The QGradient class is used in combination with QBrush to specify gradient fills. More...

#include <qbrush.h>

Inheritance diagram for QGradient:

Public Types
enum	CoordinateMode { LogicalMode, StretchToDeviceMode, ObjectBoundingMode }
	This enum specifies how gradient coordinates map to the paint device on which the gradient is used. More...

enum	InterpolationMode { ColorInterpolation, ComponentInterpolation }

enum	Spread { PadSpread, ReflectSpread, RepeatSpread }
	Specifies how the area outside the gradient area should be filled. More...

enum	Type { LinearGradient, RadialGradient, ConicalGradient, NoGradient }
	Specifies the type of gradient. More...

Public Functions
CoordinateMode	coordinateMode () const
	Returns the coordinate mode of this gradient. More...

InterpolationMode	interpolationMode () const
	Returns the interpolation mode of this gradient. More...

bool	operator!= (const QGradient &other) const
	Returns true if the gradient is the same as the other gradient specified; otherwise returns false. More...

bool	operator== (const QGradient &gradient) const
	Returns true if the gradient is the same as the other gradient specified; otherwise returns false. More...

bool	operator== (const QGradient &gradient)

	QGradient ()

void	setColorAt (qreal pos, const QColor &color)
	Creates a stop point at the given position with the given color. More...

void	setCoordinateMode (CoordinateMode mode)
	Sets the coordinate mode of this gradient to mode. More...

void	setInterpolationMode (InterpolationMode mode)
	Sets the interpolation mode of this gradient to mode. More...

void	setSpread (Spread spread)
	Specifies the spread method that should be used for this gradient. More...

void	setStops (const QGradientStops &stops)
	Replaces the current set of stop points with the given stopPoints. More...

Spread	spread () const
	Returns the spread method use by this gradient. More...

QGradientStops	stops () const
	Returns the stop points for this gradient. More...

Type	type () const
	Returns the type of gradient. More...

Properties
void *	dummy

union {
struct {
qreal angle

qreal cx

qreal cy

} conical

struct {
qreal x1

qreal x2

qreal y1

qreal y2

} linear

struct {
qreal cradius

qreal cx

qreal cy

qreal fx

qreal fy

} radial

}	m_data

Spread	m_spread

QGradientStops	m_stops

Type	m_type

Friends
class	QBrush

class	QConicalGradient

class	QLinearGradient

class	QRadialGradient

Related Functions
(Note that these are not member functions.)
	QGradientStop
	Typedef for QPair<qreal , QColor>. More...

	QGradientStops
	Typedef for QVector<QGradientStop>. More...

Detailed Description

The QGradient class is used in combination with QBrush to specify gradient fills.

Qt currently supports three types of gradient fills:

Linear gradients interpolate colors between start and end points.
Simple radial gradients interpolate colors between a focal point and end points on a circle surrounding it.
Extended radial gradients interpolate colors between a center and a focal circle.
Conical gradients interpolate colors around a center point.

A gradient's type can be retrieved using the type() function. Each of the types is represented by a subclass of QGradient:

QLinearGradient	QRadialGradient	QConicalGradient

The colors in a gradient are defined using stop points of the QGradientStop type; i.e., a position and a color. Use the setColorAt() function to define a single stop point. Alternatively, use the setStops() function to define several stop points in one go. Note that the latter function replaces the current set of stop points.

It is the gradient's complete set of stop points (accessible through the stops() function) that describes how the gradient area should be filled. If no stop points have been specified, a gradient of black at 0 to white at 1 is used.

A diagonal linear gradient from black at (100, 100) to white at (200, 200) could be specified like this:

    QLinearGradient linearGrad(QPointF(100, 100), QPointF(200, 200));
    linearGrad.setColorAt(0, Qt::black);
    linearGrad.setColorAt(1, Qt::white);

A gradient can have an arbitrary number of stop points. The following would create a radial gradient starting with red in the center, blue and then green on the edges:

    QRadialGradient radialGrad(QPointF(100, 100), 100);
    radialGrad.setColorAt(0, Qt::red);
    radialGrad.setColorAt(0.5, Qt::blue);
    radialGrad.setColorAt(1, Qt::green);

It is possible to repeat or reflect the gradient outside its area by specifiying the QGradient::Spread{spread method} using the setSpread() function. The default is to pad the outside area with the color at the closest stop point. The currently set QGradient::Spread can be retrieved using the spread() function. The QGradient::Spread enum defines three different methods:


QGradient::PadSpread{PadSpread}	QGradient::RepeatSpread{RepeatSpread}	QGradient::ReflectSpread{ReflectSpread}

Note that the setSpread() function only has effect for linear and radial gradients. The reason is that the conical gradient is closed by definition, i.e. the conical gradient fills the entire circle from 0 - 360 degrees, while the boundary of a radial or a linear gradient can be specified through its radius or final stop points, respectively.

The gradient coordinates can be specified in logical coordinates, relative to device coordinates, or relative to object bounding box coordinates. The QGradient::CoordinateMode{coordinate mode} can be set using the setCoordinateMode() function. The default is LogicalMode, where the gradient coordinates are specified in the same way as the object coordinates. To retrieve the currently set QGradient::CoordinateMode {coordinate mode} use coordinateMode().

See also: {demos/gradients}{The Gradients Demo}, QBrush

Definition at line 201 of file qbrush.h.

Enumerations

◆ CoordinateMode

enum QGradient::CoordinateMode

This enum specifies how gradient coordinates map to the paint device on which the gradient is used.

Since: 4.4

LogicalMode This is the default mode. The gradient coordinates are specified logical space just like the object coordinates.
StretchToDeviceMode In this mode the gradient coordinates are relative to the bounding rectangle of the paint device, with (0,0) in the top left corner, and (1,1) in the bottom right corner of the paint device.
ObjectBoundingMode In this mode the gradient coordinates are relative to the bounding rectangle of the object being drawn, with (0,0) in the top left corner, and (1,1) in the bottom right corner of the object's bounding rectangle.

Enumerator
LogicalMode
StretchToDeviceMode
ObjectBoundingMode

Definition at line 219 of file qbrush.h.

                         {
         LogicalMode,
         StretchToDeviceMode,
         ObjectBoundingMode
     };

◆ InterpolationMode

enum QGradient::InterpolationMode

Since: 4.5

Warning: This function is not part of the public interface.

ComponentInterpolation The color components and the alpha component are independently linearly interpolated.
ColorInterpolation The colors are linearly interpolated in premultiplied color space.

Enumerator
ColorInterpolation
ComponentInterpolation

Definition at line 225 of file qbrush.h.

                            {
         ColorInterpolation,
         ComponentInterpolation
     };

◆ Spread

enum QGradient::Spread

Specifies how the area outside the gradient area should be filled.

PadSpread The area is filled with the closest stop color. This is the default.

RepeatSpread The gradient is repeated outside the gradient area.

ReflectSpread The gradient is reflected outside the gradient area.

See also: spread(), setSpread()

Enumerator
PadSpread
ReflectSpread
RepeatSpread

Definition at line 213 of file qbrush.h.

                 {
         PadSpread,
         ReflectSpread,
         RepeatSpread
     };

◆ Type

enum QGradient::Type

Specifies the type of gradient.

LinearGradient Interpolates colors between start and end points (QLinearGradient).

RadialGradient Interpolate colors between a focal point and end points on a circle surrounding it (QRadialGradient).

ConicalGradient Interpolate colors around a center point (QConicalGradient).
NoGradient No gradient is used.

See also: type()

Enumerator
LinearGradient
RadialGradient
ConicalGradient
NoGradient

Definition at line 206 of file qbrush.h.

               {
         LinearGradient,
         RadialGradient,
         ConicalGradient,
         NoGradient
     };

Constructors and Destructors

◆ QGradient()

QGradient::QGradient ( )

Warning: This function is not part of the public interface.

Definition at line 1380 of file qbrush.cpp.

     : m_type(NoGradient), dummy(0)
 {
 }

Functions

◆ coordinateMode()

QGradient::CoordinateMode QGradient::coordinateMode ( ) const

Returns the coordinate mode of this gradient.

Since: 4.4

The default mode is LogicalMode.

Definition at line 1563 of file qbrush.cpp.

Referenced by QPainterPrivate::checkEmulation(), coordinateMode(), QEmulationPaintEngine::drawTextItem(), QEmulationPaintEngine::fill(), QPainter::fillPath(), QPainter::fillRect(), fillRegion(), needsResolving(), operator<<(), QSvgPaintEngine::saveGradientUnits(), QEmulationPaintEngine::stroke(), and QPainter::strokePath().

 {
     Q_DUMMY_ACCESSOR
     return CoordinateMode(i & 0x03);
 }

◆ interpolationMode()

QGradient::InterpolationMode QGradient::interpolationMode ( ) const

Returns the interpolation mode of this gradient.

Since: 4.5

Warning: This function is not part of the public interface.

The default mode is ColorInterpolation.

Definition at line 1607 of file qbrush.cpp.

Referenced by QGL2GradientCache::addCacheElement(), QGLGradientCache::addCacheElement(), QGradientCache::addCacheElement(), QGL2GradientCache::generateGradientColorTable(), QGLGradientCache::generateGradientColorTable(), QGradientCache::generateGradientColorTable(), QGL2GradientCache::getBuffer(), QGLGradientCache::getBuffer(), QGradientCache::getBuffer(), operator<<(), and QSvgPaintEngine::saveGradientStops().

 {
     Q_DUMMY_ACCESSOR
     return InterpolationMode((i >> 2) & 0x01);
 }

◆ operator!=()

bool QGradient::operator!= ( const QGradient & gradient ) const

inline

Returns true if the gradient is the same as the other gradient specified; otherwise returns false.

Since: 4.2

See also: operator==()

Definition at line 249 of file qbrush.h.

250 { return !operator==(other); }

QGradient::operator==

bool operator==(const QGradient &gradient) const

Returns true if the gradient is the same as the other gradient specified; otherwise returns false...

Definition: qbrush.cpp:1650

◆ operator==() [1/2]

bool QGradient::operator== ( const QGradient & gradient ) const

Returns true if the gradient is the same as the other gradient specified; otherwise returns false.

See also: operator!=()

Definition at line 1650 of file qbrush.cpp.

 {
     if (gradient.m_type != m_type
         || gradient.m_spread != m_spread
         || gradient.dummy != dummy) return false;
 
     if (m_type == LinearGradient) {
         if (m_data.linear.x1 != gradient.m_data.linear.x1
             || m_data.linear.y1 != gradient.m_data.linear.y1
             || m_data.linear.x2 != gradient.m_data.linear.x2
             || m_data.linear.y2 != gradient.m_data.linear.y2)
             return false;
     } else if (m_type == RadialGradient) {
         if (m_data.radial.cx != gradient.m_data.radial.cx
             || m_data.radial.cy != gradient.m_data.radial.cy
             || m_data.radial.fx != gradient.m_data.radial.fx
             || m_data.radial.fy != gradient.m_data.radial.fy
             || m_data.radial.cradius != gradient.m_data.radial.cradius)
             return false;
     } else { // m_type == ConicalGradient
         if (m_data.conical.cx != gradient.m_data.conical.cx
             || m_data.conical.cy != gradient.m_data.conical.cy
             || m_data.conical.angle != gradient.m_data.conical.angle)
             return false;
     }
 
     return stops() == gradient.stops();
 }

◆ operator==() [2/2]

bool QGradient::operator== ( const QGradient & gradient )

Warning: This function is not part of the public interface.

Definition at line 1682 of file qbrush.cpp.

 {
     return const_cast<const QGradient *>(this)->operator==(gradient);
 }

◆ setColorAt()

void QGradient::setColorAt	(	qreal	position,
		const QColor &	color
	)

Creates a stop point at the given position with the given color.

The given position must be in the range 0 to 1.

See also: setStops(), stops()

Definition at line 1475 of file qbrush.cpp.

Referenced by QPlastiqueStyle::drawComplexControl(), QCleanlooksStyle::drawComplexControl(), QWindowsVistaStyle::drawControl(), QCommonStyle::drawControl(), QPlastiqueStyle::drawControl(), QCleanlooksStyle::drawControl(), QMacStyle::drawControl(), QStyleHelper::drawDial(), QWindowsCEStyle::drawPrimitive(), QPlastiqueStyle::drawPrimitive(), QMacStyle::drawPrimitive(), drawTabBase(), drawTabShape(), QScriptEdit::extraAreaPaintEvent(), parseStopNode(), qt_cleanlooks_draw_buttongradient(), qt_cleanlooks_draw_gradient(), qt_cleanlooks_draw_mdibutton(), qt_plastique_draw_gradient(), and setStops().

 {
     if ((pos > 1 || pos < 0) && !qIsNaN(pos)) {
         qWarning("QGradient::setColorAt: Color position must be specified in the range 0 to 1");
         return;
     }
 
     int index = 0;
     if (!qIsNaN(pos))
         while (index < m_stops.size() && m_stops.at(index).first < pos) ++index;
 
     if (index < m_stops.size() && m_stops.at(index).first == pos)
         m_stops[index].second = color;
     else
         m_stops.insert(index, QGradientStop(pos, color));
 }

◆ setCoordinateMode()

void QGradient::setCoordinateMode ( CoordinateMode mode )

Sets the coordinate mode of this gradient to mode.

Since: 4.4

The default mode is LogicalMode.

Definition at line 1578 of file qbrush.cpp.

Referenced by QEmulationPaintEngine::drawTextItem(), operator>>(), parseBaseGradient(), and stretchGradientToUserSpace().

 {
     Q_DUMMY_ACCESSOR
     i &= ~0x03;
     i |= uint(mode);
     dummy = p;
 }

◆ setInterpolationMode()

void QGradient::setInterpolationMode ( InterpolationMode mode )

Sets the interpolation mode of this gradient to mode.

Since: 4.5

Warning: This function is not part of the public interface.

The default mode is ColorInterpolation.

Definition at line 1623 of file qbrush.cpp.

Referenced by createLinearGradientNode(), createRadialGradientNode(), and operator>>().

 {
     Q_DUMMY_ACCESSOR
     i &= ~(1 << 2);
     i |= (uint(mode) << 2);
     dummy = p;
 }

◆ setSpread()

void QGradient::setSpread ( Spread method )

inline

Specifies the spread method that should be used for this gradient.

Note that this function only has effect for linear and radial gradients.

See also: spread()

Definition at line 277 of file qbrush.h.

Referenced by operator>>(), and parseBaseGradient().

278 { m_spread = aspread; }

QGradient::m_spread

Spread m_spread

Definition: qbrush.h:261

◆ setStops()

void QGradient::setStops ( const QGradientStops & stopPoints )

Replaces the current set of stop points with the given stopPoints.

The positions of the points must be in the range 0 to 1, and must be sorted with the lowest point first.

See also: setColorAt(), stops()

Definition at line 1504 of file qbrush.cpp.

Referenced by QSvgGradientStyle::brush(), QCleanlooksStyle::drawComplexControl(), QCleanlooksStyle::drawControl(), operator>>(), parseBaseGradient(), parseStopNode(), qBrushDark(), qBrushLight(), qBrushSetAlphaF(), qMapGradientToRect(), qt_cleanlooks_draw_buttongradient(), and qt_cleanlooks_draw_gradient().

 {
     m_stops.clear();
     for (int i=0; i<stops.size(); ++i)
         setColorAt(stops.at(i).first, stops.at(i).second);
 }

◆ spread()

QGradient::Spread QGradient::spread ( ) const

inline

Returns the spread method use by this gradient.

The default is PadSpread.

See also: setSpread()

Definition at line 235 of file qbrush.h.

Referenced by cgColorForQColor(), QOpenGLPaintEnginePrivate::createGradientPaletteTexture(), operator<<(), QPdf::patternForBrush(), QCoreGraphicsPaintEnginePrivate::setFillBrush(), QSpanData::setup(), QVGPaintEnginePrivate::setupColorRamp(), and QGL2PaintEngineExPrivate::updateBrushTexture().

235 { return m_spread; }

QGradient::m_spread

Spread m_spread

Definition: qbrush.h:261

◆ stops()

QGradientStops QGradient::stops ( ) const

Returns the stop points for this gradient.

If no stop points have been specified, a gradient of black at 0 to white at 1 is used.

See also: setStops(), setColorAt()

Definition at line 1520 of file qbrush.cpp.

Referenced by QGL2GradientCache::addCacheElement(), QGLGradientCache::addCacheElement(), QGradientCache::addCacheElement(), cgColorForQColor(), QCleanlooksStyle::drawComplexControl(), QCleanlooksStyle::drawControl(), QGL2GradientCache::generateGradientColorTable(), QGLGradientCache::generateGradientColorTable(), QGradientCache::generateGradientColorTable(), QGL2GradientCache::getBuffer(), QGLGradientCache::getBuffer(), QGradientCache::getBuffer(), QBrush::isOpaque(), operator<<(), operator==(), parseBaseGradient(), parseStopNode(), QPdf::patternForBrush(), qMapGradientToRect(), rasterFallbackWarn(), QSvgGradientStyle::resolveStops(), QSvgPaintEngine::saveGradientStops(), QVGPaintEnginePrivate::setupColorRamp(), and QPdfEnginePrivate::~QPdfEnginePrivate().

 {
     if (m_stops.isEmpty()) {
         QGradientStops tmp;
         tmp << QGradientStop(0, Qt::black) << QGradientStop(1, Qt::white);
         return tmp;
     }
     return m_stops;
 }