urho3d/Source/Urho3D/UI/DropDownList.h

//
// Copyright (c) 2008-2020 the Urho3D project.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//

#pragma once

#include "../UI/Menu.h"

namespace Urho3D
{

class ListView;

/// %Menu %UI element that displays a popup list view.
class URHO3D_API DropDownList : public Menu
{
    URHO3D_OBJECT(DropDownList, Menu);

public:
    /// Construct.
    explicit DropDownList(Context* context);
    /// Destruct.
    ~DropDownList() override;
    /// Register object factory.
    static void RegisterObject(Context* context);

    /// Apply attribute changes that can not be applied immediately.
    void ApplyAttributes() override;
    /// Return UI rendering batches.
    void GetBatches(PODVector<UIBatch>& batches, PODVector<float>& vertexData, const IntRect& currentScissor) override;
    /// React to the popup being shown.
    void OnShowPopup() override;
    /// React to the popup being hidden.
    void OnHidePopup() override;
    /// React to editable status change.
    void OnSetEditable() override;

    /// Add item to the end of the list.
    void AddItem(UIElement* item);
    /// Insert item to a specific position.
    void InsertItem(unsigned index, UIElement* item);
    /// Remove specific item.
    void RemoveItem(UIElement* item);
    /// Remove item at index.
    void RemoveItem(unsigned index);
    /// Remove all items.
    void RemoveAllItems();
    /// Set selection.
    /// @property
    void SetSelection(unsigned index);
    /// Set place holder text. This is the text shown when there is no selection (-1) in drop down list. Note that if the list has items, the default is to show the first item, so the "no selection" state has to be set explicitly.
    /// @property
    void SetPlaceholderText(const String& text);
    /// Set whether popup should be automatically resized to match the dropdown button width.
    /// @property
    void SetResizePopup(bool enable);

    /// Return number of items.
    /// @property
    unsigned GetNumItems() const;
    /// Return item at index.
    /// @property{get_items}
    UIElement* GetItem(unsigned index) const;
    /// Return all items.
    PODVector<UIElement*> GetItems() const;
    /// Return selection index, or M_MAX_UNSIGNED if none selected.
    /// @property
    unsigned GetSelection() const;
    /// Return selected item, or null if none selected.
    /// @property
    UIElement* GetSelectedItem() const;

    /// Return listview element.
    /// @property
    ListView* GetListView() const { return listView_; }

    /// Return selected item placeholder element.
    /// @property
    UIElement* GetPlaceholder() const { return placeholder_; }

    /// Return place holder text.
    /// @property
    const String& GetPlaceholderText() const;

    /// Return whether popup should be automatically resized.
    /// @property
    bool GetResizePopup() const { return resizePopup_; }

    /// Set selection attribute.
    void SetSelectionAttr(unsigned index);

protected:
    /// Filter implicit attributes in serialization process.
    bool FilterImplicitAttributes(XMLElement& dest) const override;
    /// Filter implicit attributes in serialization process.
    bool FilterPopupImplicitAttributes(XMLElement& dest) const override;

    /// Listview element.
    SharedPtr<ListView> listView_;
    /// Selected item placeholder element.
    SharedPtr<UIElement> placeholder_;
    /// Resize popup flag.
    bool resizePopup_;

private:
    /// Handle listview item click event.
    void HandleItemClicked(StringHash eventType, VariantMap& eventData);
    /// Handle a key press from the listview.
    void HandleListViewKey(StringHash eventType, VariantMap& eventData);
    /// Handle the listview selection change. Set placeholder text hidden/visible as necessary.
    void HandleSelectionChanged(StringHash eventType, VariantMap& eventData);

    /// Selected item index attribute.
    unsigned selectionAttr_;
};

}