Qt Toolkit - QPaintDeviceMetrics Class

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# QPaintDeviceMetrics Class Reference

The QPaintDeviceMetrics class provides information about a paint device. More...

`#include <qpaintdevicemetrics.h>`

List of all member functions.

## Public Members

- QPaintDeviceMetrics ( const QPaintDevice * )
- enum { PdmWidth = 1, PdmHeight, PdmWidthMM, PdmHeightMM, PdmNumColors, PdmDepth, PdmDpiX, PdmDpiY }
- int width () const
- int height () const
- int widthMM () const
- int heightMM () const
- int logicalDpiX () const
- int logicalDpiY () const
- int numColors () const
- int depth () const

## Detailed Description

The QPaintDeviceMetrics class provides information about a paint device.

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:

        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 and millimeters, the number of colors the device supports, the number of bit planes, and finally the resolution of the device.

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?.

## 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).

### 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, 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.

### 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.

### int QPaintDeviceMetrics::numColors () const

Returns the number of different colors available for the paint device.

### int QPaintDeviceMetrics::width () const

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

### int QPaintDeviceMetrics::widthMM () const

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

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