Class TRgb

class TRgb;

Description

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 TRgb::Value()const, 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

Members

Defined in TRgb:

• Alpha()constGets the alpha component.
• Blue()constGets the blue component.
• Color16()constGets the index of the closest TRgb value to this, based on the matching display ...
• Color16(TInt)Gets TRgb from 4 bit colour index.
• Color16M()constGets the index of the closest TRgb value to this, based on the matching display ...
• Color16M(TInt)Gets TRgb from 16M colour index.
• Color16MA()constGets the index of the closest TRgb value to this, based on the matching display ...
• Color16MA(TUint)Gets TRgb from 16MA colour index. The function takes a 32 bit colour value with ...
• Color16MAP()constGets the index of the closest TRgb value to this, based on the matching display ...
• Color16MAP(TUint)Gets TRgb from 16MAP colour index. The function takes a 32 bit colour value with...
• Color16MU()constGets the index of the closest TRgb value to this, based on the matching display ...
• Color16MU(TInt)Gets TRgb from 16MU colour index. The function takes a 24 bit colour value with ...
• Color256()constGets the index of the closest TRgb value to this, based on the matching display ...
• Color256(TInt)Gets TRgb from 8 bit colour index.
• Color4K()constGets the index of the closest TRgb value to this, based on the matching display ...
• Color4K(TInt)Gets TRgb from 4K colour index.
• Color64K()constGets the index of the closest TRgb value to this, based on the matching display ...
• Color64K(TInt)Gets TRgb from 64K colour index.
• Difference(const TRgb &)constGets the difference between two TRgbs.
• ExternalizeL(RWriteStream &)constExternalises a TRgb object to a stream.
• Gray16()constGets the index of the closest TRgb value to this, based on the matching display ...
• Gray16(TInt)Gets TRgb from 16 level grayscale.
• Gray2()constGets the index of the closest TRgb value to this, based on the matching display ...
• Gray2(TInt)Gets TRgb from 2 level grayscale.
• Gray256()constGets the index of the closest TRgb value to this, based on the matching display ...
• Gray256(TInt)Gets TRgb from 256 level grayscale.
• Gray4()constGets the index of the closest TRgb value to this, based on the matching display ...
• Gray4(TInt)Gets TRgb from 4 level grayscale.
• Green()constGets the green component.
• Internal()constGets the 32-bit value of the TRgb as an integer.
• InternalizeL(RReadStream &)Internalises a TRgb object from a stream.
• Red()constGets the red component.
• SetAlpha(TInt)Sets the alpha component.
• SetBlue(TInt)Sets the blue component.
• SetGreen(TInt)Sets the green component.
• SetInternal(TUint32)Sets the 32-bit value of the TRgb as a 32-bit integer.
• SetRed(TInt)Sets the red component.
• TRgb()Constructs a TRgb initialised to KRgbWhite.
• TRgb(TInt,TInt,TInt)Constructs a TRgb from its three component colours.
• TRgb(TInt,TInt,TInt,TInt)Constructs a TRgb from its three colour components and alpha component.
• TRgb(TUint32)Constructs a TRgb directly from a single 32-bit integer.
• TRgb(TUint32,TInt)Constructs a TRgb from a 32-bit integer (which corresponds to a colour) and from...
• Value()constGets the 32-bit value of the TRgb as an integer. This function is deprecated. Us...
• _Color16M()constGets the index of the closest TRgb value to this, based on the matching display ...
• _Color16M(TInt)Gets TRgb from 16M colour index.
• _Color16MA()constGets the index of the closest TRgb value to this, based on the matching display ...
• _Color16MA(TUint)Gets TRgb from 16MA colour index. The function takes a 32 bit colour value with ...
• _Color16MAP()constConverts the TRgb to EColor16MAP (with color channels pre-multiplied with the al...
• _Color16MAP(TUint)Gets TRgb from 16MAP colour index. The function takes a 32 bit colour value with...
• _Color16MU()constGets the index of the closest TRgb value to this, based on the matching display ...
• _Color16MU(TInt)Gets TRgb from 16MU colour index. The function takes a 24 bit colour value with ...
• _Color4K()constGets the index of the closest TRgb value to this, based on the matching display ...
• _Color4K(TInt)Gets TRgb from 4K colour index.
• _Color64K()constGets the index of the closest TRgb value to this, based on the matching display ...
• _Color64K(TInt)Gets TRgb from 64K colour index.
• _Gray16()constGets the index of the closest TRgb value to this, based on the matching display ...
• _Gray16(TInt)Gets TRgb from 16 level grayscale.
• _Gray2()constGets the index of the closest TRgb value to this, based on the matching display ...
• _Gray2(TInt)Gets TRgb from 2 level grayscale.
• _Gray256()constGets the index of the closest TRgb value to this, based on the matching display ...
• _Gray256(TInt)Gets TRgb from 256 level grayscale.
• _Gray4()constGets the index of the closest TRgb value to this, based on the matching display ...
• _Gray4(TInt)Gets TRgb from 4 level grayscale.
• operator &(const TRgb &)Bitwise logical AND operator.
• operator &=(const TRgb &)Logical AND assignment operator.
• operator!=(const TRgb &)constCompares this colour with the specified colour for inequality.
• operator==(const TRgb &)constCompares this colour with the specified colour for equality.
• operator^(const TRgb &)Bitwise EXCLUSIVE OR operator
• operator^=(const TRgb &)Logical EXCLUSIVE OR assignment operator.
• operator|(const TRgb &)Bitwise logical OR operator.
• operator|=(const TRgb &)Logical OR assignment operator.
• operator~()constBitwise logical inversion operator.

See also:

• TDisplayModeDisplay modes.
• DynamicPaletteHooks to allow dynamic palette switching in 256 colour mode.

inline TRgb();

Description

Constructs a TRgb initialised to KRgbWhite.

inline TRgb(TUint32 aValue);

Description

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

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

For example, TRgb(2,4,8) using the 3 colour constructor is equal to TRgb(0x00080402) using this constructor.

The constructor is deprecated. Use others constructor or TRgb::SetInternal(TUint32) instead.

Parameters

inline TRgb(TUint32 aInternalValue, TInt aAlpha);

Description

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 of 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 constructor is equal to TRgb(0x00020408, 255) using this constructor.

The constructor is a replacement for TRgb::TRgb(TUint32).

Parameters

inline TRgb(TInt aRed, TInt aGreen, TInt aBlue);

Description

Constructs a TRgb from its three component colours.

Each colour has a value between 0 and 255.

Parameters

inline TRgb(TInt aRed, TInt aGreen, TInt aBlue, TInt aAlpha);

Description

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).

Parameters

inline TInt Red() const;

Description

Gets the red component.

Return value

inline TInt Green() const;

Description

Gets the green component.

Return value

inline TInt Blue() const;

Description

Gets the blue component.

Return value

inline TInt Alpha() const;

Description

Gets the alpha component.

Return value

IMPORT_C void SetRed(TInt aRed);

Description

Sets the red component.

Parameters

IMPORT_C void SetGreen(TInt aGreen);

Description

Sets the green component.

Parameters

IMPORT_C void SetBlue(TInt aBlue);

Description

Sets the blue component.

Parameters

IMPORT_C void SetAlpha(TInt aAlpha);

Description

Sets the alpha component.

Parameters

IMPORT_C static TRgb Gray2(TInt aGray2);

Description

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

Return value

IMPORT_C static TRgb Gray4(TInt aGray4);

Description

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

Return value

IMPORT_C static TRgb Gray16(TInt aGray16);

Description

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

Return value

IMPORT_C static TRgb Gray256(TInt aGray256);

Description

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

Return value

IMPORT_C static TRgb Color16(TInt aColor16);

Description

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

Return value

IMPORT_C static TRgb Color256(TInt aColor256);

Description

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

Return value

IMPORT_C static TRgb Color4K(TInt aColor4K);

Description

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

Return value

IMPORT_C static TRgb Color64K(TInt aColor64K);

Description

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

Return value

IMPORT_C static TRgb Color16M(TInt aColor16M);

Description

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

Return value

IMPORT_C TInt Gray2() const;

Description

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

Return value

IMPORT_C TInt Gray4() const;

Description

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

Return value

IMPORT_C TInt Gray16() const;

Description

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

Return value

IMPORT_C TInt Gray256() const;

Description

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

Return value

IMPORT_C TInt Color16() const;

Description

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

Return value

IMPORT_C TInt Color256() const;

Description

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

Return value

IMPORT_C TInt Color4K() const;

Description

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

Return value

IMPORT_C TInt Color64K() const;

Description

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

Return value

IMPORT_C TInt Color16M() const;

Description

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

Return value

inline TBool operator==(const TRgb &aColor) const;

Description

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

Return value

inline TBool operator!=(const TRgb &aColor) const;

Description

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

Return value

inline TRgb operator~() const;

Description

Bitwise logical inversion operator.

Return value

inline TRgb operator &(const TRgb &aColor);

Description

Bitwise logical AND operator.

Parameters

Return value

inline TRgb operator|(const TRgb &aColor);

Description

Bitwise logical OR operator.

Parameters

Return value

inline TRgb operator^(const TRgb &aColor);

Description

Bitwise EXCLUSIVE OR operator

Parameters

Return value

inline TRgb& operator &=(const TRgb &aColor);

Description

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

Return value

inline TRgb& operator|=(const TRgb &aColor);

Description

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

Return value

inline TRgb& operator^=(const TRgb &aColor);

Description

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

Return value

inline TUint32 Value() const;

Description

Gets the 32-bit value of the TRgb as an integer. This function is deprecated. Use TRgb::Internal()const instead.

Return value

inline TUint32 Internal() const;

Description

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

Return value

inline void SetInternal(TUint32 aInternal);

Description

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

Parameters

IMPORT_C TInt Difference(const TRgb &aColor) const;

Description

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

Return value

IMPORT_C void InternalizeL(RReadStream &aStream);

Description

Internalises a TRgb object from a stream.

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

Parameters

IMPORT_C void ExternalizeL(RWriteStream &aStream) const;

Description

Externalises a TRgb object to a stream.

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

Parameters

IMPORT_C static TRgb Color16MU(TInt a0RGB);

Description

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

Return value

IMPORT_C TInt Color16MU() const;

Description

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

Return value

IMPORT_C static TRgb Color16MA(TUint aARGB);

Description

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

Return value

IMPORT_C TUint Color16MA() const;

Description

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

Return value

IMPORT_C static TRgb Color16MAP(TUint aARGB);

Description

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

Return value

IMPORT_C TUint Color16MAP() const;

Description

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.

Return value

IMPORT_C TUint _Color16MAP() const;

Description

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

Return value

IMPORT_C static TRgb _Color16MAP(TUint aARGB);

Description

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

Return value

inline TInt _Gray2() const;

Description

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

Return value

inline TInt _Gray4() const;

Description

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

Return value

inline TInt _Gray16() const;

Description

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

Return value

inline TInt _Gray256() const;

Description

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

Return value

inline TInt _Color4K() const;

Description

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

Return value

inline TInt _Color64K() const;

Description

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

Return value

inline TInt _Color16M() const;

Description

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

Return value

inline TInt _Color16MU() const;

Description

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

Return value

inline TUint _Color16MA() const;

Description

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

Return value

static inline TRgb _Gray2(TInt aGray2);

Description

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

Return value

static inline TRgb _Gray4(TInt aGray4);

Description

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

Return value

static inline TRgb _Gray16(TInt aGray16);

Description

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

Return value

static inline TRgb _Gray256(TInt aGray256);

Description

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

Return value

static inline TRgb _Color4K(TInt aColor4K);

Description

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

Return value

static inline TRgb _Color64K(TInt aColor64K);

Description

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

Return value

static inline TRgb _Color16M(TInt aColor16M);

Description

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

Return value

static inline TRgb _Color16MU(TInt a0RGB);

Description

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

Return value

static inline TRgb _Color16MA(TUint aARGB);

Description

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

Return value