qpaintdevice.3qt

Linux 下的图形编程环境。

'\" t
.TH QPaintDevice 3qt "5 March 2001" "Trolltech AS" \" -*- nroff -*-
.\" Copyright 1992-2001 Trolltech AS.  All rights reserved.  See the
.\" license file included in the distribution for a complete license
.\" statement.
.\"
.ad l
.nh
.SH NAME
QPaintDevice \- Of objects that can be painted
.br
.PP
\fC#include <qpaintdevice.h>\fR
.PP
Inherited by QPicture, QPixmap, QPrinter and QWidget.
.PP
.SS "Public Members"
.in +1c
.ti -1c
.BI "virtual \fB~QPaintDevice\fR () "
.br
.ti -1c
.BI "int \fBdevType\fR () const"
.br
.ti -1c
.BI "bool \fBisExtDev\fR () const"
.br
.ti -1c
.BI "bool \fBpaintingActive\fR () const"
.br
.ti -1c
.BI "enum \fBPDevCmd\fR { 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 }"
.br
.in -1c
.SS "Protected Members"
.in +1c
.ti -1c
.BI "\fBQPaintDevice\fR ( uint devflags ) "
.br
.ti -1c
.BI "virtual bool \fBcmd\fR ( int, QPainter *, QPDevCmdParam * ) "
.br
.ti -1c
.BI "virtual int \fBmetric\fR ( int ) const"
.br
.ti -1c
.BI "virtual int \fBfontMet\fR ( QFont *, int, const char * = 0, int = 0 ) const"
.br
.ti -1c
.BI "virtual int \fBfontInf\fR ( QFont *, int ) const"
.br
.in -1c
.SH RELATED FUNCTION DOCUMENTATION
(Note that these are not member functions.)
.in +1c
.ti -1c
.BI "void \fBbitBlt\fR (QPaintDevice * " "dst" ", const QPoint & " "dp" ", const QPaintDevice * " "src" ", const QRect & " "sr" ", RasterOp " "rop" ")"
.br
.ti -1c
.BI "void \fBbitBlt\fR (QPaintDevice * " "dst" ", int " "dx" ", int " "dy" ", const QPaintDevice * " "src" ", int " "sx" ", int " "sy" ", int " "sw" ", int " "sh" ", Qt::RasterOp " "rop" ", bool " "ignoreMask" ")"
.br
.in -1c
.SH DESCRIPTION
The base class of objects that can be painted.
.PP
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.
.PP
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().
.PP
Example (draw on a paint device):
.PP
.nf
.br
    void MyWidget::paintEvent( QPaintEvent * )
.br
    {
.br
        QPainter p;                             // our painter
.br
        p.begin( this );                        // start painting widget
.br
        p.setPen( red );                        // blue outline
.br
        p.setBrush( yellow );                   // yellow fill
.br
        p.drawEllipse( 10,20, 100,100 );        // 100x100 ellipse at 10,20
.br
        p.end();                                // painting done
.br
    }
.fi
.PP
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().
.PP
Example (scroll widget contents 10 pixels to the right):
.PP
.nf
.br
    bitBlt( myWidget, 10,0, myWidget );
.fi
.PP
\fBWarning:\fR 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.
.SH MEMBER FUNCTION DOCUMENTATION
.SH "QPaintDevice::QPaintDevice ( uint devflags ) \fC[protected]\fR"
Constructs a paint device with internal flags \fIdevflags.\fR This constructor can only be invoked from subclasses of QPaintDevice.
.SH "QPaintDevice::~QPaintDevice () \fC[virtual]\fR"
Destructs the paint device and frees window system resources.
.SH "bool QPaintDevice::cmd ( int, QPainter *, QPDevCmdParam * ) \fC[virtual protected]\fR"
Internal virtual function that interprets drawing commands from the painter.
.PP
Implemented by subclasses that have no direct support for drawing graphics (external paint devices, for example QPicture).
.PP
Reimplemented in QPrinter and QPicture.
.SH "int QPaintDevice::devType () const"
Returns the device type identifier: \fCQInternal::Widget, QInternal::Pixmap, QInternal::Printer, QInternal::Picture\fR or \fCQInternal::UndefinedDevice.\fR
.SH "int QPaintDevice::fontInf ( QFont *, int ) const \fC[virtual protected]\fR"
Internal virtual function. Reserved for future use.
.SH "int QPaintDevice::fontMet ( QFont *, int, const char * = 0, int = 0 ) const \fC[virtual protected]\fR"
Internal virtual function. Reserved for future use.
.SH "bool QPaintDevice::isExtDev () const"
Returns TRUE if the device is a so-called external paint device.
.PP
External paint devices cannot be bitBlt()'ed from. QPicture and QPrinter are external paint devices.
.SH "int QPaintDevice::metric ( int ) const \fC[virtual protected]\fR"
Internal virtual function that returns paint device metrics.
.PP
Please use the QPaintDeviceMetrics class instead.
.PP
Reimplemented in QWidget, QPrinter, QPicture and QPixmap.
.SH "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.
.PP
See also QPainter::isActive().
.SH RELATED FUNCTION DOCUMENTATION
.SH "void bitBlt (QPaintDevice * dst, const QPoint & dp, const QPaintDevice * src, const QRect & sr, RasterOp rop)"
Overloaded bitBlt() with the destination point \fIdp\fR and source rectangle \fIsr.\fR
.PP
Examples:
.(l
xform/xform.cpp desktop/desktop.cpp
.)l
.SH "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).
.PP
Arguments:
.TP
\fIdst\fR is the paint device to copy to.
.TP
\fIdx\fR and \fIdy\fR is the position to copy to.
.TP
\fIsrc\fR is the paint device to copy from.
.TP
\fIsx\fR and \fIsy\fR is the position to copy from.
.TP
\fIsw\fR and \fIsh\fR is the width and height of the block to be copied.
.TP
\fIrop\fR defines the raster operation to be used when copying. If \fIsw\fR is 0 or \fIsh\fR is 0, then bitBlt will do nothing.
.PP
If \fIsw\fR is negative, then bitBlt calculates \fCsw = src->width - sx.\fR If \fIsh\fR is negative, then bitBlt calculates \fCsh = src->height - sy.\fR
.PP
The \fIrop\fR argument can be one of:
.TP
\fCCopyROP:\fR dst = src.
.TP
\fCOrROP:\fR dst = src OR dst.
.TP
\fCXorROP:\fR dst = src XOR dst.
.TP
\fCNotAndROP:\fR dst = (NOT src) AND dst
.TP
\fCNotCopyROP:\fR dst = NOT src
.TP
\fCNotOrROP:\fR dst = (NOT src) OR dst
.TP
\fCNotXorROP:\fR dst = (NOT src) XOR dst
.TP
\fCAndROP\fR dst = src AND dst
.TP
\fCNotROP:\fR dst = NOT dst
.TP
\fCClearROP:\fR dst = 0
.TP
\fCSetROP:\fR dst = 1
.TP
\fCNopROP:\fR dst = dst
.TP
\fCAndNotROP:\fR dst = src AND (NOT dst)
.TP
\fCOrNotROP:\fR dst = src OR (NOT dst)
.TP
\fCNandROP:\fR dst = NOT (src AND dst)
.TP
\fCNorROP:\fR dst = NOT (src OR dst)
.PP
The \fIignoreMask\fR argument (default FALSE) applies where \fIsrc\fR is a QPixmap with a mask. If \fIignoreMask\fR is TRUE, bitBlt ignores the pixmap's mask.
.PP
BitBlt has two restrictions:
.IP 1
The \fIsrc\fR device must be QWidget or QPixmap. You cannot copy pixels from a picture or a printer (external device).
.IP 2
 The \fIsrc\fR device may not have pixel depth greater than \fIdst.\fR
You cannot copy from an 8 bit pixmap to a 1 bit pixmap.
.SH "SEE ALSO"
.BR http://doc.trolltech.com/qpaintdevice.html
.BR http://www.trolltech.com/faq/tech.html
.SH COPYRIGHT
Copyright 1992-2001 Trolltech AS, http://www.trolltech.com.  See the
license file included in the distribution for a complete license
statement.
.SH AUTHOR
Generated automatically from the source code.
.SH BUGS
If you find a bug in Qt, please report it as described in
.BR http://doc.trolltech.com/bughowto.html .
Good bug reports make our job much simpler. Thank you.
.P
In case of content or formattting problems with this manual page, please
report them to
.BR [e-mail] .
Please include the name of the manual page (qpaintdevice.3qt) and the Qt
version (2.3.0).