仿猿题库练题里面效果,两个 View 分层,滑动中间的 View 可调节上下 View 的高度
继承 ViewGroup ,内部分为三个子 View ,分别是 top, mid (用来拖动的 View ), bottom
protected void setupViews() {
mTop = getChildAt(0);
mMid = getChildAt(1);
mBottom = getChildAt(2);
View handlerView = mMid.findViewById(R.id.handler);
if (handlerView == null) {
handlerView = mMid;
}
handlerView.setOnTouchListener(this);
}
维护一个
mSplitHeight,用来设置分割线(即上下 View 的交界处)的位置 在onMeasure(int widthMeasureSpec, int heightMeasureSpec)中初始化 mSplitHeight 并测量子view的大小
{
if (getChildCount() != 3) {
throw new RuntimeException("give 3 views");
}
int height = MeasureSpec.getSize(heightMeasureSpec);
if (mSplitHeight == 0) {
mSplitHeight = (int)(height * mSplitRatio);
}
//measure child
measureChild(mTop, widthMeasureSpec, MeasureSpec.makeMeasureSpec(mSplitHeight, MeasureSpec.EXACTLY));
measureChild(mMid, widthMeasureSpec, heightMeasureSpec);
measureChild(mBottom, widthMeasureSpec, MeasureSpec.makeMeasureSpec(getMeasuredHeight() - mSplitHeight, MeasureSpec.EXACTLY));
}
在onLayout方法中指定各个子 View 的位置
protected void onLayout(boolean changed, int l, int t, int r, int b) {
l = t = 0;
mTop.layout(l, t, l + mTop.getMeasuredWidth(), t + mTop.getMeasuredHeight());
mMid.layout(l, t + mSplitHeight - mMid.getMeasuredHeight(), l + mMid.getMeasuredWidth(), t + mSplitHeight);
mBottom.layout(l, t + mSplitHeight, l + mBottom.getMeasuredWidth(), t + mSplitHeight + mBottom.getMeasuredHeight());
}
最后要做的就是监听 mid View 滑动时改变 mSplitHeight 的值了。 在 mid 的
onTouch(View v, MotionEvent event)中判断,当 MotionEvent.ACTION_MOVE 时, 改变分割线的高度,然后再 requestLayout() 重新绘制即可。
{
case MotionEvent.ACTION_MOVE:
int delta = (int) (event.getY() - mLastMotionY);
if (Math.abs(delta) > mTouchSlop) {
if (delta > 0) {
mSplitHeight += delta - mTouchSlop;
} else {
mSplitHeight += delta + mTouchSlop;
}
if (mSplitHeight < mMinSplitTop || mSplitHeight < mMid.getHeight()) {
mSplitHeight = Math.max(mMinSplitTop, mMid.getHeight());
} else if (mSplitHeight > getHeight() || mSplitHeight > getHeight() - mMinSplitBottom) {
mSplitHeight = Math.min(getHeight(), getHeight() - mMinSplitBottom);
}
// mSplitHeight 改变之后重绘
requestLayout();
}
return true;
}