KisWidgetWithIdleTask.h

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/*
 *  SPDX-FileCopyrightText: 2023 Dmitry Kazakov <dimula73@gmail.com>
 *
 *  SPDX-License-Identifier: GPL-2.0-or-later
 */
#ifndef KISWIDGETWITHIDLETASK_H
#define KISWIDGETWITHIDLETASK_H
 
#include <QWidget>
#include "KisIdleTasksManager.h"
 
class KisCanvas2;
class KoColorSpace;
 
template <typename BaseWidget>
class KisWidgetWithIdleTask : public BaseWidget
{
public:
    KisWidgetWithIdleTask(QWidget *parent = 0, Qt::WindowFlags flags = Qt::WindowFlags())
        : BaseWidget (parent, flags)
    {
    }
 
    ~KisWidgetWithIdleTask() override = default;
 
    virtual void setCanvas(KisCanvas2 *canvas) {
        if (m_canvas) {
            m_idleTaskGuard = KisIdleTasksManager::TaskGuard();
        }
 
        m_canvas = canvas;
 
        if (m_canvas) {
            if (this->isVisible()) {
                m_idleTaskGuard = registerIdleTask(m_canvas);
            }
        }
 
        clearCachedState();
        this->update();
    }
 
    void showEvent(QShowEvent *event) override {
        BaseWidget::showEvent(event);
 
        // see a comment at the declaration of `m_isVisibleState`
        if (!m_isVisibleState) {
            m_isVisibleState = true;
 
            KIS_SAFE_ASSERT_RECOVER(!m_idleTaskGuard.isValid()) {
                m_idleTaskGuard = KisIdleTasksManager::TaskGuard();
            }
 
            if (m_canvas) {
                m_idleTaskGuard = registerIdleTask(m_canvas);
            }
            if (m_idleTaskGuard.isValid()) {
                m_idleTaskGuard.trigger();
            }
        }
    }
 
    void hideEvent(QHideEvent *event) override {
        BaseWidget::hideEvent(event);
 
        // see a comment at the declaration of `m_isVisibleState`
        if (m_isVisibleState) {
            m_isVisibleState = false;
 
            KIS_SAFE_ASSERT_RECOVER_NOOP(!m_canvas || m_idleTaskGuard.isValid());
            m_idleTaskGuard = KisIdleTasksManager::TaskGuard();
 
            clearCachedState();
        }
    }
 
    void triggerCacheUpdate() {
        if (m_idleTaskGuard.isValid()) {
            m_idleTaskGuard.trigger();
        }
    }
 
    [[nodiscard]]
    virtual KisIdleTasksManager::TaskGuard registerIdleTask(KisCanvas2 *canvas) = 0;
    virtual void clearCachedState() = 0;
 
protected:
    KisCanvas2 *m_canvas {0};
    KisIdleTasksManager::TaskGuard m_idleTaskGuard;
 
    bool m_isVisibleState {false};
};
 
#endif // KISWIDGETWITHIDLETASK_H