| // 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_BASE_MODELS_LIST_SELECTION_MODEL_H_ |
| #define UI_BASE_MODELS_LIST_SELECTION_MODEL_H_ |
| |
| #include <stddef.h> |
| |
| #include <vector> |
| |
| #include "ui/base/ui_base_export.h" |
| |
| namespace ui { |
| |
| // Selection model represented as a list of ints. In addition to the set of |
| // selected indices ListSelectionModel maintains the following: |
| // |
| // active: The index of the currently visible item in the list. This will be |
| // kUnselectedIndex if nothing is selected. |
| // |
| // anchor: The index of the last item the user clicked on. Extending the |
| // selection extends it from this index. This will be kUnselectedIndex |
| // if nothing is selected. |
| // |
| // Typically there is only one selected item, in which case the anchor and |
| // active index correspond to the same thing. |
| class UI_BASE_EXPORT ListSelectionModel { |
| public: |
| using SelectedIndices = std::vector<int>; |
| |
| // Used to identify no selection. |
| static constexpr int kUnselectedIndex = -1; |
| |
| ListSelectionModel(); |
| ListSelectionModel(const ListSelectionModel& other); |
| ListSelectionModel(ListSelectionModel&& other) noexcept; |
| |
| ~ListSelectionModel(); |
| |
| ListSelectionModel& operator=(const ListSelectionModel&); |
| ListSelectionModel& operator=(ListSelectionModel&&); |
| |
| bool operator==(const ListSelectionModel& other) const; |
| bool operator!=(const ListSelectionModel& other) const; |
| |
| // See class description for details of the anchor. |
| void set_anchor(int anchor) { anchor_ = anchor; } |
| int anchor() const { return anchor_; } |
| |
| // See class description for details of active. |
| void set_active(int active) { active_ = active; } |
| int active() const { return active_; } |
| |
| // True if nothing is selected. |
| bool empty() const { return selected_indices_.empty(); } |
| |
| // Number of selected indices. |
| size_t size() const { return selected_indices_.size(); } |
| |
| // Increments all indices >= |index|. For example, if the selection consists |
| // of [0, 1, 5] and this is invoked with 1, it results in [0, 2, 6]. This also |
| // updates the anchor and active indices. |
| // This is used when a new item is inserted into the model. |
| void IncrementFrom(int index); |
| |
| // Shifts all indices > |index| down by 1. If |index| is selected, it is |
| // removed. For example, if the selection consists of [0, 1, 5] and this is |
| // invoked with 1, it results in [0, 4]. This is used when an item is |
| // removed. |
| void DecrementFrom(int index); |
| |
| // Sets the anchor, active and selection to |index|. |
| void SetSelectedIndex(int index); |
| |
| // Returns true if |index| is selected. |
| bool IsSelected(int index) const; |
| |
| // Adds |index| to the selection. This does not change the active or anchor |
| // indices. |
| void AddIndexToSelection(int index); |
| |
| // Removes |index| from the selection. This does not change the active or |
| // anchor indices. |
| void RemoveIndexFromSelection(int index); |
| |
| // Extends the selection from the anchor to |index|. If the anchor is empty, |
| // this sets the anchor, selection and active indices to |index|. |
| void SetSelectionFromAnchorTo(int index); |
| |
| // Makes sure the indices from the anchor to |index| are selected. This only |
| // adds to the selection. |
| void AddSelectionFromAnchorTo(int index); |
| |
| // Invoked when an item moves. |old_index| is the original index, |new_index| |
| // is the target index, and |length| is the number of items that are moving. |
| // |
| // If moving to a greater index, |new_index| should be the index *after* |
| // removing the elements at the index range [old_index, old_index + length). |
| // For example, consider three list items 'A B C', to move A to the end of |
| // the list, this should be invoked with '0, 2, 1'. |
| void Move(int old_index, int new_index, int length); |
| |
| // Sets the anchor and active to kUnselectedIndex, and removes all the |
| // selected indices. |
| void Clear(); |
| |
| // Returns the selected indices. The selection is always ordered in acending |
| // order. |
| const SelectedIndices& selected_indices() const { return selected_indices_; } |
| |
| private: |
| SelectedIndices selected_indices_; |
| |
| int active_ = kUnselectedIndex; |
| |
| int anchor_ = kUnselectedIndex; |
| }; |
| |
| } // namespace ui |
| |
| #endif // UI_BASE_MODELS_LIST_SELECTION_MODEL_H_ |