WM: Remove ASCII members from wmEvent & GHOST_TEventKeyData

The `ascii` member was only kept for historic reason as some platforms
didn't support utf8 when it was first introduced.

Remove the `ascii` struct members since many checks used this as a
fall-back for utf8_buf not being set which isn't needed.
There are a few cases where it's convenient to access the ASCII value
of an event (or nil) so a function has been added to do that.

*Details*

- WM_event_utf8_to_ascii() has been added for the few cases an events
  ASCII value needs to be accessed, this just avoids having to do
  multi-byte character checks in-line.

- RNA Event.ascii remains, using utf8_buf[0] for single byte characters.

- GHOST_TEventKeyData.ascii has been removed.

- To avoid regressions non-ASCII Latin1 characters from GHOST are
  converted into multi-byte UTF8, when building X11 without
  XInput & X_HAVE_UTF8_STRING it seems like could still occur.

5 files changed, 36 insertions, 16 deletions

diff --git a/source/blender/windowmanager/WM_api.h b/source/blender/windowmanager/WM_api.h
index d852b85a3d0..f337dd9d89a 100644
--- a/source/blender/windowmanager/WM_api.h
+++ b/source/blender/windowmanager/WM_api.h
@@ -1530,6 +1530,7 @@ bool WM_event_is_modal_drag_exit(const struct wmEvent *event,
 bool WM_event_is_mouse_drag(const struct wmEvent *event);
 bool WM_event_is_mouse_drag_or_press(const wmEvent *event);
 int WM_event_drag_direction(const wmEvent *event);
+char WM_event_utf8_to_ascii(const struct wmEvent *event) ATTR_NONNULL(1) ATTR_WARN_UNUSED_RESULT;
 
 /**
  * Detect motion between selection (callers should only use this for selection picking),
diff --git a/source/blender/windowmanager/WM_types.h b/source/blender/windowmanager/WM_types.h
index 32bc2f96365..e7cbe936607 100644
--- a/source/blender/windowmanager/WM_types.h
+++ b/source/blender/windowmanager/WM_types.h
@@ -683,13 +683,11 @@ typedef struct wmEvent {
   /** Region relative mouse position (name convention before Blender 2.5). */
   int mval[2];
   /**
-   * From, ghost if utf8 is enabled for the platform,
-   * #BLI_str_utf8_size() must _always_ be valid, check
-   * when assigning s we don't need to check on every access after.
+   * A single UTF8 encoded character.
+   * #BLI_str_utf8_size() must _always_ return a valid value,
+   * check when assigning so we don't need to check on every access after.
    */
   char utf8_buf[6];
-  /** From ghost, fallback if utf8 isn't set. */
-  char ascii;
 
   /** Modifier states: #KM_SHIFT, #KM_CTRL, #KM_ALT & #KM_OSKEY. */
   uint8_t modifier;
diff --git a/source/blender/windowmanager/intern/wm_event_query.c b/source/blender/windowmanager/intern/wm_event_query.c
index 221073d288a..81044197ae7 100644
--- a/source/blender/windowmanager/intern/wm_event_query.c
+++ b/source/blender/windowmanager/intern/wm_event_query.c
@@ -112,7 +112,7 @@ void WM_event_print(const wmEvent *event)
         "wmEvent type:%d/%s, val:%d/%s, "
         "prev_type:%d/%s, prev_val:%d/%s, "
         "modifier=%s, keymodifier:%d, flag:%s, "
-        "mouse:(%d,%d), ascii:'%c', utf8:'%.*s', pointer:%p",
+        "mouse:(%d,%d), utf8:'%.*s', pointer:%p",
         event->type,
         type_id,
         event->val,
@@ -126,7 +126,6 @@ void WM_event_print(const wmEvent *event)
         flag_id,
         event->xy[0],
         event->xy[1],
-        event->ascii,
         BLI_str_utf8_size(event->utf8_buf),
         event->utf8_buf,
         (const void *)event);
@@ -401,6 +400,20 @@ void WM_event_drag_start_xy(const wmEvent *event, int r_xy[2])
 /** \} */
 
 /* -------------------------------------------------------------------- */
+/** \name Event Text Queries
+ * \{ */
+
+char WM_event_utf8_to_ascii(const struct wmEvent *event)
+{
+  if (BLI_str_utf8_size(event->utf8_buf) == 1) {
+    return event->utf8_buf[0];
+  }
+  return '\0';
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
 /** \name Event Preference Mapping
  * \{ */
 
diff --git a/source/blender/windowmanager/intern/wm_event_system.cc b/source/blender/windowmanager/intern/wm_event_system.cc
index 0395e8bda7a..a371fa7e185 100644
--- a/source/blender/windowmanager/intern/wm_event_system.cc
+++ b/source/blender/windowmanager/intern/wm_event_system.cc
@@ -2088,7 +2088,7 @@ static bool wm_eventmatch(const wmEvent *winevent, const wmKeyMapItem *kmi)
     if (winevent->val == KM_PRESS) { /* Prevent double clicks. */
       /* Not using #ISTEXTINPUT anymore because (at least on Windows) some key codes above 255
        * could have printable ascii keys, See T30479. */
-      if (ISKEYBOARD(winevent->type) && (winevent->ascii || winevent->utf8_buf[0])) {
+      if (ISKEYBOARD(winevent->type) && winevent->utf8_buf[0]) {
         return true;
       }
     }
@@ -5042,7 +5042,6 @@ static wmEvent *wm_event_add_mousemove_to_head(wmWindow *win)
     tevent = *event_last;
 
     tevent.flag = (eWM_EventFlag)0;
-    tevent.ascii = '\0';
     tevent.utf8_buf[0] = '\0';
 
     wm_event_custom_clear(&tevent);
@@ -5329,7 +5328,6 @@ void wm_event_add_ghostevent(wmWindowManager *wm, wmWindow *win, int type, void
         break;
       }
 
-      event.ascii = kd->ascii;
       /* Might be not nullptr terminated. */
       memcpy(event.utf8_buf, kd->utf8_buf, sizeof(event.utf8_buf));
       if (kd->is_repeat) {
@@ -5341,8 +5339,6 @@ void wm_event_add_ghostevent(wmWindowManager *wm, wmWindow *win, int type, void
 
       /* Exclude arrow keys, escape, etc from text input. */
       if (type == GHOST_kEventKeyUp) {
-        event.ascii = '\0';
-
         /* Ghost should do this already for key up. */
         if (event.utf8_buf[0]) {
           CLOG_ERROR(WM_LOG_EVENTS,
@@ -5351,15 +5347,28 @@ void wm_event_add_ghostevent(wmWindowManager *wm, wmWindow *win, int type, void
         event.utf8_buf[0] = '\0';
       }
       else {
-        if (event.ascii < 32 && event.ascii > 0) {
-          event.ascii = '\0';
-        }
         if (event.utf8_buf[0] < 32 && event.utf8_buf[0] > 0) {
           event.utf8_buf[0] = '\0';
         }
       }
 
       if (event.utf8_buf[0]) {
+        /* NOTE(@campbellbarton): Detect non-ASCII characters stored in `utf8_buf`,
+         * ideally this would never happen but it can't be ruled out for X11 which has
+         * special handling of Latin1 when building without UTF8 support.
+         * Avoid regressions by adding this conversions, it should eventually be removed. */
+        if ((event.utf8_buf[0] >= 0x80) && (event.utf8_buf[1] == '\0')) {
+          const uint c = (uint)event.utf8_buf[0];
+          int utf8_buf_len = BLI_str_utf8_from_unicode(c, event.utf8_buf, sizeof(event.utf8_buf));
+          CLOG_ERROR(WM_LOG_EVENTS,
+                     "ghost detected non-ASCII single byte character '%u', converting to utf8 "
+                     "('%.*s', length=%d)",
+                     c,
+                     utf8_buf_len,
+                     event.utf8_buf,
+                     utf8_buf_len);
+        }
+
         if (BLI_str_utf8_size(event.utf8_buf) == -1) {
           CLOG_ERROR(WM_LOG_EVENTS,
                      "ghost detected an invalid unicode character '%d'",
diff --git a/source/blender/windowmanager/intern/wm_window.c b/source/blender/windowmanager/intern/wm_window.c
index 36f91f8414a..70640eda605 100644
--- a/source/blender/windowmanager/intern/wm_window.c
+++ b/source/blender/windowmanager/intern/wm_window.c
@@ -1148,7 +1148,6 @@ static bool ghost_event_proc(GHOST_EventHandle evt, GHOST_TUserDataPtr C_void_pt
          */
         GHOST_TEventKeyData kdata = {
             .key = GHOST_kKeyUnknown,
-            .ascii = '\0',
             .utf8_buf = {'\0'},
             .is_repeat = false,
         };