Integration with more of Skia's SkShaper/SkParagraph APIs (#13008)

Based on https://github.com/Rusino/engine/tree/temp

third_party/txt/src/skia/paragraph_skia.cc

@@ -16,40 +16,137 @@
 
 #include "paragraph_skia.h"
 
+#include <algorithm>
+
 namespace txt {
 
 namespace skt = skia::textlayout;
 
+namespace {
+
+// Convert SkFontStyle::Weight values (ranging from 100-900) to txt::FontWeight
+// values (ranging from 0-8).
+txt::FontWeight GetTxtFontWeight(int font_weight) {
+  int txt_weight = (font_weight - 100) / 100;
+  txt_weight = std::clamp(txt_weight, static_cast<int>(txt::FontWeight::w100),
+                          static_cast<int>(txt::FontWeight::w900));
+  return static_cast<txt::FontWeight>(txt_weight);
+}
+
+txt::FontStyle GetTxtFontStyle(SkFontStyle::Slant font_slant) {
+  return font_slant == SkFontStyle::Slant::kUpright_Slant
+             ? txt::FontStyle::normal
+             : txt::FontStyle::italic;
+}
+
+TextStyle SkiaToTxt(const skt::TextStyle& skia) {
+  TextStyle txt;
+
+  txt.color = skia.getColor();
+  txt.decoration = static_cast<TextDecoration>(skia.getDecorationType());
+  txt.decoration_color = skia.getDecorationColor();
+  txt.decoration_style =
+      static_cast<TextDecorationStyle>(skia.getDecorationStyle());
+  txt.decoration_thickness_multiplier =
+      SkScalarToDouble(skia.getDecorationThicknessMultiplier());
+  txt.font_weight = GetTxtFontWeight(skia.getFontStyle().weight());
+  txt.font_style = GetTxtFontStyle(skia.getFontStyle().slant());
+
+  txt.text_baseline = static_cast<TextBaseline>(skia.getTextBaseline());
+
+  for (const SkString& font_family : skia.getFontFamilies()) {
+    txt.font_families.emplace_back(font_family.c_str());
+  }
+
+  txt.font_size = SkScalarToDouble(skia.getFontSize());
+  txt.letter_spacing = SkScalarToDouble(skia.getLetterSpacing());
+  txt.word_spacing = SkScalarToDouble(skia.getWordSpacing());
+  txt.height = SkScalarToDouble(skia.getHeight());
+
+  txt.locale = skia.getLocale().c_str();
+  if (skia.hasBackground()) {
+    txt.background = skia.getBackground();
+  }
+  if (skia.hasForeground()) {
+    txt.foreground = skia.getForeground();
+  }
+
+  txt.text_shadows.clear();
+  for (const skt::TextShadow& skia_shadow : skia.getShadows()) {
+    txt::TextShadow shadow;
+    shadow.offset = skia_shadow.fOffset;
+    shadow.blur_radius = skia_shadow.fBlurRadius;
+    shadow.color = skia_shadow.fColor;
+    txt.text_shadows.emplace_back(shadow);
+  }
+
+  return txt;
+}
+
+}  // anonymous namespace
+
 ParagraphSkia::ParagraphSkia(std::unique_ptr<skt::Paragraph> paragraph)
     : paragraph_(std::move(paragraph)) {}
 
 double ParagraphSkia::GetMaxWidth() {
-  return paragraph_->getMaxWidth();
+  return SkScalarToDouble(paragraph_->getMaxWidth());
 }
 
 double ParagraphSkia::GetHeight() {
-  return paragraph_->getHeight();
+  return SkScalarToDouble(paragraph_->getHeight());
 }
 
 double ParagraphSkia::GetLongestLine() {
-  // TODO: implement
-  return 0;
+  return SkScalarToDouble(paragraph_->getLongestLine());
+}
+
+std::vector<LineMetrics>& ParagraphSkia::GetLineMetrics() {
+  if (!line_metrics_) {
+    std::vector<skt::LineMetrics> metrics;
+    paragraph_->getLineMetrics(metrics);
+
+    line_metrics_.emplace();
+    for (const skt::LineMetrics& skm : metrics) {
+      LineMetrics& txtm = line_metrics_->emplace_back(
+          skm.fStartIndex, skm.fEndIndex, skm.fEndExcludingWhitespaces,
+          skm.fEndIncludingNewline, skm.fHardBreak);
+      txtm.ascent = skm.fAscent;
+      txtm.descent = skm.fDescent;
+      txtm.unscaled_ascent = skm.fUnscaledAscent;
+      txtm.height = skm.fHeight;
+      txtm.width = skm.fWidth;
+      txtm.left = skm.fLeft;
+      txtm.baseline = skm.fBaseline;
+      txtm.line_number = skm.fLineNumber;
+
+      for (const auto& sk_iter : skm.fLineMetrics) {
+        const skt::StyleMetrics& sk_style_metrics = sk_iter.second;
+        line_metrics_styles_.push_back(SkiaToTxt(*sk_style_metrics.text_style));
+        txtm.run_metrics.emplace(
+            std::piecewise_construct, std::forward_as_tuple(sk_iter.first),
+            std::forward_as_tuple(&line_metrics_styles_.back(),
+                                  sk_style_metrics.font_metrics));
+      }
+    }
+  }
+
+  return line_metrics_.value();
 }
 
 double ParagraphSkia::GetMinIntrinsicWidth() {
-  return paragraph_->getMinIntrinsicWidth();
+  return SkScalarToDouble(paragraph_->getMinIntrinsicWidth());
 }
 
 double ParagraphSkia::GetMaxIntrinsicWidth() {
-  return paragraph_->getMaxIntrinsicWidth();
+  return SkScalarToDouble(paragraph_->getMaxIntrinsicWidth());
 }
 
 double ParagraphSkia::GetAlphabeticBaseline() {
-  return paragraph_->getAlphabeticBaseline();
+  return SkScalarToDouble(paragraph_->getAlphabeticBaseline());
 }
 
 double ParagraphSkia::GetIdeographicBaseline() {
-  return paragraph_->getIdeographicBaseline();
+  return SkScalarToDouble(paragraph_->getIdeographicBaseline());
 }
 
 bool ParagraphSkia::DidExceedMaxLines() {
@@ -83,8 +180,15 @@ std::vector<Paragraph::TextBox> ParagraphSkia::GetRectsForRange(
 }
 
 std::vector<Paragraph::TextBox> ParagraphSkia::GetRectsForPlaceholders() {
-  // TODO: implement
-  return {};
+  std::vector<skt::TextBox> skia_boxes = paragraph_->getRectsForPlaceholders();
+
+  std::vector<Paragraph::TextBox> boxes;
+  for (const skt::TextBox skia_box : skia_boxes) {
+    boxes.emplace_back(skia_box.rect,
+                       static_cast<TextDirection>(skia_box.direction));
+  }
+
+  return boxes;
 }
 
 Paragraph::PositionWithAffinity ParagraphSkia::GetGlyphPositionAtCoordinate(

third_party/txt/src/skia/paragraph_skia.h

@@ -44,6 +44,8 @@ class ParagraphSkia : public Paragraph {
 
   double GetIdeographicBaseline() override;
 
+  std::vector<LineMetrics>& GetLineMetrics() override;
+
   bool DidExceedMaxLines() override;
 
   void Layout(double width) override;
@@ -65,6 +67,8 @@ class ParagraphSkia : public Paragraph {
 
  private:
   std::unique_ptr<skia::textlayout::Paragraph> paragraph_;
+  std::optional<std::vector<LineMetrics>> line_metrics_;
+  std::vector<TextStyle> line_metrics_styles_;
 };
 
 }  // namespace txt

third_party/txt/src/txt/run_metrics.h

@@ -27,7 +27,7 @@ class RunMetrics {
  public:
   RunMetrics(const TextStyle* style) : text_style(style) {}
 
-  RunMetrics(const TextStyle* style, SkFontMetrics& metrics)
+  RunMetrics(const TextStyle* style, const SkFontMetrics& metrics)
       : text_style(style), font_metrics(metrics) {}
 
   const TextStyle* text_style;