RenderText API Outline.

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
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+// Copyright (c) 2011 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.
+
+#ifndef UI_GFX_RENDER_TEXT_H_
+#define UI_GFX_RENDER_TEXT_H_
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "base/gtest_prod_util.h"
+#include "base/i18n/rtl.h"
+#include "base/string16.h"
+#include "third_party/skia/include/core/SkColor.h"
+#include "ui/base/range/range.h"
+#include "ui/gfx/font.h"
+#include "ui/gfx/rect.h"
+#include "ui/gfx/point.h"
+
+namespace {
+class RenderTextTest;
+}
+
+namespace gfx {
+
+class Canvas;
+
+struct StyleRange {
+
+  StyleRange::StyleRange()
+      : font(),
+        foreground(SK_ColorBLACK),
+        strike(false),
+        underline(false),
+        range() {
+  }
+
+  Font font;
+  SkColor foreground;
+  // TODO(msw): SkColor background; ???
+  bool strike;
+  bool underline;
+  ui::Range range;
+};
+
+typedef std::vector<StyleRange> StyleRanges;
+
+// TODO(msw): Implement RenderText[Win|Linux] for Uniscribe/Pango BiDi...
+
+// RenderText represents an abstract model of styled text and its corresponding
+// visual layout. Support is built in for a cursor, a selection, simple styling,
+// complex scripts, and bi-directional text. Implementations provide mechanisms
+// for rendering and translation between logical and visual data.
+class RenderText {
+ public:
+  virtual ~RenderText();
+
+  // Creates a platform-specific RenderText instance.
+  static RenderText* CreateRenderText();
+
+  const string16& text() const { return text_; }
+  virtual void SetText(const string16& text);
+
+  void set_cursor_visible(bool visible) { is_cursor_visible_ = visible; }
+
+  bool get_insert_mode() const { return insert_mode_; }
+  void set_insert_mode(bool insert_mode) { insert_mode_ = insert_mode; }
+
+  void set_focused(bool focused) { is_focused_ = focused; }
+
+  // TODO(msw): Make protected, fix RenderTextTest friending.
+  const StyleRanges& get_style_ranges() const { return style_ranges_; }
+
+  void set_default_style(StyleRange style) { default_style_ = style; }
+
+  const gfx::Rect& get_display_rect() const { return display_rect_; }
+  void set_display_rect(const gfx::Rect& r) { display_rect_ = r; }
+
+  int get_flags() const { return flags_; }
+  void set_flags(int flags) { flags_ = flags; }
+
+  size_t GetCursor() const;
+  void SetCursor(const size_t position);
+
+  // Moves the cursor left or right. Cursor movement is visual, meaning that
+  // left and right are relative to screen, not the directionality of the text.
+  // If |select| is false, the selection range is emptied at the new position.
+  // If |move_by_word| is true, the cursor moves to the nearest word boundary.
+  void MoveCursorLeft(bool select, bool move_by_word);
+  void MoveCursorRight(bool select, bool move_by_word);
+
+  // Moves the cursor to left or right end of the text as shown on screen.
+  // If |select| is false, the selection range is emptied at the new position.
+  void MoveCursorToLeftEnd(bool select);
+  void MoveCursorToRightEnd(bool select);
+
+  // Moves the cursor to the specified logical |position|.
+  // If |select| is false, the selection range is emptied at the new position.
+  // Returns true if the cursor position or selection range changed.
+  bool MoveCursorTo(size_t position, bool select);
+
+  const ui::Range& GetSelection() const;
+  void SetSelection(const ui::Range& range);
+
+  // Selects no text, all text, or the word at the current cursor position.
+  void ClearSelection();
+  void SelectAll();
+  void SelectWord();
+
+  const ui::Range& GetComposition() const;
+  void SetComposition(const ui::Range& composition_range);
+
+  // Apply |style_range| to the internal style model.
+  void ApplyStyleRange(StyleRange style_range);
+  // Apply |default_style_| over the entire text range.
+  void ApplyDefaultStyle();
+
+  base::i18n::TextDirection GetTextDirection() const;
+
+  // Get the width of the entire string.
+  int GetStringWidth() const;
+
+  virtual void Draw(gfx::Canvas* canvas) const;
+
+  // Get the logical cursor position from a visual point in local coordinates.
+  virtual size_t FindCursorPosition(const gfx::Point& point) const;
+
+  // Get the visual bounds containing the logical substring within |range|.
+  // These bounds could be visually discontiguous if the logical selection range
+  // is split by a single LTR/RTL level change.
+  virtual std::vector<gfx::Rect> GetSubstringBounds(
+      const ui::Range& range) const;
+
+  // Get the visual bounds describing the cursor at |position|. These bounds
+  // typically represent a vertical line, but if |insert_mode| is true they
+  // contain the bounds of the associated glyph.
+  virtual gfx::Rect GetCursorBounds(size_t position, bool insert_mode) const;
+
+ protected:
+  RenderText();
+
+  // Get the cursor position that visually neighbors |position|.
+  // If |move_by_word| is true, return the neighboring word delimiter position.
+  virtual size_t GetLeftCursorPosition(size_t position,
+                                       bool move_by_word) const;
+  virtual size_t GetRightCursorPosition(size_t position,
+                                        bool move_by_word) const;
+
+ private:
+   friend class ::RenderTextTest;
+
+  FRIEND_TEST_ALL_PREFIXES(RenderTextTest, DefaultStyle);
+  FRIEND_TEST_ALL_PREFIXES(RenderTextTest, CustomDefaultStyle);
+  FRIEND_TEST_ALL_PREFIXES(RenderTextTest, ApplyStyleRange);
+  FRIEND_TEST_ALL_PREFIXES(RenderTextTest, StyleRangesAdjust);
+
+  // Clear out |style_ranges_|.
+  void ClearStyleRanges();
+
+  // TODO(msw): Revise SelectWord to eliminate this?
+  bool IsPositionAtWordSelectionBoundary(size_t pos);
+
+  // Logical UTF-16 string data to be drawn.
+  string16 text_;
+
+  // Logical selection range; the range end is also the logical cursor position.
+  ui::Range selection_range_;
+
+  // The cursor visibility and insert mode.
+  bool is_cursor_visible_;
+  bool insert_mode_;
+
+  // The focus state of the text.
+  bool is_focused_;
+
+  // Composition text range.
+  ui::Range composition_range_;
+
+  // List of style ranges. Elements in the list never overlap each other.
+  StyleRanges style_ranges_;
+  // The default text style.
+  StyleRange default_style_;
+  // TODO(msw): Use StyleRange selection_style_ and composition_style_?
+
+  // The local display area for rendering the text.
+  gfx::Rect display_rect_;
+  // The offset for the text to be drawn, relative to the display area.
+  gfx::Point display_offset_;
+
+  // TODO(msw): Cache these bounds?
+  // The visual cursor bounds. These bounds typically represent a vertical line,
+  // but in insert mode they contain the bounds of the associated glyph.
+  //gfx::Rect cursor_bounds_;
+  // The visual selection bounds. These bounds could be visually discontiguous
+  // if the logical selection range is split by a single LTR/RTL level change.
+  //std::vector<gfx::Rect> selection_bounds_;
+
+  // Rendering flags, defined in Canvas.
+  int flags_;
+
+  DISALLOW_COPY_AND_ASSIGN(RenderText);
+};
+
+}  // namespace gfx;
+
+#endif  // UI_GFX_RENDER_TEXT_H_