QPaintDeviceMetrics

Section: Misc. Reference Manual Pages (3qt)
Updated: 2 February 2007
Index Return to Main Contents
 

NAME

QPaintDeviceMetrics - Information about a paint device  

SYNOPSIS

#include <qpaintdevicemetrics.h>

 

Public Members


QPaintDeviceMetrics ( const QPaintDevice * pd )

int width () const

int height () const

int widthMM () const

int heightMM () const

int logicalDpiX () const

int logicalDpiY () const

int numColors () const

int depth () const
 

DESCRIPTION

The QPaintDeviceMetrics class provides information about a paint device.

Sometimes when drawing graphics it is necessary to obtain information about the physical characteristics of a paint device. This class provides the information. For example, to compute the aspect ratio of a paint device: 



        QPaintDeviceMetrics pdm( myWidget );


        double aspect = (double)pdm.widthMM() / (double)pdm.heightMM();

QPaintDeviceMetrics contains methods to provide the width and height of a device in both pixels (width() and height()) and millimeters (widthMM() and heightMM()), the number of colors the device supports (numColors()), the number of bit planes (depth()), and the resolution of the device (logicalDpiX() and logicalDpiY()).

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 of a QPrinter that is set to "print to file": who knows what printer that file will end up on?

See also Graphics Classes and Image Processing Classes.  

MEMBER FUNCTION DOCUMENTATION

 

QPaintDeviceMetrics::QPaintDeviceMetrics ( const QPaintDevice * pd )

Constructs a metric for the paint device pd.  

int QPaintDeviceMetrics::depth () const

Returns the bit depth (number of bit planes) of the paint device.  

int QPaintDeviceMetrics::height () const

Returns the height of the paint device in default coordinate system units (e.g. pixels for QPixmap and QWidget).

Examples:  

int QPaintDeviceMetrics::heightMM () const

Returns the height of the paint device, measured in millimeters.  

int QPaintDeviceMetrics::logicalDpiX () const

Returns the horizontal resolution of the device in dots per inch, which is used when computing font sizes. For X, this is usually the same as could be computed from widthMM(), but it varies on Windows.

Example: qwerty/qwerty.cpp.  

int QPaintDeviceMetrics::logicalDpiY () const

Returns the vertical resolution of the device in dots per inch, which is used when computing font sizes. For X, this is usually the same as could be computed from heightMM(), but it varies on Windows.

Examples:  

int QPaintDeviceMetrics::numColors () const

Returns the number of different colors available for the paint device. Since this value is an int will not be sufficient to represent the number of colors on 32 bit displays, in which case INT_MAX is returned instead.  

int QPaintDeviceMetrics::width () const

Returns the width of the paint device in default coordinate system units (e.g. pixels for QPixmap and QWidget).

Examples:  

int QPaintDeviceMetrics::widthMM () const

Returns the width of the paint device, measured in millimeters.

 

SEE ALSO

http://doc.trolltech.com/qpaintdevicemetrics.html http://www.trolltech.com/faq/tech.html  

COPYRIGHT

Copyright 1992-2007 Trolltech ASA, 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 help us to help you. Thank you. The definitive Qt documentation is provided in HTML format; it is located at $QTDIR/doc/html and can be read using Qt Assistant or with a web browser. This man page is provided as a convenience for those users who prefer man pages, although this format is not officially supported by Trolltech. If you find errors in this manual page, please report them to qt-bugs@trolltech.com. Please include the name of the manual page (qpaintdevicemetrics.3qt) and the Qt version (3.3.8).