Android自定义ViewGroup实现d性滑动效果

概述自定义View实现一个d性滑动的效果，供大家参考，具体内容如下实现原理onMeasure()中测量所有子View

自定义view实现一个d性滑动的效果，供大家参考，具体内容如下

实现原理

onMeasure()中测量所有子VIEw

 @OverrIDe protected voID onMeasure(int wIDthMeasureSpec,int heightmeasureSpec) {  // 测量所有子VIEw  int count = getChildCount();  for (int i = 0; i < count; i++) {   VIEw childVIEw = getChildAt(i);   measureChild(childVIEw,wIDthMeasureSpec,heightmeasureSpec);  }  setMeasuredDimension(wIDthMeasureSpec,heightmeasureSpec); }

onLayout()中,将所有的子VIEw按照位置依次往下排列

@OverrIDe protected voID onLayout(boolean changed,int l,int t,int r,int b) {  // 设置VIEwGroup的高度,对所有子VIEw进行排列  int childCount = getChildCount();  marginLayoutParams params = (marginLayoutParams) getLayoutParams();  params.height = mScreenHeight * childCount;  for (int i = 0; i < childCount; i++) {   VIEw childVIEw = getChildAt(i);   if (childVIEw.getVisibility() != VIEw.GONE) {    // 给每个ChildVIEw放置在指定位置    childVIEw.layout(l,i * mScreenHeight,r,(i + 1) * mScreenHeight);   }  } }

ontouchEvent()中处理滑动

 @OverrIDe public boolean ontouchEvent(MotionEvent event) {  switch (event.getAction()) {   case MotionEvent.ACTION_DOWN:    mLastY = (int) event.getY();    mStart = getScrollY();    return true;   case MotionEvent.ACTION_MOVE:    if (!mScroller.isFinished()) {     // 终止滑动     mScroller.abortAnimation();    }    int offsetY = (int) (mLastY - event.getY());    Log.d(TAG,"ontouchEvent: getScrollY: " + getScrollY());    Log.d(TAG,"ontouchEvent: offsetY " + offsetY);    // 到达顶部,使用offset判断方向    if (getScrollY() + offsetY < 0) { // 当前已经滑动的 Y 位置     offsetY = 0;    }    // 到达底部    if (getScrollY() > getHeight() - mScreenHeight && offsetY > 0) {     offsetY = 0;    }    scrollBy(0,offsetY);    // 滑动完成后,重新设置LastY位置    mLastY = (int) event.getY();    break;   case MotionEvent.ACTION_UP:    mEnd = getScrollY();    int distance = mEnd - mStart;    if (distance > 0) { // 向上滑动     if (distance < mScreenHeight / 3) {      Log.d(TAG,"ontouchEvent: distance < screen/3");      // 回到原来位置      mScroller.startScroll(0,getScrollY(),-distance);     } else {      // 滚到屏幕的剩余位置      mScroller.startScroll(0,mScreenHeight - distance);     }    } else {    // 向下滑动     if (-distance < mScreenHeight / 3) {      mScroller.startScroll(0,-distance);     } else {      mScroller.startScroll(0,-mScreenHeight - distance);     }    }    postInvalIDate();  }  return super.ontouchEvent(event); }

其中ACTION_UP这段代码是处理d性滑动的

case MotionEvent.ACTION_UP:    mEnd = getScrollY();    int distance = mEnd - mStart;    if (distance > 0) { // 向上滑动     if (distance < mScreenHeight / 3) {      Log.d(TAG,-mScreenHeight - distance);     }    }    postInvalIDate();

完整代码

public class ScrollVIEwGroup extends VIEwGroup { private static final String TAG = "ScrollVIEw"; private Scroller mScroller; private int mScreenHeight; // 窗口高度 private int mLastY; private int mStart; private int mEnd; public ScrollVIEwGroup(Context context) {  this(context,null); } public ScrollVIEwGroup(Context context,AttributeSet attrs) {  this(context,attrs,0); } public ScrollVIEwGroup(Context context,AttributeSet attrs,int defStyleAttr) {  super(context,defStyleAttr);  mScroller = new Scroller(context);  // 获取屏幕高度  WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);  displayMetrics metrics = new displayMetrics();  windowManager.getDefaultdisplay().getMetrics(metrics);  mScreenHeight = metrics.heightPixels;  Log.d(TAG,"ScrollVIEwGroup: ScreenHeight " + mScreenHeight); } @OverrIDe protected voID onMeasure(int wIDthMeasureSpec,heightmeasureSpec); } @OverrIDe protected voID onLayout(boolean changed,(i + 1) * mScreenHeight);   }  } } @OverrIDe public boolean ontouchEvent(MotionEvent event) {  switch (event.getAction()) {   case MotionEvent.ACTION_DOWN:    mLastY = (int) event.getY();    mStart = getScrollY();    return true;   case MotionEvent.ACTION_MOVE:    if (!mScroller.isFinished()) {     // 终止滑动     mScroller.abortAnimation();    }    int offsetY = (int) (mLastY - event.getY());    Log.d(TAG,-mScreenHeight - distance);     }    }    postInvalIDate();  }  return super.ontouchEvent(event); } @OverrIDe public voID computeScroll() {  if (mScroller.computeScrollOffset()) {   scrollTo(mScroller.getCurrX(),mScroller.getCurrY());   postInvalIDate();  } }}

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