Support `toolkit-theme-set-functions' on Android and execute hooks safely

* java/org/gnu/emacs/EmacsNative.java (setEmacsParams): New arg
UIMODE.
(sendConfigurationChanged): New args DETAIL and UI_MODE.

* java/org/gnu/emacs/EmacsNoninteractive.java (main1): Provide
an undefined UI mode.

* java/org/gnu/emacs/EmacsService.java (EmacsService): New field
uiMode.
(onCreate): Initialize this field at start-up and provide the
same to setEmacsParams.
(onConfigurationChanged): If the UI mode has been altered,
generate a configuration changed event to match.

* src/android.c (android_ui_mode): New variable.
(setEmacsParams): New argument UI_MODE.  Initialize the same
from this variable.

* src/androidgui.h (enum android_configuration_changed): New
enum.
(struct android_configuration_changed_event): New field
`DETAIL'.  Convert fields providing specifics into a union of
display density information and a UI mode integer.

* src/androidterm.c (handle_one_android_event): Handle both
manners of configuration change events.
(android_term_init): Initialize Vtoolkit_theme from UI mode
provided at start-up.

* src/frame.c (syms_of_frame): Always define Vtoolkit_theme.
Define Qtoolkit_theme_set_functions.

* src/gtkutil.c (xg_update_dark_mode_for_all_displays):

* src/w32term.c (w32_read_socket): Generate special toolkit
theme events, rather than executing hooks directly within the
read_socket callback.

* src/keyboard.c (kbd_buffer_get_event)
<TOOLKIT_THEME_CHANGED_EVENT>: Run Qtoolkit_theme_set_functions
and set Vtoolkit_theme from event->ie.arg.

* src/termhooks.h (enum event_kind): New event
TOOLKIT_THEME_CHANGED_EVENT.

3 files changed, 25 insertions, 6 deletions

diff --git a/java/org/gnu/emacs/EmacsNative.java b/java/org/gnu/emacs/EmacsNative.java
index 49a21ce1c4d..fac4b6f01df 100644
--- a/java/org/gnu/emacs/EmacsNative.java
+++ b/java/org/gnu/emacs/EmacsNative.java
@@ -61,6 +61,9 @@ public final class EmacsNative
      scaledDensity is the DPI value used to translate point sizes to
      pixel sizes when loading fonts.
 
+     uiMode holds the bits of the system's UI mode specification
+     defining the active system theme.
+
      classPath must be the classpath of this app_process process, or
      NULL.
 
@@ -74,6 +77,7 @@ public final class EmacsNative
                                             float pixelDensityX,
                                             float pixelDensityY,
                                             float scaledDensity,
+                                            int uiMode,
                                             String classPath,
                                             EmacsService emacsService,
                                             int apiLevel);
@@ -197,8 +201,9 @@ public final class EmacsNative
   public static native void sendNotificationAction (String tag, String action);
 
   /* Send an ANDROID_CONFIGURATION_CHANGED event.  */
-  public static native void sendConfigurationChanged (float dpiX, float dpiY,
-                                                      float dpiScaled);
+  public static native void sendConfigurationChanged (int detail, float dpiX,
+                                                      float dpiY, float dpiScaled,
+                                                      int ui_mode);
 
   /* Return the file name associated with the specified file
      descriptor, or NULL if there is none.  */
diff --git a/java/org/gnu/emacs/EmacsNoninteractive.java b/java/org/gnu/emacs/EmacsNoninteractive.java
index 83ef04b1cf1..b4d055ce4c9 100644
--- a/java/org/gnu/emacs/EmacsNoninteractive.java
+++ b/java/org/gnu/emacs/EmacsNoninteractive.java
@@ -67,7 +67,7 @@ public final class EmacsNoninteractive
     cacheDir = context.getCacheDir ().getCanonicalPath ();
     EmacsNative.setEmacsParams (assets, filesDir,
                                 libDir, cacheDir, 0.0f,
-                                0.0f, 0.0f, null, null,
+                                0.0f, 0.0f, 0x0, null, null,
                                 Build.VERSION.SDK_INT);
 
     /* Now find the dump file that Emacs should use, if it has already
diff --git a/java/org/gnu/emacs/EmacsService.java b/java/org/gnu/emacs/EmacsService.java
index 3630329839f..d141f6f4d0d 100644
--- a/java/org/gnu/emacs/EmacsService.java
+++ b/java/org/gnu/emacs/EmacsService.java
@@ -150,6 +150,10 @@ public final class EmacsService extends Service
      consulted for font scaling.  */
   private double dpiX, dpiY, dpiScaled;
 
+  /* The display's previously observed UI mode as it relates to the
+     system theme.  */
+  private int uiMode;
+
   static
   {
     servicingQuery = new AtomicInteger ();
@@ -240,6 +244,7 @@ public final class EmacsService extends Service
     float tempScaledDensity;
     Resources resources;
     DisplayMetrics metrics;
+    Configuration configuration;
 
     super.onCreate ();
 
@@ -254,6 +259,8 @@ public final class EmacsService extends Service
     tempScaledDensity = ((getScaledDensity (metrics)
                           / metrics.density)
                          * pixelDensityX);
+    configuration = resources.getConfiguration ();
+    uiMode = configuration.uiMode & Configuration.UI_MODE_NIGHT_MASK;
     resolver = getContentResolver ();
     mainThread = Thread.currentThread ();
 
@@ -311,7 +318,8 @@ public final class EmacsService extends Service
               EmacsNative.setEmacsParams (manager, filesDir, libDir,
                                           cacheDir, pixelDensityX,
                                           pixelDensityY, scaledDensity,
-                                          classPath, EmacsService.this,
+                                          uiMode, classPath,
+                                          EmacsService.this,
                                           Build.VERSION.SDK_INT);
             }
           }, extraStartupArguments);
@@ -375,8 +383,14 @@ public final class EmacsService extends Service
         dpiX = pixelDensityX;
         dpiY = pixelDensityY;
         dpiScaled = scaledDensity;
-        EmacsNative.sendConfigurationChanged (pixelDensityX, pixelDensityY,
-                                              scaledDensity);
+        EmacsNative.sendConfigurationChanged (0, pixelDensityX, pixelDensityY,
+                                              scaledDensity, 0);
+      }
+
+    if ((newConfig.uiMode & Configuration.UI_MODE_NIGHT_MASK) != uiMode)
+      {
+        uiMode = newConfig.uiMode & Configuration.UI_MODE_NIGHT_MASK;
+        EmacsNative.sendConfigurationChanged (1, 0.0f, 0.0f, 0.0f, uiMode);
       }
 
     super.onConfigurationChanged (newConfig);