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<pre> /****************************************************************************
**
** Copyright (C) 2004-2006 Trolltech ASA. All rights reserved.
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** This file is part of the example classes of the Qt Toolkit.
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#include <QtGui>
#include <math.h>
#include "mandelbrotwidget.h"
const double DefaultCenterX = -0.637011f;
const double DefaultCenterY = -0.0395159f;
const double DefaultScale = 0.00403897f;
const double ZoomInFactor = 0.8f;
const double ZoomOutFactor = 1 / ZoomInFactor;
const int ScrollStep = 20;
MandelbrotWidget::MandelbrotWidget(QWidget *parent)
: QWidget(parent)
{
centerX = DefaultCenterX;
centerY = DefaultCenterY;
pixmapScale = DefaultScale;
curScale = DefaultScale;
qRegisterMetaType<QImage>("QImage");
connect(&thread, SIGNAL(renderedImage(const QImage &, double)),
this, SLOT(updatePixmap(const QImage &, double)));
setWindowTitle(tr("Mandelbrot"));
setCursor(Qt::CrossCursor);
resize(550, 400);
}
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..."));
return;
}
if (curScale == pixmapScale) {
painter.drawPixmap(pixmapOffset, pixmap);
} else {
double scaleFactor = pixmapScale / curScale;
int newWidth = int(pixmap.width() * scaleFactor);
int newHeight = int(pixmap.height() * scaleFactor);
int newX = pixmapOffset.x() + (pixmap.width() - newWidth) / 2;
int newY = pixmapOffset.y() + (pixmap.height() - newHeight) / 2;
painter.save();
painter.translate(newX, newY);
painter.scale(scaleFactor, scaleFactor);
QRectF exposed = painter.matrix().inverted().mapRect(rect()).adjusted(-1, -1, 1, 1);
painter.drawPixmap(exposed, pixmap, exposed);
painter.restore();
}
QString text = tr("Use mouse wheel to zoom. "
"Press and hold left mouse button to scroll.");
QFontMetrics metrics = painter.fontMetrics();
int textWidth = metrics.width(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);
}
void MandelbrotWidget::resizeEvent(QResizeEvent * /* event */)
{
thread.render(centerX, centerY, curScale, size());
}
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;
default:
QWidget::keyPressEvent(event);
}
}
void MandelbrotWidget::wheelEvent(QWheelEvent *event)
{
int numDegrees = event->delta() / 8;
double numSteps = numDegrees / 15.0f;
zoom(pow(ZoomInFactor, numSteps));
}
void MandelbrotWidget::mousePressEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton)
lastDragPos = event->pos();
}
void MandelbrotWidget::mouseMoveEvent(QMouseEvent *event)
{
if (event->buttons() & Qt::LeftButton) {
pixmapOffset += event->pos() - lastDragPos;
lastDragPos = event->pos();
update();
}
}
void MandelbrotWidget::mouseReleaseEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton) {
pixmapOffset += event->pos() - lastDragPos;
lastDragPos = QPoint();
int deltaX = (width() - pixmap.width()) / 2 - pixmapOffset.x();
int deltaY = (height() - pixmap.height()) / 2 - pixmapOffset.y();
scroll(deltaX, deltaY);
}
}
void MandelbrotWidget::updatePixmap(const QImage &image, double scaleFactor)
{
if (!lastDragPos.isNull())
return;
pixmap = QPixmap::fromImage(image);
pixmapOffset = QPoint();
lastDragPos = QPoint();
pixmapScale = scaleFactor;
update();
}
void MandelbrotWidget::zoom(double zoomFactor)
{
curScale *= zoomFactor;
update();
thread.render(centerX, centerY, curScale, size());
}
void MandelbrotWidget::scroll(int deltaX, int deltaY)
{
centerX += deltaX * curScale;
centerY += deltaY * curScale;
update();
thread.render(centerX, centerY, curScale, size());
}</pre>
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