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151 | /* ============================================================
*
* This file is a part of digiKam project
* https://www.digikam.org
*
* Date : 2025-12-22
* Description : a magnifier tool for the GraphicsDImgView canvas.
*
* SPDX-FileCopyrightText: 2025-2026 by Gilles Caulier <caulier dot gilles at gmail dot com>
*
* SPDX-License-Identifier: GPL-2.0-or-later
*
* ============================================================ */
#include "magnifieritem.h"
// Qt includes
#include <QPainter>
#include <QStyleOptionGraphicsItem>
namespace Digikam
{
class Q_DECL_HIDDEN MagnifierItem::Private
{
public:
Private() = default;
public:
QPixmap sourcePixmap;
QRectF sourceRect;
qreal zoomFactor = MagnifierItem::zoomFactors().constFirst();
int size = 150;
};
MagnifierItem::MagnifierItem(QGraphicsItem* const parent)
: QGraphicsItem(parent),
d (new Private)
{
setZValue(10); // Be sure that the loop is always behind the image
}
MagnifierItem::~MagnifierItem()
{
delete d;
}
QList<qreal> MagnifierItem::zoomFactors()
{
return (QList<qreal>() << 1.5 << 2.0 << 2.5 << 3.0 << 3.5 << 4.0 << 6.0 << 8.0);
}
void MagnifierItem::setSourcePixmap(const QPixmap& pixmap, const QRectF& rect)
{
d->sourcePixmap = pixmap;
d->sourceRect = rect;
update();
}
void MagnifierItem::setZoomFactor(qreal factor)
{
d->zoomFactor = factor;
update();
}
qreal MagnifierItem::zoomFactor() const
{
return d->zoomFactor;
}
void MagnifierItem::setMagnifierSize(int magnifierSize)<--- Shadow argument
{
d->size = magnifierSize;
update();
}
int MagnifierItem::magnifierSize() const
{
return d->size;
}
QRectF MagnifierItem::boundingRect() const
{
return QRectF(-d->size / 2, -d->size / 2, d->size, d->size);
}
void MagnifierItem::paint(QPainter* painter, const QStyleOptionGraphicsItem*, QWidget*)
{
if (d->sourcePixmap.isNull())
{
return;
}
// First draw the border.
QPainterPath borderPath;
borderPath.addEllipse(boundingRect());
// Define a gradient for the border.
QRadialGradient borderGradient(0, 0, d->size / 2);
borderGradient.setColorAt(0, QColor(50, 50, 50, 255)); // Darkness inside surround.
borderGradient.setColorAt(0.7, QColor(200, 200, 200, 255)); // Lightness outside surround.
// Draw a border with a large pencil.
painter->setPen(QPen(QBrush(borderGradient), 4)); // Border of 4 pixels.
painter->setBrush(Qt::NoBrush);
painter->drawPath(borderPath);
// Create a ellipsis path for the clipping.
QPainterPath clipPath;
clipPath.addEllipse(boundingRect().adjusted(2, 2, -2, -2)); // Adjustment to highlight border.
// Apply clipping.
painter->setClipPath(clipPath);
painter->setRenderHint(QPainter::Antialiasing, true);
// Draw the background of the magnifier with a gradient
QRadialGradient fillGradient(0, 0, (d->size / 2) - 2); // Preserve the border.
fillGradient.setColorAt(0, QColor(255, 255, 255, 220)); // Center semi-transparent using white.
fillGradient.setColorAt(1, QColor(255, 255, 255, 100)); // Border more transparent.
painter->setBrush(fillGradient);
painter->setPen(Qt::NoPen);
painter->drawEllipse(boundingRect().adjusted(4, 4, -4, -4)); // Draw a little bit inside the border.
// Draw the zommed pixmap.
QPixmap zoomed = d->sourcePixmap.copy(d->sourceRect.toRect())
.scaled(d->size - 2, d->size - 2,
Qt::KeepAspectRatio,
Qt::SmoothTransformation); // Adjust to preserve the border.
painter->drawPixmap(QRectF(-(d->size / 2) + 2, -(d->size / 2) + 2, d->size - 4, d->size - 4),
zoomed,
zoomed.rect());
// Reset clipping.
painter->setClipping(false);
}
} // namespace Digikam
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