QAlphaWidget Class Reference

Inheritance diagram for QAlphaWidget:

[legend]Collaboration diagram for QAlphaWidget:

[legend]List of all members.

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Detailed Description

Definition at line 57 of file qeffects.cpp.

Public Member Functions
	QAlphaWidget (QWidget *w, Qt::WindowFlags f=0)
void	run (int time)
Protected Slots
void	render ()
Protected Member Functions
void	paintEvent (QPaintEvent *e)
void	closeEvent (QCloseEvent *)
void	alphaBlend ()
Private Attributes
QPixmap	pm
double	alpha
QImage	back
QImage	front
QImage	mixed
QPointer< QAccessWidget >	widget
int	duration
int	elapsed
bool	showWidget
QTimer	anim
QTime	checkTime

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Constructor & Destructor Documentation

QAlphaWidget::QAlphaWidget	(	QWidget *	w,
		Qt::WindowFlags	f = 0
	)

Definition at line 92 of file qeffects.cpp.

References alpha, QWidget::setAttribute(), QWidget::setEnabled(), w, Qt::WA_NoSystemBackground, and widget.

    : QWidget(QApplication::desktop()->screen(QApplication::desktop()->screenNumber(w)), f)
{
#ifndef Q_WS_WIN
    setEnabled(false);
#endif

    setAttribute(Qt::WA_NoSystemBackground, true);
    widget = (QAccessWidget*)w;
    alpha = 0;
}

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Member Function Documentation

void QAlphaWidget::run

(

int

time

)

Definition at line 117 of file qeffects.cpp.

References anim, back, checkTime, QObject::connect(), QImage::copy(), QApplication::desktop(), duration, elapsed, QTime::elapsed(), QPixmap::fromImage(), front, QPixmap::grabWidget(), QPixmap::grabWindow(), QImage::isNull(), mixed, QWidget::move(), pm, qApp, render(), QWidget::resize(), QWidget::setEnabled(), QWidget::show(), showWidget, SIGNAL, SLOT, QTime::start(), QTimer::start(), QPixmap::toImage(), widget, and QWidget::winId().

Referenced by qFadeEffect().

{
    duration = time;

    if (duration < 0)
        duration = 150;

    if (!widget)
        return;

    elapsed = 0;
    checkTime.start();

    showWidget = true;
    qApp->installEventFilter(this);

    move(widget->geometry().x(),widget->geometry().y());
    resize(widget->size().width(), widget->size().height());

    front = QPixmap::grabWidget(widget).toImage();
    back = QPixmap::grabWindow(QApplication::desktop()->winId(),
                                widget->geometry().x(), widget->geometry().y(),
                                widget->geometry().width(), widget->geometry().height()).toImage();

    if (!back.isNull() && checkTime.elapsed() < duration / 2) {
        mixed = back.copy();
        pm = QPixmap::fromImage(mixed);
        show();
        setEnabled(false);

        connect(&anim, SIGNAL(timeout()), this, SLOT(render()));
        anim.start(1);
    } else {
        duration = 0;
        render();
    }
}

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void QAlphaWidget::paintEvent

(

QPaintEvent *

e

)

[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 107 of file qeffects.cpp.

References p, and pm.

{
    QPainter p(this);
    p.drawPixmap(0, 0, pm);
}

void QAlphaWidget::closeEvent

(

QCloseEvent *

e

)

[protected, virtual]

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

See also:

event(), hide(), close(), QCloseEvent, {Application Example}

Reimplemented from QWidget.

Definition at line 159 of file qeffects.cpp.

References QEvent::accept(), QWidget::closeEvent(), q_blend, render(), and showWidget.

{
    e->accept();
    if (!q_blend)
        return;

    showWidget = false;
    render();

    QWidget::closeEvent(e);
}

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void QAlphaWidget::alphaBlend

(

)

[protected]

Definition at line 217 of file qeffects.cpp.

References a, alpha, back, QImage::bits(), QImage::bytesPerLine(), QImage::depth(), fp, front, QImage::height(), mixed, qBlue(), qGreen(), qRed(), qRgb(), qRound(), and QImage::width().

Referenced by render().

{
    const int a = qRound(alpha*256);
    const int ia = 256 - a;

    const int sw = front.width();
    const int sh = front.height();
    const int bpl = front.bytesPerLine();
    switch(front.depth()) {
    case 32:
        {
            uchar *mixed_data = mixed.bits();
            const uchar *back_data = back.bits();
            const uchar *front_data = front.bits();

            for (int sy = 0; sy < sh; sy++) {
                quint32* mixed = (quint32*)mixed_data;
                const quint32* back = (const quint32*)back_data;
                const quint32* front = (const quint32*)front_data;
                for (int sx = 0; sx < sw; sx++) {
                    quint32 bp = back[sx];
                    quint32 fp = front[sx];

                    mixed[sx] =  qRgb((qRed(bp)*ia + qRed(fp)*a)>>8,
                                      (qGreen(bp)*ia + qGreen(fp)*a)>>8,
                                      (qBlue(bp)*ia + qBlue(fp)*a)>>8);
                }
                mixed_data += bpl;
                back_data += bpl;
                front_data += bpl;
            }
        }
    default:
        break;
    }
}

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void QAlphaWidget::render

(

)

[protected, slot]

Definition at line 177 of file qeffects.cpp.

References alpha, alphaBlend(), anim, checkTime, QObject::deleteLater(), duration, elapsed, QTime::elapsed(), QPixmap::fromImage(), QWidget::lower(), mixed, pm, q_blend, qApp, QWidget::repaint(), QWidget::setEnabled(), QWidget::setFocus(), showWidget, QTimer::stop(), and widget.

Referenced by closeEvent(), and run().

{
    int tempel = checkTime.elapsed();
    if (elapsed >= tempel)
        elapsed++;
    else
        elapsed = tempel;

    if (duration != 0)
        alpha = tempel / double(duration);
    else
        alpha = 1;
    if (alpha >= 1 || !showWidget) {
        anim.stop();
        qApp->removeEventFilter(this);

        if (widget) {
            if (!showWidget) {
#ifdef Q_WS_WIN
                setEnabled(true);
                setFocus();
#endif
                widget->hide();
            } else {
                widget->show();
                lower();
            }
        }
        q_blend = 0;
        deleteLater();
    } else {
        alphaBlend();
        pm = QPixmap::fromImage(mixed);
        repaint();
    }
}

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Member Data Documentation

QPixmap QAlphaWidget::pm [private]

Definition at line 74 of file qeffects.cpp.

Referenced by paintEvent(), render(), and run().

double QAlphaWidget::alpha [private]

Definition at line 75 of file qeffects.cpp.

Referenced by alphaBlend(), QAlphaWidget(), and render().

QImage QAlphaWidget::back [private]

Definition at line 76 of file qeffects.cpp.

Referenced by alphaBlend(), and run().

QImage QAlphaWidget::front [private]

Definition at line 77 of file qeffects.cpp.

Referenced by alphaBlend(), and run().

QImage QAlphaWidget::mixed [private]

Definition at line 78 of file qeffects.cpp.

Referenced by alphaBlend(), render(), and run().

QPointer<QAccessWidget> QAlphaWidget::widget [private]

Definition at line 79 of file qeffects.cpp.

Referenced by QAlphaWidget(), render(), and run().

int QAlphaWidget::duration [private]

Definition at line 80 of file qeffects.cpp.

Referenced by render(), and run().

int QAlphaWidget::elapsed [private]

Definition at line 81 of file qeffects.cpp.

Referenced by render(), and run().

bool QAlphaWidget::showWidget [private]

Definition at line 82 of file qeffects.cpp.

Referenced by closeEvent(), render(), and run().

QTimer QAlphaWidget::anim [private]

Definition at line 83 of file qeffects.cpp.

Referenced by render(), and run().

QTime QAlphaWidget::checkTime [private]

Definition at line 84 of file qeffects.cpp.

Referenced by render(), and run().

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

• src/gui/widgets/qeffects.cpp

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