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- // 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.
- #ifndef UI_GFX_SELECTION_MODEL_H_
- #define UI_GFX_SELECTION_MODEL_H_
- #include <stddef.h>
- #include <vector>
- #include <iosfwd>
- #include <string>
- #include "ui/gfx/gfx_export.h"
- #include "ui/gfx/range/range.h"
- namespace gfx {
- // VisualCursorDirection and LogicalCursorDirection represent directions of
- // motion of the cursor in BiDi text. The combinations that make sense are:
- //
- // base::i18n::TextDirection VisualCursorDirection LogicalCursorDirection
- // LEFT_TO_RIGHT CURSOR_LEFT CURSOR_BACKWARD
- // LEFT_TO_RIGHT CURSOR_RIGHT CURSOR_FORWARD
- // RIGHT_TO_LEFT CURSOR_RIGHT CURSOR_BACKWARD
- // RIGHT_TO_LEFT CURSOR_LEFT CURSOR_FORWARD
- enum VisualCursorDirection {
- CURSOR_LEFT,
- CURSOR_RIGHT,
- CURSOR_UP,
- CURSOR_DOWN
- };
- enum LogicalCursorDirection {
- CURSOR_BACKWARD,
- CURSOR_FORWARD
- };
- // TODO(xji): publish bidi-editing guide line and replace the place holder.
- // SelectionModel is used to represent the logical selection and visual
- // position of cursor.
- //
- // For bi-directional text, the mapping between visual position and logical
- // position is not one-to-one. For example, logical text "abcDEF" where capital
- // letters stand for Hebrew, the visual display is "abcFED". According to the
- // bidi editing guide (http://bidi-editing-guideline):
- // 1. If pointing to the right half of the cell of a LTR character, the current
- // position must be set after this character and the caret must be displayed
- // after this character.
- // 2. If pointing to the right half of the cell of a RTL character, the current
- // position must be set before this character and the caret must be displayed
- // before this character.
- //
- // Pointing to the right half of 'c' and pointing to the right half of 'D' both
- // set the logical cursor position to 3. But the cursor displayed visually at
- // different places:
- // Pointing to the right half of 'c' displays the cursor right of 'c' as
- // "abc|FED".
- // Pointing to the right half of 'D' displays the cursor right of 'D' as
- // "abcFED|".
- // So, besides the logical selection start point and end point, we need extra
- // information to specify to which character the visual cursor is bound. This
- // is given by a "caret affinity" which is either CURSOR_BACKWARD (indicating
- // the trailing half of the 'c' in this case) or CURSOR_FORWARD (indicating
- // the leading half of the 'D').
- class GFX_EXPORT SelectionModel {
- public:
- // Create a default SelectionModel to be overwritten later.
- SelectionModel();
- // Create a SelectionModel representing a caret |position| without a
- // selection. The |affinity| is meaningful only when the caret is positioned
- // between bidi runs that are not visually contiguous: in that case, it
- // indicates the run to which the caret is attached for display purposes.
- SelectionModel(size_t position, LogicalCursorDirection affinity);
- // Create a SelectionModel representing a selection (which may be empty).
- // The caret position is the end of the range.
- SelectionModel(const Range& selection, LogicalCursorDirection affinity);
- // Create a SelectionModel representing multiple selections (which may be
- // empty but not overlapping). The end of the first range determines the caret
- // position.
- SelectionModel(const std::vector<Range>& selections,
- LogicalCursorDirection affinity);
- SelectionModel(const SelectionModel& selection_model);
- ~SelectionModel();
- // |selection| should overlap with neither |selection_| nor
- // |secondary_selections_|.
- void AddSecondarySelection(const Range& selection);
- const Range& selection() const { return selection_; }
- size_t caret_pos() const { return selection_.end(); }
- LogicalCursorDirection caret_affinity() const { return caret_affinity_; }
- const std::vector<Range>& secondary_selections() const {
- return secondary_selections_;
- }
- std::vector<Range> GetAllSelections() const;
- // WARNING: Generally the selection start should not be changed without
- // considering the effect on the caret affinity.
- void set_selection_start(uint32_t pos) { selection_.set_start(pos); }
- bool operator==(const SelectionModel& sel) const;
- bool operator!=(const SelectionModel& sel) const { return !(*this == sel); }
- std::string ToString() const;
- private:
- // Logical selection. The logical caret position is the end of the selection.
- Range selection_;
- // Secondary selections not associated with the cursor. Do not overlap.
- std::vector<Range> secondary_selections_;
- // The logical direction from the caret position (selection_.end()) to the
- // character it is attached to for display purposes. This matters only when
- // the surrounding characters are not visually contiguous, which happens only
- // in bidi text (and only at bidi run boundaries). The text is treated as
- // though it was surrounded on both sides by runs in the dominant text
- // direction. For example, supposing the dominant direction is LTR and the
- // logical text is "abcDEF", where DEF is right-to-left text, the visual
- // cursor will display as follows:
- // caret position CURSOR_BACKWARD affinity CURSOR_FORWARD affinity
- // 0 |abcFED |abcFED
- // 1 a|bcFED a|bcFED
- // 2 ab|cFED ab|cFED
- // 3 abc|FED abcFED|
- // 4 abcFE|D abcFE|D
- // 5 abcF|ED abcF|ED
- // 6 abc|FED abcFED|
- LogicalCursorDirection caret_affinity_;
- };
- GFX_EXPORT std::ostream& operator<<(std::ostream& out,
- const SelectionModel& model);
- } // namespace gfx
- #endif // UI_GFX_SELECTION_MODEL_H_
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