随笔记录1、惯性滑动颜色渐变的Scrollview

     随着Scrollview滚动颜色渐变设置，在Scrollview嵌套RecycleView的时候惯性滑动消失，以下就是解决此问题的自定义Scrollview

第一步：        

public class ObservableScrollView extends ScrollView {

private int downY;
private int mTouchSlop;

public interface ScrollViewListener {

void onScrollChanged(ObservableScrollView scrollView, int x, int y,
int oldx, int oldy);

}

private ScrollViewListener scrollViewListener = null;

public ObservableScrollView(Context context) {
super(context);
//触发移动事件的最小距离
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
}

public ObservableScrollView(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
}

public ObservableScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
}

public void setScrollViewListener(ScrollViewListener scrollViewListener) {
this.scrollViewListener = scrollViewListener;
}
@Override
protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) {
return 0;
}
@Override
protected void onScrollChanged(int x, int y, int oldx, int oldy) {
super.onScrollChanged(x, y, oldx, oldy);
if (scrollViewListener != null) {
scrollViewListener.onScrollChanged(this, x, y, oldx, oldy);
}
}

//随手势惯性滚动
@Override
public boolean onInterceptTouchEvent(MotionEvent e) {
int action = e.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
downY = (int) e.getRawY();
break;
case MotionEvent.ACTION_MOVE:
int moveY = (int) e.getRawY();
if (Math.abs(moveY - downY) > mTouchSlop) {
return true;
}
}
return super.onInterceptTouchEvent(e);
}
}

第二步：当然是在xml中加载布局文件了，这里就不贴代码了
第三步：想要随着Scrollview滚动view的颜色渐变，当然还要在Activity中调用

View.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
convenientBanner.getViewTreeObserver().removeGlobalOnLayoutListener(
this);
mViewHeight = View.getHeight() ;//view的高度

mScrollView.setScrollViewListener(new ObservableScrollView.ScrollViewListener() {
@Override
public void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy) {
if (y <= 0) {
mTitleView.setBackgroundColor(Color.argb((int) 0, 227, 29, 26));
} else if (y > 0 && y <= mViewHeight) {

4000
float scale = (float) y / mViewHeight;
float alpha = (255 * scale);
View.setBackgroundColor(Color.argb((int) alpha, 65, 179, 252));
} else {
View.setBackgroundColor(Color.argb((int) 255, 65, 179, 252));
}
}
});
}
});