Module org.freedesktop.cairo

Package org.freedesktop.cairo

Class Gradient

java.lang.Object

io.github.jwharm.cairobindings.Proxy

org.freedesktop.cairo.Pattern

org.freedesktop.cairo.Gradient

Direct Known Subclasses:

LinearGradient, RadialGradient

public abstract class Gradient
extends Pattern

Base class for (linear or radial) gradient patterns.

Constructor Summary

Constructors

Constructor	Description
Gradient(MemorySegment address)	Constructor used internally to instantiate a java GradientPattern object for a native cairo_pattern_t instance

Method Summary

Modifier and Type	Method	Description
void	addColorStopRGB(double offset, double red, double green, double blue)	Adds an opaque color stop to a gradient pattern.
void	addColorStopRGBA(double offset, double red, double green, double blue, double alpha)	Adds a translucent color stop to a gradient pattern.
int	getColorStopCount()	Gets the number of color stops specified in the given gradient pattern.
double[]	getColorStopRGBA(int index)	Gets the color and offset information at the given index for a gradient pattern.

Methods inherited from class org.freedesktop.cairo.Pattern

destroy, getDither, getExtend, getFilter, getMatrix, getPatternType, getType, getUserData, setDither, setExtend, setFilter, setMatrix, setUserData, status

Methods inherited from class io.github.jwharm.cairobindings.Proxy

equals, handle, hashCode

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Gradient

public Gradient(MemorySegment address)

Constructor used internally to instantiate a java GradientPattern object for a native cairo_pattern_t instance

Parameters:

address - the memory address of the native cairo_pattern_t instance

Method Details

addColorStopRGB

public void addColorStopRGB(double offset,
 double red,
 double green,
 double blue)

Adds an opaque color stop to a gradient pattern. The offset specifies the location along the gradient's control vector. For example, a linear gradient's control vector is from (x0,y0) to (x1,y1) while a radial gradient's control vector is from any point on the start circle to the corresponding point on the end circle.

The color is specified in the same way as in Context.setSourceRGB(double, double, double).

If two (or more) stops are specified with identical offset values, they will be sorted according to the order in which the stops are added, (stops added earlier will compare less than stops added later). This can be useful for reliably making sharp color transitions instead of the typical blend.

Parameters:

offset - an offset in the range [0.0 .. 1.0]

red - red component of color

green - green component of color

blue - blue component of color

Since:

1.0

addColorStopRGBA

public void addColorStopRGBA(double offset,
 double red,
 double green,
 double blue,
 double alpha)

Adds a translucent color stop to a gradient pattern. The offset specifies the location along the gradient's control vector. For example, a linear gradient's control vector is from (x0,y0) to (x1,y1) while a radial gradient's control vector is from any point on the start circle to the corresponding point on the end circle.

The color is specified in the same way as in Context.setSourceRGBA(double, double, double, double).

If two (or more) stops are specified with identical offset values, they will be sorted according to the order in which the stops are added, (stops added earlier will compare less than stops added later). This can be useful for reliably making sharp color transitions instead of the typical blend.

Parameters:

offset - an offset in the range [0.0 .. 1.0]

red - red component of color

green - green component of color

blue - blue component of color

alpha - alpha component of color

Since:

1.0

getColorStopCount

public int getColorStopCount()

Gets the number of color stops specified in the given gradient pattern.

Returns:

the number of color stops

Since:

1.4

getColorStopRGBA

public double[] getColorStopRGBA(int index)
                          throws IndexOutOfBoundsException

Gets the color and offset information at the given index for a gradient pattern. Values of index range from 0 to n-1 where n is the number returned by getColorStopCount().

Note that the color and alpha values are not premultiplied.

Parameters:

index - index of the stop to return data for

Returns:

a 5-element array with the offset and red, green, blue and alpha color components

Throws:

IndexOutOfBoundsException - if index is not valid for the given pattern (see Status.INVALID_INDEX).

Since:

1.4