为什么我无法用布局重力锁定DrawerLayout

Question

我使用DrawerLayout,最近我想在drawerLayout中改变listView的重力.但是在我将listView的重力改为android:layout_gravity="start|bottom"from后android:layout_gravity="start",drawerLayout无法锁定

mDrawer.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED);

setDrawerLockMode()使用;

<android.support.v4.widget.DrawerLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
</RelativeLayout>

<ListView
    android:id="@+id/drawer_list"
    android:layout_width="320dp"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:background="#F3F3F4"
    android:choiceMode="singleChoice" >
</ListView>

但它没有锁定;

<android.support.v4.widget.DrawerLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
</RelativeLayout>

<ListView
    android:id="@+id/drawer_list"
    android:layout_width="320dp"
    android:layout_height="match_parent"
    android:layout_gravity="start|bottom"
    android:background="#F3F3F4"
    android:choiceMode="singleChoice" >
</ListView>

`

任何线索为什么我不能使用其他重力的锁模式？

谢谢!

Answer 1

基于对文档中,只可以使用可用的比重是Gravity.LEFT,Gravity.RIGHT或者GravityCompat.START,GravityCompat.END.

(强调我的):

使用子视图上的android:layout_gravity属性控制抽屉定位和布局,该属性对应于您希望抽屉出现的视图的哪一侧:左侧或右侧.(或者在支持布局方向的平台版本上开始/结束.)

看源代码

public void setDrawerLockMode(int lockMode, int edgeGravity) {
  final int absGrav = GravityCompat.getAbsoluteGravity(edgeGravity,
                                                       ViewCompat.getLayoutDirection(this));
  if (absGrav == Gravity.LEFT) {
    mLockModeLeft = lockMode;
  } else if (absGrav == Gravity.RIGHT) {
    mLockModeRight = lockMode;
  }
  if (lockMode != LOCK_MODE_UNLOCKED) {
    // Cancel interaction in progress
    final ViewDragHelper helper = absGrav == Gravity.LEFT ? mLeftDragger : mRightDragger;
    helper.cancel();
  }
  switch (lockMode) {
    case LOCK_MODE_LOCKED_OPEN:
      final View toOpen = findDrawerWithGravity(absGrav);
      if (toOpen != null) {
        openDrawer(toOpen);
      }
      break;
    case LOCK_MODE_LOCKED_CLOSED:
      final View toClose = findDrawerWithGravity(absGrav);
      if (toClose != null) {
        closeDrawer(toClose);
      }
      break;
      // default: do nothing
  }
}

该方法本身仅在重力是检查LEFT或RIGHT(但使用GravityCompat的方法,所以START与END应适当翻译).

这意味着通过设置引力"start|bottom",你引入了无效的引力,这导致setDrawerLockMode()什么都不做.