// 遍歷所有的子View
for (int i = 0, childCount = getChildCount(); i < childCount; ++i) {
  View childView = getChildAt(i);
  // measure子View，并獲取它的寬度和高度
  LayoutParams childLayoutParams = childView.getLayoutParams();
  childView.measure(
      getChildMeasureSpec(widthMeasureSpec, paddingLeft + paddingRight, childLayoutParams.width),
      getChildMeasureSpec(heightMeasureSpec, paddingTop + paddingBottom, childLayoutParams.height));
  int childWidth = childView.getMeasuredWidth();
  int childHeight = childView.getMeasuredHeight();
  // 計(jì)算當(dāng)前行的高度（當(dāng)前行所有子View中最高的那個(gè)）
  lineHeight = Math.max(childHeight, lineHeight);
  // 把當(dāng)前child view放到上一個(gè)child view的右邊，如果放不下，則換行
  if (childLeft + childWidth + paddingRight > myWidth) {
    childLeft = paddingLeft;
    childTop += mVerticalSpacing + lineHeight;
    lineHeight = childHeight;
  } else {
    childLeft += childWidth + mHorizontalSpacing;
  }
}
int wantedHeight = childTop + lineHeight + paddingBottom;
// 計(jì)算FlowLayout所需要高度
setMeasuredDimension(myWidth, resolveSize(wantedHeight, heightMeasureSpec));

for (int i = 0, childCount = getChildCount(); i < childCount; ++i) {
  View childView = getChildAt(i);
  if (childView.getVisibility() == View.GONE) {
    continue;
  }
  int childWidth = childView.getMeasuredWidth();
  int childHeight = childView.getMeasuredHeight();
  lineHeight = Math.max(childHeight, lineHeight);
  if (childLeft + childWidth + paddingRight > myWidth) {
    childLeft = paddingLeft;
    childTop += mVerticalSpacing + lineHeight;
    lineHeight = childHeight;
  }
  // 關(guān)鍵代碼
  childView.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);
  childLeft += childWidth + mHorizontalSpacing;
}