QwtPaintBuffer Class Reference

Paint buffer for Qwt widgets. More...

#include <qwt_paint_buffer.h>

List of all members.

Public Member Functions
	QwtPaintBuffer ()
	Default constructor.
	QwtPaintBuffer (QPaintDevice *, const QRect &, QPainter *p=NULL)
virtual	~QwtPaintBuffer ()
void	open (QPaintDevice *, const QRect &, QPainter *p=NULL)
void	close ()
QPainter *	painter ()
const QPaintDevice *	device ()
const QPixmap &	buffer () const
	Return Buffer used for double buffering.
Static Public Member Functions
static void	setEnabled (bool enable)
static bool	isEnabled ()
Protected Member Functions
void	flush ()

---

Detailed Description

Paint buffer for Qwt widgets.

QwtPaintBuffer offers a simple way to en/disable double buffering. Double buffering is enabled as default and in general there will be no reason to change this.

Definition at line 29 of file qwt_paint_buffer.h.

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Constructor & Destructor Documentation

QwtPaintBuffer::QwtPaintBuffer

(

)

[explicit]

Default constructor.

Definition at line 21 of file qwt_paint_buffer.cpp.

                              :
    d_device(0),
    d_painter(0),
    d_devicePainter(0)
{
}

QwtPaintBuffer::QwtPaintBuffer	(	QPaintDevice *	device,
		const QRect &	rect,
		QPainter *	painter = NULL
	)		[explicit]

Create an open paint buffer

Parameters:

device	Device to paint on
rect	Rect to paint on
painter	Painter to paint on device. In case of 0 QwtPaintBuffer uses an internal painter

See also:

open()

Definition at line 38 of file qwt_paint_buffer.cpp.

References open().

                                             :
    d_device(0),
    d_painter(0),
    d_devicePainter(0)
{
    open(device, rect, painter);
}

QwtPaintBuffer::~QwtPaintBuffer

(

)

[virtual]

Closes the buffer

See also:

close()

Definition at line 51 of file qwt_paint_buffer.cpp.

References close().

{
    close();
}

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Member Function Documentation

const QPixmap& QwtPaintBuffer::buffer

(

)

const [inline]

Return Buffer used for double buffering.

Definition at line 47 of file qwt_paint_buffer.h.

{ return d_pixBuffer; }

void QwtPaintBuffer::close

(

)

Flush the internal pixmap buffer to the device and close the buffer.

Definition at line 180 of file qwt_paint_buffer.cpp.

References flush().

Referenced by open(), and ~QwtPaintBuffer().

{
    flush();

    if ( d_painter )
    {
        if ( d_painter->isActive() )
            d_painter->end();

        if ( d_painter != d_devicePainter )
            delete d_painter;
    }

    if ( !d_pixBuffer.isNull() )
        d_pixBuffer = QPixmap();

    d_device = 0;
    d_painter = 0;
    d_devicePainter = 0;
} 

const QPaintDevice * QwtPaintBuffer::device

(

)

Returns:

Device to paint on

Definition at line 70 of file qwt_paint_buffer.cpp.

Referenced by flush(), and open().

{ 
    return d_device; 
}

void QwtPaintBuffer::flush

(

)

[protected]

Flush the internal pixmap buffer to the device.

Definition at line 153 of file qwt_paint_buffer.cpp.

References device().

Referenced by close().

{
    if ( d_enabled && d_device != 0 && d_rect.isValid())
    {
        // We need a painter to find out if
        // there is a painter redirection for d_device.

        QPainter *p;
        if ( d_devicePainter == 0 )
            p = new QPainter(d_device);
        else 
            p = d_devicePainter;

        QPaintDevice *device = p->device();
        if ( device->isExtDev() )
            d_devicePainter->drawPixmap(d_rect.topLeft(), d_pixBuffer);
        else
            bitBlt(device, d_rect.topLeft(), &d_pixBuffer );

        if ( d_devicePainter == 0 )
            delete p;
    }
}

bool QwtPaintBuffer::isEnabled

(

)

[static]

Returns:

true if double buffering is enabled, false otherwise.

Definition at line 88 of file qwt_paint_buffer.cpp.

Referenced by open().

{ 
    return d_enabled; 
}

void QwtPaintBuffer::open	(	QPaintDevice *	device,
		const QRect &	rect,
		QPainter *	painter = NULL
	)

Open the buffer

Parameters:

device	Device to paint on
rect	Rect to paint on
painter	Painter to paint on device. In case of 0 QwtPaintBuffer uses an internal painter

Definition at line 101 of file qwt_paint_buffer.cpp.

References close(), device(), isEnabled(), and painter().

Referenced by QwtPaintBuffer().

{
    close();

    if ( device == 0 || !rect.isValid() )
        return;

    d_device = device;
    d_devicePainter = painter;
    d_rect = rect;

    if ( isEnabled() )
    {
#ifdef Q_WS_X11
        if ( d_pixBuffer.x11Screen() != d_device->x11Screen() )
            d_pixBuffer.x11SetScreen(d_device->x11Screen());
#endif
        d_pixBuffer.resize(d_rect.size());

        d_painter = new QPainter();
        if ( d_device->devType() == QInternal::Widget )
        {
            QWidget *w = (QWidget *)d_device;
            d_pixBuffer.fill(w, d_rect.topLeft());
            d_painter->begin(&d_pixBuffer, w);
            d_painter->translate(-d_rect.x(), -d_rect.y());
        }
        else
        {
            d_painter->begin(&d_pixBuffer);
        }
    }
    else
    {
        if ( d_devicePainter )
            d_painter = d_devicePainter;
        else
            d_painter = new QPainter(d_device);

        if ( d_device->devType() == QInternal::Widget )
        {
            QWidget *w = (QWidget *)d_device;
            if ( w->testWFlags( Qt::WNoAutoErase ) )
                d_painter->eraseRect(d_rect);
        }
    }
}

QPainter * QwtPaintBuffer::painter

(

)

Returns:

Depending on isEnabled() the painter connected to an internal pixmap buffer otherwise the painter connected to the device.

Definition at line 62 of file qwt_paint_buffer.cpp.

Referenced by open(), QwtWheel::paintEvent(), QwtThermo::paintEvent(), QwtSlider::paintEvent(), QwtScaleWidget::paintEvent(), QwtKnob::paintEvent(), and QwtDial::paintEvent().

{ 
    return d_painter; 
}

void QwtPaintBuffer::setEnabled

(

bool

enable )

[static]

Enable/Disable double buffering. Please note that this is a global switch for all QwtPaintBuffers, but won't change opened buffers.

Definition at line 80 of file qwt_paint_buffer.cpp.

{ 
    d_enabled = enable; 
}

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

• qwt_paint_buffer.h
• qwt_paint_buffer.cpp