qpaintdevicemetrics.3qt

Linux 下的图形编程环境。

'\" t
.TH QPaintDeviceMetrics 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
QPaintDeviceMetrics \- Information about a paint device
.br
.PP
\fC#include <qpaintdevicemetrics.h>\fR
.PP
.SS "Public Members"
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.BI "\fBQPaintDeviceMetrics\fR ( const QPaintDevice * ) "
.br
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.BI "enum { PdmWidth = 1, PdmHeight, PdmWidthMM, PdmHeightMM, PdmNumColors, PdmDepth, PdmDpiX, PdmDpiY }"
.br
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.BI "int \fBwidth\fR () const"
.br
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.BI "int \fBheight\fR () const"
.br
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.BI "int \fBwidthMM\fR () const"
.br
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.BI "int \fBheightMM\fR () const"
.br
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.BI "int \fBlogicalDpiX\fR () const"
.br
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.BI "int \fBlogicalDpiY\fR () const"
.br
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.BI "int \fBnumColors\fR () const"
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.BI "int \fBdepth\fR () const"
.br
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.SH DESCRIPTION
The QPaintDeviceMetrics class provides information about a paint device.
.PP
Sometimes it is necessary to obtain information about the physical characteristics of a paint device when drawing graphics. This class provides just that. For example, to compute the aspect ratio of a paint device:
.PP
.nf
.br
    QPaintDeviceMetrics pdm( myWidget );
.br
    double aspect = (double)pdm.widthMM() / (double)pdm.heightMM();
.fi
.PP
QPaintDeviceMetrics contains methods to provide the width and height of a device in both pixels and millimeters, the number of colors the device supports, the number of bit planes, and finally the resolution of the device.
.PP
Note that it is not always possible for QPaintDeviceMetrics to compute the values you ask for, particularly for external devices. The ultimate example is asking for the resolution of a QPrinter that is set to "print to file" - who knows what printer that file will end up?.
.SH MEMBER FUNCTION DOCUMENTATION
.SH "QPaintDeviceMetrics::QPaintDeviceMetrics ( const QPaintDevice * pd )"
Constructs a metric for the paint device \fIpd.\fR
.SH "int QPaintDeviceMetrics::depth () const"
Returns the bit depth (number of bit planes) of the paint device.
.SH "int QPaintDeviceMetrics::height () const"
Returns the height of the paint device, in default coordinate system units (e.g. pixels for QPixmap and QWidget).
.SH "int QPaintDeviceMetrics::heightMM () const"
Returns the height of the paint device, measured in millimeters.
.SH "int QPaintDeviceMetrics::logicalDpiX () const"
Returns the horizontal resolution of the device, in dots per inch, that is used when computing font sizes. For X this is usually the same as could be computed from widthMM(), but on Windows this varies.
.SH "int QPaintDeviceMetrics::logicalDpiY () const"
Returns the vertical resolution of the device, in dots per inch, that is used when computing font sizes. For X this is usually the same as could be computed from heightMM(), but on Windows this varies.
.SH "int QPaintDeviceMetrics::numColors () const"
Returns the number of different colors available for the paint device.
.SH "int QPaintDeviceMetrics::width () const"
Returns the width of the paint device, in default coordinate system units (e.g. pixels for QPixmap and QWidget).
.SH "int QPaintDeviceMetrics::widthMM () const"
Returns the width of the paint device, measured in millimeters.
.SH "SEE ALSO"
.BR http://doc.trolltech.com/qpaintdevicemetrics.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 (qpaintdevicemetrics.3qt) and the Qt
version (2.3.0).