android - measureSpec 返回错误值

Question

我正在尝试使用以下代码测量布局的高度:

int widthMeasureSpec = View.MeasureSpec.makeMeasureSpec(toExpand.getWidth(), View.MeasureSpec.EXACTLY);
        int heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
        layoutHeight.measure(widthMeasureSpec, heightMeasureSpec);
        int height = layoutHeight.getMeasuredHeight();

如果我在创建布局后调用它，它会返回良好的值，但我也在应用程序启动时调用它，当 fragment 被附加时，它返回比预期高得多的值。

有什么想法吗？感谢转发

Answer 1

通过将 onGlobalLayout 监听器与 viewTreeObserver 一起使用解决了这个问题。这是代码:

ViewTreeObserver vto = ((View) loadingLayout.getParent()).getViewTreeObserver();
vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
    @Override
    public void onGlobalLayout() {
        ViewTreeObserver vto = ((View) loadingLayout.getParent()).getViewTreeObserver();
        int widthMeasureSpec = View.MeasureSpec.makeMeasureSpec(toExpand.getWidth(), View.MeasureSpec.EXACTLY);
        int heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
        layoutHeight.measure(widthMeasureSpec, heightMeasureSpec);
        int height = layoutHeight.getMeasuredHeight();
        if(toExpand.getHeight() == height){
            hide(toExpand, 0);
        }else{
            expand(toExpand, height);
        }
        if (Build.VERSION.SDK_INT < 16) {
            //deprecated od API level 16
            vto.removeGlobalOnLayoutListener(this);
        } else {
            vto.removeOnGlobalLayoutListener(this);
        }
    }
});