[core] Use UTF-16 instead of UTF-32 for label features to avoid extra conversions and reduce in-memory size.

Continue to use uint32 as glyph ID to maintain Glyph PBF, even though we're only using 16 bits of that uint32.
Use std::codecvt instead of boost::unicode_iterator for UTF8->UTF16 conversions.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/mbgl/layout/symbol_layout.cpp b/src/mbgl/layout/symbol_layout.cpp
index d974e6a357..7f8e8d5f83 100644
--- a/src/mbgl/layout/symbol_layout.cpp
+++ b/src/mbgl/layout/symbol_layout.cpp
@@ -90,10 +90,10 @@ SymbolLayout::SymbolLayout(std::string bucketName_,
                 u8string = platform::lowercase(u8string);
             }
 
-            ft.text = util::utf8_to_utf32::convert(u8string);
+            ft.text = util::utf8_to_utf16::convert( u8string );
 
             // Loop through all characters of this text and collect unique codepoints.
-            for (char32_t chr : *ft.text) {
+            for (char16_t chr : *ft.text) {
                 ranges.insert(getGlyphRange(chr));
             }
         }
@@ -309,7 +309,7 @@ void SymbolLayout::addFeature(const GeometryCollection &lines,
     }
 }
 
-bool SymbolLayout::anchorIsTooClose(const std::u32string &text, const float repeatDistance, Anchor &anchor) {
+bool SymbolLayout::anchorIsTooClose(const std::u16string &text, const float repeatDistance, Anchor &anchor) {
     if (compareText.find(text) == compareText.end()) {
         compareText.emplace(text, Anchors());
     } else {