From 9d5ab91b6af513efaeb08e9bf747897641f2a809 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Tue, 7 Dec 2021 19:55:52 +0100
Subject: [PATCH] =?UTF-8?q?kitty:=20initial=20support=20for=20=E2=80=9Crep?=
 =?UTF-8?q?ort=20alternate=20key=E2=80=9D?=
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In this mode, the “shifted” and “base layout” keys are added to the
CSIs, as sub-parameters to the “key” parameter.

Note that this PR only implements the “shifted” key, not the “base
layout key”.

This is done by converting the original XKB symbol to it’s
corresponding UTF-32 codepoint. If this codepoint is different from
the one we use as “key” in the CSI, we add it as a sub-parameter.

Related to #319
---
 CHANGELOG.md |  3 +++
 input.c      | 10 +++++++++-
 terminal.h   |  1 +
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 828f51aa..6a16da7d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -44,6 +44,9 @@
 * Kitty keyboard protocol:
   - [Report event types](https://sw.kovidgoyal.net/kitty/keyboard-protocol/#report-events)
     (mode `0b10`)
+  - [Report alternate keys](https://sw.kovidgoyal.net/kitty/keyboard-protocol/#report-alternates)
+    (mode `0b100`, but not that only the _shifted_ key is reported,
+    not the _base layout key_)
   - [Report all keys as escape codes](https://sw.kovidgoyal.net/kitty/keyboard-protocol/#report-all-keys)
     (mode `0b1000`)
   - [Report associated text](https://sw.kovidgoyal.net/kitty/keyboard-protocol/#report-text)
diff --git a/input.c b/input.c
index 869e1c67..dbbcc82b 100644
--- a/input.c
+++ b/input.c
@@ -1161,6 +1161,7 @@ kitty_kbd_protocol(struct seat *seat, struct terminal *term,
 
     const bool disambiguate = flags & KITTY_KBD_DISAMBIGUATE;
     const bool report_events = flags & KITTY_KBD_REPORT_EVENT;
+    const bool report_alternate = flags & KITTY_KBD_REPORT_ALTERNATE;
     const bool report_all_as_escapes = flags & KITTY_KBD_REPORT_ALL;
 
     if (!report_events && released)
@@ -1252,7 +1253,7 @@ emit_escapes:
         encoded_mods |= mods & (1 << seat->kbd.mod_num)   ? (1 << 7) : 0;
     encoded_mods++;
 
-    int key = -1;
+    int key = -1, alternate = -1;
     char final;
 
     switch (sym) {
@@ -1435,6 +1436,8 @@ emit_escapes:
             key = xkb_keysym_to_utf32(sym_to_use);
             if (key == 0)
                 key = sym_to_use;
+            else
+                alternate = xkb_keysym_to_utf32(sym);
         }
 
         final = 'u';
@@ -1465,6 +1468,11 @@ emit_escapes:
         bytes = snprintf(p, left, "\x1b[%u", key);
         p += bytes; left -= bytes;
 
+        if (report_alternate && alternate > 0 && alternate != key) {
+            bytes = snprintf(p, left, ":%u", alternate);
+            p += bytes; left -= bytes;
+        }
+
         if (encoded_mods > 1 || event[0] != '\0' || report_associated_text) {
             bytes = snprintf(p, left, ";%u%s", encoded_mods, event);
             p += bytes; left -= bytes;
diff --git a/terminal.h b/terminal.h
index 394871f6..09b04614 100644
--- a/terminal.h
+++ b/terminal.h
@@ -135,6 +135,7 @@ enum kitty_kbd_flags {
     KITTY_KBD_REPORT_ASSOCIATED = 0x10,
     KITTY_KBD_SUPPORTED = (KITTY_KBD_DISAMBIGUATE |
                            KITTY_KBD_REPORT_EVENT |
+                           KITTY_KBD_REPORT_ALTERNATE |
                            KITTY_KBD_REPORT_ALL |
                            KITTY_KBD_REPORT_ASSOCIATED),
 };