Implement font fallback functionality and refactor some code. (#322)

Tencent · Nov 18, 2024 · 4802e56 · 4802e56
1 parent 110c3ee
commit 4802e56
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Showing 7 changed files with 1,100 additions and 75 deletions.
diff --git a/include/tgfx/layers/TextLayer.h b/include/tgfx/layers/TextLayer.h
@@ -144,6 +144,75 @@ class TextLayer : public Layer {
   TextAlign _textAlign = TextAlign::Left;
   bool _autoWrap = false;
 
-  std::string preprocessNewLines(const std::string& text);
+  class GlyphInfo final {
+   public:
+    GlyphInfo(Unichar unichar, GlyphID glyphID, std::shared_ptr<Typeface> typeface)
+        : _unichar(unichar), _glyphID(glyphID), _typeface(std::move(typeface)) {
+    }
+
+    Unichar getUnichar() const {
+      return _unichar;
+    }
+
+    GlyphID getGlyphID() const {
+      return _glyphID;
+    }
+
+    std::shared_ptr<Typeface> getTypeface() const {
+      return _typeface;
+    }
+
+   private:
+    Unichar _unichar = 0;
+    GlyphID _glyphID = 0;
+    std::shared_ptr<Typeface> _typeface = nullptr;
+  };
+
+  class GlyphLine final {
+   public:
+    GlyphLine() = default;
+
+    void append(const std::shared_ptr<GlyphInfo>& glyphInfo, const float advance) {
+      _glyphInfosAndAdvance.emplace_back(std::move(glyphInfo), advance);
+    }
+
+    size_t getGlyphCount() const {
+      return _glyphInfosAndAdvance.size();
+    }
+
+    std::shared_ptr<GlyphInfo> getGlyphInfo(const size_t index) const {
+      return _glyphInfosAndAdvance[index].first;
+    }
+
+    float getAdvance(const size_t index) const {
+      return _glyphInfosAndAdvance[index].second;
+    }
+
+    float getLineWidth() const {
+      float lineWidth = 0.0f;
+      for (const auto& glyphInfoAndAdvance : _glyphInfosAndAdvance) {
+        lineWidth += glyphInfoAndAdvance.second;
+      }
+      return lineWidth;
+    }
+
+   private:
+    std::vector<std::pair<std::shared_ptr<GlyphInfo>, float>> _glyphInfosAndAdvance = {};
+  };
+
+  static std::string PreprocessNewLines(const std::string& text);
+  static std::vector<std::shared_ptr<GlyphInfo>> ShapeText(
+      const std::string& text, const std::shared_ptr<Typeface>& typeface);
+
+  float calcAdvance(const std::shared_ptr<GlyphInfo>& glyphInfo, float emptyAdvance) const;
+  float getLineHeight(const std::shared_ptr<GlyphLine>& glyphLine) const;
+  void TruncateGlyphLines(std::vector<std::shared_ptr<GlyphLine>>& glyphLines) const;
+  void resolveTextAlignment(const std::vector<std::shared_ptr<GlyphLine>>& glyphLines,
+                            float emptyAdvance,
+                            std::vector<std::shared_ptr<GlyphInfo>>& finalGlyphInfos,
+                            std::vector<Point>& positions) const;
+  void buildGlyphRunList(const std::vector<std::shared_ptr<GlyphInfo>>& finalGlyphs,
+                         const std::vector<Point>& positions,
+                         std::vector<GlyphRun>& glyphRunList) const;
 };
 }  // namespace tgfx
diff --git a/src/core/GlyphRunList.cpp b/src/core/GlyphRunList.cpp
@@ -38,8 +38,8 @@ GlyphRunList::GlyphRunList(GlyphRun glyphRun) {
 
 GlyphRunList::GlyphRunList(std::vector<GlyphRun> glyphRuns) : _glyphRuns(std::move(glyphRuns)) {
   DEBUG_ASSERT(!_glyphRuns.empty());
-  DEBUG_ASSERT(std::all_of(glyphRuns.begin(), glyphRuns.end(),
-                           [hasColor = glyphRuns[0].font.hasColor()](const GlyphRun& glyphRun) {
+  DEBUG_ASSERT(std::all_of(_glyphRuns.begin(), _glyphRuns.end(),
+                           [hasColor = _glyphRuns[0].font.hasColor()](const GlyphRun& glyphRun) {
                              return !glyphRun.glyphs.empty() &&
                                     glyphRun.glyphs.size() == glyphRun.positions.size() &&
                                     glyphRun.font.hasColor() == hasColor;

diff --git a/src/core/TextBlob.cpp b/src/core/TextBlob.cpp
@@ -26,8 +26,8 @@ std::shared_ptr<TextBlob> TextBlob::MakeFrom(const std::string& text, const Font
   const char* textStop = textStart + text.size();
   GlyphRun glyphRun = {};
   glyphRun.font = font;
-  auto emptyGlyphID = font.getGlyphID(" ");
-  auto emptyAdvance = font.getAdvance(emptyGlyphID);
+  // Use half the font size as width for spaces
+  auto emptyAdvance = font.getSize() / 2.0f;
   float xOffset = 0;
   while (textStart < textStop) {
     auto unichar = UTF::NextUTF8(&textStart, textStop);