标签：viewgroup viewpager horizontalscrollview 自定义组件
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 stub
mScroller = new Scroller(context);
mCurScreen = mDefaultScreen;
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
}
@Override
protected 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;
}
}
}
}
@Override
protected 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 page
whichScreen = 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
@Override
public 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());
}
@Override
public 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 right
Log.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;
}
@Override
public 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;
}
}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);
}
@Override
protected 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());
}
}
}
}
@Override
public 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;
}
}标签：viewgroup viewpager horizontalscrollview 自定义组件
原文地址：http://blog.csdn.net/honeybaby201314/article/details/42920359
