPage < subChildCount - 1) {currentPage++;smoothScrollTo(pointList.get(currentPage), 0);}}private void smoothScrollToPrePage() {if (currentPage > 0) {currentPage--;smoothScrollTo(pointList.get(currentPage), 0);}}/** * 下一页 */public void nextPage() {smoothScrollToNextPage();}/** * 上一页 */public void prePage() {smoothScrollToPrePage();}/** * 跳转到指定的页面 *  * @param page * @return */public boolean gotoPage(int page) {if (page > 0 && page < subChildCount - 1) {smoothScrollTo(pointList.get(page), 0);currentPage = page;return true;}return false;}}