Android Tutorial Material Design 4 - Modifyable and advanced Menu

Note: You should use B4A 6.0 or above for this tutorial.

With the ACToolBar(Light|Dark) object we can get access to the Menu object of the activity. This opens the possibility for modifyable menus and some other advanced menu features.

Basics

With the ToolBar.Menu property we have access to the menu of the ToolBar. For a standalone ToolBar (which is not set as the activity ActionBar) we can just access the property everywhere in our code and do what we want to do with it just like adding/removing menu items.

If the ToolBar is our activities ActionBar we have to handle the menu in a special way because if we don't do this, B4As own menu handling will conflict with our handling.

In Android the menu is created and initalized with two methods: onCreateOptionsMenu() and onPrepareOptionsMenu(). I don't want to explain the whole menu system here you just need to know, that B4A uses these methods internally to create it's own menu and they get called "at some time" in the activity initialization process.

With the itroduction of inline Java code in B4A 4.30 we now have the possibility to add our own code to handle the application menu. The idea is to call an event to set up the menu and here is an example how this can be done:

B4X:
#If Java

public boolean _onCreateOptionsMenu(android.view.Menu menu) {
    if (processBA.subExists("activity_createmenu")) {
        processBA.raiseEvent2(null, true, "activity_createmenu", false, new de.amberhome.objects.appcompat.ACMenuWrapper(menu));
        return true;
    }
    else
        return false;
}
#End If

In this code we use the _onCreateOptionsMenu hook to check if a Sub named "Activity_CreateMenu" exists. If yes, then we call it and we provide the activities menu as a parameter. If the sub does not exist, the normal B4A menu-handling is done.

Now we need the implementation of Activity_CreateMenu:

B4X:
Sub Activity_CreateMenu(Menu As ACMenu)
    Menu.Clear

    Dim item As ACMenuItem
    Menu.Add2(10, 1, "Plus one", xml.GetDrawable("ic_plus_one_black_24dp")).ShowAsAction = item.SHOW_AS_ACTION_IF_ROOM
    Menu.Add2(20, 2, "Refresh", xml.GetDrawable("ic_refresh_black_24dp")).ShowAsAction = item.SHOW_AS_ACTION_ALWAYS

    Menu.Add(1, 3, "Overflow1", Null)
    Menu.Add(2, 4, "Overflow2", Null)
    Menu.Add(3, 5, "Overflow3", Null)

    'Sync Checkboxes with the Menu
    SetCheckBoxState(Menu)

End Sub
First we clear the menu to be sure that there are no old entries in it. Then we just use the Menu object to add some additional menus. Easy, isn't it? (For this example we sync the menu with the checkboxes with SetCheckBoxState())

It is good practice to use a Toolbar as your ActionBar. If you do this you can access the menu with ToolBar.Menu everywhere in your code to modify the menu.

Some advanced menu features

With the ACMenu and ACMenuItem objects we have access to some advanced menu features.

When you add a menu item to the menu you can specify a menu ID and a sort order. So with the sort order you can later add menu entries which are displayed above other menu items. With the ID you can access this item later and modify it.

You can create checkable menu itemes. The ACMenu.Add() methods return the added menu item so you can directly modify it and make it checkable or set it as an action item or even make it invisible.

It is even possible to add or remove menu items dynamically.

B4X:
Sub cbItemVisible_CheckedChange(Checked As Boolean)
  ToolBar.Menu.FindItem(1).Visible = Checked
End Sub

Sub cbItemCheckable_CheckedChange(Checked As Boolean)
  ToolBar.Menu.FindItem(2).Checkable = Checked
End Sub

Sub cbItemDisable_CheckedChange(Checked As Boolean)
  ToolBar.Menu.FindItem(3).Enabled = Not(Checked)
End Sub

Look at the example project for better understanding.

overflow_menu.png
 

Attachments

  • ToolBarMenuExample2_0.zip
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Last edited:

MichalK73

Active Member
Licensed User
I wrote 4 posts above.
I can not move up the entire code.
Even when not working Acive_Touch AcToolBar is used in the window. As if the program did not see this code, nothing happens.

Add:
I do not know what is the cause of the ACToolBar so I had to get around to creating a visible icon.
 

corwin42

Expert
Licensed User
Be sure to use the latest AppCompat library. V3.41 had a bug which caused that the ToolBars didn't raise their events. Current version is V3.50.

I have attached a simple example with a ToolBar and NavigationDrawer. The ToolBar_NavigationItemClick fires as expected.
 

Attachments

  • SimpleNavigationDrawerExample.zip
    110.2 KB · Views: 531

MichalK73

Active Member
Licensed User
@ corwin32
So yes you're right. I used the old version of the library and not noticed. You have a total right to 3.51 works very well. Many thanks for the explaination me where I made a mistake.

+100
 
If you just want to let the contextual ActionBar overlap the ToolBar, just add the following line to the theme file:
B4X:
<item name="windowActionModeOverlay">true</item>

If you want to disable the contextual ActionBar completely use this:
After loading the layout or initializing the EditText:
B4X:
Dim jo As JavaObject = EditText1
Dim e As Object = jo.CreateEvent("android.view.ActionMode.Callback", "Action", False)
jo.RunMethod("setCustomSelectionActionModeCallback", Array As Object(e))

And add the following Event sub:
B4X:
Sub Action_Event (MethodName As String, Args() As Object) As Object
    Return False
End Sub



Hello Mr. Corwin
I have a question for you that I know is not the right place here, but I have tried different ways and I have not come to a conclusion and I think you know the answer to my question well.
I want to be able to access the text selected from the label when a part of the text of a label is selected by the user, for example I can change the color of that part of the text. I found that the method is very similar to what you have done here, so I tried several times myself but unfortunately I could not implement it well.
I have also created a new thread for this question, please help me there if you can. Thank you very much.

 
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