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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
#include "mandelbrotwidget.h"
#include <QPainter>
#include <QKeyEvent>
#include <math.h>
//! [0]
const double DefaultCenterX = -0.637011;
const double DefaultCenterY = -0.0395159;
const double DefaultScale = 0.00403897;
const double ZoomInFactor = 0.8;
const double ZoomOutFactor = 1 / ZoomInFactor;
const int ScrollStep = 20;
//! [0]
//! [1]
MandelbrotWidget::MandelbrotWidget(QWidget *parent) :
QWidget(parent),
centerX(DefaultCenterX),
centerY(DefaultCenterY),
pixmapScale(DefaultScale),
curScale(DefaultScale)
{
help = tr("Use mouse wheel or the '+' and '-' keys to zoom. "
"Press and hold left mouse button to scroll.");
connect(&thread, &RenderThread::renderedImage,
this, &MandelbrotWidget::updatePixmap);
setWindowTitle(tr("Mandelbrot"));
#if QT_CONFIG(cursor)
setCursor(Qt::CrossCursor);
#endif
}
//! [1]
//! [2]
void MandelbrotWidget::paintEvent(QPaintEvent * /* event */)
{
QPainter painter(this);
painter.fillRect(rect(), Qt::black);
if (pixmap.isNull()) {
painter.setPen(Qt::white);
painter.drawText(rect(), Qt::AlignCenter, tr("Rendering initial image, please wait..."));
//! [2] //! [3]
return;
//! [3] //! [4]
}
//! [4]
//! [5]
if (qFuzzyCompare(curScale, pixmapScale)) {
//! [5] //! [6]
painter.drawPixmap(pixmapOffset, pixmap);
//! [6] //! [7]
} else {
//! [7] //! [8]
auto previewPixmap = qFuzzyCompare(pixmap.devicePixelRatio(), qreal(1))
? pixmap
: pixmap.scaled(pixmap.deviceIndependentSize().toSize(), Qt::KeepAspectRatio,
Qt::SmoothTransformation);
double scaleFactor = pixmapScale / curScale;
int newWidth = int(previewPixmap.width() * scaleFactor);
int newHeight = int(previewPixmap.height() * scaleFactor);
int newX = pixmapOffset.x() + (previewPixmap.width() - newWidth) / 2;
int newY = pixmapOffset.y() + (previewPixmap.height() - newHeight) / 2;
painter.save();
painter.translate(newX, newY);
painter.scale(scaleFactor, scaleFactor);
QRectF exposed = painter.transform().inverted().mapRect(rect()).adjusted(-1, -1, 1, 1);
painter.drawPixmap(exposed, previewPixmap, exposed);
painter.restore();
}
//! [8] //! [9]
QString text = help;
if (!info.isEmpty())
text += ' ' + info;
QFontMetrics metrics = painter.fontMetrics();
int textWidth = metrics.horizontalAdvance(text);
painter.setPen(Qt::NoPen);
painter.setBrush(QColor(0, 0, 0, 127));
painter.drawRect((width() - textWidth) / 2 - 5, 0, textWidth + 10, metrics.lineSpacing() + 5);
painter.setPen(Qt::white);
painter.drawText((width() - textWidth) / 2, metrics.leading() + metrics.ascent(), text);
}
//! [9]
//! [10]
void MandelbrotWidget::resizeEvent(QResizeEvent * /* event */)
{
thread.render(centerX, centerY, curScale, size(), devicePixelRatio());
}
//! [10]
//! [11]
void MandelbrotWidget::keyPressEvent(QKeyEvent *event)
{
switch (event->key()) {
case Qt::Key_Plus:
zoom(ZoomInFactor);
break;
case Qt::Key_Minus:
zoom(ZoomOutFactor);
break;
case Qt::Key_Left:
scroll(-ScrollStep, 0);
break;
case Qt::Key_Right:
scroll(+ScrollStep, 0);
break;
case Qt::Key_Down:
scroll(0, -ScrollStep);
break;
case Qt::Key_Up:
scroll(0, +ScrollStep);
break;
case Qt::Key_Q:
close();
break;
default:
QWidget::keyPressEvent(event);
}
}
//! [11]
#if QT_CONFIG(wheelevent)
//! [12]
void MandelbrotWidget::wheelEvent(QWheelEvent *event)
{
const int numDegrees = event->angleDelta().y() / 8;
const double numSteps = numDegrees / double(15);
zoom(pow(ZoomInFactor, numSteps));
}
//! [12]
#endif
//! [13]
void MandelbrotWidget::mousePressEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton)
lastDragPos = event->position().toPoint();
}
//! [13]
//! [14]
void MandelbrotWidget::mouseMoveEvent(QMouseEvent *event)
{
if (event->buttons() & Qt::LeftButton) {
pixmapOffset += event->position().toPoint() - lastDragPos;
lastDragPos = event->position().toPoint();
update();
}
}
//! [14]
//! [15]
void MandelbrotWidget::mouseReleaseEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton) {
pixmapOffset += event->position().toPoint() - lastDragPos;
lastDragPos = QPoint();
const auto pixmapSize = pixmap.deviceIndependentSize().toSize();
int deltaX = (width() - pixmapSize.width()) / 2 - pixmapOffset.x();
int deltaY = (height() - pixmapSize.height()) / 2 - pixmapOffset.y();
scroll(deltaX, deltaY);
}
}
//! [15]
//! [16]
void MandelbrotWidget::updatePixmap(const QImage &image, double scaleFactor)
{
if (!lastDragPos.isNull())
return;
info = image.text(RenderThread::infoKey());
pixmap = QPixmap::fromImage(image);
pixmapOffset = QPoint();
lastDragPos = QPoint();
pixmapScale = scaleFactor;
update();
}
//! [16]
//! [17]
void MandelbrotWidget::zoom(double zoomFactor)
{
curScale *= zoomFactor;
update();
thread.render(centerX, centerY, curScale, size(), devicePixelRatio());
}
//! [17]
//! [18]
void MandelbrotWidget::scroll(int deltaX, int deltaY)
{
centerX += deltaX * curScale;
centerY += deltaY * curScale;
update();
thread.render(centerX, centerY, curScale, size(), devicePixelRatio());
}
//! [18]
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