Windows implementation of multiline RenderText

ui/gfx/render_text.h

Index: ui/gfx/render_text.h
diff --git a/ui/gfx/render_text.h b/ui/gfx/render_text.h
index c4d48fd79058f9e81fb51816ea923052d7a02165..009aed1529288bc1d922e6fd600527057748fd92 100644
--- a/ui/gfx/render_text.h
+++ b/ui/gfx/render_text.h
@@ -13,6 +13,8 @@
 
 #include "base/gtest_prod_util.h"
 #include "base/i18n/rtl.h"
+#include "base/memory/scoped_vector.h"
+#include "base/stl_util.h"
 #include "base/strings/string16.h"
 #include "skia/ext/refptr.h"
 #include "third_party/skia/include/core/SkColor.h"
@@ -111,6 +113,35 @@ class StyleIterator {
   DISALLOW_COPY_AND_ASSIGN(StyleIterator);
 };
 
+struct LineSegment {
+  ui::Range x_pos; // x coord, in text coordinates.
+  ui::Range char_pos;
+};
+
+struct Line {
+  Line() : width(0),

[msw, 2013/07/17 06:47:18]

nit: make this all one line or indent intitializers to match |width|.

[ckocagil, 2013/07/19 19:40:50]

Done.

+    height(0),
+    preceding_heights(0),
+    baseline(0) {
+  }
+  Line(Line& other) {
+    *this = other;
+  }
+  Line& operator=(Line& other) {
+    width = other.width;
+    height = other.height;
+    preceding_heights = other.preceding_heights;
+    baseline = other.baseline;
+    segments.swap(other.segments);

[msw, 2013/07/17 06:47:18]

Swap makes this destructive to the right hand side of an assignment. Can you
avoid that, or is this okay because it's only used for STL containers? (if so
note that in a comment).

[ckocagil, 2013/07/19 19:40:50]

Yes, these are for STL containers only. I'm adding a comment for now. One way to
avoid this is to keep "ScopedVector<Line>" instead of "std::vector<Line>" which
would allow us to disallow copying and assigning. Let me know if you think the
latter solution would be better.

[msw, 2013/08/15 02:44:17]

Use ScopedVector and avoid copy/assign if possible and not too complex.

+    return *this;
+  }
+  ScopedVector<LineSegment> segments;
+  int width;
+  int height; // Maximum text height of all runs on this line.

[msw, 2013/07/17 06:47:18]

See Yuki's ongoing work to find common heights and baselines in:
https://codereview.chromium.org/19352002/
We'll want to use that logic to find per-line values.

+  int preceding_heights; // Sum of |height| fields of preceding lines.
+  int baseline; // Maximum baseline of all runs on this line.
+};
+
 }  // namespace internal
 
 // RenderText represents an abstract model of styled text and its corresponding
@@ -179,6 +210,9 @@ class UI_EXPORT RenderText {
   bool obscured() const { return obscured_; }
   void SetObscured(bool obscured);
 
+  bool multiline() const { return multiline_; }
+  void set_multiline(bool multiline) { multiline_ = multiline; }
+
   // Makes a char in obscured text at |index| to be revealed. |index| should be
   // a UTF16 text index. If there is a previous revealed index, the previous one
   // is cleared and only the last set index will be revealed. If |index| is -1
@@ -287,6 +321,11 @@ class UI_EXPORT RenderText {
   // the margin area of text shadows.
   virtual Size GetStringSize() = 0;
 
+  // Returns the size required to display the current multiline text, which is
+  // horizontally capped by the width of |display_rect()|.
+  // TODO(ckocagil): Merge with GetContentWidth.
+  virtual Size GetMultilineTextSize() = 0;
+
   // Returns the width of content, which reserves room for the cursor if
   // |cursor_enabled_| is true.
   int GetContentWidth();
@@ -347,6 +386,14 @@ class UI_EXPORT RenderText {
   const BreakList<SkColor>& colors() const { return colors_; }
   const std::vector<BreakList<bool> >& styles() const { return styles_; }
 
+  const std::vector<size_t>& line_breaks() const { return line_breaks_; }
+
+  const std::vector<internal::Line>& lines() const { return lines_; }
+  void set_lines(std::vector<internal::Line>* lines) { lines_.swap(*lines); }
+
+  bool lines_valid() const { return lines_valid_; }
+  void set_lines_valid(bool lines_valid) { lines_valid_ = lines_valid; }
+
   const Vector2d& GetUpdatedDisplayOffset();
 
   void set_cached_bounds_and_offset_valid(bool valid) {
@@ -405,7 +452,7 @@ class UI_EXPORT RenderText {
   // Reset the layout to be invalid.
   virtual void ResetLayout() = 0;
 
-  // Ensure the text is laid out.
+  // Ensure the text is laid out, lines are computed, and |lines_| is valid.
   virtual void EnsureLayout() = 0;
 
   // Draw the text.
@@ -418,18 +465,22 @@ class UI_EXPORT RenderText {
   void ApplyCompositionAndSelectionStyles();
   void UndoCompositionAndSelectionStyles();
 
-  // Returns the text offset from the origin after applying text alignment and
+  // Returns the line offset from the origin after applying text alignment and
   // display offset.
-  Vector2d GetTextOffset();
+  Vector2d GetLineOffset(int line);

[msw, 2013/07/17 06:47:18]

Rename to |line_number| to clarify the arg; and use size_t.

[ckocagil, 2013/07/19 19:40:50]

Done.

 
   // Convert points from the text space to the view space and back.
   // Handles the display area, display offset, and the application LTR/RTL mode.

[msw, 2013/07/17 06:47:18]

Update the comment, to reflect the new multi-line handling. Consider:
"Handles display area, display offset, LTR/RTL, and multi-line."

[ckocagil, 2013/07/19 19:40:50]

Done.

   Point ToTextPoint(const Point& point);
   Point ToViewPoint(const Point& point);
 
-  // Returns the text offset from the origin, taking into account text alignment
+  // Convert the range in text coordinates to rects in view coordinates that
+  // cover the given range.
+  std::vector<Rect> RangeToViewRects(const ui::Range& x);

[msw, 2013/07/17 06:47:18]

I'm trying to think of a better name, maybe: TextBoundsToViewBounds?

[ckocagil, 2013/07/19 19:40:50]

Changed to TextBoundsToViewBounds.

+
+  // Returns the line offset from the origin, taking into account text alignment
   // only.
-  Vector2d GetAlignmentOffset();
+  Vector2d GetAlignmentOffset(int line);

[msw, 2013/07/17 06:47:18]

Ditto: Rename to |line_number| to clarify the arg; and use size_t.

[ckocagil, 2013/07/19 19:40:50]

Done.

 
   // Applies fade effects to |renderer|.
   void ApplyFadeEffects(internal::SkiaTextRenderer* renderer);
@@ -546,6 +597,10 @@ class UI_EXPORT RenderText {
   // The obscured and/or truncated text that will be displayed.
   base::string16 layout_text_;
 
+  // Whether the text should be broken into multiple lines. Uses the width of
+  // |display_rect_| as the width cap.
+  bool multiline_;
+
   // Fade text head and/or tail, if text doesn't fit into |display_rect_|.
   bool fade_head_;
   bool fade_tail_;
@@ -573,6 +628,16 @@ class UI_EXPORT RenderText {
   // Text shadows to be drawn.
   ShadowValues text_shadows_;
 
+  // Positions at which we can break the line.
+  std::vector<size_t> line_breaks_;
+
+  // Lines computed by EnsureLayout. Valid when |lines_valid_| is true.
+  std::vector<internal::Line> lines_;
+
+  // Whether the current |lines_| is valid. |lines_| is invalidated whenever

[msw, 2013/07/17 06:47:18]

Since we reconstruct |lines_| on ComputeLines, can we just use an empty vector
via lines_.clear() to mark |lines_| invalid?

[ckocagil, 2013/07/19 19:40:50]

Done.

+  // the text, styles or |display_rect_| changes.
+  bool lines_valid_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderText);
 };