Question

在我看来，DrawerLayout实施中缺少一件事：在抽屉打开之前触发的事件。

drawerToggle = new ActionBarDrawerToggle(this, drawerLayout, R.drawable.ic_drawer, R.string.drawer_open, R.string.drawer_close) {
  public void onDrawerClosed(View view) {
    //...
  }

  public void onBeforeDrawerOpened(View drawerView) {
    //...
  }

  public void onDrawerOpened(View drawerView) {
    //...
  }
};

需要它的原因是设置抽屉项目的状态，如选择，启用和类似的菜单项。把它放到onDrawerOpened()回调有点可行，但在打开后更改菜单外观看起来不太合适。

我的第一个想法是扩展ActionBarDrawerToggle并提供新事件。我应该重新发明轮子:-)还是已经有人这样做了？

Answer 1

此链接可以帮助您解决问题。 How to detect that the DrawerLayout started opening?

使用onDrawerStateChanged(int newState)回调

你需要听STATE_SETTLING个州 - 这个状态是   每当抽屉开始移动（打开或关闭）时报告。所以   一旦你看到这种状态 - 检查抽屉是否现在打开并采取行动   相应地：
Function Bootstrap(S As Range, Z As Range, L As Double) As Double
Dim j As Integer
Dim a As Variant
Dim b As Variant
Dim n As Integer
Dim Q() As Double
Dim sum As Double
Dim P As Double
Dim dt As Double

n = Application.WorksheetFunction.Max(S.Columns.Count, Z.Columns.Count)
a = S.Value
b = Z.Value
dt = 1
sum = 0
ReDim Q(0 To n)
Q(0) = 0

For j = 1 To n - 1
    P = b(1, j) * (L * Q(j - 1)) - (L + dt * a(1, j) * Q(j - 1))
    sum = sum + P
    Q(j) = sum
Next j

Bootstrap = sum
End Function

Answer 2

当我遇到这个问题并且在任何地方找不到确切的答案时，我在google上发现了这个，所以我决定发布完整的答案。希望它可以节省一些时间。

我找到的最佳解决方案是监控抽屉状态，并使用isDrawerOpen方法确定它是打开还是关闭。务必将重力设置为与打开/关闭抽屉时使用的重力相匹配。

DrawerLayout mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
// ...
ActionBarDrawerToggle mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
R.drawable.ic_playlist, R.string.drawer_open, R.string.drawer_close) {
    public void onDrawerStateChanged(int newState) {
        if(newState == DrawerLayout.STATE_DRAGGING){
            if(mDrawerLayout.isDrawerOpen(Gravity.LEFT)){
                //closing

            }else{
                //opening

            }
        }
    }
}

Answer 3

来自Lenny和Fred的混合人对Kotlin的回答：

@GetMapping("/user/home")
public ModelAndView getUser(
                        @RequestParam(name="userId", required = true) String userId,
                        @RequestParam(name="message", required = false) String message,
                        HttpSession session){
    ModelAndView mv = new ModelAndView();

    User user = (User)session.getAttribute("user");

    mv.addObject("message", message);
    mv.setViewName("user/home/view");
    return mv;
}

Answer 4

已接受的答案中推荐的setDrawerListener方法现在为deprecated。完成此操作的新方法是使用addDrawerListener方法。

在科特林：

初始化DrawerLayout视图

val drawerLayout: DrawerLayout = findViewById(R.id.drawer_layout)

在您的主要活动中，创建一个内部类，该内部类是DrawerLayout.DrawerListener的子类。 DrawerLayout类实现DrawerListener接口。您可以在onDrawerSlide中跟踪更改的抽屉位置，并确定抽屉是打开还是关闭：

inner class CustomDrawer : DrawerLayout.DrawerListener{
  override fun onDrawerStateChanged(newState: Int) {
  }

var last: Float = 0f

override fun onDrawerSlide(drawerView: View, slideOffset: Float) {
    imm.hideSoftInputFromWindow(drawerView?.getWindowToken(), 0)

    var opening: Boolean = slideOffset>last
    var closing: Boolean = slideOffset<last

    if(opening) {
        Log.i("Drawer","opening")
        Log.d("Last",last.toString())
    } else if(closing) {
        Log.i("Drawer","closing")
        Log.d("Last",last.toString())
    } else {
        Log.i("Drawer","doing nothing")
        Log.d("Last",last.toString())
    }
}

override fun onDrawerClosed(drawerView: View) {

  }

override fun onDrawerOpened(drawerView: View) {

  }
}

将您的自定义DrawerListener添加到抽屉布局（我将其放在onCreate方法中）
```
var drawerListener = CustomDrawer()
drawerLayout.addDrawerListener(drawerListener)
```

DrawerLayout打开前的事件

4 个答案: