Support notifying applications on color scheme change

docs/changelog.rst

@@ -93,6 +93,8 @@ Detailed list of changes
 
 - Graphics: Fix deleted but not freed images without any references being incorrectly freed on a subsequent delete command (:disc:`8129`)
 
+- Add support for `escape code protocol <https://github.com/contour-terminal/contour/blob/master/docs/vt-extensions/color-palette-update-notifications.md>`__ for notifying applications on dark/light color scheme change
+
 0.38.0 [2024-12-15]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

kitty/boss.py

@@ -1550,6 +1550,7 @@ class Boss:
     def default_bg_changed_for(self, window_id: int) -> None:
         w = self.window_id_map.get(window_id)
         if w is not None:
+            w.on_color_scheme_preference_change()
             tm = self.os_window_map.get(w.os_window_id)
             if tm is not None:
                 tm.update_tab_bar_data()

kitty/colors.c

@@ -673,7 +673,13 @@ rgb_get(Color *self, void *closure UNUSED) {
 
 static PyObject*
 luminance_get(Color *self, void *closure UNUSED) {
-    return PyFloat_FromDouble(rgb_luminance(self->color));
+    return PyFloat_FromDouble(rgb_luminance(self->color) / 255.0);
+}
+
+static PyObject*
+is_dark_get(Color *self, void *closure UNUSED) {
+    if (rgb_luminance(self->color) / 255.0 < 0.5) Py_RETURN_TRUE;
+    Py_RETURN_FALSE;
 }
 
 static PyObject*
@@ -721,6 +727,7 @@ static PyGetSetDef color_getsetters[] = {
     {"luminance", (getter) luminance_get, NULL, "luminance", NULL},
     {"as_sgr", (getter) sgr_get, NULL, "as_sgr", NULL},
     {"as_sharp", (getter) sharp_get, NULL, "as_sharp", NULL},
+    {"is_dark", (getter) is_dark_get, NULL, "is_dark", NULL},
     {NULL}  /* Sentinel */
 };
 

kitty/fast_data_types.pyi

@@ -746,6 +746,10 @@ class Color:
     def luminance(self) -> float:
         pass
 
+    @property
+    def is_dark(self) -> bool:
+        pass
+
     @property
     def as_sgr(self) -> str:
         pass
@@ -1191,6 +1195,7 @@ class Screen:
     linebuf: LineBuf
     in_bracketed_paste_mode: bool
     in_band_resize_notification: bool
+    color_preference_notification: bool
     cursor_visible: bool
     scrolled_by: int
     cursor: Cursor

kitty/modes.h

@@ -85,6 +85,9 @@
 // Pending updates mode
 #define PENDING_UPDATE (2026 << 5)
 
+// Notification of color preference change
+#define COLOR_PREFERENCE_NOTIFICATION (2031 << 5)
+
 // In-band resize notification mode
 #define INBAND_RESIZE_NOTIFICATION (2048 << 5)
 

kitty/screen.c

@@ -1116,6 +1116,7 @@ set_mode_from_const(Screen *self, unsigned int mode, bool val) {
         SIMPLE_MODE(DECARM)
         SIMPLE_MODE(BRACKETED_PASTE)
         SIMPLE_MODE(FOCUS_TRACKING)
+        SIMPLE_MODE(COLOR_PREFERENCE_NOTIFICATION)
         SIMPLE_MODE(HANDLE_TERMIOS_SIGNALS)
         MOUSE_MODE(MOUSE_BUTTON_TRACKING, mouse_tracking_mode, BUTTON_MODE)
         MOUSE_MODE(MOUSE_MOTION_TRACKING, mouse_tracking_mode, MOTION_MODE)
@@ -1691,6 +1692,7 @@ copy_specific_mode(Screen *self, unsigned int mode, const ScreenModes *src, Scre
         SIMPLE_MODE(DECARM)
         SIMPLE_MODE(BRACKETED_PASTE)
         SIMPLE_MODE(FOCUS_TRACKING)
+        SIMPLE_MODE(COLOR_PREFERENCE_NOTIFICATION)
         SIMPLE_MODE(INBAND_RESIZE_NOTIFICATION)
         SIMPLE_MODE(DECCKM)
         SIMPLE_MODE(DECTCEM)
@@ -1732,6 +1734,7 @@ copy_specific_modes(Screen *self, const ScreenModes *src, ScreenModes *dest) {
     copy_specific_mode(self, DECARM, src, dest);
     copy_specific_mode(self, BRACKETED_PASTE, src, dest);
     copy_specific_mode(self, FOCUS_TRACKING, src, dest);
+    copy_specific_mode(self, COLOR_PREFERENCE_NOTIFICATION, src, dest);
     copy_specific_mode(self, INBAND_RESIZE_NOTIFICATION, src, dest);
     copy_specific_mode(self, DECCKM, src, dest);
     copy_specific_mode(self, DECTCEM, src, dest);
@@ -2191,8 +2194,6 @@ screen_manipulate_title_stack(Screen *self, unsigned int op, unsigned int which)
 
 void
 report_device_status(Screen *self, unsigned int which, bool private) {
-    // We don't implement the private device status codes, since I haven't come
-    // across any programs that use them
     unsigned int x, y;
     static char buf[64];
     switch(which) {
@@ -2210,6 +2211,10 @@ report_device_status(Screen *self, unsigned int which, bool private) {
             int sz = snprintf(buf, sizeof(buf) - 1, "%s%u;%uR", (private ? "?": ""), y + 1, x + 1);
             if (sz > 0) write_escape_code_to_child(self, ESC_CSI, buf);
             break;
+        case 996: // https://github.com/contour-terminal/contour/blob/master/docs/vt-extensions/color-palette-update-notifications.md
+            if (private) {
+                CALLBACK("report_color_scheme_preference", NULL);
+            } break;
     }
 }
 
@@ -2233,6 +2238,7 @@ report_mode_status(Screen *self, unsigned int which, bool private) {
         KNOWN_MODE(DECCKM);
         KNOWN_MODE(BRACKETED_PASTE);
         KNOWN_MODE(FOCUS_TRACKING);
+        KNOWN_MODE(COLOR_PREFERENCE_NOTIFICATION);
         KNOWN_MODE(INBAND_RESIZE_NOTIFICATION);
 #undef KNOWN_MODE
         case ALTERNATE_SCREEN:
@@ -3872,6 +3878,7 @@ WRAP0(clear_scrollback)
 
 MODE_GETSET(in_bracketed_paste_mode, BRACKETED_PASTE)
 MODE_GETSET(focus_tracking_enabled, FOCUS_TRACKING)
+MODE_GETSET(color_preference_notification, COLOR_PREFERENCE_NOTIFICATION)
 MODE_GETSET(in_band_resize_notification, INBAND_RESIZE_NOTIFICATION)
 MODE_GETSET(auto_repeat_enabled, DECARM)
 MODE_GETSET(cursor_visible, DECTCEM)
@@ -4898,6 +4905,7 @@ static PyMethodDef methods[] = {
 
 static PyGetSetDef getsetters[] = {
     GETSET(in_bracketed_paste_mode)
+    GETSET(color_preference_notification)
     GETSET(auto_repeat_enabled)
     GETSET(focus_tracking_enabled)
     GETSET(in_band_resize_notification)

kitty/screen.h

@@ -15,7 +15,7 @@
 typedef enum ScrollTypes { SCROLL_LINE = -999999, SCROLL_PAGE, SCROLL_FULL } ScrollType;
 
 typedef struct {
-    bool mLNM, mIRM, mDECTCEM, mDECSCNM, mDECOM, mDECAWM, mDECCOLM, mDECARM, mDECCKM,
+    bool mLNM, mIRM, mDECTCEM, mDECSCNM, mDECOM, mDECAWM, mDECCOLM, mDECARM, mDECCKM, mCOLOR_PREFERENCE_NOTIFICATION,
          mBRACKETED_PASTE, mFOCUS_TRACKING, mDECSACE, mHANDLE_TERMIOS_SIGNALS, mINBAND_RESIZE_NOTIFICATION;
     MouseTrackingMode mouse_tracking_mode;
     MouseTrackingProtocol mouse_tracking_protocol;

kitty/window.py

@@ -1325,6 +1325,15 @@ class Window:
         if default_bg_changed:
             get_boss().default_bg_changed_for(self.id)
 
+    def on_color_scheme_preference_change(self) -> None:
+        if self.screen.color_preference_notification:
+            self.report_color_scheme_preference()
+
+    def report_color_scheme_preference(self) -> None:
+        cp = self.screen.color_profile
+        n = 1 if cp.default_bg.is_dark else 2
+        self.screen.send_escape_code_to_child(ESC_CSI, f'?997;{n}n')
+
     def set_color_table_color(self, code: int, bvalue: Optional[memoryview] = None) -> None:
         value = str(bvalue or b'', 'utf-8', 'replace')
         cp = self.screen.color_profile