emacs/java/org/gnu/emacs/EmacsContextMenu.java

/* Communication module for Android terminals.  -*- c-file-style: "GNU" -*-

Copyright (C) 2023 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */

package org.gnu.emacs;

import java.util.List;
import java.util.ArrayList;

import android.content.Context;
import android.content.Intent;

import android.os.Bundle;

import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.SubMenu;

import android.util.Log;

import android.widget.PopupMenu;

/* Context menu implementation.  This object is built from JNI and
   describes a menu hiearchy.  Then, `inflate' can turn it into an
   Android menu, which can be turned into a popup (or other kind of)
   menu.  */

public class EmacsContextMenu
{
  private static final String TAG = "EmacsContextMenu";

  /* Whether or not an item was selected.  */
  public static boolean itemAlreadySelected;

  /* Whether or not a submenu was selected.  */
  public static boolean wasSubmenuSelected;

  private class Item implements MenuItem.OnMenuItemClickListener
  {
    public int itemID;
    public String itemName;
    public EmacsContextMenu subMenu;
    public boolean isEnabled, isCheckable, isChecked;

    @Override
    public boolean
    onMenuItemClick (MenuItem item)
    {
      Log.d (TAG, "onMenuItemClick: " + itemName + " (" + itemID + ")");

      if (subMenu != null)
	{
	  /* After opening a submenu within a submenu, Android will
	     send onContextMenuClosed for a ContextMenuBuilder.  This
	     will normally confuse Emacs into thinking that the
	     context menu has been dismissed.  Wrong!

	     Setting this flag makes EmacsActivity to only handle
	     SubMenuBuilder being closed, which always means the menu
	     has actually been dismissed.  */
	  wasSubmenuSelected = true;
	  return false;
	}

      /* Send a context menu event.  */
      EmacsNative.sendContextMenu ((short) 0, itemID);

      /* Say that an item has already been selected.  */
      itemAlreadySelected = true;
      return true;
    }
  };

  public List<Item> menuItems;
  public String title;
  private EmacsContextMenu parent;

  /* Create a context menu with no items inside and the title TITLE,
     which may be NULL.  */

  public static EmacsContextMenu
  createContextMenu (String title)
  {
    EmacsContextMenu menu;

    menu = new EmacsContextMenu ();
    menu.menuItems = new ArrayList<Item> ();
    menu.title = title;

    return menu;
  }

  /* Add a normal menu item to the context menu with the id ITEMID and
     the name ITEMNAME.  Enable it if ISENABLED, else keep it
     disabled.

     If this is not a submenu and ISCHECKABLE is set, make the item
     checkable.  Likewise, if ISCHECKED is set, make the item
     checked.  */

  public void
  addItem (int itemID, String itemName, boolean isEnabled,
	   boolean isCheckable, boolean isChecked)
  {
    Item item;

    item = new Item ();
    item.itemID = itemID;
    item.itemName = itemName;
    item.isEnabled = isEnabled;
    item.isCheckable = isCheckable;
    item.isChecked = isChecked;

    menuItems.add (item);
  }

  /* Create a disabled menu item with the name ITEMNAME.  */

  public void
  addPane (String itemName)
  {
    Item item;

    item = new Item ();
    item.itemName = itemName;

    menuItems.add (item);
  }

  /* Add a submenu to the context menu with the specified title and
     item name.  */

  public EmacsContextMenu
  addSubmenu (String itemName, String title)
  {
    EmacsContextMenu submenu;
    Item item;

    item = new Item ();
    item.itemID = 0;
    item.itemName = itemName;
    item.subMenu = createContextMenu (title);
    item.subMenu.parent = this;

    menuItems.add (item);
    return item.subMenu;
  }

  /* Add the contents of this menu to MENU.  */

  private void
  inflateMenuItems (Menu menu)
  {
    Intent intent;
    MenuItem menuItem;
    SubMenu submenu;

    for (Item item : menuItems)
      {
	if (item.subMenu != null)
	  {
	    try
	      {
		/* This is a submenu.  On versions of Android which
		   support doing so, create the submenu and add the
		   contents of the menu to it.  */
		submenu = menu.addSubMenu (item.itemName);
		item.subMenu.inflateMenuItems (submenu);
	      }
	    catch (UnsupportedOperationException exception)
	      {
		/* This version of Android has a restriction
		   preventing submenus from being added to submenus.
		   Inflate everything into the parent menu
		   instead.  */
		item.subMenu.inflateMenuItems (menu);
		continue;
	      }

	    /* This is still needed to set wasSubmenuSelected.  */
	    menuItem = submenu.getItem ();
	    menuItem.setOnMenuItemClickListener (item);
	  }
	else
	  {
	    menuItem = menu.add (item.itemName);
	    menuItem.setOnMenuItemClickListener (item);

	    /* If the item ID is zero, then disable the item.  */
	    if (item.itemID == 0 || !item.isEnabled)
	      menuItem.setEnabled (false);

	    /* Now make the menu item display a checkmark as
	       appropriate.  */

	    if (item.isCheckable)
	      menuItem.setCheckable (true);

	    if (item.isChecked)
	      menuItem.setChecked (true);
	  }
      }
  }

  /* Enter the items in this context menu to MENU.  Create each menu
     item with an Intent containing a Bundle, where the key
     "emacs:menu_item_hi" maps to the high 16 bits of the
     corresponding item ID, and the key "emacs:menu_item_low" maps to
     the low 16 bits of the item ID.  */

  public void
  expandTo (Menu menu)
  {
    inflateMenuItems (menu);
  }

  /* Return the parent or NULL.  */

  public EmacsContextMenu
  parent ()
  {
    return this.parent;
  }

  /* Like display, but does the actual work and runs in the main
     thread.  */

  private boolean
  display1 (EmacsWindow window, int xPosition, int yPosition)
  {
    /* Set this flag to false.  It is used to decide whether or not to
       send 0 in response to the context menu being closed.  */
    itemAlreadySelected = false;

    /* No submenu has been selected yet.  */
    wasSubmenuSelected = false;

    return window.view.popupMenu (this, xPosition, yPosition);
  }

  /* Display this context menu on WINDOW, at xPosition and
     yPosition.  */

  public boolean
  display (final EmacsWindow window, final int xPosition,
	   final int yPosition)
  {
    Runnable runnable;
    final Holder<Boolean> rc;

    rc = new Holder<Boolean> ();

    runnable = new Runnable () {
	@Override
	public void
	run ()
	{
	  synchronized (this)
	    {
	      rc.thing = display1 (window, xPosition, yPosition);
	      notify ();
	    }
	}
      };

    EmacsService.syncRunnable (runnable);
    return rc.thing;
  }

  /* Dismiss this context menu.  WINDOW is the window where the
     context menu is being displayed.  */

  public void
  dismiss (final EmacsWindow window)
  {
    Runnable runnable;

    EmacsService.SERVICE.runOnUiThread (new Runnable () {
	@Override
	public void
	run ()
	{
	  window.view.cancelPopupMenu ();
	  itemAlreadySelected = false;
	}
      });
  }
};