#include <gdi.h>
Link against: gdi.lib
| 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
See also: TDisplayMode DynamicPalette
| 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.
Deprecated
| Parameters | |
|---|---|
| aValue | Integer representing colour value. Takes form 0x00bbggrr. |
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 | |
|---|---|
| aInternalValue | Integer representing a colour value, which takes the form 0x00rrggbb. |
| aAlpha | Alpha component of the colour (0 - 255). |
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 | |
|---|---|
| aRed | Red component of the colour (0 - 255). |
| aGreen | Green component of the colour (0 - 255). |
| aBlue | Blue component of the colour (0 - 255). |
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 | |
|---|---|
| aRed | Red component of the colour (0 - 255). |
| aGreen | Green component of the colour (0 - 255). |
| aBlue | Blue component of the colour (0 - 255). |
| aAlpha | Alpha component of the colour (0 - 255). |
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 | |
|---|---|
| aARGB | The color - A, R, G, B bytes. / BGRA - little endian format / |
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 | |
|---|---|
| aARGB | The pre-multiplied (EColor16MAP) color value. |
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 | |
|---|---|
| a0RGB | The color - 0, R, G, B bytes. / BGR0 - little endian format / |
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 | |
|---|---|
| aColor | The TRgb to be compared. |
| 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 | |
|---|---|
| aStream | Stream to which the object is externalised. |
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 | |
|---|---|
| aGray16 | Grayscale value to be converted. |
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 | |
|---|---|
| aGray2 | Grayscale value to be converted. |
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 | |
|---|---|
| aGray256 | Grayscale value to be converted. |
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 | |
|---|---|
| aGray4 | Grayscale value to be converted. |
| 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.
See also: operator>>()
| Parameters | |
|---|---|
| aStream | Stream from which the object is internalised. |
| IMPORT_C void | SetAlpha | ( | TInt | aAlpha | ) |
Sets the alpha component.
| Parameters | |
|---|---|
| aAlpha | Alpha component (0- 255). |
| IMPORT_C void | SetGreen | ( | TInt | aGreen | ) |
Sets the green component.
| Parameters | |
|---|---|
| aGreen | Green component (0 - 255). |
| 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.
Deprecated
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 | |
|---|---|
| aARGB | The color - A, R, G, B bytes. / BGR0 - little endian format / |
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 | |
|---|---|
| aARGB | The pre-multiplied (EColor16MAP) color value. |
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 | |
|---|---|
| a0RGB | The color - 0, R, G, B bytes. / BGR0 - little endian format / |
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 | |
|---|---|
| aGray16 | Grayscale value to be converted. |
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 | |
|---|---|
| aGray2 | Grayscale value to be converted. |
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 | |
|---|---|
| aGray256 | Grayscale value to be converted. |
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 | |
|---|---|
| aGray4 | Grayscale value to be converted. |
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 | |
|---|---|
| aColor | Colour to be compared. |
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 | |
|---|---|
| aColor | Colour to be compared. |
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 | |
|---|---|
| aColor | Colour to be compared. |
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 | |
|---|---|
| aColor | Colour to be compared. |
| TRgb | operator~ | ( | ) | const [inline] |
Bitwise logical inversion operator.