Qt 4.8: QCustomRasterPaintDevice Class Reference

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# QCustomRasterPaintDevice Class Reference

The QCustomRasterPaintDevice class is provided to activate hardware accelerated paint engines in Qt for Embedded Linux. More...

     #include <QCustomRasterPaintDevice>

This class is under development and is subject to change.

Inherits: QPaintDevice.

This class was introduced in Qt 4.2.

- List of all members, including inherited members

## Public Functions

| QCustomRasterPaintDevice ( QWidget * widget )
virtual int | bytesPerLine () const
virtual QImage::Format | format () const
virtual void * | memory () const

## Reimplemented Public Functions

virtual int | metric ( PaintDeviceMetric m ) const

- 13 public functions inherited from QPaintDevice

### Additional Inherited Members

- 1 protected function inherited from QPaintDevice

## Detailed Description

The QCustomRasterPaintDevice class is provided to activate hardware accelerated paint engines in Qt for Embedded Linux.

Note that this class is only available in Qt for Embedded Linux.

In Qt for Embedded Linux, painting is a pure software implementation. But starting with Qt 4.2, it is possible to add an accelerated graphics driver to take advantage of available hardware resources.

Hardware acceleration is accomplished by creating a custom screen driver, accelerating the copying from memory to the screen, and implementing a custom paint engine accelerating the various painting operations. Then a custom paint device (derived from the QCustomRasterPaintDevice class) and a custom window surface (derived from QWSWindowSurface) must be implemented to make Qt for Embedded Linux aware of the accelerated driver.

See the Adding an Accelerated Graphics Driver to Qt for Embedded Linux documentation for details.

See also QRasterPaintEngine and QPaintDevice.

## Member Function Documentation

### QCustomRasterPaintDevice::QCustomRasterPaintDevice ( QWidget * widget )

Constructs a custom raster based paint device for the given top-level widget.

### int QCustomRasterPaintDevice::bytesPerLine () const`[virtual]`

Returns the number of bytes per line in the framebuffer. Note that this number might be larger than the framebuffer width.

### QImage::Format QCustomRasterPaintDevice::format () const`[virtual]`

Returns the format of the device's memory buffet.

The default format is QImage::Format_ARGB32_Premultiplied. The only other valid format is QImage::Format_RGB16.

### void * QCustomRasterPaintDevice::memory () const`[virtual]`

Returns a pointer to the paint device's memory buffer, or 0 if no such buffer exists.

### int QCustomRasterPaintDevice::metric ( PaintDeviceMetric m ) const`[virtual]`

Reimplemented from QPaintDevice::metric().