MandelbrotWidget Class Reference

#include <mandelbrotwidget.h>

Inheritance diagram for MandelbrotWidget:

[legend]Collaboration diagram for MandelbrotWidget:

[legend]List of all members.

---

Detailed Description

Definition at line 32 of file mandelbrotwidget.h.

Public Member Functions
	MandelbrotWidget (QWidget *parent=0)
Protected Member Functions
void	paintEvent (QPaintEvent *event)
void	resizeEvent (QResizeEvent *event)
void	keyPressEvent (QKeyEvent *event)
void	wheelEvent (QWheelEvent *event)
void	mousePressEvent (QMouseEvent *event)
void	mouseMoveEvent (QMouseEvent *event)
void	mouseReleaseEvent (QMouseEvent *event)
Private Slots
void	updatePixmap (const QImage &image, double scaleFactor)
Private Member Functions
void	zoom (double zoomFactor)
void	scroll (int deltaX, int deltaY)
Private Attributes
RenderThread	thread
QPixmap	pixmap
QPoint	pixmapOffset
QPoint	lastDragPos
double	centerX
double	centerY
double	pixmapScale
double	curScale

---

Constructor & Destructor Documentation

MandelbrotWidget::MandelbrotWidget

(

QWidget *

parent = 0

)

Definition at line 38 of file mandelbrotwidget.cpp.

References centerX, centerY, QObject::connect(), Qt::CrossCursor, curScale, DefaultCenterX, DefaultCenterY, DefaultScale, pixmapScale, QWidget::resize(), QWidget::setCursor(), QWidget::setWindowTitle(), SIGNAL, SLOT, QObject::thread(), and updatePixmap().

    : 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);
}

Here is the call graph for this function:

---

Member Function Documentation

void MandelbrotWidget::paintEvent

(

QPaintEvent *

event

)

[protected, virtual]

This event handler can be reimplemented in a subclass to receive paint events which are passed in the event parameter.

A paint event is a request to repaint all or part of the widget. It can happen as a result of repaint() or update(), or because the widget was obscured and has now been uncovered, or for many other reasons.

Many widgets can simply repaint their entire surface when asked to, but some slow widgets need to optimize by painting only the requested region: QPaintEvent::region(). This speed optimization does not change the result, as painting is clipped to that region during event processing. QListView and QTableView do this, for example.

Qt also tries to speed up painting by merging multiple paint events into one. When update() is called several times or the window system sends several paint events, Qt merges these events into one event with a larger region (see QRegion::united()). repaint() does not permit this optimization, so we suggest using update() whenever possible.

When the paint event occurs, the update region has normally been erased, so that you're painting on the widget's background.

The background can be set using setBackgroundRole() and setPalette().

From Qt 4.0, QWidget automatically double-buffers its painting, so there's no need to write double-buffering code in paintEvent() to avoid flicker.

Note: Under X11 it is possible to toggle the global double buffering by calling qt_x11_set_global_double_buffer(). Example usage:

    ...
    extern void qt_x11_set_global_double_buffer(bool);
    qt_x11_set_global_double_buffer(false);
    ...

See also:

event(), repaint(), update(), QPainter, QPixmap, QPaintEvent, {Analog Clock Example}

Reimplemented from QWidget.

Definition at line 55 of file mandelbrotwidget.cpp.

References QRect::adjusted(), Qt::AlignCenter, Qt::black, curScale, QPainter::drawPixmap(), QPainter::drawRect(), QPainter::drawText(), QPainter::fillRect(), QPainter::fontMetrics(), QPixmap::height(), int, QMatrix::inverted(), QPixmap::isNull(), QMatrix::mapRect(), QPainter::matrix(), metrics(), Qt::NoPen, pixmap, pixmapOffset, pixmapScale, QWidget::rect(), QPainter::restore(), QPainter::save(), QPainter::scale(), QPainter::setBrush(), QPainter::setPen(), QPainter::translate(), Qt::white, QPixmap::width(), QWidget::width(), QPoint::x(), and QPoint::y().

{
    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);
}

Here is the call graph for this function:

void MandelbrotWidget::resizeEvent

(

QResizeEvent *

event

)

[protected, virtual]

This event handler can be reimplemented in a subclass to receive widget resize events which are passed in the event parameter. When resizeEvent() is called, the widget already has its new geometry. The old size is accessible through QResizeEvent::oldSize().

The widget will be erased and receive a paint event immediately after processing the resize event. No drawing need be (or should be) done inside this handler.

See also:

moveEvent(), event(), resize(), QResizeEvent, paintEvent(), {Scribble Example}

Reimplemented from QWidget.

Definition at line 98 of file mandelbrotwidget.cpp.

References centerX, centerY, curScale, QWidget::size(), and QObject::thread().

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

Here is the call graph for this function:

void MandelbrotWidget::keyPressEvent

(

QKeyEvent *

event

)

[protected, virtual]

This event handler, for event event, can be reimplemented in a subclass to receive key press events for the widget.

A widget must call setFocusPolicy() to accept focus initially and have focus in order to receive a key press event.

If you reimplement this handler, it is very important that you ignore() the event if you do not understand it, so that the widget's parent can interpret it.

The default implementation closes popup widgets if the user presses Esc. Otherwise the event is ignored.

See also:

keyReleaseEvent(), QKeyEvent::ignore(), setFocusPolicy(), focusInEvent(), focusOutEvent(), event(), QKeyEvent, {Tetrix Example}

Reimplemented from QWidget.

Definition at line 103 of file mandelbrotwidget.cpp.

References QWidget::event(), Qt::Key_Down, Qt::Key_Left, Qt::Key_Minus, Qt::Key_Plus, Qt::Key_Right, Qt::Key_Up, QWidget::keyPressEvent(), scroll(), ScrollStep, zoom(), ZoomInFactor, and ZoomOutFactor.

{
    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);
    }
}

Here is the call graph for this function:

void MandelbrotWidget::wheelEvent

(

QWheelEvent *

event

)

[protected, virtual]

This event handler, for event event, can be reimplemented in a subclass to receive wheel events for the widget.

If you reimplement this handler, it is very important that you ignore() the event if you do not handle it, so that the widget's parent can interpret it.

The default implementation ignores the event.

See also:

QWheelEvent::ignore(), QWheelEvent::accept(), event(), QWheelEvent

Reimplemented from QWidget.

Definition at line 129 of file mandelbrotwidget.cpp.

References QWidget::event(), zoom(), and ZoomInFactor.

{
    int numDegrees = event->delta() / 8;
    double numSteps = numDegrees / 15.0f;
    zoom(pow(ZoomInFactor, numSteps));
}

Here is the call graph for this function:

void MandelbrotWidget::mousePressEvent

(

QMouseEvent *

event

)

[protected, virtual]

This event handler, for event event, can be reimplemented in a subclass to receive mouse press events for the widget.

If you create new widgets in the mousePressEvent() the mouseReleaseEvent() may not end up where you expect, depending on the underlying window system (or X11 window manager), the widgets' location and maybe more.

The default implementation implements the closing of popup widgets when you click outside the window. For other widget types it does nothing.

See also:

mouseReleaseEvent(), mouseDoubleClickEvent(), mouseMoveEvent(), event(), QMouseEvent, {Scribble Example}

Reimplemented from QWidget.

Definition at line 136 of file mandelbrotwidget.cpp.

References QWidget::event(), lastDragPos, and Qt::LeftButton.

{
    if (event->button() == Qt::LeftButton)
        lastDragPos = event->pos();
}

Here is the call graph for this function:

void MandelbrotWidget::mouseMoveEvent

(

QMouseEvent *

event

)

[protected, virtual]

This event handler, for event event, can be reimplemented in a subclass to receive mouse move events for the widget.

If mouse tracking is switched off, mouse move events only occur if a mouse button is pressed while the mouse is being moved. If mouse tracking is switched on, mouse move events occur even if no mouse button is pressed.

QMouseEvent::pos() reports the position of the mouse cursor, relative to this widget. For press and release events, the position is usually the same as the position of the last mouse move event, but it might be different if the user's hand shakes. This is a feature of the underlying window system, not Qt.

See also:

setMouseTracking(), mousePressEvent(), mouseReleaseEvent(), mouseDoubleClickEvent(), event(), QMouseEvent, {Scribble Example}

Reimplemented from QWidget.

Definition at line 142 of file mandelbrotwidget.cpp.

References QWidget::event(), lastDragPos, Qt::LeftButton, pixmapOffset, and QWidget::update().

{
    if (event->buttons() & Qt::LeftButton) {
        pixmapOffset += event->pos() - lastDragPos;
        lastDragPos = event->pos();
        update();
    }
}

Here is the call graph for this function:

void MandelbrotWidget::mouseReleaseEvent

(

QMouseEvent *

event

)

[protected, virtual]

This event handler, for event event, can be reimplemented in a subclass to receive mouse release events for the widget.

See also:

mousePressEvent(), mouseDoubleClickEvent(), mouseMoveEvent(), event(), QMouseEvent, {Scribble Example}

Reimplemented from QWidget.

Definition at line 151 of file mandelbrotwidget.cpp.

References QWidget::event(), QPixmap::height(), QWidget::height(), lastDragPos, Qt::LeftButton, pixmap, pixmapOffset, scroll(), QPixmap::width(), QWidget::width(), QPoint::x(), and QPoint::y().

{
    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);
    }
}

Here is the call graph for this function:

void MandelbrotWidget::updatePixmap	(	const QImage &	image,
		double	scaleFactor
	)			[private, slot]

Definition at line 163 of file mandelbrotwidget.cpp.

References QPixmap::fromImage(), image, QPoint::isNull(), lastDragPos, pixmap, pixmapOffset, pixmapScale, and QWidget::update().

Referenced by MandelbrotWidget().

{
    if (!lastDragPos.isNull())
        return;

    pixmap = QPixmap::fromImage(image);
    pixmapOffset = QPoint();
    lastDragPos = QPoint();
    pixmapScale = scaleFactor;
    update();
}

void MandelbrotWidget::zoom

(

double

zoomFactor

)

[private]

Definition at line 175 of file mandelbrotwidget.cpp.

References centerX, centerY, curScale, QWidget::size(), QObject::thread(), and QWidget::update().

Referenced by keyPressEvent(), and wheelEvent().

{
    curScale *= zoomFactor;
    update();
    thread.render(centerX, centerY, curScale, size());
}

Here is the call graph for this function:

void MandelbrotWidget::scroll	(	int	deltaX,
		int	deltaY
	)			[private]

Scrolls the widget including its children dx pixels to the right and dy downward. Both dx and dy may be negative.

After scrolling, the widgets will receive paint events for the areas that need to be repainted. For widgets that Qt knows to be opaque, this is only the newly exposed parts. For example, if an opaque widget is scrolled 8 pixels to the left, only an 8-pixel wide stripe at the right edge needs updating.

Since widgets propagate the contents of their parents by default, you need to set the autoFillBackground property, or use setAttribute() to set the Qt::WA_OpaquePaintEvent attribute, to make a widget opaque.

For widgets that use contents propagation, a scroll will cause an update of the entire scroll area.

See also:

{Transparency and Double Buffering}

Reimplemented from QWidget.

Definition at line 182 of file mandelbrotwidget.cpp.

References centerX, centerY, curScale, QWidget::size(), QObject::thread(), and QWidget::update().

Referenced by keyPressEvent(), and mouseReleaseEvent().

{
    centerX += deltaX * curScale;
    centerY += deltaY * curScale;
    update();
    thread.render(centerX, centerY, curScale, size());
}

Here is the call graph for this function:

---

Member Data Documentation

RenderThread MandelbrotWidget::thread [private]

Definition at line 55 of file mandelbrotwidget.h.

QPixmap MandelbrotWidget::pixmap [private]

Definition at line 56 of file mandelbrotwidget.h.

Referenced by mouseReleaseEvent(), paintEvent(), and updatePixmap().

QPoint MandelbrotWidget::pixmapOffset [private]

Definition at line 57 of file mandelbrotwidget.h.

Referenced by mouseMoveEvent(), mouseReleaseEvent(), paintEvent(), and updatePixmap().

QPoint MandelbrotWidget::lastDragPos [private]

Definition at line 58 of file mandelbrotwidget.h.

Referenced by mouseMoveEvent(), mousePressEvent(), mouseReleaseEvent(), and updatePixmap().

double MandelbrotWidget::centerX [private]

Definition at line 59 of file mandelbrotwidget.h.

Referenced by MandelbrotWidget(), resizeEvent(), scroll(), and zoom().

double MandelbrotWidget::centerY [private]

Definition at line 60 of file mandelbrotwidget.h.

Referenced by MandelbrotWidget(), resizeEvent(), scroll(), and zoom().

double MandelbrotWidget::pixmapScale [private]

Definition at line 61 of file mandelbrotwidget.h.

Referenced by MandelbrotWidget(), paintEvent(), and updatePixmap().

double MandelbrotWidget::curScale [private]

Definition at line 62 of file mandelbrotwidget.h.

Referenced by MandelbrotWidget(), paintEvent(), resizeEvent(), scroll(), and zoom().

---

The documentation for this class was generated from the following files:

• examples/threads/mandelbrot/mandelbrotwidget.h
• examples/threads/mandelbrot/mandelbrotwidget.cpp

---