Update Android port

* doc/emacs/android.texi (Android File System): Describe an
easier way to disable scoped storage.
* java/AndroidManifest.xml.in: Add new permission to allow that.
* java/README: Add more text describing Java.
* java/org/gnu/emacs/EmacsContextMenu.java (Item): New fields
`isCheckable' and `isChecked'.
(EmacsContextMenu, addItem): New arguments.
(inflateMenuItems): Set checked status as appropriate.

* java/org/gnu/emacs/EmacsCopyArea.java (perform): Disallow
operations where width and height are less than or equal to
zero.
* lisp/menu-bar.el (menu-bar-edit-menu): Make
execute-extended-command available as a menu item.
* src/androidmenu.c (android_init_emacs_context_menu)
(android_menu_show):
* src/menu.c (have_boxes): Implement menu check boxes.

4 files changed, 88 insertions, 7 deletions

diff --git a/java/AndroidManifest.xml.in b/java/AndroidManifest.xml.in
index 527ce74c474..09e4e788e0b 100644
--- a/java/AndroidManifest.xml.in
+++ b/java/AndroidManifest.xml.in
@@ -52,6 +52,10 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>. -->
   <uses-permission android:name="android.permission.RECORD_AUDIO" />
   <uses-permission android:name="android.permission.CAMERA" />
 
+  <!-- This is required on Android 11 or later to access /sdcard.  -->
+
+  <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"/>
+
   <uses-sdk android:minSdkVersion="@ANDROID_MIN_SDK@"
             android:targetSdkVersion="33"/>
 
diff --git a/java/README b/java/README
index 44f5a415162..3bce2556403 100644
--- a/java/README
+++ b/java/README
@@ -292,15 +292,15 @@ public class EmacsFrobinicator
   }
 }
 
-Java arrays are similar to C arrays in that they can not grow.  But
+Java arrays are similar to C arrays in that they can not grow.  But
 they are very much unlike C arrays in that they are always references
-(as opposed to decaying into pointers in various situations), and
+(as opposed to decaying into pointers in only some situations), and
 contain information about their length.
 
 If another function named ``frobinicate1'' takes an array as an
 argument, then it need not take the length of the array.
 
-Instead, it simply iterates over the array like so:
+Instead, it may simply iterate over the array like so:
 
 int i, k;
 
@@ -339,10 +339,65 @@ struct emacs_array_container
 
 or, possibly even better,
 
-typedef int my_array[10];
+typedef int emacs_array_container[10];
 
 Alas, Java has no equivalent of `typedef'.
 
+Like in C, Java string literals are delimited by double quotes.
+Unlike C, however, strings are not NULL-terminated arrays of
+characters, but a distinct type named ``String''.  They store their
+own length, characters in Java's 16-bit ``char'' type, and are capable
+of holding NULL bytes.
+
+Instead of writing:
+
+wchar_t character;
+extern char *s;
+size_t s;
+
+  for (/* determine n, s in a loop.  */)
+    s += mbstowc (&character, s, n);
+
+or:
+
+const char *byte;
+
+for (byte = my_string; *byte; ++byte)
+  /* do something with *byte.  */;
+
+or perhaps even:
+
+size_t length, i;
+char foo;
+
+length = strlen (my_string);
+
+for (i = 0; i < length; ++i)
+  foo = my_string[i];
+
+you write:
+
+char foo;
+int i;
+
+for (i = 0; i < myString.length (); ++i)
+  foo = myString.charAt (0);
+
+Java also has stricter rules on what can be used as a truth value in a
+conditional.  While in C, any non-zero value is true, Java requires
+that every truth value be of the boolean type ``boolean''.
+
+What this means is that instead of simply writing:
+
+  if (foo || bar)
+
+where foo can either be 1 or 0, and bar can either be NULL or a
+pointer to something, you must explicitly write:
+
+  if (foo != 0 || bar != null)
+
+in Java.
+
 JAVA NATIVE INTERFACE
 
 Java also provides an interface for C code to interface with Java.
diff --git a/java/org/gnu/emacs/EmacsContextMenu.java b/java/org/gnu/emacs/EmacsContextMenu.java
index 056d8fb692c..92429410d03 100644
--- a/java/org/gnu/emacs/EmacsContextMenu.java
+++ b/java/org/gnu/emacs/EmacsContextMenu.java
@@ -56,7 +56,7 @@ public class EmacsContextMenu
     public int itemID;
     public String itemName;
     public EmacsContextMenu subMenu;
-    public boolean isEnabled;
+    public boolean isEnabled, isCheckable, isChecked;
 
     @Override
     public boolean
@@ -108,10 +108,15 @@ public class EmacsContextMenu
 
   /* 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.  */
+     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)
+  addItem (int itemID, String itemName, boolean isEnabled,
+           boolean isCheckable, boolean isChecked)
   {
     Item item;
 
@@ -119,6 +124,8 @@ public class EmacsContextMenu
     item.itemID = itemID;
     item.itemName = itemName;
     item.isEnabled = isEnabled;
+    item.isCheckable = isCheckable;
+    item.isChecked = isChecked;
 
     menuItems.add (item);
   }
@@ -198,6 +205,15 @@ public class EmacsContextMenu
             /* 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);
           }
       }
   }
diff --git a/java/org/gnu/emacs/EmacsCopyArea.java b/java/org/gnu/emacs/EmacsCopyArea.java
index 7a97d706794..f8974e17c2e 100644
--- a/java/org/gnu/emacs/EmacsCopyArea.java
+++ b/java/org/gnu/emacs/EmacsCopyArea.java
@@ -99,6 +99,12 @@ public class EmacsCopyArea
     if (src_y + height > srcBitmap.getHeight ())
       height = srcBitmap.getHeight () - src_y;
 
+    /* If width and height are empty or negative, then skip the entire
+       CopyArea operation lest createBitmap throw an exception.  */
+
+    if (width <= 0 || height <= 0)
+      return;
+
     rect = new Rect (dest_x, dest_y, dest_x + width,
                      dest_y + height);