2 files changed, 9 insertions, 0 deletions
diff --git a/src/mbgl/util/i18n.cpp b/src/mbgl/util/i18n.cpp
index 3e3a68e248..1fc13bfb7d 100644
--- a/src/mbgl/util/i18n.cpp
+++ b/src/mbgl/util/i18n.cpp
@@ -392,6 +392,11 @@ bool allowsIdeographicBreaking(char16_t chr) {
     //        || isInCJKCompatibilityIdeographsSupplement(chr));
 }
 
+bool allowsFixedWidthGlyphGeneration(char16_t chr) {
+    // Mirrors conservative set of characters used in glyph_manager.js/_tinySDF
+    return isInCJKUnifiedIdeographs(chr) || isInHangulSyllables(chr);
+}
+
 bool allowsVerticalWritingMode(const std::u16string& string) {
     for (char32_t chr : string) {
         if (hasUprightVerticalOrientation(chr)) {
diff --git a/src/mbgl/util/i18n.hpp b/src/mbgl/util/i18n.hpp
index 61c5a1ea96..b3960c743c 100644
--- a/src/mbgl/util/i18n.hpp
+++ b/src/mbgl/util/i18n.hpp
@@ -23,6 +23,10 @@ bool allowsIdeographicBreaking(const std::u16string& string);
     by the given Unicode codepoint due to ideographic breaking. */
 bool allowsIdeographicBreaking(char16_t chr);
 
+/** Conservative set of characters expected to have relatively fixed sizes and
+    advances */
+bool allowsFixedWidthGlyphGeneration(char16_t chr);
+
 /** Returns whether any substring of the given string can be drawn as vertical
     text with upright glyphs. */
 bool allowsVerticalWritingMode(const std::u16string& string);