raven-rhel8/extras/KF6/gear/gwenview/gwenview-24.05.1/lib/zoomwidget.cpp

// vim: set tabstop=4 shiftwidth=4 expandtab:
/*
Gwenview: an image viewer
Copyright 2008 Aurélien Gâteau <agateau@kde.org>

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Cambridge, MA 02110-1301, USA.

*/
// Self
#include "zoomwidget.h"

// stdc++
#include <cmath>

// Qt
#include <QAction>
#include <QActionGroup>
#include <QHBoxLayout>
#include <QSlider>
#include <QToolButton>
// KF

// Local
#include "signalblocker.h"
#include "zoomcombobox/zoomcombobox.h"
#include "zoomslider.h"

namespace Gwenview
{
static const qreal MAGIC_K = 1.04;
static const qreal MAGIC_OFFSET = 16.;
static const qreal PRECISION = 100.;
inline int sliderValueForZoom(qreal zoom)
{
    return int(PRECISION * (log(zoom) / log(MAGIC_K) + MAGIC_OFFSET));
}

inline qreal zoomForSliderValue(int sliderValue)
{
    return pow(MAGIC_K, sliderValue / PRECISION - MAGIC_OFFSET);
}

struct ZoomWidgetPrivate {
    ZoomWidget *q = nullptr;

    QToolButton *mFitButton = nullptr;
    ZoomSlider *mZoomSlider = nullptr;
    ZoomComboBox *mZoomComboBox = nullptr;
    QAction *mActualSizeAction = nullptr;

    bool mZoomUpdatedBySlider;

    void emitZoomChanged()
    {
        // Use QSlider::sliderPosition(), not QSlider::value() because when we are
        // called from slotZoomSliderActionTriggered(), QSlider::value() has not
        // been updated yet.
        qreal zoom = zoomForSliderValue(mZoomSlider->slider()->sliderPosition());
        mZoomUpdatedBySlider = true;
        Q_EMIT q->zoomChanged(zoom);
        mZoomUpdatedBySlider = false;
    }
};

ZoomWidget::ZoomWidget(QWidget *parent)
    : QFrame(parent)
    , d(new ZoomWidgetPrivate)
{
    d->q = this;
    d->mZoomUpdatedBySlider = false;

    setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Preferred);

    d->mFitButton = new QToolButton(this);

    d->mZoomSlider = new ZoomSlider(this);
    d->mZoomSlider->setMinimumWidth(150);
    d->mZoomSlider->slider()->setSingleStep(int(PRECISION));
    d->mZoomSlider->slider()->setPageStep(3 * int(PRECISION));
    connect(d->mZoomSlider->slider(), &QAbstractSlider::actionTriggered, this, &ZoomWidget::slotZoomSliderActionTriggered);

    d->mZoomComboBox = new ZoomComboBox(this);
    connect(d->mZoomComboBox, &ZoomComboBox::zoomChanged, this, &ZoomWidget::zoomChanged);

    // Layout
    auto layout = new QHBoxLayout(this);
    layout->setContentsMargins(0, 0, 0, 0);
    layout->setSpacing(0);
    layout->addWidget(d->mFitButton);
    layout->addWidget(d->mZoomSlider);
    layout->addWidget(d->mZoomComboBox);
}

ZoomWidget::~ZoomWidget()
{
    delete d;
}

void ZoomWidget::setActions(QAction *zoomToFitAction, QAction *actualSizeAction, QAction *zoomInAction, QAction *zoomOutAction, QAction *zoomToFillAction)
{
    d->mFitButton->setDefaultAction(zoomToFitAction);
    d->mFitButton->setToolButtonStyle(Qt::ToolButtonStyle::ToolButtonTextOnly);

    d->mZoomSlider->setZoomInAction(zoomInAction);
    d->mZoomSlider->setZoomOutAction(zoomOutAction);

    d->mZoomComboBox->setActions(zoomToFitAction, zoomToFillAction, actualSizeAction);

    auto actionGroup = new QActionGroup(d->q);
    actionGroup->addAction(zoomToFitAction);
    actionGroup->addAction(zoomToFillAction);
    actionGroup->addAction(actualSizeAction);
    actionGroup->setExclusionPolicy(QActionGroup::ExclusionPolicy::ExclusiveOptional);

    d->mActualSizeAction = actualSizeAction;
}

void ZoomWidget::slotZoomSliderActionTriggered()
{
    // The slider value changed because of the user (not because of range
    // changes). In this case disable zoom and apply slider value.
    d->emitZoomChanged();
}

void ZoomWidget::setZoom(qreal zoom)
{
    if (zoom != 1.0) {
        d->mActualSizeAction->setChecked(false);
    }
    d->mZoomComboBox->setValue(zoom);

    // Don't change slider value if we come here because the slider change,
    // avoids choppy sliding scroll.
    if (!d->mZoomUpdatedBySlider) {
        QSlider *slider = d->mZoomSlider->slider();
        SignalBlocker blocker(slider);
        int value = sliderValueForZoom(zoom);

        if (value < slider->minimum()) {
            // It is possible that we are called *before* setMinimumZoom() as
            // been called. In this case, define the minimum ourself.
            d->mZoomSlider->setMinimum(value);
        }
        d->mZoomSlider->setValue(value);
    }
}

void ZoomWidget::setMinimumZoom(qreal minimumZoom)
{
    d->mZoomSlider->setMinimum(sliderValueForZoom(minimumZoom));
    d->mZoomComboBox->setMinimum(minimumZoom);
}

void ZoomWidget::setMaximumZoom(qreal zoom)
{
    d->mZoomSlider->setMaximum(sliderValueForZoom(zoom));
    d->mZoomComboBox->setMaximum(zoom);
}

} // namespace

#include "moc_zoomwidget.cpp"