在自定义ViewGroup中使用onLayout正确布局子级 [英] Correctly layout children with onLayout in Custom ViewGroup

问题描述

我正在创建一个自定义ViewGroup.我确实需要一个在另一个之上的2 FrameLayout；停留在底部的那个必须是20dp，而另一个必须覆盖其余的视图.

I am creating a custom ViewGroup. I does need to have 2 FrameLayout one above the other; the one that stays to the bottom must be 20dp, while the other one must cover the rest of the view.

onMeasure

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    int widthSize = MeasureSpec.getSize(widthMeasureSpec);
    int heightSize = MeasureSpec.getSize(heightMeasureSpec);
    setMeasuredDimension(widthSize, heightSize);

    final View content = getChildAt(CONTENT_INDEX);
    final View bar = getChildAt(BAR_INDEX);

    content.measure(
        MeasureSpec.makeMeasureSpec(widthSize, MeasureSpec.EXACTLY),
        MeasureSpec.makeMeasureSpec(heightSize - getPixels(BAR_HEIGHT), MeasureSpec.EXACTLY)
    );

    bar.measure(
        MeasureSpec.makeMeasureSpec(widthSize, MeasureSpec.EXACTLY),
        MeasureSpec.makeMeasureSpec(getPixels(BAR_HEIGHT), MeasureSpec.EXACTLY)
    );

onLayout

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    mInLayout = true;

    final View content = getChildAt(CONTENT_INDEX);
    final View bar = getChildAt(BAR_INDEX);

    if (content.getVisibility() != GONE) {
        content.layout(0, 0, content.getMeasuredWidth(), content.getMeasuredHeight());
     }

     if (bar.getVisibility() != GONE) {
         bar.layout(0, content.getMeasuredHeight(), bar.getMeasuredWidth(), 0);
     }

     mInLayout = false;
     mFirstLayout = false;
 }
    }

我要添加到此自定义ViewGroup的视图

LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);

mContentContainer = new FrameLayout(getContext());
mContentContainer.setLayoutParams(lp);

mBarContainer = new FrameLayout(getContext());
mBarContainer.setLayoutParams(lp);

// ... adding stuff to both containers ....

addView(mContentContainer, 0);
addView(mBarContainer, 1);

问题

mContentContainer 可以正确渲染(从top = 0到bottom =(totalHeight-栏高度)，并与父级的宽度匹配)，而不会渲染栏.

mContentContainer gets rendered correctly (from top=0 to bottom=(totalHeight - bar height) and match parent for the width), while the bar is not rendered.

推荐答案

View#layout()方法中的最后一个参数是 View 的底部.对于您的 bar ，您正在传递 0 ，但是它应该是自定义 View 的高度，您可以从> t 和 b 值传递到 onLayout()中.

The last parameter in the View#layout() method is the bottom of the View. For your bar, you're passing 0, but it should be the height of your custom View, which you can figure from the t and b values passed into onLayout().

bar.layout(0, content.getMeasuredHeight(), bar.getMeasuredWidth(), b - t);

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