Windows implementation of multiline RenderText

ui/gfx/render_text.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/render_text.h"
 
 #include <algorithm>
 
 #include "base/i18n/break_iterator.h"
 #include "base/logging.h"
@@ skipping 290 matching lines @@
     style_[i] = styles_[i].GetBreak(position);
 }
 
 }  // namespace internal
 
 RenderText::~RenderText() {
 }
 
 void RenderText::SetText(const base::string16& text) {
   DCHECK(!composition_range_.IsValid());
+  if (text_ == text)
+    return;
   text_ = text;
 
   // Adjust ranged styles and colors to accommodate a new text length.
   const size_t text_length = text_.length();
   colors_.SetMax(text_length);
   for (size_t style = 0; style < NUM_TEXT_STYLES; ++style)
     styles_[style].SetMax(text_length);
   cached_bounds_and_offset_valid_ = false;
 
   // Reset selection model. SetText should always followed by SetSelectionModel
@@ skipping 69 matching lines @@
 
   obscured_reveal_index_ = index;
   cached_bounds_and_offset_valid_ = false;
   UpdateLayoutText();
   ResetLayout();
 }
 
 void RenderText::SetDisplayRect(const Rect& r) {
   display_rect_ = r;
   cached_bounds_and_offset_valid_ = false;
+  lines_.clear();
 }
 
 void RenderText::SetCursorPosition(size_t position) {
   MoveCursorTo(position, false);
 }
 
 void RenderText::MoveCursor(BreakType break_type,
                             VisualCursorDirection direction,
                             bool select) {
   SelectionModel position(cursor_position(), selection_model_.caret_affinity());
@@ skipping 346 matching lines @@
       selection_color_(kDefaultColor),
       selection_background_focused_color_(kDefaultSelectionBackgroundColor),
       focused_(false),
       composition_range_(ui::Range::InvalidRange()),
       colors_(kDefaultColor),
       styles_(NUM_TEXT_STYLES),
       composition_and_selection_styles_applied_(false),
       obscured_(false),
       obscured_reveal_index_(-1),
       truncate_length_(0),
+      multiline_(false),
       fade_head_(false),
       fade_tail_(false),
       background_is_transparent_(false),
       clip_to_display_rect_(true),
       cached_bounds_and_offset_valid_(false) {
 }
 
 const Vector2d& RenderText::GetUpdatedDisplayOffset() {
   UpdateCachedBoundsAndOffset();
   return display_offset_;
@@ skipping 49 matching lines @@
 }
 
 void RenderText::UndoCompositionAndSelectionStyles() {
   // Restore the underline and color breaks to undo the temporary styles.
   DCHECK(composition_and_selection_styles_applied_);
   colors_ = saved_colors_;
   styles_[UNDERLINE] = saved_underlines_;
   composition_and_selection_styles_applied_ = false;
 }
 
-Vector2d RenderText::GetTextOffset() {
+Vector2d RenderText::GetLineOffset(size_t line_number) {
   Vector2d offset = display_rect().OffsetFromOrigin();
-  offset.Add(GetUpdatedDisplayOffset());
-  offset.Add(GetAlignmentOffset());
+  if (!multiline())
+    offset.Add(GetUpdatedDisplayOffset());
+  else
+    offset.Add(Vector2d(0, lines()[line_number].preceding_heights));
+  offset.Add(GetAlignmentOffset(line_number));
   return offset;
 }
 
 Point RenderText::ToTextPoint(const Point& point) {
-  return point - GetTextOffset();
+  return point - GetLineOffset(0);
+  // TODO(ckocagil): implement multiline.
 }
 
 Point RenderText::ToViewPoint(const Point& point) {
-  return point + GetTextOffset();
+  if (!multiline())
+    return point + GetLineOffset(0);
+
+  // TODO(ckocagil): refactor this to traverse all line segments to support rtl.
+  DCHECK(!lines_.empty());
+  int x = point.x();
+  unsigned int line = 0;
+  while (line < lines_.size() && x > lines()[line].width) {
+    x -= lines()[line].width;
+    ++line;
+  }
+  return Point(x, point.y()) + GetLineOffset(line);
 }
 
-Vector2d RenderText::GetAlignmentOffset() {
+std::vector<Rect> RenderText::TextBoundsToViewBounds(const ui::Range& x) {
+  std::vector<Rect> rects;
+
+  if (!multiline()) {
+    rects.push_back(Rect(ToViewPoint(Point(x.GetMin(), 0)),
+                         Size(x.length(), GetStringSize().height())));
+    return rects;
+  }
+
+  EnsureLayout();
+
+  // Each line segments keeps its position in text coordinates. Traverse all
+  // line segments and if the segment intersects with the given range, add the
+  // view rect corresponding to the intersection to |rects|.
+  for (size_t line = 0; line < lines().size(); ++line) {
+    int line_x = 0;
+    Vector2d offset = GetLineOffset(line);
+    for (size_t i = 0; i < lines()[line].segments.size(); ++i) {
+      const internal::LineSegment* segment = lines()[line].segments[i];
+      ui::Range intersection = segment->x_pos.Intersect(x);
+      if (!intersection.is_empty()) {
+        Rect rect(line_x + intersection.start() - segment->x_pos.start(),
+                  0, intersection.length(), lines()[line].height);
+        rect += offset;
+        rects.push_back(rect);
+      }
+      line_x += segment->x_pos.length();
+    }
+  }
+
+  return rects;
+}
+
+
+Vector2d RenderText::GetAlignmentOffset(size_t line_number) {
+  DCHECK(!lines_.empty());
+  const int width = lines()[line_number].width;
   Vector2d offset;
   if (horizontal_alignment_ != ALIGN_LEFT) {
-    offset.set_x(display_rect().width() - GetContentWidth());
+    offset.set_x(display_rect().width() - width);
     if (horizontal_alignment_ == ALIGN_CENTER)
       offset.set_x(offset.x() / 2);
   }
   if (vertical_alignment_ != ALIGN_TOP) {
-    offset.set_y(display_rect().height() - GetStringSize().height());
+    offset.set_y(display_rect().height() - GetMultilineTextSize().height());
     if (vertical_alignment_ == ALIGN_VCENTER)
       offset.set_y(offset.y() / 2);
   }
   return offset;
 }
 
 void RenderText::ApplyFadeEffects(internal::SkiaTextRenderer* renderer) {
-  if (!fade_head() && !fade_tail())
+  if (multiline() || !fade_head() && !fade_tail())
     return;
 
-  const int text_width = GetStringSize().width();
   const int display_width = display_rect().width();
 
   // If the text fits as-is, no need to fade.
-  if (text_width <= display_width)
+  if (GetStringSize().width() <= display_width)
     return;
 
   int gradient_width = CalculateFadeGradientWidth(GetFont(), display_width);
   if (gradient_width == 0)
     return;
 
   bool fade_left = fade_head();
   bool fade_right = fade_tail();
   // Under RTL, |fade_right| == |fade_head|.
   // TODO(asvitkine): This is currently not based on GetTextDirection() because
@@ skipping 10 matching lines @@
     left_part.Inset(0, 0, solid_part.width() - gradient_width, 0);
     solid_part.Inset(gradient_width, 0, 0, 0);
   }
   if (fade_right) {
     right_part = solid_part;
     right_part.Inset(solid_part.width() - gradient_width, 0, 0, 0);
     solid_part.Inset(0, 0, gradient_width, 0);
   }
 
   Rect text_rect = display_rect();
-  text_rect.Inset(GetAlignmentOffset().x(), 0, 0, 0);
+  text_rect.Inset(GetAlignmentOffset(0).x(), 0, 0, 0);
 
   // TODO(msw): Use the actual text colors corresponding to each faded part.
   skia::RefPtr<SkShader> shader = CreateFadeShader(
       text_rect, left_part, right_part, colors_.breaks().front().second);
   if (shader)
     renderer->SetShader(shader.get(), display_rect());
 }
 
 void RenderText::ApplyTextShadows(internal::SkiaTextRenderer* renderer) {
   skia::RefPtr<SkDrawLooper> looper = CreateShadowDrawLooper(text_shadows_);
@@ skipping 43 matching lines @@
     }
   }
 
   const base::string16& text = obscured_ ? layout_text_ : text_;
   if (truncate_length_ > 0 && truncate_length_ < text.length()) {
     // Truncate the text at a valid character break and append an ellipsis.
     icu::StringCharacterIterator iter(text.c_str());
     iter.setIndex32(truncate_length_ - 1);
     layout_text_.assign(text.substr(0, iter.getIndex()) + ui::kEllipsisUTF16);
   }
+
+  const string16& layout_text = GetLayoutText();
+  line_breaks_.SetValue(0);
+  line_breaks_.SetMax(layout_text.length());
+  base::i18n::BreakIterator iter(layout_text,
+                                 base::i18n::BreakIterator::BREAK_LINE);

[Alexei Svitkine (slow), 2013/07/22 20:52:05]

There's a comment in download_item_view.cc that BREAK_LINE can be slow
(especially for CJK).

As such, I'm worried that you're now doing it unconditionally every time we do
text layout.

At the very least, you shouldn't do it unless the instance is multi-line
enabled. But also, it might make sense to do it lazily completely. For example,
if your algorithm first tries to add a run completely to see if it fits in the
current line and if it does, then there's no line break analysis needed to be
done on that run at all. So perhaps this should be done per-run on an as-needed
basis.

[ckocagil, 2013/08/07 12:59:20]

Done, it's completely lazy now.

+  bool success = iter.Init();
+  CHECK(success);
+  do {
+    line_breaks_.ApplyValue(iter.pos(),
+                            ui::Range(iter.pos(), layout_text.length()));
+  } while (iter.Advance());
 }
 
 void RenderText::UpdateCachedBoundsAndOffset() {
   if (cached_bounds_and_offset_valid_)
     return;
 
+  // TODO(ckocagil): Add vertical offset support for scrolling multi-line text.
+
   // First, set the valid flag true to calculate the current cursor bounds using
   // the stale |display_offset_|. Applying |delta_offset| at the end of this
   // function will set |cursor_bounds_| and |display_offset_| to correct values.
   cached_bounds_and_offset_valid_ = true;
   cursor_bounds_ = GetCursorBounds(selection_model_, insert_mode_);
 
   // Update |display_offset_| to ensure the current cursor is visible.
   const int display_width = display_rect_.width();
   const int content_width = GetContentWidth();
 
@@ skipping 30 matching lines @@
   cursor_bounds_ += delta_offset;
 }
 
 void RenderText::DrawSelection(Canvas* canvas) {
   const std::vector<Rect> sel = GetSubstringBounds(selection());
   for (std::vector<Rect>::const_iterator i = sel.begin(); i < sel.end(); ++i)
     canvas->FillRect(*i, selection_background_focused_color_);
 }
 
 }  // namespace gfx