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.

3 files changed, 13 insertions, 17 deletions

diff --git a/intern/ghost/GHOST_Types.h b/intern/ghost/GHOST_Types.h
index 2fc84349eb9..fa74bfde866 100644
--- a/intern/ghost/GHOST_Types.h
+++ b/intern/ghost/GHOST_Types.h
@@ -547,17 +547,6 @@ typedef struct {
   /** The key code. */
   GHOST_TKey key;
 
-  /* ascii / utf8: both should always be set when possible,
-   * - ascii may be '\0' however if the user presses a non ascii key
-   * - unicode may not be set if the system has no unicode support
-   *
-   * These values are intended to be used as follows.
-   * For text input use unicode when available, fallback to ascii.
-   * For areas where unicode is not needed, number input for example, always
-   * use ascii, unicode is ignored - campbell.
-   */
-  /** The ascii code for the key event ('\0' if none). */
-  char ascii;
   /** The unicode character. if the length is 6, not NULL terminated if all 6 are set. */
   char utf8_buf[6];
 
diff --git a/intern/ghost/intern/GHOST_EventKey.h b/intern/ghost/intern/GHOST_EventKey.h
index 1c3156c27d2..d3cfbbeddd7 100644
--- a/intern/ghost/intern/GHOST_EventKey.h
+++ b/intern/ghost/intern/GHOST_EventKey.h
@@ -28,7 +28,6 @@ class GHOST_EventKey : public GHOST_Event {
       : GHOST_Event(msec, type, window)
   {
     m_keyEventData.key = key;
-    m_keyEventData.ascii = '\0';
     m_keyEventData.utf8_buf[0] = '\0';
     m_keyEventData.is_repeat = is_repeat;
     m_data = &m_keyEventData;
@@ -51,11 +50,17 @@ class GHOST_EventKey : public GHOST_Event {
       : GHOST_Event(msec, type, window)
   {
     m_keyEventData.key = key;
-    m_keyEventData.ascii = ascii;
-    if (utf8_buf)
+    if (utf8_buf) {
       memcpy(m_keyEventData.utf8_buf, utf8_buf, sizeof(m_keyEventData.utf8_buf));
-    else
+    }
+    else {
       m_keyEventData.utf8_buf[0] = '\0';
+    }
+    /* TODO(@campbellbarton): phase out `ascii` and always use `utf8_buf`, this needs to be done
+     * on all platforms though, so for now write the ascii into the utf8_buf. */
+    if (m_keyEventData.utf8_buf[0] == '\0' && ascii) {
+      m_keyEventData.utf8_buf[0] = ascii;
+    }
     m_keyEventData.is_repeat = is_repeat;
     m_data = &m_keyEventData;
   }
diff --git a/intern/ghost/test/multitest/EventToBuf.c b/intern/ghost/test/multitest/EventToBuf.c
index baab32328c3..846a867a371 100644
--- a/intern/ghost/test/multitest/EventToBuf.c
+++ b/intern/ghost/test/multitest/EventToBuf.c
@@ -218,8 +218,10 @@ void event_to_buf(GHOST_EventHandle evt, char buf[128])
     case GHOST_kEventKeyUp: {
       GHOST_TEventKeyData *kd = data;
       pos += sprintf(pos, " - key: %s (%d)", keytype_to_string(kd->key), kd->key);
-      if (kd->ascii)
-        pos += sprintf(pos, " ascii: '%c' (%d)", kd->ascii, kd->ascii);
+      /* TODO: ideally this would print the unicode character. */
+      if (kd->utf8_buf[0]) {
+        pos += sprintf(pos, " ascii: '%c' (%d)", kd->utf8_buf[0], kd->utf8_buf[0]);
+      }
       break;
     }
   }