Qt 4.2 User's Guide: CannonField Class Reference

CannonField::CannonField ( QWidget * parent = 0 )

Definition at line 29 of file cannonfield.cpp.

References currentAngle, currentForce, QWidget::setAutoFillBackground(), and QWidget::setPalette().

00030     : QWidget(parent)
00031 {
00032     currentAngle = 45;
00033     currentForce = 0;
00034     setPalette(QPalette(QColor(250, 250, 200)));
00035     setAutoFillBackground(true);
00036 }

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CannonField::CannonField ( QWidget * parent = 0 )

int CannonField::angle ( ) const [inline]

Definition at line 36 of file cannonfield.h.

References currentAngle.

00036 { return currentAngle; }

int CannonField::force ( ) const [inline]

Definition at line 37 of file cannonfield.h.

References currentForce.

00037 { return currentForce; }

void CannonField::setAngle ( int angle ) [slot]

Definition at line 38 of file cannonfield.cpp.

References angleChanged(), cannonRect(), currentAngle, emit, and QWidget::update().

Referenced by mouseMoveEvent().

00039 {
00040     if (angle < 5)
00041         angle = 5;
00042     if (angle > 70)
00043         angle = 70;
00044     if (currentAngle == angle)
00045         return;
00046     currentAngle = angle;
00047     update(cannonRect());
00048     emit angleChanged(currentAngle);
00049 }

void CannonField::setForce ( int force ) [slot]

Definition at line 51 of file cannonfield.cpp.

References currentForce, emit, and forceChanged().

00052 {
00053     if (force < 0)
00054         force = 0;
00055     if (currentForce == force)
00056         return;
00057     currentForce = force;
00058     emit forceChanged(currentForce);
00059 }

void CannonField::angleChanged ( int newAngle ) [signal]

Referenced by setAngle().

void CannonField::forceChanged ( int newForce ) [signal]

Referenced by setForce().

void CannonField::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 61 of file cannonfield.cpp.

References Qt::blue, currentAngle, QPainter::drawPie(), QPainter::drawRect(), QWidget::height(), Qt::NoPen, QPainter::rotate(), QPainter::setBrush(), QPainter::setPen(), and QPainter::translate().

00062 {
00063     QPainter painter(this);
00064 
00065     painter.setPen(Qt::NoPen);
00066     painter.setBrush(Qt::blue);
00067 
00068     painter.translate(0, height());
00069     painter.drawPie(QRect(-35, -35, 70, 70), 0, 90 * 16);
00070     painter.rotate(-currentAngle);
00071     painter.drawRect(QRect(30, -5, 20, 10));
00072 }

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QRect CannonField::cannonRect ( ) const [private]

Definition at line 74 of file cannonfield.cpp.

References QRect::moveBottomLeft(), and QWidget::rect().

Referenced by setAngle().

00075 {
00076     QRect result(0, 0, 50, 50);
00077     result.moveBottomLeft(rect().bottomLeft());
00078     return result;
00079 }

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int CannonField::angle ( ) const [inline]

Definition at line 38 of file cannonfield.h.

References currentAngle.

00038 { return currentAngle; }

int CannonField::force ( ) const [inline]

Definition at line 39 of file cannonfield.h.

References currentForce.

00039 { return currentForce; }

void CannonField::setAngle ( int angle ) [slot]

void CannonField::setForce ( int force ) [slot]

void CannonField::shoot ( ) [slot]

Definition at line 69 of file cannonfield.cpp.

References autoShootTimer, currentAngle, currentForce, QTimer::isActive(), shootAngle, shootForce, QTimer::start(), and timerCount.

Referenced by GameBoard::fire().

00070 {
00071     if (autoShootTimer->isActive())
00072         return;
00073     timerCount = 0;
00074     shootAngle = currentAngle;
00075     shootForce = currentForce;
00076     autoShootTimer->start(5);
00077 }

void CannonField::moveShot ( ) [private, slot]

Definition at line 79 of file cannonfield.cpp.

References autoShootTimer, QWidget::height(), shotRect(), QTimer::stop(), timerCount, QRegion::unite(), QWidget::update(), QWidget::width(), QRect::x(), and QRect::y().

00080 {
00081     QRegion region = shotRect();
00082     ++timerCount;
00083 
00084     QRect shotR = shotRect();
00085 
00086     if (shotR.x() > width() || shotR.y() > height()) {
00087         autoShootTimer->stop();
00088     } else {
00089         region = region.unite(shotR);
00090     }
00091     update(region);
00092 }