Member Function Documentation

[protected] QPaintDevice::QPaintDevice()

Constructs a paint device. This constructor can be invoked only from subclasses of QPaintDevice.

[virtual] QPaintDevice::~QPaintDevice()

Destroys the paint device and frees window system resources.

int QPaintDevice::colorCount() const

Returns the number of different colors available for the paint device. If the number of colors available is too great to be represented by the int data type, then INT_MAX will be returned instead.

int QPaintDevice::depth() const

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

int QPaintDevice::devicePixelRatio() const

Returns the device pixel ratio for device.

Common values are 1 for normal-dpi displays and 2 for high-dpi "retina" displays.

qreal QPaintDevice::devicePixelRatioF() const

Returns the device pixel ratio for the device as a floating point number.

This function was introduced in Qt 5.6.

int QPaintDevice::height() const

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

See also heightMM().

int QPaintDevice::heightMM() const

Returns the height of the paint device in millimeters. Due to platform limitations it may not be possible to use this function to determine the actual physical size of a widget on the screen.

See also height().

int QPaintDevice::logicalDpiX() const

Returns the horizontal resolution of the device in dots per inch, which is used when computing font sizes. For X11, this is usually the same as could be computed from widthMM().

Note that if the logicalDpiX() doesn't equal the physicalDpiX(), the corresponding QPaintEngine must handle the resolution mapping.

See also logicalDpiY() and physicalDpiX().

int QPaintDevice::logicalDpiY() const

Returns the vertical resolution of the device in dots per inch, which is used when computing font sizes. For X11, this is usually the same as could be computed from heightMM().

Note that if the logicalDpiY() doesn't equal the physicalDpiY(), the corresponding QPaintEngine must handle the resolution mapping.

See also logicalDpiX() and physicalDpiY().

[virtual protected] int QPaintDevice::metric(QPaintDevice::PaintDeviceMetric metric) const

Returns the metric information for the given paint device metric.

See also PaintDeviceMetric.

[pure virtual] QPaintEngine *QPaintDevice::paintEngine() const

Returns a pointer to the paint engine used for drawing on the device.

bool QPaintDevice::paintingActive() const

Returns true if the device is currently being painted on, i.e. someone has called QPainter::begin() but not yet called QPainter::end() for this device; otherwise returns false.

See also QPainter::isActive().

int QPaintDevice::physicalDpiX() const

Returns the horizontal resolution of the device in dots per inch. For example, when printing, this resolution refers to the physical printer's resolution. The logical DPI on the other hand, refers to the resolution used by the actual paint engine.

Note that if the physicalDpiX() doesn't equal the logicalDpiX(), the corresponding QPaintEngine must handle the resolution mapping.

See also physicalDpiY() and logicalDpiX().

int QPaintDevice::physicalDpiY() const

Returns the horizontal resolution of the device in dots per inch. For example, when printing, this resolution refers to the physical printer's resolution. The logical DPI on the other hand, refers to the resolution used by the actual paint engine.

Note that if the physicalDpiY() doesn't equal the logicalDpiY(), the corresponding QPaintEngine must handle the resolution mapping.

See also physicalDpiX() and logicalDpiY().

int QPaintDevice::width() const

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

See also widthMM().

int QPaintDevice::widthMM() const

Returns the width of the paint device in millimeters. Due to platform limitations it may not be possible to use this function to determine the actual physical size of a widget on the screen.

See also width().