fix(runtime): Font weight layout measure fix (#10766) 0ae985862d

With certain fonts, the expected font features/variations aren't available until a frame after the text is measured, so for example, we measure glyphs using its default weight rather than the weight set in the style, which causes the rendered text not to fit within the measured area, thus incorrectly wrap to the next line. This fix updates variable fonts whenever TextStyle::font() is called IF the variable font hasn't previously been cached.

Specifically this issue was reproducible when using Solos to toggle between components which had text wrapped in layouts.

Co-authored-by: Philip Chung <philterdesign@gmail.com>

.rive_head

@@ -1 +1 @@
-01c1b43af9ac51debb54e99a326405460b873fda
+0ae985862d83742ed0883cb0228b6e06dbea1286

include/rive/text/text_style.hpp

@@ -34,7 +34,7 @@ public:
     Core* clone() const override;
     void addVariation(TextStyleAxis* axis);
     void addFeature(TextStyleFeature* feature);
-    void updateVariableFont();
+    void updateVariableFont() const;
     StatusCode onAddedClean(CoreContext* context) override;
     void onDirty(ComponentDirt dirt) override;
     bool validate(CoreContext* context) override;
@@ -47,12 +47,12 @@ protected:
 
 private:
     std::unique_ptr<TextVariationHelper> m_variationHelper;
-    rcp<Font> m_variableFont;
+    mutable rcp<Font> m_variableFont;
 
-    std::vector<Font::Coord> m_coords;
+    mutable std::vector<Font::Coord> m_coords;
     std::vector<TextStyleAxis*> m_variations;
     std::vector<TextStyleFeature*> m_styleFeatures;
-    std::vector<Font::Feature> m_features;
+    mutable std::vector<Font::Feature> m_features;
     TextInterface* m_text = nullptr;
 };
 } // namespace rive

src/text/text_style.cpp

@@ -78,11 +78,24 @@ const rcp<Font> TextStyle::font() const
         return m_variableFont;
     }
 
+    // Lazily build the variable font if variations/features are present but
+    // the variable font hasn't been created yet. This ensures the very first
+    // shape/measure uses the intended axes (e.g. wght) rather than the font's
+    // default axis values.
+    if ((!m_variations.empty() || !m_styleFeatures.empty()))
+    {
+        updateVariableFont();
+        if (m_variableFont != nullptr)
+        {
+            return m_variableFont;
+        }
+    }
+
     auto asset = fontAsset();
     return asset == nullptr ? nullptr : asset->font();
 }
 
-void TextStyle::updateVariableFont()
+void TextStyle::updateVariableFont() const
 {
     auto asset = fontAsset();
     rcp<Font> baseFont = asset == nullptr ? nullptr : asset->font();