RenderText API Outline.

ui/gfx/render_text.h

+// 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 <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 {
+
+// Strike line width.
+const int kStrikeWidth = 2;
+
+// Color settings for text, backgrounds and cursor.
+// These are tentative, and should be derived from theme, system
+// settings and current settings.
+// TODO(oshima): Change this to match the standard chrome
+// before dogfooding textfield views.
+const SkColor kSelectedTextColor = SK_ColorWHITE;
+const SkColor kFocusedSelectionColor = SK_ColorCYAN;
+const SkColor kUnfocusedSelectionColor = SK_ColorLTGRAY;
+const SkColor kCursorColor = SK_ColorBLACK;
+
+}  // namespace
+
+namespace gfx {
+
+class Canvas;
+class RenderTextTest;
+
+// A visual style applicable to a range of text.
+struct UI_API StyleRange {
+  StyleRange();
+
+  Font font;
+  SkColor foreground;
+  bool strike;
+  bool underline;
+  ui::Range range;
+};
+
+typedef std::vector<StyleRange> StyleRanges;
+
+// TODO(msw): Distinguish between logical character and glyph?
+enum BreakType {
+  CHARACTER_BREAK,
+  WORD_BREAK,
+  LINE_BREAK,
+};
+
+// 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 UI_API 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);
+
+  bool cursor_visible() const { return cursor_visible_; }
+  void set_cursor_visible(bool visible) { cursor_visible_ = visible; }
+
+  bool insert_mode() const { return insert_mode_; }
+  void toggle_insert_mode() { insert_mode_ = !insert_mode_; }
+
+  bool focused() const { return focused_; }
+  void set_focused(bool focused) { focused_ = focused; }
+
+  const StyleRange& default_style() const { return default_style_; }
+  void set_default_style(StyleRange style) { default_style_ = style; }
+
+  const gfx::Rect& display_rect() const { return display_rect_; }
+  void set_display_rect(const gfx::Rect& r) { display_rect_ = r; }
+
+  size_t GetCursorPosition() const;
+  void SetCursorPosition(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 |break_type| is CHARACTER_BREAK, move to the neighboring character.
+  // If |break_type| is WORD_BREAK, move to the nearest word boundary.
+  // If |break_type| is LINE_BREAK, move to text edge as shown on screen.
+  void MoveCursorLeft(BreakType break_type, bool select);
+  void MoveCursorRight(BreakType break_type, 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);
+
+  // Move the cursor to the position associated with the clicked point.
+  // If |select| is false, the selection range is emptied at the new position.
+  bool MoveCursorTo(const gfx::Point& point, bool select);
+
+  const ui::Range& GetSelection() const;
+  void SetSelection(const ui::Range& range);
+
+  // Returns true if the local point is over selected text.
+  bool IsPointInSelection(const gfx::Point& point) const;
+
+  // Selects no text, all text, or the word at the current cursor position.
+  void ClearSelection();
+  void SelectAll();
+  void SelectWord();
+
+  const ui::Range& GetCompositionRange() const;
+  void SetCompositionRange(const ui::Range& composition_range);
+
+  // Apply |style_range| to the internal style model.
+  virtual void ApplyStyleRange(StyleRange style_range);
+
+  // Apply |default_style_| over the entire text range.
+  virtual void ApplyDefaultStyle();
+
+  base::i18n::TextDirection GetTextDirection() const;
+
+  // Get the width of the entire string.
+  int GetStringWidth() const;
+
+  virtual void Draw(gfx::Canvas* canvas);
+
+  // TODO(msw): Deprecate this function. Logical and visual cursors are not
+  //  mapped one-to-one. See the selection_range_ TODO for more information.
+  // 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 an odd number of 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();
+
+  const StyleRanges& style_ranges() const { return style_ranges_; }
+
+  const gfx::Point& display_offset() const { return display_offset_; }
+
+  // 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();
+
+  bool IsPositionAtWordSelectionBoundary(size_t pos);
+
+  // Logical UTF-16 string data to be drawn.
+  string16 text_;
+
+  // TODO(msw): A single logical cursor position doesn't support two potential
+  //  visual cursor positions. For example, clicking right of 'c' & 'D' yeilds:
+  //  (visually: 'abc|FEDghi' and 'abcFED|ghi', both logically: 'abc|DEFghi').
+  //  Similarly, one visual position may have two associated logical positions.
+  //  For example, clicking the right side of 'D' and left side of 'g' yields:
+  //  (both visually: 'abcFED|ghi', logically: 'abc|DEFghi' and 'abcDEF|ghi').
+  //  Update the cursor model with a leading/trailing flag, a level association,
+  //  or a disjoint visual position to satisfy the proposed visual behavior.
+  // Logical selection range; the range end is also the logical cursor position.
+  ui::Range selection_range_;
+
+  // The cursor visibility and insert mode.
+  bool cursor_visible_;
+  bool insert_mode_;
+
+  // The focus state of the text.
+  bool 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_;
+
+  // 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_;
+
+  DISALLOW_COPY_AND_ASSIGN(RenderText);
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_RENDER_TEXT_H_