/****************************************************************************
**
** Copyright (C) 2004-2008 Trolltech ASA. All rights reserved.
**
** This file is part of the example classes of the Qt Toolkit.
**
** This file may be used under the terms of the GNU General Public
** License versions 2.0 or 3.0 as published by the Free Software
** Foundation and appearing in the files LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file.  Alternatively you may (at
** your option) use any later version of the GNU General Public
** License if such license has been publicly approved by Trolltech ASA
** (or its successors, if any) and the KDE Free Qt Foundation. In
** addition, as a special exception, Trolltech gives you certain
** additional rights. These rights are described in the Trolltech GPL
** Exception version 1.2, which can be found at
** http://www.trolltech.com/products/qt/gplexception/ and in the file
** GPL_EXCEPTION.txt in this package.
**
** Please review the following information to ensure GNU General
** Public Licensing requirements will be met:
** http://trolltech.com/products/qt/licenses/licensing/opensource/. If
** you are unsure which license is appropriate for your use, please
** review the following information:
** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
** or contact the sales department at sales@trolltech.com.
**
** In addition, as a special exception, Trolltech, as the sole
** copyright holder for Qt Designer, grants users of the Qt/Eclipse
** Integration plug-in the right for the Qt/Eclipse Integration to
** link to functionality provided by Qt Designer and its related
** libraries.
**
** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE. Trolltech reserves all rights not expressly
** granted herein.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

#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 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);
}

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());
}
