macOS: Allow assigning only the left or right :kbd:Option key to work as the :kbd:Alt key. See :opt:macos_option_as_alt for details

Fixes #1022

docs/changelog.rst

@@ -30,6 +30,9 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
 - macOS: Workaround for cocoa bug that could cause the mouse cursor to become
   hidden in other applications in rare circumstances (:iss:`1218`)
 
+- macOS: Allow assigning only the left or right :kbd:`Option` key to work as the
+  :kbd:`Alt` key. See :opt:`macos_option_as_alt` for details (:iss:`1022`)
+
 - Fix using remote control to set cursor text color causing errors when
   creating new windows (:iss:`1326`)
 

glfw/cocoa_platform.h

@@ -35,7 +35,7 @@ typedef void* id;
 #endif
 
 typedef VkFlags VkMacOSSurfaceCreateFlagsMVK;
-typedef int (* GLFWcocoatextinputfilterfun)(int,int,int);
+typedef int (* GLFWcocoatextinputfilterfun)(int,int,unsigned int, unsigned long);
 typedef int (* GLFWapplicationshouldhandlereopenfun)(int);
 typedef int (* GLFWcocoatogglefullscreenfun)(GLFWwindow*);
 

glfw/cocoa_window.m

@@ -818,7 +818,7 @@ is_ascii_control_char(char x) {
     const NSUInteger flags = [event modifierFlags];
     const int mods = translateFlags(flags);
     const int key = translateKey(scancode, GLFW_TRUE);
-    const GLFWbool process_text = !window->ns.textInputFilterCallback || window->ns.textInputFilterCallback(key, mods, scancode) != 1;
+    const GLFWbool process_text = !window->ns.textInputFilterCallback || window->ns.textInputFilterCallback(key, mods, scancode, flags) != 1;
     _glfw.ns.text[0] = 0;
     if (!_glfw.ns.unicodeData) {
         // Using the cocoa API for key handling is disabled, as there is no

glfw/glfw.py

@@ -196,7 +196,7 @@ const char *action_text, int32_t timeout, GLFWDBusnotificationcreatedfun callbac
 
 {}
 
-typedef int (* GLFWcocoatextinputfilterfun)(int,int,unsigned int);
+typedef int (* GLFWcocoatextinputfilterfun)(int,int,unsigned int,unsigned long);
 typedef int (* GLFWapplicationshouldhandlereopenfun)(int);
 typedef int (* GLFWcocoatogglefullscreenfun)(GLFWwindow*);
 typedef void (*GLFWwaylandframecallbackfunc)(unsigned long long id);

kitty/cocoa_window.m

@@ -348,6 +348,15 @@ cocoa_make_window_resizable(void *w, bool resizable) {
     return true;
 }
 
+#define NSLeftAlternateKeyMask  (0x000020 | NSEventModifierFlagOption)
+#define NSRightAlternateKeyMask (0x000040 | NSEventModifierFlagOption)
+
+bool
+cocoa_alt_option_key_pressed(NSUInteger flags) {
+    NSUInteger q = (OPT(macos_option_as_alt) == 1) ? NSRightAlternateKeyMask : NSLeftAlternateKeyMask;
+    return ((q & flags) == q) ? true : false;
+}
+
 void
 cocoa_focus_window(void *w) {
     NSWindow *window = (NSWindow*)w;

kitty/config_data.py

@@ -9,7 +9,8 @@ from gettext import gettext as _
 from . import fast_data_types as defines
 from .conf.definition import option_func
 from .conf.utils import (
-    choices, positive_float, positive_int, to_cmdline, to_color, unit_float
+    choices, positive_float, positive_int, to_bool, to_cmdline, to_color,
+    unit_float
 )
 from .constants import config_dir, is_macos
 from .fast_data_types import CURSOR_BEAM, CURSOR_BLOCK, CURSOR_UNDERLINE
@@ -809,11 +810,27 @@ incompatible with :opt:`background_opacity`. If you want to use both, you are
 probably better off just hiding the titlebar with :opt:`hide_window_decorations`.
 '''))
 
-o('macos_option_as_alt', True, long_text=_('''
-Use the option key as an alt key. With this set to no, kitty will use
+
+def macos_option_as_alt(x):
+    x = x.lower()
+    if x == 'both':
+        return 0b11
+    if x == 'left':
+        return 0b10
+    if x == 'right':
+        return 0b01
+    if to_bool(x):
+        return 0b11
+    return 0
+
+
+o('macos_option_as_alt', 0b11, option_type=macos_option_as_alt, long_text=_('''
+Use the option key as an alt key. With this set to :code:`no`, kitty will use
 the macOS native :kbd:`Option+Key` = unicode character behavior. This will
 break any :kbd:`Alt+key` keyboard shortcuts in your terminal programs, but you
-can use the macOS unicode input technique.
+can use the macOS unicode input technique. You can use the values:
+:code:`left`, :code:`right`, or :code:`both` to use only the left, right or
+both Option keys as Alt.
 '''))
 
 o('macos_hide_from_tasks', False, long_text=_('''

kitty/glfw-wrapper.h

@@ -923,9 +923,9 @@ typedef void (* GLFWerrorfun)(int,const char*);
  *
  *  @param[in] window The window that was moved.
  *  @param[in] xpos The new x-coordinate, in screen coordinates, of the
- *  upper-left corner of the client area of the window.
+ *  upper-left corner of the content area of the window.
  *  @param[in] ypos The new y-coordinate, in screen coordinates, of the
- *  upper-left corner of the client area of the window.
+ *  upper-left corner of the content area of the window.
  *
  *  @sa @ref window_pos
  *  @sa @ref glfwSetWindowPosCallback
@@ -1102,9 +1102,9 @@ typedef void (* GLFWmousebuttonfun)(GLFWwindow*,int,int,int);
  *
  *  @param[in] window The window that received the event.
  *  @param[in] xpos The new cursor x-coordinate, relative to the left edge of
- *  the client area.
+ *  the content area.
  *  @param[in] ypos The new cursor y-coordinate, relative to the top edge of the
- *  client area.
+ *  content area.
  *
  *  @sa @ref cursor_pos
  *  @sa @ref glfwSetCursorPosCallback
@@ -1391,7 +1391,7 @@ typedef struct GLFWgamepadstate
  */
 
 
-typedef int (* GLFWcocoatextinputfilterfun)(int,int,unsigned int);
+typedef int (* GLFWcocoatextinputfilterfun)(int,int,unsigned int,unsigned long);
 typedef int (* GLFWapplicationshouldhandlereopenfun)(int);
 typedef int (* GLFWcocoatogglefullscreenfun)(GLFWwindow*);
 typedef void (*GLFWwaylandframecallbackfunc)(unsigned long long id);

kitty/glfw.c

@@ -14,6 +14,7 @@ extern bool cocoa_toggle_fullscreen(void *w, bool);
 extern void cocoa_create_global_menu(void);
 extern void cocoa_set_hide_from_tasks(void);
 extern void cocoa_set_titlebar_color(void *w, color_type color);
+extern bool cocoa_alt_option_key_pressed(unsigned long);
 
 
 #if GLFW_KEY_LAST >= MAX_KEY_COUNT
@@ -421,8 +422,12 @@ toggle_fullscreen_for_os_window(OSWindow *w) {
 
 #ifdef __APPLE__
 static int
-filter_option(int key UNUSED, int mods, unsigned int scancode UNUSED) {
-    return ((mods == GLFW_MOD_ALT) || (mods == (GLFW_MOD_ALT | GLFW_MOD_SHIFT))) ? 1 : 0;
+filter_option(int key UNUSED, int mods, unsigned int scancode UNUSED, unsigned long flags) {
+    if ((mods == GLFW_MOD_ALT) || (mods == (GLFW_MOD_ALT | GLFW_MOD_SHIFT))) {
+        if (OPT(macos_option_as_alt) == 3) return 1;
+        if (cocoa_alt_option_key_pressed(flags)) return 1;
+    }
+    return 0;
 }
 
 static GLFWwindow *application_quit_canary = NULL;

kitty/state.c

@@ -388,7 +388,7 @@ PYWRAP1(set_options) {
     S(sync_to_monitor, PyObject_IsTrue);
     S(close_on_child_death, PyObject_IsTrue);
     S(window_alert_on_bell, PyObject_IsTrue);
-    S(macos_option_as_alt, PyObject_IsTrue);
+    S(macos_option_as_alt, PyLong_AsUnsignedLong);
     S(macos_traditional_fullscreen, PyObject_IsTrue);
     S(macos_quit_when_last_window_closed, PyObject_IsTrue);
     S(macos_show_window_title_in_menubar, PyObject_IsTrue);

kitty/state.h

@@ -24,7 +24,8 @@ typedef struct {
     color_type url_color, background, active_border_color, inactive_border_color, bell_border_color;
     double repaint_delay, input_delay;
     bool focus_follows_mouse, hide_window_decorations;
-    bool macos_option_as_alt, macos_hide_from_tasks, macos_quit_when_last_window_closed, macos_window_resizable, macos_traditional_fullscreen, macos_show_window_title_in_menubar;
+    bool macos_hide_from_tasks, macos_quit_when_last_window_closed, macos_window_resizable, macos_traditional_fullscreen, macos_show_window_title_in_menubar;
+    unsigned int macos_option_as_alt;
     float macos_thicken_font;
     int adjust_line_height_px, adjust_column_width_px;
     float adjust_line_height_frac, adjust_column_width_frac;