// Either expand children with weight to take up available space or
// shrink them if they extend beyond our current bounds
int delta = heightSize - mTotalLength;
if (delta != 0 && totalWeight > 0.0f) {
float weightSum = mWeightSum > 0.0f ? mWeightSum : totalWeight;
mTotalLength = 0;
for (int i = 0; i < count; ++i) {
final View child = getVirtualChildAt(i);
if (child.getVisibility() == View.GONE) {
continue;
}
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) child.getLayoutParams();
float childExtra = lp.weight;
if (childExtra > 0) {
// Child said it could absorb extra space -- give him his share
int share = (int) (childExtra * delta / weightSum);
weightSum -= childExtra;
delta -= share;
final int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec,
mPaddingLeft + mPaddingRight +
lp.leftMargin + lp.rightMargin, lp.width);
// TODO: Use a field like lp.isMeasured to figure out if this
// child has been previously measured
if ((lp.height != 0) || (heightMode != MeasureSpec.EXACTLY)) {
// child was measured once already above...
// base new measurement on stored values
int childHeight = child.getMeasuredHeight() + share;
if (childHeight < 0) {
childHeight = 0;
}
child.measure(childWidthMeasureSpec,
MeasureSpec.makeMeasureSpec(childHeight, MeasureSpec.EXACTLY));
} else {
// child was skipped in the loop above.
// Measure for this first time here
child.measure(childWidthMeasureSpec,
MeasureSpec.makeMeasureSpec(share > 0 ? share : 0,
MeasureSpec.EXACTLY));
}
// Child may now not fit in vertical dimension.
childState = combineMeasuredStates(childState, child.getMeasuredState()
& (MEASURED_STATE_MASK>>MEASURED_HEIGHT_STATE_SHIFT));
}
final int margin = lp.leftMargin + lp.rightMargin;
final int measuredWidth = child.getMeasuredWidth() + margin;
maxWidth = Math.max(maxWidth, measuredWidth);
boolean matchWidthLocally = widthMode != MeasureSpec.EXACTLY &&
lp.width == LayoutParams.MATCH_PARENT;
alternativeMaxWidth = Math.max(alternativeMaxWidth,
matchWidthLocally ? margin : measuredWidth);
allFillParent = allFillParent && lp.width == LayoutParams.MATCH_PARENT;
final int totalLength = mTotalLength;
mTotalLength = Math.max(totalLength, totalLength + child.getMeasuredHeight() +
lp.topMargin + lp.bottomMargin + getNextLocationOffset(child));
}
// Add in our padding
mTotalLength += mPaddingTop + mPaddingBottom;
// TODO: Should we recompute the heightSpec based on the new total length?
- 通過heightSize-mTotalLength得到delta，也就是還剩余的高度差，它有可能是負數
- 判斷delta不為0并且totalWeight大于0，那么才開始進行多余空間的分配
- 判斷mWeightSum是否大于0，這個屬性是從外部設置的，如果沒有設置的話，就會用自己算出來的totalWeight來作為總weight
- 開始遍歷所有的子View，并且將空View或者Visible為GONE的子View排除
- 從子View的LayoutParams中獲取lp.weight屬性
- 通過計算share，來獲取子View可以獲得多少的剩余空間
- 通過getChildMeasureSpec獲取子View的widthMeasureSpec
- 將上次measure出的子View高度再加上share的高度獲取子View的新高度，再調用child.measure重新計算子View的新高度
- 通過child.getMeasuredWidth+margin獲取最大的寬度
- 判斷widthMode不為MeasureSpec.EXACTLY，并且lp.width為LayoutParams.MATCH_PARENT，那么alrtnativeMaxWidth就是margin
- 將mTotalLength再加上子View的高度，算出總共的高度
