[core] Release quad data after vertex buffers are created

4 files changed, 172 insertions, 87 deletions

diff --git a/src/mbgl/layout/symbol_instance.cpp b/src/mbgl/layout/symbol_instance.cpp
index 809aa2f451..133cdec698 100644
--- a/src/mbgl/layout/symbol_instance.cpp
+++ b/src/mbgl/layout/symbol_instance.cpp
@@ -18,20 +18,63 @@ const Shaping& getAnyShaping(const ShapedTextOrientations& shapedTextOrientation
 
 } // namespace
 
+SymbolInstanceSharedData::SymbolInstanceSharedData(GeometryCoordinates line_,
+                                                   const ShapedTextOrientations& shapedTextOrientations,
+                                                   const optional<PositionedIcon>& shapedIcon,
+                                                   const style::SymbolLayoutProperties::Evaluated& layout,
+                                                   const float layoutTextSize,
+                                                   const style::SymbolPlacementType textPlacement,
+                                                   const std::array<float, 2>& textOffset,
+                                                   const GlyphPositions& positions) : line(std::move(line_)) {
+    // Create the quads used for rendering the icon and glyphs.
+    if (shapedIcon) {
+        iconQuad = getIconQuad(*shapedIcon, layout, layoutTextSize, shapedTextOrientations.horizontal);
+    }
+
+    bool singleLineInitialized = false;
+    const auto initHorizontalGlyphQuads = [&] (SymbolQuads& quads, const Shaping& shaping) {
+        if (!shapedTextOrientations.singleLine) {
+            quads = getGlyphQuads(shaping, textOffset, layout, textPlacement, positions);
+            return;
+        }
+        if (!singleLineInitialized) {
+            rightJustifiedGlyphQuads = getGlyphQuads(shaping, textOffset, layout, textPlacement, positions);
+            singleLineInitialized = true;
+        }
+    };
+
+    if (shapedTextOrientations.right) {
+        initHorizontalGlyphQuads(rightJustifiedGlyphQuads, shapedTextOrientations.right);
+    }
+
+    if (shapedTextOrientations.center) {
+        initHorizontalGlyphQuads(centerJustifiedGlyphQuads, shapedTextOrientations.center);
+    }
+
+    if (shapedTextOrientations.left) {
+        initHorizontalGlyphQuads(leftJustifiedGlyphQuads, shapedTextOrientations.left);
+    }
+
+    if (shapedTextOrientations.vertical) {
+        verticalGlyphQuads = getGlyphQuads(shapedTextOrientations.vertical, textOffset, layout, textPlacement, positions);
+    }
+}
+
+bool SymbolInstanceSharedData::empty() const {
+    return rightJustifiedGlyphQuads.empty() && centerJustifiedGlyphQuads.empty() && leftJustifiedGlyphQuads.empty() && verticalGlyphQuads.empty();
+}
+
 SymbolInstance::SymbolInstance(Anchor& anchor_,
-                               GeometryCoordinates line_,
+                               std::shared_ptr<SymbolInstanceSharedData> sharedData_,
                                const ShapedTextOrientations& shapedTextOrientations,
-                               optional<PositionedIcon> shapedIcon,
-                               const SymbolLayoutProperties::Evaluated& layout,
-                               const float layoutTextSize,
+                               const optional<PositionedIcon>& shapedIcon,
                                const float textBoxScale_,
                                const float textPadding,
                                const SymbolPlacementType textPlacement,
-                               const std::array<float, 2> textOffset_,
+                               const std::array<float, 2>& textOffset_,
                                const float iconBoxScale,
                                const float iconPadding,
-                               const std::array<float, 2> iconOffset_,
-                               const GlyphPositions& positions,
+                               const std::array<float, 2>& iconOffset_,
                                const IndexedSubfeature& indexedFeature,
                                const std::size_t layoutFeatureIndex_,
                                const std::size_t dataFeatureIndex_,
@@ -39,15 +82,15 @@ SymbolInstance::SymbolInstance(Anchor& anchor_,
                                const float overscaling,
                                const float rotate,
                                float radialTextOffset_) :
+    sharedData(std::move(sharedData_)),
     anchor(anchor_),
-    line(line_),
-    hasText(false),
+    // 'hasText' depends on finding at least one glyph in the shaping that's also in the GlyphPositionMap
+    hasText(!sharedData->empty()),
     hasIcon(shapedIcon),
-
     // Create the collision features that will be used to check whether this symbol instance can be placed
     // As a collision approximation, we can use either the vertical or any of the horizontal versions of the feature
-    textCollisionFeature(line_, anchor, getAnyShaping(shapedTextOrientations), textBoxScale_, textPadding, textPlacement, indexedFeature, overscaling, rotate),
-    iconCollisionFeature(line_, anchor, shapedIcon, iconBoxScale, iconPadding, indexedFeature, rotate),
+    textCollisionFeature(sharedData->line, anchor, getAnyShaping(shapedTextOrientations), textBoxScale_, textPadding, textPlacement, indexedFeature, overscaling, rotate),
+    iconCollisionFeature(sharedData->line, anchor, shapedIcon, iconBoxScale, iconPadding, indexedFeature, rotate),
     writingModes(WritingModeType::None),
     layoutFeatureIndex(layoutFeatureIndex_),
     dataFeatureIndex(dataFeatureIndex_),
@@ -58,43 +101,52 @@ SymbolInstance::SymbolInstance(Anchor& anchor_,
     radialTextOffset(radialTextOffset_),
     singleLine(shapedTextOrientations.singleLine) {
 
-    // Create the quads used for rendering the icon and glyphs.
-    if (shapedIcon) {
-        iconQuad = getIconQuad(*shapedIcon, layout, layoutTextSize, shapedTextOrientations.horizontal);
-    }
-    
-    bool singleLineInitialized = false;
-    const auto initHorizontalGlyphQuads = [&] (SymbolQuads& quads, const Shaping& shaping) {
+    rightJustifiedGlyphQuadsSize = sharedData->rightJustifiedGlyphQuads.size();
+    centerJustifiedGlyphQuadsSize = sharedData->centerJustifiedGlyphQuads.size();
+    leftJustifiedGlyphQuadsSize = sharedData->leftJustifiedGlyphQuads.size();
+    verticalGlyphQuadsSize = sharedData->verticalGlyphQuads.size();
+
+    if (rightJustifiedGlyphQuadsSize || centerJustifiedGlyphQuadsSize || leftJustifiedGlyphQuadsSize) {
         writingModes |= WritingModeType::Horizontal;
-        if (!singleLine) {
-            quads = getGlyphQuads(shaping, textOffset, layout, textPlacement, positions);
-            return;
-        }
-        if (!singleLineInitialized) {
-            rightJustifiedGlyphQuads = getGlyphQuads(shaping, textOffset, layout, textPlacement, positions);
-            singleLineInitialized = true;
-        }
-    };
-    
-    if (shapedTextOrientations.right) {
-        initHorizontalGlyphQuads(rightJustifiedGlyphQuads, shapedTextOrientations.right);
     }
 
-    if (shapedTextOrientations.center) {
-        initHorizontalGlyphQuads(centerJustifiedGlyphQuads, shapedTextOrientations.center);
+    if (verticalGlyphQuadsSize) {
+        writingModes |= WritingModeType::Vertical;
     }
+}
 
-    if (shapedTextOrientations.left) {
-        initHorizontalGlyphQuads(leftJustifiedGlyphQuads, shapedTextOrientations.left);
-    }
+const GeometryCoordinates& SymbolInstance::line() const {
+    assert(sharedData);
+    return sharedData->line;
+}
 
-    if (shapedTextOrientations.vertical) {
-        writingModes |= WritingModeType::Vertical;
-        verticalGlyphQuads = getGlyphQuads(shapedTextOrientations.vertical, textOffset, layout, textPlacement, positions);
-    }
+const SymbolQuads& SymbolInstance::rightJustifiedGlyphQuads() const {
+    assert(sharedData);
+    return sharedData->rightJustifiedGlyphQuads;
+}
 
-    // 'hasText' depends on finding at least one glyph in the shaping that's also in the GlyphPositionMap
-    hasText = !rightJustifiedGlyphQuads.empty() || !centerJustifiedGlyphQuads.empty() || !leftJustifiedGlyphQuads.empty() || !verticalGlyphQuads.empty();
+const SymbolQuads& SymbolInstance::leftJustifiedGlyphQuads() const {
+    assert(sharedData);
+    return sharedData->leftJustifiedGlyphQuads;
+}
+
+const SymbolQuads& SymbolInstance::centerJustifiedGlyphQuads() const {
+    assert(sharedData);
+    return sharedData->centerJustifiedGlyphQuads;
+}
+
+const SymbolQuads& SymbolInstance::verticalGlyphQuads() const {
+    assert(sharedData);
+    return sharedData->verticalGlyphQuads;
+}
+
+const optional<SymbolQuad>& SymbolInstance::iconQuad() const {
+    assert(sharedData);
+    return sharedData->iconQuad;
+}
+
+void SymbolInstance::releaseSharedData() {
+    sharedData.reset();
 }
 
 optional<size_t> SymbolInstance::getDefaultHorizontalPlacedTextIndex() const {
diff --git a/src/mbgl/layout/symbol_instance.hpp b/src/mbgl/layout/symbol_instance.hpp
index 95159deeb1..48bb2f0cbc 100644
--- a/src/mbgl/layout/symbol_instance.hpp
+++ b/src/mbgl/layout/symbol_instance.hpp
@@ -21,23 +21,39 @@ struct ShapedTextOrientations {
     bool singleLine = false;
 };
 
+struct SymbolInstanceSharedData {
+    SymbolInstanceSharedData(GeometryCoordinates line,
+                            const ShapedTextOrientations& shapedTextOrientations,
+                            const optional<PositionedIcon>& shapedIcon,
+                            const style::SymbolLayoutProperties::Evaluated& layout,
+                            const float layoutTextSize,
+                            const style::SymbolPlacementType textPlacement,
+                            const std::array<float, 2>& textOffset,
+                            const GlyphPositions& positions);
+    bool empty() const;
+    GeometryCoordinates line;
+    // Note: When singleLine == true, only `rightJustifiedGlyphQuads` is populated.
+    SymbolQuads rightJustifiedGlyphQuads;
+    SymbolQuads centerJustifiedGlyphQuads;
+    SymbolQuads leftJustifiedGlyphQuads;
+    SymbolQuads verticalGlyphQuads;
+    optional<SymbolQuad> iconQuad;
+};
+
 class SymbolInstance {
 public:
-    SymbolInstance(Anchor& anchor,
-                   GeometryCoordinates line,
+    SymbolInstance(Anchor& anchor_,
+                   std::shared_ptr<SymbolInstanceSharedData> sharedData,
                    const ShapedTextOrientations& shapedTextOrientations,
-                   optional<PositionedIcon> shapedIcon,
-                   const style::SymbolLayoutProperties::Evaluated&,
-                   const float layoutTextSize,
+                   const optional<PositionedIcon>& shapedIcon,
                    const float textBoxScale,
                    const float textPadding,
-                   style::SymbolPlacementType textPlacement,
-                   const std::array<float, 2> textOffset,
+                   const style::SymbolPlacementType textPlacement,
+                   const std::array<float, 2>& textOffset,
                    const float iconBoxScale,
                    const float iconPadding,
-                   const std::array<float, 2> iconOffset,
-                   const GlyphPositions&,
-                   const IndexedSubfeature&,
+                   const std::array<float, 2>& iconOffset,
+                   const IndexedSubfeature& indexedFeature,
                    const std::size_t layoutFeatureIndex,
                    const std::size_t dataFeatureIndex,
                    std::u16string key,
@@ -46,18 +62,27 @@ public:
                    float radialTextOffset);
 
     optional<size_t> getDefaultHorizontalPlacedTextIndex() const;
+    const GeometryCoordinates& line() const;
+    const SymbolQuads& rightJustifiedGlyphQuads() const;
+    const SymbolQuads& leftJustifiedGlyphQuads() const;
+    const SymbolQuads& centerJustifiedGlyphQuads() const;
+    const SymbolQuads& verticalGlyphQuads() const;
+    const optional<SymbolQuad>& iconQuad() const;
+    void releaseSharedData();
+
+private:
+    std::shared_ptr<SymbolInstanceSharedData> sharedData;
+
+public:
     Anchor anchor;
-    GeometryCoordinates line;
     bool hasText;
     bool hasIcon;
-    // Note: When singleLine == true, only `rightJustifiedGlyphQuads` is populated.
-    SymbolQuads rightJustifiedGlyphQuads;
-    SymbolQuads centerJustifiedGlyphQuads;
-    SymbolQuads leftJustifiedGlyphQuads;
 
-    SymbolQuads verticalGlyphQuads;
+    std::size_t rightJustifiedGlyphQuadsSize;
+    std::size_t centerJustifiedGlyphQuadsSize;
+    std::size_t leftJustifiedGlyphQuadsSize;
+    std::size_t verticalGlyphQuadsSize;
 
-    optional<SymbolQuad> iconQuad;
     CollisionFeature textCollisionFeature;
     CollisionFeature iconCollisionFeature;
     WritingModeType writingModes;
diff --git a/src/mbgl/layout/symbol_layout.cpp b/src/mbgl/layout/symbol_layout.cpp
index 21642b01e3..d269ca4144 100644
--- a/src/mbgl/layout/symbol_layout.cpp
+++ b/src/mbgl/layout/symbol_layout.cpp
@@ -397,7 +397,7 @@ void SymbolLayout::prepareSymbols(const GlyphMap& glyphMap, const GlyphPositions
 void SymbolLayout::addFeature(const std::size_t layoutFeatureIndex,
                               const SymbolFeature& feature,
                               const ShapedTextOrientations& shapedTextOrientations,
-                              optional<PositionedIcon> shapedIcon,
+                              const optional<PositionedIcon>& shapedIcon,
                               const GlyphPositions& glyphPositions,
                               Point<float> offset) {
     const float minScale = 0.5f;
@@ -433,7 +433,8 @@ void SymbolLayout::addFeature(const std::size_t layoutFeatureIndex,
     const auto evaluatedLayoutProperties = layout->evaluate(zoom, feature);
     IndexedSubfeature indexedFeature(feature.index, sourceLayer->getName(), bucketLeaderID, symbolInstances.size());
 
-    auto addSymbolInstance = [&] (const GeometryCoordinates& line, Anchor& anchor) {
+    auto addSymbolInstance = [&] (Anchor& anchor, std::shared_ptr<SymbolInstanceSharedData> sharedData) {
+        assert(sharedData);
         const bool anchorInsideTile = anchor.point.x >= 0 && anchor.point.x < util::EXTENT && anchor.point.y >= 0 && anchor.point.y < util::EXTENT;
 
         if (mode == MapMode::Tile || anchorInsideTile) {
@@ -442,20 +443,26 @@ void SymbolLayout::addFeature(const std::size_t layoutFeatureIndex,
             // In tiled rendering mode, add all symbols in the buffers so that we can:
             //  (1) render symbols that overlap into this tile
             //  (2) approximate collision detection effects from neighboring symbols
-            symbolInstances.emplace_back(anchor, line, shapedTextOrientations, shapedIcon,
-                    evaluatedLayoutProperties, layoutTextSize,
+            symbolInstances.emplace_back(anchor, std::move(sharedData), shapedTextOrientations, shapedIcon,
                     textBoxScale, textPadding, textPlacement, textOffset,
-                    iconBoxScale, iconPadding, iconOffset,
-                    glyphPositions, indexedFeature, layoutFeatureIndex, feature.index,
-                    feature.formattedText ? feature.formattedText->rawText() : std::u16string(), overscaling, rotation, radialTextOffset);
+                    iconBoxScale, iconPadding, iconOffset, indexedFeature,
+                    layoutFeatureIndex, feature.index,
+                    feature.formattedText ? feature.formattedText->rawText() : std::u16string(),
+                    overscaling, rotation, radialTextOffset);
         }
     };
 
+    const auto createSymbolInstanceSharedData = [&] (GeometryCoordinates line) {
+        return std::make_shared<SymbolInstanceSharedData>(std::move(line),
+            shapedTextOrientations, shapedIcon, evaluatedLayoutProperties, layoutTextSize,
+            textPlacement, textOffset, glyphPositions);
+    };
+
     const auto& type = feature.getType();
 
     if (layout->get<SymbolPlacement>() == SymbolPlacementType::Line) {
         auto clippedLines = util::clipLines(feature.geometry, 0, 0, util::EXTENT, util::EXTENT);
-        for (const auto& line : clippedLines) {
+        for (auto& line : clippedLines) {
             Anchors anchors = getAnchors(line,
                                          symbolSpacing,
                                          textMaxAngle,
@@ -466,10 +473,10 @@ void SymbolLayout::addFeature(const std::size_t layoutFeatureIndex,
                                          glyphSize,
                                          textMaxBoxScale,
                                          overscaling);
-
+            auto sharedData = createSymbolInstanceSharedData(std::move(line));
             for (auto& anchor : anchors) {
                 if (!feature.formattedText || !anchorIsTooClose(feature.formattedText->rawText(), textRepeatDistance, anchor)) {
-                    addSymbolInstance(line, anchor);
+                    addSymbolInstance(anchor, sharedData);
                 }
             }
         }
@@ -487,7 +494,7 @@ void SymbolLayout::addFeature(const std::size_t layoutFeatureIndex,
                                                           glyphSize,
                                                           textMaxBoxScale);
                 if (anchor) {
-                    addSymbolInstance(line, *anchor);
+                    addSymbolInstance(*anchor, createSymbolInstanceSharedData(line));
                 }
             }
         }
@@ -505,18 +512,18 @@ void SymbolLayout::addFeature(const std::size_t layoutFeatureIndex,
             // 1 pixel worth of precision, in tile coordinates
             auto poi = mapbox::polylabel(poly, double(util::EXTENT / util::tileSize));
             Anchor anchor(poi.x, poi.y, 0, minScale);
-            addSymbolInstance(polygon[0], anchor);
+            addSymbolInstance(anchor, createSymbolInstanceSharedData(polygon[0]));
         }
     } else if (type == FeatureType::LineString) {
         for (const auto& line : feature.geometry) {
             Anchor anchor(line[0].x, line[0].y, 0, minScale);
-            addSymbolInstance(line, anchor);
+            addSymbolInstance(anchor, createSymbolInstanceSharedData(line));
         }
     } else if (type == FeatureType::Point) {
         for (const auto& points : feature.geometry) {
             for (const auto& point : points) {
                 Anchor anchor(point.x, point.y, 0, minScale);
-                addSymbolInstance({point}, anchor);
+                addSymbolInstance(anchor, createSymbolInstanceSharedData({point}));
             }
         }
     }
@@ -576,36 +583,36 @@ void SymbolLayout::createBucket(const ImagePositions&, std::unique_ptr<FeatureIn
             optional<std::size_t> lastAddedSection;
             if (singleLine) {
                 optional<std::size_t> placedTextIndex;
-                lastAddedSection = addSymbolGlyphQuads(*bucket, symbolInstance, feature, symbolInstance.writingModes, placedTextIndex, symbolInstance.rightJustifiedGlyphQuads, lastAddedSection);
+                lastAddedSection = addSymbolGlyphQuads(*bucket, symbolInstance, feature, symbolInstance.writingModes, placedTextIndex, symbolInstance.rightJustifiedGlyphQuads(), lastAddedSection);
                 symbolInstance.placedRightTextIndex = placedTextIndex;
                 symbolInstance.placedCenterTextIndex = placedTextIndex;
                 symbolInstance.placedLeftTextIndex = placedTextIndex;
             } else {
-                if (!symbolInstance.rightJustifiedGlyphQuads.empty()) {
-                    lastAddedSection = addSymbolGlyphQuads(*bucket, symbolInstance, feature, symbolInstance.writingModes, symbolInstance.placedRightTextIndex, symbolInstance.rightJustifiedGlyphQuads, lastAddedSection);
+                if (symbolInstance.rightJustifiedGlyphQuadsSize) {
+                    lastAddedSection = addSymbolGlyphQuads(*bucket, symbolInstance, feature, symbolInstance.writingModes, symbolInstance.placedRightTextIndex, symbolInstance.rightJustifiedGlyphQuads(), lastAddedSection);
                 }
-                if (!symbolInstance.centerJustifiedGlyphQuads.empty()) {
-                    lastAddedSection = addSymbolGlyphQuads(*bucket, symbolInstance, feature, symbolInstance.writingModes, symbolInstance.placedCenterTextIndex, symbolInstance.centerJustifiedGlyphQuads, lastAddedSection);
+                if (symbolInstance.centerJustifiedGlyphQuadsSize) {
+                    lastAddedSection = addSymbolGlyphQuads(*bucket, symbolInstance, feature, symbolInstance.writingModes, symbolInstance.placedCenterTextIndex, symbolInstance.centerJustifiedGlyphQuads(), lastAddedSection);
                 }
-                if (!symbolInstance.leftJustifiedGlyphQuads.empty()) {
-                    lastAddedSection = addSymbolGlyphQuads(*bucket, symbolInstance, feature, symbolInstance.writingModes, symbolInstance.placedLeftTextIndex, symbolInstance.leftJustifiedGlyphQuads, lastAddedSection);
+                if (symbolInstance.leftJustifiedGlyphQuadsSize) {
+                    lastAddedSection = addSymbolGlyphQuads(*bucket, symbolInstance, feature, symbolInstance.writingModes, symbolInstance.placedLeftTextIndex, symbolInstance.leftJustifiedGlyphQuads(), lastAddedSection);
                 }
             }
-            if (symbolInstance.writingModes & WritingModeType::Vertical) {
-                lastAddedSection = addSymbolGlyphQuads(*bucket, symbolInstance, feature, WritingModeType::Vertical, symbolInstance.placedVerticalTextIndex, symbolInstance.verticalGlyphQuads, lastAddedSection);
+            if (symbolInstance.writingModes & WritingModeType::Vertical && symbolInstance.verticalGlyphQuadsSize) {
+                lastAddedSection = addSymbolGlyphQuads(*bucket, symbolInstance, feature, WritingModeType::Vertical, symbolInstance.placedVerticalTextIndex, symbolInstance.verticalGlyphQuads(), lastAddedSection);
             }
             assert(lastAddedSection); // True, as hasText == true;
             updatePaintPropertiesForSection(*bucket, feature, *lastAddedSection);
         }
 
         if (hasIcon) {
-            if (symbolInstance.iconQuad) {
+            if (symbolInstance.hasIcon) {
                 const Range<float> sizeData = bucket->iconSizeBinder->getVertexSizeData(feature);
                 bucket->icon.placedSymbols.emplace_back(symbolInstance.anchor.point, symbolInstance.anchor.segment, sizeData.min, sizeData.max,
-                        symbolInstance.iconOffset, WritingModeType::None, symbolInstance.line, std::vector<float>());
+                        symbolInstance.iconOffset, WritingModeType::None, symbolInstance.line(), std::vector<float>());
                 symbolInstance.placedIconIndex = bucket->icon.placedSymbols.size() - 1;
                 PlacedSymbol& iconSymbol = bucket->icon.placedSymbols.back();
-                iconSymbol.vertexStartIndex = addSymbol(bucket->icon, sizeData, *symbolInstance.iconQuad,
+                iconSymbol.vertexStartIndex = addSymbol(bucket->icon, sizeData, *symbolInstance.iconQuad(),
                                                         symbolInstance.anchor, iconSymbol, feature.sortKey);
 
                 for (auto& pair : bucket->paintProperties) {
@@ -613,6 +620,7 @@ void SymbolLayout::createBucket(const ImagePositions&, std::unique_ptr<FeatureIn
                 }
             }
         }
+        symbolInstance.releaseSharedData();
     }
 
     if (showCollisionBoxes) {
@@ -649,7 +657,7 @@ std::size_t SymbolLayout::addSymbolGlyphQuads(SymbolBucket& bucket,
     const bool hasFormatSectionOverrides = bucket.hasFormatSectionOverrides();
 
     bucket.text.placedSymbols.emplace_back(symbolInstance.anchor.point, symbolInstance.anchor.segment, sizeData.min, sizeData.max,
-            symbolInstance.textOffset, writingMode, symbolInstance.line, CalculateTileDistances(symbolInstance.line, symbolInstance.anchor));
+            symbolInstance.textOffset, writingMode, symbolInstance.line(), CalculateTileDistances(symbolInstance.line(), symbolInstance.anchor));
     placedIndex = bucket.text.placedSymbols.size() - 1;
     PlacedSymbol& placedSymbol = bucket.text.placedSymbols.back();
 
diff --git a/src/mbgl/layout/symbol_layout.hpp b/src/mbgl/layout/symbol_layout.hpp
index 23f883f56c..581c3ccb04 100644
--- a/src/mbgl/layout/symbol_layout.hpp
+++ b/src/mbgl/layout/symbol_layout.hpp
@@ -51,7 +51,7 @@ private:
     void addFeature(const size_t,
                     const SymbolFeature&,
                     const ShapedTextOrientations& shapedTextOrientations,
-                    optional<PositionedIcon> shapedIcon,
+                    const optional<PositionedIcon>& shapedIcon,
                     const GlyphPositions&,
                     Point<float> textOffset);