JUCE: ColourGradient Class Reference

JUCE

Public Member Functions | Static Public Member Functions | Public Attributes | List of all members
ColourGradient Class Referencefinal
juce_graphics » colour

Describes the layout and colours that should be used to paint a colour gradient. More...

`#include <juce_ColourGradient.h>`

## Public Member Functions
| ColourGradient () noexcept
| Creates an uninitialised gradient. More...
| ColourGradient (const ColourGradient &)
| ColourGradient (ColourGradient &&) noexcept
ColourGradient & | operator= (const ColourGradient &)
ColourGradient & | operator= (ColourGradient &&) noexcept
| ColourGradient (Colour colour1, float x1, float y1, Colour colour2, float x2, float y2, bool isRadial)
| Creates a gradient object. More...
| ColourGradient (Colour colour1, Point< float > point1, Colour colour2, Point< float > point2, bool isRadial)
| Creates a gradient object. More...
| ~ColourGradient ()
| Destructor. More...
void | clearColours ()
| Removes any colours that have been added. More...
int | addColour (double proportionAlongGradient, Colour colour)
| Adds a colour at a point along the length of the gradient. More...
void | removeColour (int index)
| Removes one of the colours from the gradient. More...
void | multiplyOpacity (float multiplier) noexcept
| Multiplies the alpha value of all the colours by the given scale factor. More...
int | getNumColours () const noexcept
| Returns the number of colour-stops that have been added. More...
double | getColourPosition (int index) const noexcept
| Returns the position along the length of the gradient of the colour with this index. More...
Colour | getColour (int index) const noexcept
| Returns the colour that was added with a given index. More...
void | setColour (int index, Colour newColour) noexcept
| Changes the colour at a given index. More...
Colour | getColourAtPosition (double position) const noexcept
| Returns the an interpolated colour at any position along the gradient. More...
int | createLookupTable (const AffineTransform &transform, HeapBlock< PixelARGB > &resultLookupTable) const
| Creates a set of interpolated premultiplied ARGB values. More...
void | createLookupTable (PixelARGB *resultLookupTable, int numEntries) const noexcept
| Creates a set of interpolated premultiplied ARGB values. More...
bool | isOpaque () const noexcept
| Returns true if all colours are opaque. More...
bool | isInvisible () const noexcept
| Returns true if all colours are completely transparent. More...
bool | operator== (const ColourGradient &) const noexcept
bool | operator!= (const ColourGradient &) const noexcept

## Static Public Member Functions
static ColourGradient | vertical (Colour colour1, float y1, Colour colour2, float y2)
| Creates a vertical linear gradient between two Y coordinates. More...
static ColourGradient | horizontal (Colour colour1, float x1, Colour colour2, float x2)
| Creates a horizontal linear gradient between two X coordinates. More...
template<typename Type >
static ColourGradient | vertical (Colour colourTop, Colour colourBottom, Rectangle< Type > area)
| Creates a vertical linear gradient from top to bottom in a rectangle. More...
template<typename Type >
static ColourGradient | horizontal (Colour colourLeft, Colour colourRight, Rectangle< Type > area)
| Creates a horizontal linear gradient from right to left in a rectangle. More...

## Public Attributes
Point< float > | point1
Point< float > | point2
bool | isRadial
| If true, the gradient should be filled circularly, centred around point1, with point2 defining a point on the circumference. More...

## Detailed Description

Describes the layout and colours that should be used to paint a colour gradient.

See also
  Graphics::setGradientFill

## Constructor & Destructor Documentation

## ◆ ColourGradient() [1/5]

ColourGradient::ColourGradient | ( |  | ) |
| noexcept

Creates an uninitialised gradient.

If you use this constructor instead of the other one, be sure to set all the object's public member variables before using it!

## ◆ ColourGradient() [2/5]

ColourGradient::ColourGradient | ( | const ColourGradient & |  | ) |

## ◆ ColourGradient() [3/5]

ColourGradient::ColourGradient | ( | ColourGradient && |  | ) |
| noexcept

## ◆ ColourGradient() [4/5]

ColourGradient::ColourGradient | ( | Colour | colour1,
|  | float | x1,
|  | float | y1,
|  | Colour | colour2,
|  | float | x2,
|  | float | y2,
|  | bool | isRadial
| ) |  |

Creates a gradient object.

(x1, y1) is the location to draw with colour1. Likewise (x2, y2) is where colour2 should be. In between them there's a gradient.

If isRadial is true, the colours form a circular gradient with (x1, y1) at its centre.

The alpha transparencies of the colours are used, so note that if you blend from transparent to a solid colour, the RGB of the transparent colour will become visible in parts of the gradient. e.g. blending from Colour::transparentBlack to Colours::white will produce a muddy grey colour midway, but Colour::transparentWhite to Colours::white will be white all the way across.

See also
  ColourGradient

## ◆ ColourGradient() [5/5]

ColourGradient::ColourGradient | ( | Colour | colour1,
|  | Point< float > | point1,
|  | Colour | colour2,
|  | Point< float > | point2,
|  | bool | isRadial
| ) |  |

Creates a gradient object.

point1 is the location to draw with colour1. Likewise point2 is where colour2 should be. In between them there's a gradient.

If isRadial is true, the colours form a circular gradient with point1 at its centre.

The alpha transparencies of the colours are used, so note that if you blend from transparent to a solid colour, the RGB of the transparent colour will become visible in parts of the gradient. e.g. blending from Colour::transparentBlack to Colours::white will produce a muddy grey colour midway, but Colour::transparentWhite to Colours::white will be white all the way across.

See also
  ColourGradient

## ◆ ~ColourGradient()

ColourGradient::~ColourGradient | ( |  | ) |

Destructor.

## Member Function Documentation

## ◆ operator=() [1/2]

ColourGradient & ColourGradient::operator= | ( | const ColourGradient & |  | ) |

## ◆ operator=() [2/2]

ColourGradient & ColourGradient::operator= | ( | ColourGradient && |  | ) |
| noexcept

## ◆ vertical() [1/2]

static ColourGradient ColourGradient::vertical | ( | Colour | colour1,
|  | float | y1,
|  | Colour | colour2,
|  | float | y2
| ) |  |
| static

Creates a vertical linear gradient between two Y coordinates.

## ◆ horizontal() [1/2]

static ColourGradient ColourGradient::horizontal | ( | Colour | colour1,
|  | float | x1,
|  | Colour | colour2,
|  | float | x2
| ) |  |
| static

Creates a horizontal linear gradient between two X coordinates.

## ◆ vertical() [2/2]

template<typename Type >

static ColourGradient ColourGradient::vertical | ( | Colour | colourTop,
|  | Colour | colourBottom,
|  | Rectangle< Type > | area
| ) |  |
| static

Creates a vertical linear gradient from top to bottom in a rectangle.

## ◆ horizontal() [2/2]

template<typename Type >

static ColourGradient ColourGradient::horizontal | ( | Colour | colourLeft,
|  | Colour | colourRight,
|  | Rectangle< Type > | area
| ) |  |
| static

Creates a horizontal linear gradient from right to left in a rectangle.

References Rectangle< ValueType >::getRight(), and Rectangle< ValueType >::getX().

## ◆ clearColours()

void ColourGradient::clearColours | ( |  | ) |

Removes any colours that have been added.

This will also remove any start and end colours, so the gradient won't work. You'll need to add more colours with addColour().

## ◆ addColour()

int ColourGradient::addColour | ( | double | proportionAlongGradient,
|  | Colour | colour
| ) |  |

Adds a colour at a point along the length of the gradient.

This allows the gradient to go through a spectrum of colours, instead of just a start and end colour.

Parameters

  proportionAlongGradient | a value between 0 and 1.0, which is the proportion of the distance along the line between the two points at which the colour should occur.
  colour | the colour that should be used at this point

Returns
  the index at which the new point was added

## ◆ removeColour()

void ColourGradient::removeColour | ( | int | index | ) |

Removes one of the colours from the gradient.

## ◆ multiplyOpacity()

void ColourGradient::multiplyOpacity | ( | float | multiplier | ) |
| noexcept

Multiplies the alpha value of all the colours by the given scale factor.

## ◆ getNumColours()

int ColourGradient::getNumColours | ( |  | ) | const
| noexcept

Returns the number of colour-stops that have been added.

## ◆ getColourPosition()

double ColourGradient::getColourPosition | ( | int | index | ) | const
| noexcept

Returns the position along the length of the gradient of the colour with this index.

The index is from 0 to getNumColours() - 1. The return value will be between 0.0 and 1.0

## ◆ getColour()

Colour ColourGradient::getColour | ( | int | index | ) | const
| noexcept

Returns the colour that was added with a given index.

The index is from 0 to getNumColours() - 1.

## ◆ setColour()

void ColourGradient::setColour | ( | int | index,
|  | Colour | newColour
| ) |  |
| noexcept

Changes the colour at a given index.

The index is from 0 to getNumColours() - 1.

## ◆ getColourAtPosition()

Colour ColourGradient::getColourAtPosition | ( | double | position | ) | const
| noexcept

Returns the an interpolated colour at any position along the gradient.

Parameters

  position | the position along the gradient, between 0 and 1

## ◆ createLookupTable() [1/2]

int ColourGradient::createLookupTable | ( | const AffineTransform & | transform,
|  | HeapBlock< PixelARGB > & | resultLookupTable
| ) |  | const

Creates a set of interpolated premultiplied ARGB values.

This will resize the HeapBlock, fill it with the colours, and will return the number of colours that it added. When calling this, the ColourGradient must have at least 2 colour stops specified.

## ◆ createLookupTable() [2/2]

void ColourGradient::createLookupTable | ( | PixelARGB * | resultLookupTable,
|  | int | numEntries
| ) |  | const
| noexcept

Creates a set of interpolated premultiplied ARGB values.

This will fill an array of a user-specified size with the gradient, interpolating to fit. The numEntries argument specifies the size of the array, and this size must be greater than zero. When calling this, the ColourGradient must have at least 2 colour stops specified.

## ◆ isOpaque()

bool ColourGradient::isOpaque | ( |  | ) | const
| noexcept

Returns true if all colours are opaque.

## ◆ isInvisible()

bool ColourGradient::isInvisible | ( |  | ) | const
| noexcept

Returns true if all colours are completely transparent.

## ◆ operator==()

bool ColourGradient::operator== | ( | const ColourGradient & |  | ) | const
| noexcept

## ◆ operator!=()

bool ColourGradient::operator!= | ( | const ColourGradient & |  | ) | const
| noexcept

References operator!=(), and operator==().

## Member Data Documentation

## ◆ point1

Point<float> ColourGradient::point1

## ◆ point2

Point<float> ColourGradient::point2

## ◆ isRadial

bool ColourGradient::isRadial

If true, the gradient should be filled circularly, centred around point1, with point2 defining a point on the circumference.

If false, the gradient is linear between the two points.

The documentation for this class was generated from the following file:

- juce_ColourGradient.h