DrawerLayout 在Remove了以后重新Add的时候可能出现openDrawer卡住的问题

本文探讨了在DrawerLayout布局中移除并重新添加视图时伴随动画出现的卡顿问题。通过分析openDrawer方法及onDetachedFromWindow、onAttachedToWindow方法中的mFirstLayout变量设置，找到了解决方案。

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之前做项目的时候，发现如果在DrawerLayout布局中，如果要Remove掉这个View，然后重新Add，期间有做动画，就会发现在调用openDrawer会卡住一会再打开，找了很久然后发现 openDrawer有下面这个方法，注意

mFirstLayout

public void openDrawer(@NonNull View drawerView, boolean animate) {
    if (!isDrawerView(drawerView)) {
        throw new IllegalArgumentException("View " + drawerView + " is not a sliding drawer");
    }

    final LayoutParams lp = (LayoutParams) drawerView.getLayoutParams();
    if (mFirstLayout) {
        lp.onScreen = 1.f;
        lp.openState = LayoutParams.FLAG_IS_OPENED;

        updateChildrenImportantForAccessibility(drawerView, true);
    } else if (animate) {
        lp.openState |= LayoutParams.FLAG_IS_OPENING;

        if (checkDrawerViewAbsoluteGravity(drawerView, Gravity.LEFT)) {
            mLeftDragger.smoothSlideViewTo(drawerView, 0, drawerView.getTop());
        } else {
            mRightDragger.smoothSlideViewTo(drawerView, getWidth() - drawerView.getWidth(),
                    drawerView.getTop());
        }
    } else {
        moveDrawerToOffset(drawerView, 1.f);
        updateDrawerState(lp.gravity, STATE_IDLE, drawerView);
        drawerView.setVisibility(VISIBLE);
    }
    invalidate();
}

输出的时候发现在onDetachedFromWindow 和onAttachedToWindow的时候都会把这个参数置为true

@Override
protected void onDetachedFromWindow() {
    super.onDetachedFromWindow();
    mFirstLayout = true;
}

@Override
protected void onAttachedToWindow() {
    super.onAttachedToWindow();
    mFirstLayout = true;
}

在onLayout才会置为false，一般都会调用onLayout，但是重新add的时候有时没有调用onLayout，

所以我就手动调用就没问题了