[core] Shape images in labels at bucket zoom level

src/mbgl/layout/symbol_layout.cpp

@@ -355,6 +355,7 @@ void SymbolLayout::prepareSymbols(const GlyphMap& glyphMap,
         optional<PositionedIcon> shapedIcon;
         std::array<float, 2> textOffset{{0.0f, 0.0f}};
         const float layoutTextSize = layout->evaluate<TextSize>(zoom + 1, feature);
+        const float layoutTextSizeAtBucketZoomLevel = layout->evaluate<TextSize>(zoom, feature);
         const float layoutIconSize = layout->evaluate<IconSize>(zoom + 1, feature);
 
         // if feature has text, shape the text
@@ -381,6 +382,7 @@ void SymbolLayout::prepareSymbols(const GlyphMap& glyphMap,
                     /* glyphs */ glyphPositions,
                     /* images */ imagePositions,
                     layoutTextSize,
+                    layoutTextSizeAtBucketZoomLevel,
                     allowVerticalPlacement);
 
                 return result;

src/mbgl/text/shaping.cpp

@@ -532,6 +532,7 @@ const Shaping getShaping(const TaggedString& formattedString,
                          const GlyphPositions& glyphPositions,
                          const ImagePositions& imagePositions,
                          float layoutTextSize,
+                         float layoutTextSizeAtBucketZoomLevel,
                          bool allowVerticalPlacement) {
     assert(layoutTextSize);
     std::vector<TaggedString> reorderedLines;
@@ -561,7 +562,7 @@ const Shaping getShaping(const TaggedString& formattedString,
                glyphMap,
                glyphPositions,
                imagePositions,
-               layoutTextSize,
+               layoutTextSizeAtBucketZoomLevel,
                allowVerticalPlacement);
 
     return shaping;

src/mbgl/text/shaping.hpp

@@ -73,6 +73,7 @@ const Shaping getShaping(const TaggedString& string,
                          const GlyphPositions& glyphPositions,
                          const ImagePositions& imagePositions,
                          float layoutTextSize,
+                         float layoutTextSizeAtBucketZoomLevel,
                          bool allowVerticalPlacement);
 
 } // namespace mbgl

test/text/shaping.test.cpp

@@ -25,6 +25,8 @@ TEST(Shaping, ZWSP) {
     auto immutableGlyph = Immutable<Glyph>(makeMutable<Glyph>(std::move(glyph)));
     const std::vector<std::string> fontStack{{"font-stack"}};
     const SectionOptions sectionOptions(1.0f, fontStack);
+    const float layoutTextSize = 16.0f;
+    const float layoutTextSizeAtBucketZoomLevel = 16.0f;
     GlyphMap glyphs = {
         { FontStackHasher()(fontStack), {{u'中', std::move(immutableGlyph)}} }
     };
@@ -44,7 +46,8 @@ TEST(Shaping, ZWSP) {
                           glyphs,
                           glyphPositions,
                           imagePositions,
-                          16.0,
+                          layoutTextSize,
+                          layoutTextSizeAtBucketZoomLevel,
                           /*allowVerticalPlacement*/ false);
     };