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
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网站的支持!