DebouncedAction.h

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// SPDX-FileCopyrightText: 2026 fuddlesworth
// SPDX-License-Identifier: LGPL-2.1-or-later
 
#pragma once
 
#include <phosphorcompositor_export.h>
 
#include <QObject>
#include <QRect>
#include <QTimer>
#include <functional>
 
namespace PhosphorCompositor {
 
class PHOSPHORCOMPOSITOR_EXPORT DebouncedScreenAction : public QObject
{
    Q_OBJECT
 
public:
    explicit DebouncedScreenAction(int debounceMs, QObject* parent = nullptr)
        : QObject(parent)
    {
        m_debounce.setSingleShot(true);
        m_debounce.setInterval(debounceMs);
        connect(&m_debounce, &QTimer::timeout, this, &DebouncedScreenAction::onDebounceTimeout);
    }
 
    void stop()
    {
        m_debounce.stop();
        m_pending = false;
    }
 
    void geometryChanged(const QRect& currentGeometry)
    {
        if (m_hasLastGeometry && currentGeometry == m_lastGeometry && !m_pending) {
            if (m_applyInProgress) {
                requestReapply();
            }
            return;
        }
        m_lastGeometry = currentGeometry;
        m_hasLastGeometry = true;
        m_pending = true;
        m_debounce.start();
    }
 
    void requestReapply()
    {
        if (m_applyInProgress) {
            m_reapplyPending = true;
            return;
        }
        Q_EMIT applyRequested();
    }
 
    void markApplyStarted()
    {
        m_applyInProgress = true;
    }
 
    void markApplyCompleted()
    {
        m_applyInProgress = false;
        if (m_reapplyPending) {
            m_reapplyPending = false;
            QTimer::singleShot(0, this, [this]() {
                Q_EMIT applyRequested();
            });
        }
    }
 
    bool isChangeInProgress() const
    {
        return m_pending || m_applyInProgress;
    }
 
    void setLastGeometry(const QRect& geo)
    {
        m_lastGeometry = geo;
        m_hasLastGeometry = true;
    }
 
Q_SIGNALS:
    void applyRequested();
 
private Q_SLOTS:
    void onDebounceTimeout()
    {
        // Subclass or signal receiver provides currentGeometry
        // For now, just signal that we need to apply
        m_pending = false;
        Q_EMIT applyRequested();
    }
 
private:
    QTimer m_debounce;
    QRect m_lastGeometry;
    bool m_hasLastGeometry = false;
    bool m_pending = false;
    bool m_applyInProgress = false;
    bool m_reapplyPending = false;
};
 
} // namespace PhosphorCompositor