Proposal #2 to restore how UI/dialogs used to render by prioritizing fallback fonts.

With the emojis support, a new font was added, which not only provides emojis
but also fancy colorful replacements for UTF-8 characters that used to be
supported by our fallback (monochrome) fonts: this causes discrepancies and
unwanted/undesired changes in scripted objects menus (e.g. an empty circle or
square may render as a black, full one, a heart may render red instead of white),
not to mention the larger font size used by the emoji characters...

This patch restores the aspect of such menus/dialogs/UI elements with UTF-8
characters that *are* supported by the usual fallback fonts (fonts which may
also vary from one viewer to another, and from one OS to another), so that
everything keeps working/rendering as it always did so far, while not impairing
the use of new colorful emojis.

This second proposal ensures that:
- "genuine" emojis (in the 0x1f000-0x1ffff range), will *always* be rendered
  using the new emojis font (this solves, for example, the monochrome "yellow
  faces" issue seen with some characters in my first proposal).
- Special UTF-8 characters (in the 0x2000-0x32FF range) which have been used by
  scripters so far, will render as they used to, using the monochrome fallback
  fonts (this repairs scripted dialogs menus).
- Remaining special characters, that do not have a corresponding glyph in the
  monochrome font, but do have one in the emojis font, will use the latter font
  to render.

It also got the nice side-effect of removing the dependency on the ICU4C library.

Note however that the recent commit:
https://github.com/secondlife/viewer/commit/326055ba82c22fedde186c6a56bafd4fe87e613a
will need to be reverted to allow this patch to actually fix scripted dialogs.

Also, some cleanup might be needed in skins/default/xui/*/emoji_characters.xml to
remove from it the special UTF-8 characters that will no longer be rendered with
fanciful colors, but instead with the monochrome font glyphs.

1 files changed, 2 insertions, 1 deletions

diff --git a/indra/llcommon/llstring.h b/indra/llcommon/llstring.h
index a40359115e..a8d910298c 100644
--- a/indra/llcommon/llstring.h
+++ b/indra/llcommon/llstring.h
@@ -189,7 +189,8 @@ public:
 	static bool isAlnum(char a) { return isalnum((unsigned char)a) != 0; }
 	static bool isAlnum(llwchar a) { return iswalnum(a) != 0; }
 
-	static bool isEmoji(llwchar wch);
+    // Returns true when 'a' corresponds to a "genuine" emoji. HB
+	static bool isEmoji(llwchar a);
 
 	static S32	collate(const char* a, const char* b) { return strcoll(a, b); }
 	static S32	collate(const llwchar* a, const llwchar* b);