QPaintDevice(3qt)QPaintDevice(3qt)NAMEQPaintDevice - Of objects that can be painted
#include <qpaintdevice.h>
Inherited by QPicture, QPixmap, QPrinter and QWidget.
Public Members
virtual ~QPaintDevice ()
int devType () const
bool isExtDev () const
bool paintingActive () const
enum PDevCmd { PdcNOP = 0, PdcDrawPoint = 1, PdcDrawFirst
= PdcDrawPoint, PdcMoveTo = 2, PdcLineTo = 3,
PdcDrawLine = 4, PdcDrawRect = 5, PdcDrawRoundRect =
6, PdcDrawEllipse = 7, PdcDrawArc = 8, PdcDrawPie = 9,
PdcDrawChord = 10, PdcDrawLineSegments = 11,
PdcDrawPolyline = 12, PdcDrawPolygon = 13,
PdcDrawQuadBezier = 14, PdcDrawText = 15,
PdcDrawTextFormatted = 16, PdcDrawPixmap = 17,
PdcDrawImage = 18, PdcDrawText2 = 19,
PdcDrawText2Formatted = 20, PdcDrawLast =
PdcDrawText2Formatted, PdcBegin = 30, PdcEnd = 31,
PdcSave = 32, PdcRestore = 33, PdcSetdev = 34,
PdcSetBkColor = 40, PdcSetBkMode = 41, PdcSetROP = 42,
PdcSetBrushOrigin = 43, PdcSetFont = 45, PdcSetPen =
46, PdcSetBrush = 47, PdcSetTabStops = 48,
PdcSetTabArray = 49, PdcSetUnit = 50, PdcSetVXform =
51, PdcSetWindow = 52, PdcSetViewport = 53,
PdcSetWXform = 54, PdcSetWMatrix = 55, PdcSaveWMatrix
= 56, PdcRestoreWMatrix = 57, PdcSetClip = 60,
PdcSetClipRegion = 61, PdcReservedStart = 0,
PdcReservedStop = 199 }
Protected Members
QPaintDevice ( uint devflags )
virtual bool cmd ( int, QPainter *, QPDevCmdParam * )
virtual int metric ( int ) const
virtual int fontMet ( QFont *, int, const char * = 0, int
= 0 ) const
virtual int fontInf ( QFont *, int ) const
RELATED FUNCTION DOCUMENTATION
(Note that these are not member functions.)
void bitBlt (QPaintDevice * dst, const QPoint & dp, const
QPaintDevice * src, const QRect & sr, RasterOp rop)
void bitBlt (QPaintDevice * dst, int dx, int dy, const
QPaintDevice * src, int sx, int sy, int sw, int sh,
Qt::RasterOp rop, bool ignoreMask)
DESCRIPTION
The base class of objects that can be painted.
Trolltech AS 13 June 2001 1
QPaintDevice(3qt)QPaintDevice(3qt)
A paint device is an abstraction of a two-dimensional
space that can be drawn using a QPainter. The drawing
capabilities are implemented by the subclasses: QWidget,
QPixmap, QPicture and QPrinter.
The default coordinate system of a paint device has its
origin located at the top left position. X increases to
the right and Y increases downwards. The unit is one
pixel. There are several ways to set up a user-defined
coordinate system using the painter, for example by
QPainter::setWorldMatrix().
Example (draw on a paint device):
void MyWidget::paintEvent( QPaintEvent * )
{
QPainter p; // our painter
p.begin( this ); // start painting widget
p.setPen( red ); // blue outline
p.setBrush( yellow ); // yellow fill
p.drawEllipse( 10,20, 100,100 ); // 100x100 ellipse at 10,20
p.end(); // painting done
}
The bit block transfer is an extremely useful operation
for copying pixels from one paint device to another (or to
itself). It is implemented as the global function
bitBlt().
Example (scroll widget contents 10 pixels to the right):
bitBlt( myWidget, 10,0, myWidget );
Warning: Qt requires that a QApplication object must exist
before any paint devices can be created. Paint devices
access window system resources, and these resources are
not initialized before an application object is created.
MEMBER FUNCTION DOCUMENTATIONQPaintDevice::QPaintDevice ( uint devflags ) [protected]
Constructs a paint device with internal flags devflags.
This constructor can only be invoked from subclasses of
QPaintDevice.
QPaintDevice::~QPaintDevice () [virtual]
Destructs the paint device and frees window system
resources.
bool QPaintDevice::cmd ( int, QPainter *, QPDevCmdParam * )
[virtual protected]
Internal virtual function that interprets drawing commands
from the painter.
Implemented by subclasses that have no direct support for
Trolltech AS 13 June 2001 2
QPaintDevice(3qt)QPaintDevice(3qt)
drawing graphics (external paint devices, for example
QPicture).
Reimplemented in QPrinter and QPicture.
int QPaintDevice::devType () const
Returns the device type identifier: QInternal::Widget,
QInternal::Pixmap, QInternal::Printer, QInternal::Picture
or QInternal::UndefinedDevice.
int QPaintDevice::fontInf ( QFont *, int ) const [virtual
protected]
Internal virtual function. Reserved for future use.
int QPaintDevice::fontMet ( QFont *, int, const char * = 0, int =
0 ) const [virtual protected]
Internal virtual function. Reserved for future use.
bool QPaintDevice::isExtDev () const
Returns TRUE if the device is a so-called external paint
device.
External paint devices cannot be bitBlt()'ed from.
QPicture and QPrinter are external paint devices.
int QPaintDevice::metric ( int ) const [virtual protected]
Internal virtual function that returns paint device
metrics.
Please use the QPaintDeviceMetrics class instead.
Reimplemented in QWidget, QPrinter, QPicture and QPixmap.
bool QPaintDevice::paintingActive () const
Returns TRUE if the device is being painted, i.e. someone
has called QPainter::begin() and not yet QPainter::end()
for this device.
See also QPainter::isActive().
RELATED FUNCTION DOCUMENTATIONvoid bitBlt (QPaintDevice * dst, const QPoint & dp, const
QPaintDevice * src, const QRect & sr, RasterOp rop)
Overloaded bitBlt() with the destination point dp and
source rectangle sr.
Examples: xform/xform.cpp desktop/desktop.cpp
void bitBlt (QPaintDevice * dst, int dx, int dy, const
QPaintDevice * src, int sx, int sy, int sw, int sh,
Qt::RasterOp rop, bool ignoreMask)
This function copies a block of pixels from one paint
device to another (bitBlt means bit block transfer).
Trolltech AS 13 June 2001 3
QPaintDevice(3qt)QPaintDevice(3qt)
Arguments:
dst is the paint device to copy to.
dx and dy is the position to copy to.
src is the paint device to copy from.
sx and sy is the position to copy from.
sw and sh is the width and height of the block to be
copied.
rop defines the raster operation to be used when copying.
If sw is 0 or sh is 0, then bitBlt will do nothing.
If sw is negative, then bitBlt calculates sw = src->width
- sx. If sh is negative, then bitBlt calculates sh =
src->height - sy.
The rop argument can be one of:
CopyROP: dst = src.
OrROP: dst = src OR dst.
XorROP: dst = src XOR dst.
NotAndROP: dst = (NOT src) AND dst
NotCopyROP: dst = NOT src
NotOrROP: dst = (NOT src) OR dst
NotXorROP: dst = (NOT src) XOR dst
AndROP dst = src AND dst
NotROP: dst = NOT dst
ClearROP: dst = 0
SetROP: dst = 1
NopROP: dst = dst
AndNotROP: dst = src AND (NOT dst)
OrNotROP: dst = src OR (NOT dst)
NandROP: dst = NOT (src AND dst)
NorROP: dst = NOT (src OR dst)
Trolltech AS 13 June 2001 4
QPaintDevice(3qt)QPaintDevice(3qt)
The ignoreMask argument (default FALSE) applies where src
is a QPixmap with a mask. If ignoreMask is TRUE, bitBlt
ignores the pixmap's mask.
BitBlt has two restrictions:
1 The src device must be QWidget or QPixmap. You
cannot copy pixels from a picture or a printer
(external device).
2 The src device may not have pixel depth greater
than dst. You cannot copy from an 8 bit pixmap to
a 1 bit pixmap.
SEE ALSO
http://doc.trolltech.com/qpaintdevice.html
http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2001 Trolltech AS,
http://www.trolltech.com. See the license file included
in the distribution for a complete license statement.
AUTHOR
Generated automatically from the source code.
BUGS
If you find a bug in Qt, please report it as described in
http://doc.trolltech.com/bughowto.html. Good bug reports
make our job much simpler. Thank you.
In case of content or formattting problems with this
manual page, please report them to qt-bugs@trolltech.com.
Please include the name of the manual page
(qpaintdevice.3qt) and the Qt version (2.3.1).
Trolltech AS 13 June 2001 5
