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50
51#include "mandelbrotwidget.h"
52
53#include <QPainter>
54#include <QKeyEvent>
55
56#include <math.h>
57
58//! [0]
59const double DefaultCenterX = -0.637011;
60const double DefaultCenterY = -0.0395159;
61const double DefaultScale = 0.00403897;
62
63const double ZoomInFactor = 0.8;
64const double ZoomOutFactor = 1 / ZoomInFactor;
65const int ScrollStep = 20;
66//! [0]
67
68//! [1]
69MandelbrotWidget::MandelbrotWidget(QWidget *parent) :
70 QWidget(parent),
71 centerX(DefaultCenterX),
72 centerY(DefaultCenterY),
73 pixmapScale(DefaultScale),
74 curScale(DefaultScale)
75{
76 connect(&thread, &RenderThread::renderedImage,
77 this, &MandelbrotWidget::updatePixmap);
78
79 setWindowTitle(tr("Mandelbrot"));
80#if QT_CONFIG(cursor)
81 setCursor(Qt::CrossCursor);
82#endif
83 resize(550, 400);
84
85}
86//! [1]
87
88//! [2]
89void MandelbrotWidget::paintEvent(QPaintEvent * /* event */)
90{
91 QPainter painter(this);
92 painter.fillRect(rect(), Qt::black);
93
94 if (pixmap.isNull()) {
95 painter.setPen(Qt::white);
96 painter.drawText(rect(), Qt::AlignCenter, tr("Rendering initial image, please wait..."));
97//! [2] //! [3]
98 return;
99//! [3] //! [4]
100 }
101//! [4]
102
103//! [5]
104 if (qFuzzyCompare(curScale, pixmapScale)) {
105//! [5] //! [6]
106 painter.drawPixmap(pixmapOffset, pixmap);
107//! [6] //! [7]
108 } else {
109//! [7] //! [8]
110 auto previewPixmap = qFuzzyCompare(pixmap.devicePixelRatio(), qreal(1))
111 ? pixmap
112 : pixmap.scaled(pixmap.size() / pixmap.devicePixelRatio(), Qt::KeepAspectRatio,
113 Qt::SmoothTransformation);
114 double scaleFactor = pixmapScale / curScale;
115 int newWidth = int(previewPixmap.width() * scaleFactor);
116 int newHeight = int(previewPixmap.height() * scaleFactor);
117 int newX = pixmapOffset.x() + (previewPixmap.width() - newWidth) / 2;
118 int newY = pixmapOffset.y() + (previewPixmap.height() - newHeight) / 2;
119
120 painter.save();
121 painter.translate(newX, newY);
122 painter.scale(scaleFactor, scaleFactor);
123
124 QRectF exposed = painter.transform().inverted().mapRect(rect()).adjusted(-1, -1, 1, 1);
125 painter.drawPixmap(exposed, previewPixmap, exposed);
126 painter.restore();
127 }
128//! [8] //! [9]
129
130 QString text = tr("Use mouse wheel or the '+' and '-' keys to zoom. "
131 "Press and hold left mouse button to scroll.");
132 QFontMetrics metrics = painter.fontMetrics();
133 int textWidth = metrics.horizontalAdvance(text);
134
135 painter.setPen(Qt::NoPen);
136 painter.setBrush(QColor(0, 0, 0, 127));
137 painter.drawRect((width() - textWidth) / 2 - 5, 0, textWidth + 10, metrics.lineSpacing() + 5);
138 painter.setPen(Qt::white);
139 painter.drawText((width() - textWidth) / 2, metrics.leading() + metrics.ascent(), text);
140}
141//! [9]
142
143//! [10]
144void MandelbrotWidget::resizeEvent(QResizeEvent * /* event */)
145{
146 thread.render(centerX, centerY, curScale, size(), devicePixelRatio());
147}
148//! [10]
149
150//! [11]
151void MandelbrotWidget::keyPressEvent(QKeyEvent *event)
152{
153 switch (event->key()) {
154 case Qt::Key_Plus:
155 zoom(ZoomInFactor);
156 break;
157 case Qt::Key_Minus:
158 zoom(ZoomOutFactor);
159 break;
160 case Qt::Key_Left:
161 scroll(-ScrollStep, 0);
162 break;
163 case Qt::Key_Right:
164 scroll(+ScrollStep, 0);
165 break;
166 case Qt::Key_Down:
167 scroll(0, -ScrollStep);
168 break;
169 case Qt::Key_Up:
170 scroll(0, +ScrollStep);
171 break;
172 default:
173 QWidget::keyPressEvent(event);
174 }
175}
176//! [11]
177
178#if QT_CONFIG(wheelevent)
179//! [12]
180void MandelbrotWidget::wheelEvent(QWheelEvent *event)
181{
182 const int numDegrees = event->angleDelta().y() / 8;
183 const double numSteps = numDegrees / double(15);
184 zoom(pow(ZoomInFactor, numSteps));
185}
186//! [12]
187#endif
188
189//! [13]
190void MandelbrotWidget::mousePressEvent(QMouseEvent *event)
191{
192 if (event->button() == Qt::LeftButton)
193 lastDragPos = event->position().toPoint();
194}
195//! [13]
196
197//! [14]
198void MandelbrotWidget::mouseMoveEvent(QMouseEvent *event)
199{
200 if (event->buttons() & Qt::LeftButton) {
201 pixmapOffset += event->position().toPoint() - lastDragPos;
202 lastDragPos = event->position().toPoint();
203 update();
204 }
205}
206//! [14]
207
208//! [15]
209void MandelbrotWidget::mouseReleaseEvent(QMouseEvent *event)
210{
211 if (event->button() == Qt::LeftButton) {
212 pixmapOffset += event->position().toPoint() - lastDragPos;
213 lastDragPos = QPoint();
214
215 const auto pixmapSize = pixmap.size() / pixmap.devicePixelRatio();
216 int deltaX = (width() - pixmapSize.width()) / 2 - pixmapOffset.x();
217 int deltaY = (height() - pixmapSize.height()) / 2 - pixmapOffset.y();
218 scroll(deltaX, deltaY);
219 }
220}
221//! [15]
222
223//! [16]
224void MandelbrotWidget::updatePixmap(const QImage &image, double scaleFactor)
225{
226 if (!lastDragPos.isNull())
227 return;
228
229 pixmap = QPixmap::fromImage(image);
230 pixmapOffset = QPoint();
231 lastDragPos = QPoint();
232 pixmapScale = scaleFactor;
233 update();
234}
235//! [16]
236
237//! [17]
238void MandelbrotWidget::zoom(double zoomFactor)
239{
240 curScale *= zoomFactor;
241 update();
242 thread.render(centerX, centerY, curScale, size(), devicePixelRatio());
243}
244//! [17]
245
246//! [18]
247void MandelbrotWidget::scroll(int deltaX, int deltaY)
248{
249 centerX += deltaX * curScale;
250 centerY += deltaY * curScale;
251 update();
252 thread.render(centerX, centerY, curScale, size(), devicePixelRatio());
253}
254//! [18]
255