首先来看一下效果:

 

 大体思路如下:

总体布局用了一个自定义的ViewGroup,里面包了两个View(top View,bottomView)

我在bottomView里放了ViewPager,里面又有Fragment,Fragment里放的是ListView

原理:

ViewGroup在分发touchEvent的时候先通过手势GestureDetector判断手势方向,当向上滑动的时候让topView和bottomView同时向上移动,反之亦然。

整体思路不是很难如下是干货:

布局文件

<com.lin.gesturedetector.MyViewGroup
  android:id="@+id/view_group"
  android:layout_width="match_parent"
  android:layout_height="match_parent">
  <include
   android:id="@+id/group_top"
   layout="@layout/view_top" />
  <include
   android:id="@+id/group_bottom"
   layout="@layout/view_bottom" />
 </com.lin.gesturedetector.MyViewGroup>

手势监听重要的是打log看一下上下滑动是数值的变化,找到其规律:           

 @Override
   public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
    Log.i(tag, "onScroll -> distanceY" + distanceY);
    if (distanceY < 0) {// 手势向下滑动是负值
     animatorLayoutOffset(1);
    }
    if (distanceY > 0) {
     animatorLayoutOffset(0f);
    }
    return true;
   }

一定记得在ViewGroup内查找控件需要在onFinishInflate后才能找到:   

 @Override
 protected void onFinishInflate() {
  super.onFinishInflate();
  viewTop = findViewById(R.id.group_top);
  viewBottom = findViewById(R.id.group_bottom);
 }

在ViewGroup布局的逻辑中需要处理的有一下几点:

1、onMeasure的时候要把子控件测量出来

2、onLayout时需要手动将子控件布局

接下来就是监听手势设置动画,不停的onLayout以达到topView和bottomView的布局效果  

@Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  int width = MeasureSpec.getSize(widthMeasureSpec);
  int height = MeasureSpec.getSize(heightMeasureSpec);
  viewTop.measure(MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(height, MeasureSpec.AT_MOST));
  viewBottom.measure(MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY));
  setMeasuredDimension(width, height);
 }
 @Override
 protected void onLayout(boolean changed, int l, int t, int r, int b) {
  int topHeight = viewTop.getMeasuredHeight();
  float offset = layoutOffset * topHeight;
  int width = r - l;
  float topViewYTop = offset - topHeight;
  float topViewYBottom = topViewYTop + topHeight;
  viewTop.layout(0, (int) topViewYTop, width, (int) topViewYBottom);
  viewBottom.layout(0, (int) topViewYBottom, width, (int) topViewYBottom + viewBottom.getMeasuredHeight());
 }
 private void animatorLayoutOffset(float offset) {
  if (animator != null && animator.isRunning()) {
   return;
  }
  animator = ObjectAnimator.ofFloat(this, "layoutOffset", layoutOffset, offset);
  animator.setDuration(500);
  animator.start();
 }

项目地址在这:

GitHub

总结

以上所述是小编给大家介绍的Android 根据手势顶部View自动展示与隐藏效果,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持!

01-30 18:39