高级UI
自定义 flowLayout 流失布局，主要是两个方法重写
a、onMeasure(int, int) 确定所有子元素的大小
b、onLayout(boolean, int, int, int, int) View分配所有的子元素的大小和位置
github地址： https://github.com/haoda2328/flowLayout
/** * 记录所有行的 view 集合 */ private var alls: ArrayList<ArrayList<View>> = ArrayList() /** * 临时记录每一行的 view 集合 */ private var lines: ArrayList<View?> = ArrayList() /** * 子类布局的 LayoutParams */ private var params: RelativeLayout.LayoutParams? = null /** * 测量布局大小 */ override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) { super.onMeasure(widthMeasureSpec, heightMeasureSpec) //重新计算时数据 归零 alls.clear() lines.clear() //子类 View val count = childCount if (count == 0) { return } //需要计算出来的宽、高值 var width = 0 var height = 0 //根据父类计算出 当前flowlayout 的 大小值（参考作用） val selftWidth = MeasureSpec.getSize(widthMeasureSpec) val selfHeight = MeasureSpec.getSize(heightMeasureSpec) //根据父类计算出 MeasureSpec mode val modeWidht = MeasureSpec.getMode(widthMeasureSpec) val modeHeight = MeasureSpec.getMode(heightMeasureSpec) for (i in 0 until count) { params = getChildAt(i).layoutParams as LayoutParams? val childWidthMeasureSpec = params?.width?.let { getChildMeasureSpec( widthMeasureSpec , paddingLeft + paddingRight, it ) } val childHeightMeasureSpec = params?.height?.let { getChildMeasureSpec( heightMeasureSpec , paddingTop + paddingBottom, it ) } //子类测量 childWidthMeasureSpec?.let { childHeightMeasureSpec?.let { it1 -> getChildAt(i).measure( it, it1 ) } } val childWidth = getChildAt(i).measuredWidth val childHeigth = getChildAt(i).measuredWidth width += childWidth if (width > selftWidth - paddingLeft - paddingRight) { width = 0 alls.add(lines.clone() as java.util.ArrayList<View>) lines.clear() } lines.add(getChildAt(i)) } alls.add(lines.clone() as java.util.ArrayList<View>) if (alls.size > 1) { width = selftWidth height = alls.size * (getChildAt(0).measuredHeight + paddingBottom + paddingTop) } else { width = getChildAt(0).measuredHeight } width = when (modeWidht) { MeasureSpec.AT_MOST -> { width } MeasureSpec.UNSPECIFIED -> { width } MeasureSpec.EXACTLY -> { selftWidth } else -> { width } } when (modeHeight) { MeasureSpec.AT_MOST -> { } MeasureSpec.UNSPECIFIED -> { } MeasureSpec.EXACTLY -> height = selfHeight } Log.i("layoutParams", "width == $width height == $height") setMeasuredDimension(width, height) } /** * 显示位置计算 */ override fun onLayout(changed: Boolean, l: Int, t: Int, r: Int, b: Int) { super.onLayout(changed, l, t, r, b) if (alls.size == 0) { return } var top = paddingTop for (i in alls.indices) { val mtop = alls[0][0].measuredHeight var left = paddingLeft val datas = alls[i] for (j in datas.indices) { val view = datas[j] val mleft = view.measuredWidth view.layout(left, top, left + mleft, top + mtop) Log.i("layoutParams", "left == $left ") //宽度 累加计算 left += mleft //换行 时高度 累加计算 if (j == datas.size - 1) { top += mtop } } } }