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TRgb Class Reference

class TRgb

24-bit RGB colour value with 8 bits each for red, green and blue.

All Graphics drawing functions are specified in terms of a 32-bit TRgb colour containing the three colour values plus 8 bits for alpha channel. For hardware which does not support 24-bit colour, a mapping from TRgb to display colours is performed.

Generally, the convention for the alpha blending fact is 0 = transparent, 255 = opaque, unless otherwise stated. The exception to this are the TRgb constructor taking a single value, where the top byte of the passed in parameter is used for alpha information and the function Value(), which returns alpha information in the top byte. In both these cases, 0 means opaque, 255 means transparent.

The supported display modes are enumerated in the TDisplayMode type. In each display mode a unique index can represent each physical colours supported, and which can be mapped onto a full RGB value. The mappings are as follows:

16-colour displays use the EGA colour set: black, white, and then both light and dark versions of grey, red, green, blue, cyan, magenta and yellow

256-colour displays support 216 colours made up of 6x6x6 RGB values, each containing all possible multiples of 51 for R,G,B values. Additionally, all remaining 10 shades of pure red, green, blue and grey are represented, by adding all remaining multiples of 17. This use of 256 colours is sometimes known as the Netscape colour cube.

4096-colour displays effectively support RGB values with 4 bits per primary colour

64k-colour displays effectively support RGB values with 5 bits allocated to red, 6 to green and 5 to blue

16 million-colour displays support true colour with 8 bits allocated to each primary colour

TDisplayMode DynamicPalette

Public Member Functions
	TRgb()
	TRgb(TUint32)
	TRgb(TUint32, TInt)
	TRgb(TInt, TInt, TInt)
	TRgb(TInt, TInt, TInt, TInt)
TInt	Alpha()
TInt	Blue()
IMPORT_C TRgb	Color16(TInt)
IMPORT_C TInt	Color16()
IMPORT_C TRgb	Color16M(TInt)
IMPORT_C TInt	Color16M()
IMPORT_C TRgb	Color16MA(TUint)
IMPORT_C TUint	Color16MA()
IMPORT_C TRgb	Color16MAP(TUint)
IMPORT_C TUint	Color16MAP()
IMPORT_C TRgb	Color16MU(TInt)
IMPORT_C TInt	Color16MU()
IMPORT_C TRgb	Color256(TInt)
IMPORT_C TInt	Color256()
IMPORT_C TRgb	Color4K(TInt)
IMPORT_C TInt	Color4K()
IMPORT_C TRgb	Color64K(TInt)
IMPORT_C TInt	Color64K()
IMPORT_C TInt	Difference(const TRgb &)
IMPORT_C void	ExternalizeL(RWriteStream &)
IMPORT_C TRgb	Gray16(TInt)
IMPORT_C TInt	Gray16()
IMPORT_C TRgb	Gray2(TInt)
IMPORT_C TInt	Gray2()
IMPORT_C TRgb	Gray256(TInt)
IMPORT_C TInt	Gray256()
IMPORT_C TRgb	Gray4(TInt)
IMPORT_C TInt	Gray4()
TInt	Green()
TUint32	Internal()
IMPORT_C void	InternalizeL(RReadStream &)
TInt	Red()
IMPORT_C void	SetAlpha(TInt)
IMPORT_C void	SetBlue(TInt)
IMPORT_C void	SetGreen(TInt)
void	SetInternal(TUint32)
IMPORT_C void	SetRed(TInt)
TUint32	Value()
TInt	_Color16M()
TRgb	_Color16M(TInt)
TUint	_Color16MA()
TRgb	_Color16MA(TUint)
IMPORT_C TUint	_Color16MAP()
IMPORT_C TRgb	_Color16MAP(TUint)
TInt	_Color16MU()
TRgb	_Color16MU(TInt)
TInt	_Color4K()
TRgb	_Color4K(TInt)
TInt	_Color64K()
TRgb	_Color64K(TInt)
TInt	_Gray16()
TRgb	_Gray16(TInt)
TInt	_Gray2()
TRgb	_Gray2(TInt)
TInt	_Gray256()
TRgb	_Gray256(TInt)
TInt	_Gray4()
TRgb	_Gray4(TInt)
TBool	operator!=(const TRgb &)
TRgb	operator&(const TRgb &)
TRgb &	operator&=(const TRgb &)
TBool	operator==(const TRgb &)
TRgb	operator^(const TRgb &)
TRgb &	operator^=(const TRgb &)
TRgb	operator\|(const TRgb &)
TRgb &	operator\|=(const TRgb &)
TRgb	operator~()

Private Attributes
TUint32	iValue

Constructor & Destructor Documentation

TRgb()

TRgb

(

)

[inline]

Constructs a TRgb initialised to KRgbWhite.

TRgb(TUint32)

TRgb

(

TUint32

aValue

)

[inline]

Constructs a TRgb directly from a single 32-bit integer.

The integer is of the form 0xaabbggrr, where bb is the hex number for blue, gg is the hex number for green, rr is the hex number for red, and aa is the hex number for "transparency" alpha (0 means opaque, 255 means transparent).

This constructor is deprecated. The byte order of Red ,Green and Blue does not match other constructors and methods in this class, and the meaning of alpha is reversed compared to current convention.

For example, TRgb(0x00080402) using this constructor can be replaced with the 3 colour constructor TRgb(2,4,8). The equivalent explicit alpha constructors are TRgb(0x020408,0xff) and TRgb(2,4,8,255). The equivalent call to SetInternal is SetInternal(0xff020408).

This constructor is deprecated. Use other constructors or SetInternal() instead.

Parameters

TUint32 aValue

Integer representing colour value. Takes form 0x00bbggrr.

TRgb(TUint32, TInt)

TRgb	(	TUint32	aInternalValue,
		TInt	aAlpha
	)	[inline]

Constructs a TRgb from a 32-bit integer (which corresponds to a colour) and from an alpha value.

The first parameter is of the form 0x00rrggbb, where rr is the hex number for red, gg is the hex number for green, and bb is the hex number for blue.

The second parameter corresponds to an alpha channel (0 means transparent, 255 means opaque).

For example, TRgb(2,4,8,255) using the 3 colour+alpha constructor is equal to TRgb(0x00020408, 255) using this constructor.

This constructor, which implements alpha in the conventional way, replaces TRgb( TUint32 aValue ) which is deprecated.

Parameters

TUint32 aInternalValue	Integer representing a colour value, which takes the form 0x00rrggbb.
TInt aAlpha	Alpha component of the colour (0 - 255).

TRgb(TInt, TInt, TInt)

TRgb	(	TInt	aRed,
		TInt	aGreen,
		TInt	aBlue
	)	[inline]

Constructs a TRgb from its three component colours.

Each colour has a value between 0 and 255. The alpha component is always set to opaque (255)

Parameters

TInt aRed	Red component of the colour (0 - 255).
TInt aGreen	Green component of the colour (0 - 255).
TInt aBlue	Blue component of the colour (0 - 255).

TRgb(TInt, TInt, TInt, TInt)

TRgb	(	TInt	aRed,
		TInt	aGreen,
		TInt	aBlue,
		TInt	aAlpha
	)	[inline]

Constructs a TRgb from its three colour components and alpha component.

Each component has a value between 0 and 255. The fourth parameter corresponds to an alpha channel (0 means transparent, 255 means opaque).

This constructor, which implements alpha in the conventional way, replaces TRgb( TUint32 aValue ) which is deprecated.

Parameters

TInt aRed	Red component of the colour (0 - 255).
TInt aGreen	Green component of the colour (0 - 255).
TInt aBlue	Blue component of the colour (0 - 255).
TInt aAlpha	Alpha component of the colour (0 - 255).

Member Functions Documentation

Alpha()

TInt

Alpha

(

)

const [inline]

Gets the alpha component.

Blue()

TInt

Blue

(

)

const [inline]

Gets the blue component.

Color16(TInt)

IMPORT_C TRgb

Color16

(

TInt

aColor16

)

[static]

Gets TRgb from 4 bit colour index.

The function takes a 4 bit index into a colour palette and returns a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aColor16

4 bit index into a colour palette

Color16()

IMPORT_C TInt

Color16

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode.

Color16M(TInt)

IMPORT_C TRgb

Color16M

(

TInt

aColor16M

)

[static]

Gets TRgb from 16M colour index.

The function takes a 24 bit index into a colour palette and returns the TRgb whose red, green and blue values represent it exactly.

Parameters

TInt aColor16M

24 bit index into a colour palette

Color16M()

IMPORT_C TInt

Color16M

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode.

Color16MA(TUint)

IMPORT_C TRgb

Color16MA

(

TUint

aARGB

)

[static]

Gets TRgb from 16MA colour index. The function takes a 32 bit colour value with eight bits for each component, blue in the low byte, and returns the TRgb whose red, green, blue and alpha values represent it exactly.

Parameters

TUint aARGB

The color - A, R, G, B bytes. / BGRA - little endian format /

Color16MA()

IMPORT_C TUint

Color16MA

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode.

Color16MAP(TUint)

IMPORT_C TRgb

Color16MAP

(

TUint

aARGB

)

[static]

Gets TRgb from 16MAP colour index. The function takes a 32 bit colour value with eight bits for each component, blue in the low byte, and returns the TRgb whose red, green, and blue vales are divided by the alpha value.

Parameters

TUint aARGB

The pre-multiplied (EColor16MAP) color value.

Color16MAP()

IMPORT_C TUint

Color16MAP

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode. pre-multiplies the alpha channels with the color channel.

Color16MU(TInt)

IMPORT_C TRgb

Color16MU

(

TInt

a0RGB

)

[static]

Gets TRgb from 16MU colour index. The function takes a 24 bit colour value with eight bits for each component, blue in the low byte, and returns the TRgb whose red, green and blue values represent it exactly.

Parameters

TInt a0RGB

The color - 0, R, G, B bytes. / BGR0 - little endian format /

Color16MU()

IMPORT_C TInt

Color16MU

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode.

Color256(TInt)

IMPORT_C TRgb

Color256

(

TInt

aColor256

)

[static]

Gets TRgb from 8 bit colour index.

The function takes an 8 bit index into a colour palette and returns a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aColor256

8 bit index into a colour palette.

Color256()

IMPORT_C TInt

Color256

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode.

Color4K(TInt)

IMPORT_C TRgb

Color4K

(

TInt

aColor4K

)

[static]

Gets TRgb from 4K colour index.

The function takes a 12 bit index into a colour palette and returns a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aColor4K

12 bit index into a colour palette

Color4K()

IMPORT_C TInt

Color4K

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode.

Color64K(TInt)

IMPORT_C TRgb

Color64K

(

TInt

aColor64K

)

[static]

Gets TRgb from 64K colour index.

The function takes a 16 bit index into a colour palette and returns a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aColor64K

16 bit index into a colour palette

Color64K()

IMPORT_C TInt

Color64K

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode.

Difference(const TRgb &)

IMPORT_C TInt

Difference

(

const TRgb &

aColor

)

const

Gets the difference between two TRgbs.

This difference is defined as the sum of the absolute values of the difference in the red, green and blue components.

Parameters

const TRgb & aColor

The TRgb to be compared.

ExternalizeL(RWriteStream &)

IMPORT_C void

ExternalizeL

(

RWriteStream &

aStream

)

const

Externalises a TRgb object to a stream.

The presence of this function means that the standard templated stream operator<<() is available to externalise objects of this class.

Parameters

RWriteStream & aStream

Stream to which the object is externalised.

Gray16(TInt)

IMPORT_C TRgb

Gray16

(

TInt

aGray16

)

[static]

Gets TRgb from 16 level grayscale.

The function takes a grayscale argument and return a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aGray16

Grayscale value to be converted.

Gray16()

IMPORT_C TInt

Gray16

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode.

Gray2(TInt)

IMPORT_C TRgb

Gray2

(

TInt

aGray2

)

[static]

Gets TRgb from 2 level grayscale.

The function takes a grayscale argument and return a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aGray2

Grayscale value to be converted.

Gray2()

IMPORT_C TInt

Gray2

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode.

Gray256(TInt)

IMPORT_C TRgb

Gray256

(

TInt

aGray256

)

[static]

Gets TRgb from 256 level grayscale.

The function takes a grayscale argument and return a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aGray256

Grayscale value to be converted.

Gray256()

IMPORT_C TInt

Gray256

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode.

Gray4(TInt)

IMPORT_C TRgb

Gray4

(

TInt

aGray4

)

[static]

Gets TRgb from 4 level grayscale.

The function takes a grayscale argument and return a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aGray4

Grayscale value to be converted.

Gray4()

IMPORT_C TInt

Gray4

(

)

const

Gets the index of the closest TRgb value to this, based on the matching display mode.

Green()

TInt

Green

(

)

const [inline]

Gets the green component.

Internal()

TUint32

Internal

(

)

const [inline]

Gets the 32-bit value of the TRgb as an integer.

InternalizeL(RReadStream &)

IMPORT_C void

InternalizeL

(

RReadStream &

aStream

)

Internalises a TRgb object from a stream.

The presence of this function means that the standard templated stream operator>>() is available to internalise objects of this class.

operator>>()

Parameters

RReadStream & aStream

Stream from which the object is internalised.

Red()

TInt

Red

(

)

const [inline]

Gets the red component.

SetAlpha(TInt)

IMPORT_C void

SetAlpha

(

TInt

aAlpha

)

Sets the alpha component.

Parameters

TInt aAlpha

Alpha component (0 - 255).

SetBlue(TInt)

IMPORT_C void

SetBlue

(

TInt

aBlue

)

Sets the blue component.

Parameters

TInt aBlue

Blue component (0 - 255).

SetGreen(TInt)

IMPORT_C void

SetGreen

(

TInt

aGreen

)

Sets the green component.

Parameters

TInt aGreen

Green component (0 - 255).

SetInternal(TUint32)

void

SetInternal

(

TUint32

aInternal

)

[inline]

Sets the 32-bit value of the TRgb as a 32-bit integer.

Parameters

TUint32 aInternal

Colour internal representation. Has the form 0xaarrggbb.

SetRed(TInt)

IMPORT_C void

SetRed

(

TInt

aRed

)

Sets the red component.

Parameters

TInt aRed

Red component (0 - 255).

Value()

TUint32

Value

(

)

const [inline]

Gets the 32-bit value of the TRgb as an integer. This function is deprecated. Use Internal() instead. Note: the order of Red, Green and Blue components returned by this method is reversed compared to all other methods. The alpha value is also reversed in meaning compared to current convention, such that 0 represents opaque and 0xff represents transparent.

_Color16M()

TInt

_Color16M

(

)

const [inline]

Gets the index of the closest TRgb value to this, based on the matching display mode.

_Color16M(TInt)

TRgb

_Color16M

(

TInt

aColor16M

)

[static, inline]

Gets TRgb from 16M colour index.

The function takes a 24 bit index into a colour palette and returns the TRgb whose red, green and blue values represent it exactly.

Parameters

TInt aColor16M

24 bit index into a colour palette

_Color16MA()

TUint

_Color16MA

(

)

const [inline]

Gets the index of the closest TRgb value to this, based on the matching display mode.

_Color16MA(TUint)

TRgb

_Color16MA

(

TUint

aARGB

)

[static, inline]

Parameters

TUint aARGB

The color - A, R, G, B bytes. / BGR0 - little endian format /

_Color16MAP()

IMPORT_C TUint

_Color16MAP

(

)

const

Converts the TRgb to EColor16MAP (with color channels pre-multiplied with the alpha channel.

_Color16MAP(TUint)

IMPORT_C TRgb

_Color16MAP

(

TUint

aARGB

)

[static]

Parameters

TUint aARGB

The pre-multiplied (EColor16MAP) color value.

_Color16MU()

TInt

_Color16MU

(

)

const [inline]

Gets the index of the closest TRgb value to this, based on the matching display mode.

_Color16MU(TInt)

TRgb

_Color16MU

(

TInt

a0RGB

)

[static, inline]

Parameters

TInt a0RGB

The color - 0, R, G, B bytes. / BGR0 - little endian format /

_Color4K()

TInt

_Color4K

(

)

const [inline]

Gets the index of the closest TRgb value to this, based on the matching display mode.

_Color4K(TInt)

TRgb

_Color4K

(

TInt

aColor4K

)

[static, inline]

Gets TRgb from 4K colour index.

The function takes a 12 bit index into a colour palette and returns a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aColor4K

12 bit index into a colour palette

_Color64K()

TInt

_Color64K

(

)

const [inline]

Gets the index of the closest TRgb value to this, based on the matching display mode.

_Color64K(TInt)

TRgb

_Color64K

(

TInt

aColor64K

)

[static, inline]

Gets TRgb from 64K colour index.

The function takes a 16 bit index into a colour palette and returns a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aColor64K

16 bit index into a colour palette

_Gray16()

TInt

_Gray16

(

)

const [inline]

Gets the index of the closest TRgb value to this, based on the matching display mode.

_Gray16(TInt)

TRgb

_Gray16

(

TInt

aGray16

)

[static, inline]

Gets TRgb from 16 level grayscale.

The function takes a grayscale argument and return a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aGray16

Grayscale value to be converted.

_Gray2()

TInt

_Gray2

(

)

const [inline]

Gets the index of the closest TRgb value to this, based on the matching display mode.

_Gray2(TInt)

TRgb

_Gray2

(

TInt

aGray2

)

[static, inline]

Gets TRgb from 2 level grayscale.

The function takes a grayscale argument and return a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aGray2

Grayscale value to be converted.

_Gray256()

TInt

_Gray256

(

)

const [inline]

Gets the index of the closest TRgb value to this, based on the matching display mode.

_Gray256(TInt)

TRgb

_Gray256

(

TInt

aGray256

)

[static, inline]

Gets TRgb from 256 level grayscale.

The function takes a grayscale argument and return a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aGray256

Grayscale value to be converted.

_Gray4()

TInt

_Gray4

(

)

const [inline]

Gets the index of the closest TRgb value to this, based on the matching display mode.

_Gray4(TInt)

TRgb

_Gray4

(

TInt

aGray4

)

[static, inline]

Gets TRgb from 4 level grayscale.

The function takes a grayscale argument and return a TRgb whose red, green and blue values are set to an appropriate level.

Parameters

TInt aGray4

Grayscale value to be converted.

operator!=(const TRgb &)

TBool

operator!=

(

const TRgb &

aColor

)

const [inline]

Compares this colour with the specified colour for inequality.

Two colours are unequal if one at least one of their red, green and blue components are unequal.

Parameters

const TRgb & aColor

Colour to be compared.

operator&(const TRgb &)

TRgb

operator&

(

const TRgb &

aColor

)

[inline]

Bitwise logical AND operator.

Parameters

const TRgb & aColor

Colour to be compared.

operator&=(const TRgb &)

TRgb &

operator&=

(

const TRgb &

aColor

)

[inline]

Logical AND assignment operator.

The operator ANDs the first operand with the second and then assigns the result back to the first operand.

Note:

This operates in the TRgb domain. Graphics defines logical operations for drawing primitives which operate in the device colour domain.

Parameters

const TRgb & aColor

Colour to be compared.

operator==(const TRgb &)

TBool

operator==

(

const TRgb &

aColor

)

const [inline]

Compares this colour with the specified colour for equality.

For two colours to be equal, their red, green and blue components must all be equal.

Parameters

const TRgb & aColor

Colour to be compared.

operator^(const TRgb &)

TRgb

operator^

(

const TRgb &

aColor

)

[inline]

Bitwise EXCLUSIVE OR operator

Parameters

const TRgb & aColor

Colour to be compared.

operator^=(const TRgb &)

TRgb &

operator^=

(

const TRgb &

aColor

)

[inline]

Logical EXCLUSIVE OR assignment operator.

The operator Exclusive ORs the first operand with the second and then assigns the result back to the first operand.

Note:

This operates in the TRgb domain. Graphics defines logical operations for drawing primitives which operate in the device colour domain.

Parameters

const TRgb & aColor

Colour to be compared.

operator|(const TRgb &)

TRgb

operator|

(

const TRgb &

aColor

)

[inline]

Bitwise logical OR operator.

Parameters

const TRgb & aColor

Colour to be compared.

operator|=(const TRgb &)

TRgb &

operator|=

(

const TRgb &

aColor

)

[inline]

Logical OR assignment operator.

The operator ORs the first operand with the second and then assigns the result back to the first operand.

Note:

This operates in the TRgb domain. Graphics defines logical operations for drawing primitives which operate in the device colour domain.

Parameters

const TRgb & aColor

Colour to be compared.

operator~()

TRgb

operator~

(

)

const [inline]

Bitwise logical inversion operator.

Member Data Documentation

TUint32 iValue

TUint32

iValue

[private]