tdf#125497 allow backspace to remove CJK IVS.

Japanese users prefer to remove a CJK IVS character
when pressing the backspace instead of removing
the selector part of IVS.

Change-Id: I4313d69ed52d82c5a7e4e4823b1da06f1d90bdad
Reviewed-on: https://gerrit.libreoffice.org/72971
Tested-by: Jenkins
Reviewed-by: Mark Hung <marklh9@gmail.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/include/rtl/character.hxx b/include/rtl/character.hxx
index a18d05d6a5e8..2a8933668964 100644
--- a/include/rtl/character.hxx
+++ b/include/rtl/character.hxx
@@ -57,6 +57,35 @@ inline bool isAscii(sal_uInt32 code)
     return code <= 0x7F;
 }
 
+/** Check for Unicode variation sequence selectors
+
+    @param code  A Unicode code point.
+
+    @return  True if code is an Unicode variation sequence selector.
+
+    @since LibreOffice 6.3
+ */
+inline bool isIVSSelector(sal_uInt32 nCode)
+{
+    return (nCode >= 0xFE00 && nCode <= 0xFE0F)   // Variation Selectors block
+        || (nCode >= 0xE0100 && nCode <= 0xE01EF);// Variation Selectors Supplement block
+}
+
+/** Check for base characters of a CJK ideographic variation sequence (IVS)
+
+    @param code  A Unicode code point.
+
+    @return  True if code is an Unicode base character part of CJK IVS
+
+    @since LibreOffice 6.3
+ */
+inline bool isCJKIVSCharacter(sal_uInt32 nCode)
+{
+    return (nCode >= 0x4E00 && nCode <= 0x9FFF)       // CJK Unified Ideographs
+        || (nCode >= 0x3400 && nCode <= 0x4DBF)       // CJK Unified Ideographs Extension A
+        || (nCode >= 0x20000 && nCode <= 0x2A6DF);    // CJK Unified Ideographs Extension B
+}
+
 #if defined LIBO_INTERNAL_ONLY
 bool isAscii(char) = delete;
 bool isAscii(signed char) = delete;