Keyboard shortcuts to control background opacity

kitty/boss.py

@@ -19,11 +19,12 @@ from .constants import (
     appname, config_dir, editor, set_boss, supports_primary_selection
 )
 from .fast_data_types import (
-    ChildMonitor, change_background_opacity, create_os_window,
-    current_os_window, destroy_global_data, destroy_sprite_map,
-    get_clipboard_string, glfw_post_empty_event, layout_sprite_map,
-    mark_os_window_for_close, set_clipboard_string, set_dpi_from_os_window,
-    set_in_sequence_mode, show_window, toggle_fullscreen, viewport_for_window
+    ChildMonitor, background_opacity_of, change_background_opacity,
+    create_os_window, current_os_window, destroy_global_data,
+    destroy_sprite_map, get_clipboard_string, glfw_post_empty_event,
+    layout_sprite_map, mark_os_window_for_close, set_clipboard_string,
+    set_dpi_from_os_window, set_in_sequence_mode, show_window,
+    toggle_fullscreen, viewport_for_window
 )
 from .fonts.render import prerender, resize_fonts, set_font_family
 from .keys import get_shortcut, shortcut_matches
@@ -362,7 +363,23 @@ class Boss:
         self._change_font_size()
 
     def _set_os_window_background_opacity(self, os_window_id, opacity):
-        change_background_opacity(os_window_id, opacity)
+        change_background_opacity(os_window_id, max(0.1, min(opacity, 1.0)))
+
+    def set_background_opacity(self, opacity):
+        window = self.active_window
+        if window is None or not opacity:
+            return
+        os_window_id = window.os_window_id
+        if opacity[0] in '+-':
+            opacity = background_opacity_of(os_window_id)
+            if opacity is None:
+                return
+            opacity += float(opacity)
+        elif opacity == 'default':
+            opacity = self.opts.background_opacity
+        else:
+            opacity = float(opacity)
+        self._set_os_window_background_opacity(os_window_id, opacity)
 
     @property
     def active_tab_manager(self):

kitty/config.py

@@ -124,6 +124,8 @@ def parse_key_action(action):
             func = 'kitten'
     elif func == 'goto_tab':
         args = (max(0, int(rest)), )
+    elif func == 'set_background_opacity':
+        args = [rest]
     elif func == 'goto_layout' or func == 'kitty_shell':
         args = [rest]
     elif func == 'set_font_size':

kitty/kitty.conf

@@ -501,6 +501,10 @@ map kitty_mod+u        input_unicode_character
 map kitty_mod+f2       edit_config_file
 # Open the kitty shell in a new window/tab/overlay/os_window to control kitty using commands.
 map kitty_mod+escape   kitty_shell window
+map kitty_mod+a>shift+= set_background_opacity +0.1
+map kitty_mod+a>shift+- set_background_opacity -0.1
+map kitty_mod+a>shift+1 set_background_opacity 1
+map kitty_mod+a>shift+d set_background_opacity default
 
 # Sending arbitrary text on shortcut key presses
 # You can tell kitty to send arbitrary (UTF-8) encoded text to

kitty/state.c

@@ -517,6 +517,14 @@ PYWRAP1(change_background_opacity) {
     Py_RETURN_FALSE;
 }
 
+PYWRAP1(background_opacity_of) {
+    id_type os_window_id = PyLong_AsUnsignedLongLong(args);
+    WITH_OS_WINDOW(os_window_id)
+        return PyFloat_FromDouble((double)os_window->background_opacity);
+    END_WITH_OS_WINDOW
+    Py_RETURN_NONE;
+}
+
 static inline bool
 fix_window_idx(Tab *tab, id_type window_id, unsigned int *window_idx) {
     for (id_type fix = 0; fix < tab->num_windows; fix++) {
@@ -645,6 +653,7 @@ static PyMethodDef module_methods[] = {
     MW(set_titlebar_color, METH_VARARGS),
     MW(mark_tab_bar_dirty, METH_O),
     MW(change_background_opacity, METH_VARARGS),
+    MW(background_opacity_of, METH_O),
     MW(update_window_visibility, METH_VARARGS),
     MW(set_boss, METH_O),
     MW(set_display_state, METH_VARARGS),