Android compatibility fixes

* doc/emacs/android.texi (Android Windowing): Document
restrictions on number of windows under Android 4.4 and earlier.

* java/AndroidManifest.xml.in <EmacsActivity>
<EmacsOpenActivity, EmacsMultitaskActivity>: Assign each class
of activity a unique task affinity.

* java/org/gnu/emacs/EmacsDesktopNotification.java (display1):
Remove redundant priority assignment.

* java/org/gnu/emacs/EmacsOpenActivity.java (onCreate): Handle
file URIs when processing attachments from a mailto URI, and
check for KitKat before opening content ones.

* java/org/gnu/emacs/EmacsWindow.java <pointerMap>
(figureChange): Replace coordinate HashMap with a SparseArray.

* java/org/gnu/emacs/EmacsWindowAttachmentManager.java
(registerWindow): Don't specify FLAG_ACTIVITY_NEW_DOCUMENT on
systems where it is absent.

doc/emacs/android.texi

@@ -864,6 +864,12 @@ behalf of a specific frame, Emacs deletes the frame displayed within
 that window.
 @end itemize
 
+  When the system predates Android 5.0, the window manager will not
+accept more than one user-created Emacs window.  If frame creation gives
+rise to windows in excess of this limit, the window manager will
+arbitrarily select one of their number to display, with the rest
+remaining invisible until that window is destroyed with its frame.
+
 @cindex windowing limitations, android
 @cindex frame parameters, android
 Emacs only supports a limited subset of GUI features on Android; the

java/AndroidManifest.xml.in

@@ -218,6 +218,7 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>. -->
 
     <activity android:name="org.gnu.emacs.EmacsActivity"
 	      android:launchMode="singleInstance"
+	      android:taskAffinity="emacs.primary_frame"
 	      android:windowSoftInputMode="adjustResize"
 	      android:exported="true"
 	      android:configChanges="orientation|screenSize|screenLayout|keyboardHidden|locale|fontScale">
@@ -229,7 +230,7 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>. -->
     </activity>
 
     <activity android:name="org.gnu.emacs.EmacsOpenActivity"
-	      android:taskAffinity="open.dialog"
+	      android:taskAffinity="emacs.open_dialog"
 	      android:excludeFromRecents="true"
 	      android:exported="true">
 
@@ -273,6 +274,7 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>. -->
     </activity>
 
     <activity android:name="org.gnu.emacs.EmacsMultitaskActivity"
+	      android:taskAffinity="emacs.secondary_frame"
 	      android:windowSoftInputMode="adjustResize"
 	      android:exported="true"
 	      android:configChanges="orientation|screenSize|screenLayout|keyboardHidden|locale|fontScale"/>

java/org/gnu/emacs/EmacsDesktopNotification.java

@@ -208,22 +208,6 @@ else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB)
 	   distinct categories, but permit an importance to be
 	   assigned to each individual notification.  */
 
-	switch (importance)
-	  {
-	  case 2: /* IMPORTANCE_LOW */
-	  default:
-	    priority = Notification.PRIORITY_LOW;
-	    break;
-
-	  case 3: /* IMPORTANCE_DEFAULT */
-	    priority = Notification.PRIORITY_DEFAULT;
-	    break;
-
-	  case 4: /* IMPORTANCE_HIGH */
-	    priority = Notification.PRIORITY_HIGH;
-	    break;
-	  }
-
 	builder = new Notification.Builder (context);
 	builder.setContentTitle (title);
 	builder.setContentText (content);
@@ -231,15 +215,28 @@ else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB)
 
 	if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
 	  {
+	    switch (importance)
+	      {
+	      case 2: /* IMPORTANCE_LOW */
+	      default:
+		priority = Notification.PRIORITY_LOW;
+		break;
+
+	      case 3: /* IMPORTANCE_DEFAULT */
+		priority = Notification.PRIORITY_DEFAULT;
+		break;
+
+	      case 4: /* IMPORTANCE_HIGH */
+		priority = Notification.PRIORITY_HIGH;
+		break;
+	      }
+
 	    builder.setPriority (priority);
 	    insertActions (context, builder);
 	    notification = builder.build ();
 	  }
 	else
 	  notification = builder.getNotification ();
-
-	if (Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN)
-	  notification.priority = priority;
       }
     else
       {

java/org/gnu/emacs/EmacsOpenActivity.java

@@ -535,7 +535,9 @@ private class EmacsClientThread extends Thread
 		  uri = intent.getParcelableExtra (Intent.EXTRA_STREAM);
 
 		if ((scheme = uri.getScheme ()) != null
-		    && scheme.equals ("content"))
+		    && scheme.equals ("content")
+		    && (Build.VERSION.SDK_INT
+			>= Build.VERSION_CODES.KITKAT))
 		  {
 		    tem1 = EmacsService.buildContentName (uri, resolver);
 		    attachmentString = ("'(\"" + (tem1.replace ("\\", "\\\\")
@@ -543,6 +545,14 @@ private class EmacsClientThread extends Thread
 						  .replace ("$", "\\$"))
 					+ "\")");
 		  }
+		else if (scheme != null && scheme.equals ("file"))
+		  {
+		    tem1 = uri.getPath ();
+		    attachmentString = ("'(\"" + (tem1.replace ("\\", "\\\\")
+						  .replace ("\"", "\\\"")
+						  .replace ("$", "\\$"))
+					+ "\")");
+		  }
 	      }
 	    else
 	      {
@@ -567,7 +577,9 @@ private class EmacsClientThread extends Thread
 
 			if (uri != null
 			    && (scheme = uri.getScheme ()) != null
-			    && scheme.equals ("content"))
+			    && scheme.equals ("content")
+			    && (Build.VERSION.SDK_INT
+				>= Build.VERSION_CODES.KITKAT))
 			  {
 			    tem1
 			      = EmacsService.buildContentName (uri, resolver);
@@ -577,6 +589,16 @@ private class EmacsClientThread extends Thread
 					    .replace ("$", "\\$"));
 			    builder.append ("\"");
 			  }
+			else if (scheme != null
+				 && scheme.equals ("file"))
+			  {
+			    tem1 = uri.getPath ();
+			    builder.append ("\"");
+			    builder.append (tem1.replace ("\\", "\\\\")
+					    .replace ("\"", "\\\"")
+					    .replace ("$", "\\$"));
+			    builder.append ("\"");
+			  }
 		      }
 
 		    builder.append (")");
@@ -604,7 +626,13 @@ private class EmacsClientThread extends Thread
 	  {
 	    fileName = null;
 
-	    if (scheme.equals ("content"))
+	    if (scheme.equals ("content")
+		/* Retrieving the native file descriptor of a
+		   ParcelFileDescriptor requires Honeycomb, and
+		   proceeding without this capability is pointless on
+		   systems before KitKat, since Emacs doesn't support
+		   opening content files on those.  */
+		&& Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB)
 	      {
 		/* This is one of the annoying Android ``content''
 		   URIs.  Most of the time, there is actually an

java/org/gnu/emacs/EmacsWindow.java

@@ -23,7 +23,6 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.ListIterator;
-import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
@@ -50,6 +49,7 @@
 import android.view.ViewManager;
 import android.view.WindowManager;
 
+import android.util.SparseArray;
 import android.util.Log;
 
 import android.os.Build;
@@ -109,7 +109,7 @@ private static class Coordinate
 
   /* Map between pointer identifiers and last known position.  Used to
      compute which pointer changed upon a touch event.  */
-  private HashMap<Integer, Coordinate> pointerMap;
+  private SparseArray<Coordinate> pointerMap;
 
   /* The window consumer currently attached, if it exists.  */
   private EmacsWindowAttachmentManager.WindowConsumer attached;
@@ -166,7 +166,7 @@ private static class Coordinate
     super (handle);
 
     rect = new Rect (x, y, x + width, y + height);
-    pointerMap = new HashMap<Integer, Coordinate> ();
+    pointerMap = new SparseArray<Coordinate> ();
 
     /* Create the view from the context's UI thread.  The window is
        unmapped, so the view is GONE.  */
@@ -1001,7 +1001,8 @@ private static class Coordinate
       case MotionEvent.ACTION_CANCEL:
 	/* Primary pointer released with index 0.  */
 	pointerID = event.getPointerId (0);
-	coordinate = pointerMap.remove (pointerID);
+	coordinate = pointerMap.get (pointerID);
+	pointerMap.delete (pointerID);
 	break;
 
       case MotionEvent.ACTION_POINTER_DOWN:
@@ -1020,7 +1021,8 @@ private static class Coordinate
 	/* Pointer removed.  Remove it from the map.  */
 	pointerIndex = event.getActionIndex ();
 	pointerID = event.getPointerId (pointerIndex);
-	coordinate = pointerMap.remove (pointerID);
+	coordinate = pointerMap.get (pointerID);
+	pointerMap.delete (pointerID);
 	break;
 
       default:

java/org/gnu/emacs/EmacsWindowAttachmentManager.java

@@ -124,10 +124,15 @@ public interface WindowConsumer
 
     intent = new Intent (EmacsService.SERVICE,
 			 EmacsMultitaskActivity.class);
-    intent.addFlags (Intent.FLAG_ACTIVITY_NEW_DOCUMENT
-		     | Intent.FLAG_ACTIVITY_NEW_TASK
+
+    intent.addFlags (Intent.FLAG_ACTIVITY_NEW_TASK
 		     | Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
 
+    /* Intent.FLAG_ACTIVITY_NEW_DOCUMENT is lamentably unavailable on
+       older systems than Lolipop.  */
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
+      intent.addFlags (Intent.FLAG_ACTIVITY_NEW_DOCUMENT);
+
     if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N)
       EmacsService.SERVICE.startActivity (intent);
     else