[LayoutNG] Initial letter-spacing and word-spacing support

third_party/WebKit/Source/platform/fonts/shaping/ShapeResultSpacing.cpp

Index: third_party/WebKit/Source/platform/fonts/shaping/ShapeResultSpacing.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/shaping/ShapeResultSpacing.cpp b/third_party/WebKit/Source/platform/fonts/shaping/ShapeResultSpacing.cpp
index 4f9c362bea108eca4b1d720a1ba00b43018eaffd..5c597de643a50e4b8d5de9fc649976a56310dba9 100644
--- a/third_party/WebKit/Source/platform/fonts/shaping/ShapeResultSpacing.cpp
+++ b/third_party/WebKit/Source/platform/fonts/shaping/ShapeResultSpacing.cpp
@@ -9,39 +9,80 @@
 
 namespace blink {
 
-ShapeResultSpacing::ShapeResultSpacing(const TextRun& run,
-                                       const FontDescription& font_description)
-    : text_run_(run),
-      letter_spacing_(font_description.LetterSpacing()),
-      word_spacing_(font_description.WordSpacing()),
-      expansion_(run.Expansion()),
+template <typename TextContainerType>
+ShapeResultSpacing<TextContainerType>::ShapeResultSpacing(
+    const TextContainerType& text)
+    : text_(text),
+      letter_spacing_(0),
+      word_spacing_(0),
+      expansion_(0),
       expansion_per_opportunity_(0),
       expansion_opportunity_count_(0),
       text_justify_(TextJustify::kTextJustifyAuto),
       has_spacing_(false),
-      normalize_space_(run.NormalizeSpace()),
-      allow_tabs_(run.AllowTabs()),
+      normalize_space_(false),
+      allow_tabs_(false),
       is_after_expansion_(false),
-      is_vertical_offset_(font_description.IsVerticalAnyUpright()) {
-  if (text_run_.SpacingDisabled())
-    return;
-
-  if (!letter_spacing_ && !word_spacing_ && !expansion_)
-    return;
+      is_vertical_offset_(false) {}
+
+template <typename TextContainerType>
+bool ShapeResultSpacing<TextContainerType>::SetSpacing(
+    const FontDescription& font_description) {
+  if (!font_description.LetterSpacing() && !font_description.WordSpacing()) {
+    has_spacing_ = false;
+    return false;
+  }
 
+  letter_spacing_ = font_description.LetterSpacing();
+  word_spacing_ = font_description.WordSpacing();
+  is_vertical_offset_ = font_description.IsVerticalAnyUpright();
+  DCHECK(!normalize_space_);
+  allow_tabs_ = true;
   has_spacing_ = true;
+  return true;
+}
+
+template <typename TextContainerType>
+void ShapeResultSpacing<TextContainerType>::SetSpacingAndExpansion(
+    const FontDescription& font_description) {
+  // Available only for TextRun since it has expansion data.
+  NOTREACHED();
+}
 
-  if (!expansion_)
+template <>
+void ShapeResultSpacing<TextRun>::SetSpacingAndExpansion(
+    const FontDescription& font_description) {
+  letter_spacing_ = font_description.LetterSpacing();
+  word_spacing_ = font_description.WordSpacing();
+  expansion_ = text_.Expansion();
+  has_spacing_ = letter_spacing_ || word_spacing_ || expansion_;
+  if (!has_spacing_)
     return;
 
-  // Setup for justifications (expansions.)
-  text_justify_ = run.GetTextJustify();
-  is_after_expansion_ = !run.AllowsLeadingExpansion();
+  is_vertical_offset_ = font_description.IsVerticalAnyUpright();
+  normalize_space_ = text_.NormalizeSpace();
+  allow_tabs_ = text_.AllowTabs();
+
+  if (expansion_) {
+    ComputeExpansion(text_.AllowsLeadingExpansion(),
+                     text_.AllowsTrailingExpansion(), text_.GetTextJustify());
+  }
+}
+
+template <typename TextContainerType>
+void ShapeResultSpacing<TextContainerType>::ComputeExpansion(
+    bool allows_leading_expansion,
+    bool allows_trailing_expansion,
+    TextJustify text_justify) {
+  DCHECK_GT(expansion_, 0);
+
+  text_justify_ = text_justify;
+  is_after_expansion_ = !allows_leading_expansion;
 
   bool is_after_expansion = is_after_expansion_;
   expansion_opportunity_count_ =
-      Character::ExpansionOpportunityCount(run, is_after_expansion);
-  if (is_after_expansion && !run.AllowsTrailingExpansion()) {
+      Character::ExpansionOpportunityCount(text_, is_after_expansion);
+  if (is_after_expansion && !allows_trailing_expansion) {
     DCHECK_GT(expansion_opportunity_count_, 0u);
     --expansion_opportunity_count_;
   }
@@ -50,7 +91,8 @@ ShapeResultSpacing::ShapeResultSpacing(const TextRun& run,
     expansion_per_opportunity_ = expansion_ / expansion_opportunity_count_;
 }
 
-float ShapeResultSpacing::NextExpansion() {
+template <typename TextContainerType>
+float ShapeResultSpacing<TextContainerType>::NextExpansion() {
   if (!expansion_opportunity_count_) {
     NOTREACHED();
     return 0;
@@ -68,16 +110,18 @@ float ShapeResultSpacing::NextExpansion() {
   return expansion_per_opportunity_;
 }
 
-bool ShapeResultSpacing::IsFirstRun(const TextRun& run) const {
-  if (&run == &text_run_)
-    return true;
-  return run.Is8Bit() ? run.Characters8() == text_run_.Characters8()
-                      : run.Characters16() == text_run_.Characters16();
+template <typename TextContainerType>
+bool ShapeResultSpacing<TextContainerType>::IsFirstRun(
+    const TextContainerType& run) const {
+  return &run == &text_ || run.Bytes() == text_.Bytes();
 }
 
-float ShapeResultSpacing::ComputeSpacing(const TextRun& run,
-                                         size_t index,
-                                         float& offset) {
+template <typename TextContainerType>
+float ShapeResultSpacing<TextContainerType>::ComputeSpacing(
+    const TextContainerType& run,
+    size_t index,
+    float& offset) {
+  DCHECK(has_spacing_);
   UChar32 character = run[index];
   bool treat_as_space =
       (Character::TreatAsSpace(character) ||
@@ -129,4 +173,8 @@ float ShapeResultSpacing::ComputeSpacing(const TextRun& run,
   return spacing + NextExpansion();
 }
 
+// Instantiate the template class.
+template class ShapeResultSpacing<TextRun>;
+template class ShapeResultSpacing<StringView>;
+
 }  // namespace blink