Draft implementation of DDS for {text,icon}-size

Ports mapbox/mapbox-gl-js#4455

Author: Anand Thakker

include/mbgl/style/data_driven_property_value.hpp

@@ -45,6 +45,15 @@ class DataDrivenPropertyValue {
     bool isDataDriven() const {
         return value.template is<SourceFunction<T>>() || value.template is<CompositeFunction<T>>();
     }
+    
+    bool isZoomConstant() const {
+        return !value.template is<CameraFunction<T>>() && !value.template is<CompositeFunction<T>>();
+    }
+    
+    template <class... Ts>
+    auto match(Ts&&... ts) const {
+        return value.match(std::forward<Ts>(ts)...);
+    }
 
     template <typename Evaluator>
     auto evaluate(const Evaluator& evaluator) const {

include/mbgl/style/function/camera_function.hpp

@@ -28,6 +28,24 @@ class CameraFunction {
             return s.evaluate(Value(double(zoom))).value_or(T());
         });
     }
+    
+    // TODO: this is duped from composite function; dedupe it.
+    Range<float> coveringZoomStops(float lowerZoom, float upperZoom) const {
+        return stops.match(
+            [&] (const auto& s) {
+                assert(!s.stops.empty());
+                auto minIt = s.stops.lower_bound(lowerZoom);
+                auto maxIt = s.stops.upper_bound(upperZoom);
+                if (minIt != s.stops.begin()) {
+                    minIt--;
+                }
+                return Range<float> {
+                    minIt == s.stops.end() ? s.stops.rbegin()->first : minIt->first,
+                    maxIt == s.stops.end() ? s.stops.rbegin()->first : maxIt->first
+                };
+            }
+        );
+    }
 
     friend bool operator==(const CameraFunction& lhs,
                            const CameraFunction& rhs) {

include/mbgl/style/function/composite_function.hpp

@@ -72,6 +72,23 @@ class CompositeFunction {
             }
         );
     }
+    
+    Range<float> coveringZoomStops(float lowerZoom, float upperZoom) const {
+        return stops.match(
+            [&] (const auto& s) {
+                assert(!s.stops.empty());
+                auto minIt = s.stops.lower_bound(lowerZoom);
+                auto maxIt = s.stops.upper_bound(upperZoom);
+                if (minIt != s.stops.begin()) {
+                    minIt--;
+                }
+                return Range<float> {
+                    minIt == s.stops.end() ? s.stops.rbegin()->first : minIt->first,
+                    maxIt == s.stops.end() ? s.stops.rbegin()->first : maxIt->first
+                };
+            }
+        );
+    }
 
     template <class Feature>
     Range<T> evaluate(Range<InnerStops> coveringStops,

src/mbgl/layout/symbol_instance.cpp

@@ -10,6 +10,7 @@ SymbolInstance::SymbolInstance(Anchor& anchor,
                                const std::pair<Shaping, Shaping>& shapedTextOrientations,
                                const PositionedIcon& shapedIcon,
                                const SymbolLayoutProperties::Evaluated& layout,
+                               const float layoutTextSize,
                                const bool addToBuffers,
                                const uint32_t index_,
                                const float textBoxScale,
@@ -26,15 +27,18 @@ SymbolInstance::SymbolInstance(Anchor& anchor,
     hasText(shapedTextOrientations.first || shapedTextOrientations.second),
     hasIcon(shapedIcon),
 
+
     // Create the collision features that will be used to check whether this symbol instance can be placed
     textCollisionFeature(line, anchor, shapedTextOrientations.second ?: shapedTextOrientations.first, textBoxScale, textPadding, textPlacement, indexedFeature),
     iconCollisionFeature(line, anchor, shapedIcon, iconBoxScale, iconPadding, iconPlacement, indexedFeature),
     featureIndex(featureIndex_) {
+        
+    
 
     // Create the quads used for rendering the icon and glyphs.
     if (addToBuffers) {
         if (shapedIcon) {
-            iconQuad = getIconQuad(anchor, shapedIcon, line, layout, iconPlacement, shapedTextOrientations.first);
+            iconQuad = getIconQuad(anchor, shapedIcon, line, layout, layoutTextSize, iconPlacement, shapedTextOrientations.first);
         }
         if (shapedTextOrientations.first) {
             auto quads = getGlyphQuads(anchor, shapedTextOrientations.first, textBoxScale, line, layout, textPlacement, face);
@@ -55,6 +59,8 @@ SymbolInstance::SymbolInstance(Anchor& anchor,
     } else {
         writingModes = WritingModeType::None;
     }
+    
+    
 }
 
 } // namespace mbgl

src/mbgl/layout/symbol_instance.hpp

@@ -17,6 +17,7 @@ class SymbolInstance {
                    const std::pair<Shaping, Shaping>& shapedTextOrientations,
                    const PositionedIcon& shapedIcon,
                    const style::SymbolLayoutProperties::Evaluated&,
+                   const float layoutTextSize,
                    const bool inside,
                    const uint32_t index,
                    const float textBoxScale,

src/mbgl/layout/symbol_layout.cpp

@@ -41,7 +41,10 @@ SymbolLayout::SymbolLayout(const BucketParameters& parameters,
       mode(parameters.mode),
       spriteAtlas(spriteAtlas_),
       tileSize(util::tileSize * overscaling),
-      tilePixelRatio(float(util::EXTENT) / tileSize) {
+      tilePixelRatio(float(util::EXTENT) / tileSize),
+      textSize(layers.at(0)->as<SymbolLayer>()->impl->layout.unevaluated.get<TextSize>()),
+      iconSize(layers.at(0)->as<SymbolLayer>()->impl->layout.unevaluated.get<IconSize>())
+    {
 
     const SymbolLayer::Impl& leader = *layers.at(0)->as<SymbolLayer>()->impl;
 
@@ -67,12 +70,7 @@ SymbolLayout::SymbolLayout(const BucketParameters& parameters,
     if (layout.get<TextPitchAlignment>() == AlignmentType::Auto) {
         layout.get<TextPitchAlignment>() = layout.get<TextRotationAlignment>();
     }
-
-    textMaxSize = leader.layout.evaluate<TextSize>(PropertyEvaluationParameters(18));
-
-    layout.get<IconSize>() = leader.layout.evaluate<IconSize>(PropertyEvaluationParameters(zoom + 1));
-    layout.get<TextSize>() = leader.layout.evaluate<TextSize>(PropertyEvaluationParameters(zoom + 1));
-          
+    
     const bool hasTextField = layout.get<TextField>().match(
         [&] (const std::string& s) { return !s.empty(); },
         [&] (const auto&) { return true; }
@@ -92,7 +90,7 @@ SymbolLayout::SymbolLayout(const BucketParameters& parameters,
             layer->as<SymbolLayer>()->impl->textPaintProperties()
         ));
     }
-
+    
     // Determine and load glyph ranges
     const size_t featureCount = sourceLayer.featureCount();
     for (size_t i = 0; i < featureCount; ++i) {
@@ -307,11 +305,20 @@ void SymbolLayout::addFeature(const std::size_t index,
                               const GlyphPositions& face) {
     const float minScale = 0.5f;
     const float glyphSize = 24.0f;
-
-    const float fontScale = layout.get<TextSize>() / glyphSize;
+    
+    const float layoutTextSize = layout.evaluate<TextSize>(zoom + 1, feature);
+    const float layoutIconSize = layout.evaluate<IconSize>(zoom + 1, feature);
+    
+    // To reduce the number of labels that jump around when zooming we need
+    // to use a text-size value that is the same for all zoom levels.
+    // This calculates text-size at a high zoom level so that all tiles can
+    // use the same value when calculating anchor positions.
+    const float textMaxSize = layout.evaluate<TextSize>(18, feature);
+    
+    const float fontScale = layoutTextSize / glyphSize;
     const float textBoxScale = tilePixelRatio * fontScale;
     const float textMaxBoxScale = tilePixelRatio * textMaxSize / glyphSize;
-    const float iconBoxScale = tilePixelRatio * layout.get<IconSize>();
+    const float iconBoxScale = tilePixelRatio * layoutIconSize;
     const float symbolSpacing = tilePixelRatio * layout.get<SymbolSpacing>();
     const bool avoidEdges = layout.get<SymbolAvoidEdges>() && layout.get<SymbolPlacement>() != SymbolPlacementType::Line;
     const float textPadding = layout.get<TextPadding>() * tilePixelRatio;
@@ -325,6 +332,8 @@ void SymbolLayout::addFeature(const std::size_t index,
                                                   : layout.get<SymbolPlacement>();
     const float textRepeatDistance = symbolSpacing / 2;
     IndexedSubfeature indexedFeature = {feature.index, sourceLayerName, bucketName, symbolInstances.size()};
+    
+    
 
     auto addSymbolInstance = [&] (const GeometryCoordinates& line, Anchor& anchor) {
         // https://github.com/mapbox/vector-tile-spec/tree/master/2.1#41-layers
@@ -347,7 +356,8 @@ void SymbolLayout::addFeature(const std::size_t index,
 
         const bool addToBuffers = mode == MapMode::Still || withinPlus0;
 
-        symbolInstances.emplace_back(anchor, line, shapedTextOrientations, shapedIcon, layout, addToBuffers, symbolInstances.size(),
+        symbolInstances.emplace_back(anchor, line, shapedTextOrientations, shapedIcon, layout, layoutTextSize,
+                addToBuffers, symbolInstances.size(),
                 textBoxScale, textPadding, textPlacement,
                 iconBoxScale, iconPadding, iconPlacement,
                 face, indexedFeature, index);
@@ -422,7 +432,7 @@ bool SymbolLayout::anchorIsTooClose(const std::u16string& text, const float repe
 }
 
 std::unique_ptr<SymbolBucket> SymbolLayout::place(CollisionTile& collisionTile) {
-    auto bucket = std::make_unique<SymbolBucket>(layout, layerPaintProperties, zoom, sdfIcons, iconsNeedLinear);
+    auto bucket = std::make_unique<SymbolBucket>(layout, layerPaintProperties, textSize, iconSize, zoom, sdfIcons, iconsNeedLinear);
 
     // Calculate which labels can be shown and when they can be shown and
     // create the bufers used for rendering.
@@ -486,6 +496,7 @@ std::unique_ptr<SymbolBucket> SymbolLayout::place(CollisionTile& collisionTile)
             iconScale = util::max(iconScale, glyphScale);
         }
 
+        const auto& feature = features.at(symbolInstance.featureIndex);
 
         // Insert final placement into collision tree and add glyphs/icons to buffers
 
@@ -495,7 +506,7 @@ std::unique_ptr<SymbolBucket> SymbolLayout::place(CollisionTile& collisionTile)
             if (glyphScale < collisionTile.maxScale) {
                 for (const auto& symbol : symbolInstance.glyphQuads) {
                     addSymbol(
-                        bucket->text, symbol, placementZoom,
+                        bucket->text, bucket->textSizeData, symbol, feature, textSize, placementZoom,
                         keepUpright, textPlacement, collisionTile.config.angle, symbolInstance.writingModes);
                 }
             }
@@ -506,12 +517,11 @@ std::unique_ptr<SymbolBucket> SymbolLayout::place(CollisionTile& collisionTile)
             collisionTile.insertFeature(symbolInstance.iconCollisionFeature, iconScale, layout.get<IconIgnorePlacement>());
             if (iconScale < collisionTile.maxScale && symbolInstance.iconQuad) {
                 addSymbol(
-                    bucket->icon, *symbolInstance.iconQuad, placementZoom,
+                    bucket->icon, bucket->iconSizeData, *symbolInstance.iconQuad, feature, iconSize, placementZoom,
                     keepUpright, iconPlacement, collisionTile.config.angle, symbolInstance.writingModes);
             }
         }
 
-        const auto& feature = features.at(symbolInstance.featureIndex);
         for (auto& pair : bucket->paintPropertyBinders) {
             pair.second.first.populateVertexVectors(feature, bucket->icon.vertices.vertexSize());
             pair.second.second.populateVertexVectors(feature, bucket->text.vertices.vertexSize());
@@ -527,7 +537,10 @@ std::unique_ptr<SymbolBucket> SymbolLayout::place(CollisionTile& collisionTile)
 
 template <typename Buffer>
 void SymbolLayout::addSymbol(Buffer& buffer,
+                             SymbolSizeData& sizeData,
                              const SymbolQuad& symbol,
+                             const SymbolFeature& feature,
+                             const style::DataDrivenPropertyValue<float>& size,
                              const float placementZoom,
                              const bool keepUpright,
                              const style::SymbolPlacementType placement,
@@ -589,6 +602,36 @@ void SymbolLayout::addSymbol(Buffer& buffer,
                         minZoom, maxZoom, placementZoom, glyphAngle));
     buffer.vertices.emplace_back(SymbolLayoutAttributes::vertex(anchorPoint, br, tex.x + tex.w, tex.y + tex.h,
                         minZoom, maxZoom, placementZoom, glyphAngle));
+    
+
+    size.match(
+        [&] (const style::CompositeFunction<float>& fn) {
+            const auto sizeVertex = SymbolSizeAttributes::Vertex {
+                {{
+                    static_cast<uint16_t>(fn.evaluate(sizeData.coveringZoomStops->min, feature, sizeData.defaultSize) * 10),
+                    static_cast<uint16_t>(fn.evaluate(sizeData.coveringZoomStops->max, feature, sizeData.defaultSize) * 10),
+                    static_cast<uint16_t>(fn.evaluate(zoom + 1, feature, sizeData.defaultSize) * 10)
+                }}
+            };
+            auto& vertexVector = sizeData.vertices.get<gl::VertexVector<SymbolSizeAttributes::Vertex>>();
+            vertexVector.emplace_back(sizeVertex);
+            vertexVector.emplace_back(sizeVertex);
+            vertexVector.emplace_back(sizeVertex);
+            vertexVector.emplace_back(sizeVertex);
+        },
+        [&] (const style::SourceFunction<float>& fn) {
+            const auto sizeVertex = SymbolSizeAttributes::SourceFunctionVertex {
+                {{ static_cast<uint16_t>(fn.evaluate(feature, sizeData.defaultSize) * 10) }}
+            };
+            
+            auto& vertexVector = sizeData.vertices.get<gl::VertexVector<SymbolSizeAttributes::SourceFunctionVertex>>();
+            vertexVector.emplace_back(sizeVertex);
+            vertexVector.emplace_back(sizeVertex);
+            vertexVector.emplace_back(sizeVertex);
+            vertexVector.emplace_back(sizeVertex);
+        },
+        [] (const auto&) {}
+    );
 
     // add the two triangles, referencing the four coordinates we just inserted.
     buffer.triangles.emplace_back(index + 0, index + 1, index + 2);

src/mbgl/layout/symbol_layout.hpp

@@ -6,6 +6,7 @@
 #include <mbgl/layout/symbol_instance.hpp>
 #include <mbgl/text/bidi.hpp>
 #include <mbgl/style/layers/symbol_layer_impl.hpp>
+#include <mbgl/programs/symbol_program.hpp>
 
 #include <memory>
 #include <map>
@@ -68,7 +69,8 @@ class SymbolLayout {
 
     // Adds placed items to the buffer.
     template <typename Buffer>
-    void addSymbol(Buffer&, const SymbolQuad&, float scale,
+    void addSymbol(Buffer&, SymbolSizeData& sizeData, const SymbolQuad&, const SymbolFeature& feature,
+                    const style::DataDrivenPropertyValue<float>& size, float scale,
                     const bool keepUpright, const style::SymbolPlacementType, const float placementAngle,
                     WritingModeType writingModes);
 
@@ -79,7 +81,6 @@ class SymbolLayout {
     const MapMode mode;
 
     style::SymbolLayoutProperties::Evaluated layout;
-    float textMaxSize;
 
     SpriteAtlas& spriteAtlas;
 
@@ -88,6 +89,9 @@ class SymbolLayout {
 
     bool sdfIcons = false;
     bool iconsNeedLinear = false;
+    
+    style::TextSize::UnevaluatedType textSize;
+    style::IconSize::UnevaluatedType iconSize;
 
     GlyphRangeSet ranges;
     std::vector<SymbolInstance> symbolInstances;

src/mbgl/programs/attributes.hpp

@@ -25,10 +25,15 @@ MBGL_DEFINE_ATTRIBUTE(int16_t, 2, a_extrude);
 MBGL_DEFINE_ATTRIBUTE(int16_t, 4, a_pos_offset);
 MBGL_DEFINE_ATTRIBUTE(uint16_t, 2, a_texture_pos);
 
-template <std::size_t N>
+template <std::size_t N, typename T>
 struct a_data {
     static auto name() { return "a_data"; }
-    using Type = gl::Attribute<uint8_t, N>;
+    using Type = gl::Attribute<T, N>;
+};
+
+struct a_size {
+    static auto name() { return "a_size"; }
+    using Type = gl::Attribute<uint16_t, 3>;
 };
 
 template <std::size_t N>