static/source/qt5-mandelbrot/mandelbrotwidget.cxx

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