qwasmwindowstack.h

Go to the documentation of this file.

// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
 
#ifndef QWASMWINDOWSTACK_H
#define QWASMWINDOWSTACK_H
 
#include <qglobal.h>
#include <QtCore/qlist.h>
#include <QDebug>
 
#include <vector>
 
QT_BEGIN_NAMESPACE
 
class QWasmWindow;
 
// Maintains a z-order hierarchy for a set of windows. The first added window is always treated as
// the 'root', which always stays at the bottom. Other windows are 'regular', which means they are
// subject to z-order changes via |raise| and |lower|/
// If the root is ever removed, all of the current and future windows in the stack are treated as
// regular.
// Access to the top element is facilitated by |topWindow|.
// Changes to the top element are signaled via the |topWindowChangedCallback| supplied at
// construction.
 
// Requirement Window
//
// type Window {
//    Window *transientParent() const;
//    Qt::WindowFlags windowFlags() const;
//    bool isModal() const;
// };
 
template <typename Window=QWasmWindow>
class Q_AUTOTEST_EXPORT QWasmWindowStack
{
private:
    QWasmWindowStack(const QWasmWindowStack &) = delete;
    QWasmWindowStack(QWasmWindowStack &&) = delete;
 
    QWasmWindowStack &operator=(const QWasmWindowStack &) = delete;
    QWasmWindowStack &&operator=(QWasmWindowStack &&) = delete;
 
public:
    enum class PositionPreference {
        StayOnBottom,
        Regular,
        StayOnTop,
        StayAboveTransientParent // Parent is transientParent()
    };
 
    using WindowOrderChangedCallbackType = std::function<void()>;
    using StorageType = QList<Window *>;
 
    using iterator = typename StorageType::reverse_iterator;
    using const_iterator = typename StorageType::const_reverse_iterator;
    using const_reverse_iterator = typename StorageType::const_iterator;
 
    explicit QWasmWindowStack(WindowOrderChangedCallbackType topWindowChangedCallback);
    ~QWasmWindowStack();
 
    void pushWindow(Window *window, PositionPreference position, bool insertAtRegionBegin = false,
                    bool callCallbacks = true);
    void removeWindow(Window *window, bool callCallbacks = true);
    void raise(Window *window);
    void lower(Window *window);
    void windowPositionPreferenceChanged(Window *window, PositionPreference position);
 
    // Iterates top-to-bottom
    iterator begin();
    iterator end();
    const_iterator begin() const;
    const_iterator end() const;
 
    // Iterates bottom-to-top
    const_reverse_iterator rbegin() const;
    const_reverse_iterator rend() const;
 
    bool empty() const;
    size_t size() const;
    Window *topWindow() const;
 
    PositionPreference getWindowPositionPreference(typename StorageType::const_iterator windowIt,
                                                   bool testStayAbove = true) const;
private:
    bool raiseImpl(Window *window);
    bool lowerImpl(Window *window);
    bool shouldBeAboveTransientParent(const Window *window) const;
    bool shouldBeAboveTransientParentFlags(Qt::WindowFlags flags) const;
    void invariant();
    WindowOrderChangedCallbackType m_windowOrderChangedCallback;
 
    StorageType m_windowStack;
    typename StorageType::iterator m_regularWindowsBegin;
    typename StorageType::iterator m_alwaysOnTopWindowsBegin;
};
 
#include "qwasmwindowstack.inc"
 
QT_END_NAMESPACE
 
#endif // QWASMWINDOWSTACK_H