/**
-
@author :huangxianfeng on 2016/10/13.
-
继承ViewGroup实现自定义布局
*/
public class HorizontalScrollViewEx extends ViewGroup{
private static final String TAG = "HorizontalScrollViewEx";
private int mChildrenSize;
private int mChildWidth;
private int mChildIndex;
//分别记录上次滑动的坐标
private int mLastX = 0;
private int mLastY = 0;
//分别记录上次滑动的坐标（onInterceptTouchEvent）
private int mLastXIntercept = 0;
private int mLastYIntercept = 0;
private Scroller mScroller;
private VelocityTracker mVelocityTracker;
public HorizontalScrollViewEx(Context context) {
super(context);
init();
}
public HorizontalScrollViewEx(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public HorizontalScrollViewEx(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
if (mScroller==null){
mScroller = new Scroller(getContext());
mVelocityTracker = VelocityTracker.obtain();
}
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
boolean intercepted = false;
int x = (int)ev.getX();
int y = (int)ev.getY();
switch (ev.getAction()){
case MotionEvent.ACTION_DOWN:
intercepted = false;
if (!mScroller.isFinished()){
mScroller.abortAnimation();
intercepted = true;
}
break;
case MotionEvent.ACTION_MOVE:
int detlaX = x-mLastXIntercept;
int detlaY = y-mLastYIntercept;
if (Math.abs(detlaX) > Math.abs(detlaY)){
intercepted = true;
}else{
intercepted = false;
}
break;
case MotionEvent.ACTION_UP:
intercepted = false;
break;
default:
break;
}
Log.d(TAG,"intercepted = "+intercepted);
mLastX = x;
mLastY = y;
mLastXIntercept = x;
mLastYIntercept = y;
return intercepted;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
mVelocityTracker.addMovement(event);
int x = (int)getX();
int y = (int)getY();
switch (event.getAction()){
case MotionEvent.ACTION_DOWN:
if (!mScroller.isFinished()){
mScroller.abortAnimation();
}
break;
case MotionEvent.ACTION_MOVE:
int detalX = x-mLastX;
int detalY = y-mLastY;
scrollBy(-detalX,0);
break;
case MotionEvent.ACTION_UP:
int scrollX = getScrollX();
mVelocityTracker.computeCurrentVelocity(1000);
float xVelocity = mVelocityTracker.getXVelocity();
if (Math.abs(xVelocity) >= 50){
mChildIndex = xVelocity > 0 ? mChildIndex -1 : mChildIndex + 1;
}else{
mChildIndex = (scrollX + mChildWidth / 2) / mChildWidth;
}
mChildIndex = Math.max(0,Math.min(mChildIndex,mChildrenSize -1 ));
int dx = mChildIndex * mChildWidth - scrollX;
smoothScrollBy(dx, 0);
mVelocityTracker.clear();
break;
default:
break;
}
mLastX = x;
mLastY = y;
return true;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int measuredWidth = 0;
int measuredHeight = 0;
//拿到自己含有子元素的个数
final int childCount = getChildCount();
measureChildren(widthMeasureSpec,heightMeasureSpec);
int widthSpaceSize = MeasureSpec.getSize(widthMeasureSpec);
int widthSpaceMode = MeasureSpec.getMode(widthMeasureSpec);
int heightSpaceSize = MeasureSpec.getSize(heightMeasureSpec);
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