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#include <QtGui>

#include <math.h>

#include "mandelbrotwidget.h"

//! [0]

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;

//! [0]

//! [1]

MandelbrotWidget::MandelbrotWidget(QWidget *parent)

    : QWidget(parent)

{

    centerX = DefaultCenterX;

    centerY = DefaultCenterY;

    pixmapScale = DefaultScale;

    curScale = DefaultScale;

    qRegisterMetaType<QImage>("QImage");

    connect(&thread, SIGNAL(renderedImage(QImage,double)),

            this, SLOT(updatePixmap(QImage,double)));

    setWindowTitle(tr("Mandelbrot"));

#ifndef QT_NO_CURSOR

    setCursor(Qt::CrossCursor);

#endif

    resize(550, 400);

}

//! [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 (curScale == pixmapScale) {

//! [5] //! [6]

        painter.drawPixmap(pixmapOffset, pixmap);

//! [6] //! [7]

    } else {

//! [7] //! [8]

        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();

    }

//! [8] //! [9]

    QString text = tr("Use mouse wheel or the '+' and '-' keys 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);

}

//! [9]

//! [10]

void MandelbrotWidget::resizeEvent(QResizeEvent * /* event */)

{

    thread.render(centerX, centerY, curScale, size());

}

//! [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;

    default:

        QWidget::keyPressEvent(event);

    }

}

//! [11]

//! [12]

void MandelbrotWidget::wheelEvent(QWheelEvent *event)

{

    int numDegrees = event->delta() / 8;

    double numSteps = numDegrees / 15.0f;

    zoom(pow(ZoomInFactor, numSteps));

}

//! [12]

//! [13]

void MandelbrotWidget::mousePressEvent(QMouseEvent *event)

{

    if (event->button() == Qt::LeftButton)

        lastDragPos = event->pos();

}

//! [13]

//! [14]

void MandelbrotWidget::mouseMoveEvent(QMouseEvent *event)

{

    if (event->buttons() & Qt::LeftButton) {

        pixmapOffset += event->pos() - lastDragPos;

        lastDragPos = event->pos();

        update();

    }

}

//! [14]

//! [15]

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);

    }

}

//! [15]

//! [16]

void MandelbrotWidget::updatePixmap(const QImage &image, double scaleFactor)

{

    if (!lastDragPos.isNull())

        return;

    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());

}

//! [17]

//! [18]

void MandelbrotWidget::scroll(int deltaX, int deltaY)

{

    centerX += deltaX * curScale;

    centerY += deltaY * curScale;

    update();

    thread.render(centerX, centerY, curScale, size());

}

//! [18]