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classPiiColorBase

#include <PiiColor.h>

A structure that represents a three-channel color.

Inherited by PiiColor< T >, PiiColor4< T >

Description

The data type of the color channels is a template parameter with a default value of unsigned char. This should work for most cases because color spaces with more than four channels or more than eight bits per channel are seldom used.

The generic way of accessing color channels is via the channel array. In PiiColor, the array can be accessed with indices from 0 to 2. In PiiColor4, 3 can also be used. (The array is defined to have space for three elements only, but the arrangement of classes in memory makes it possible to utilize array overflow in a constructive fashion.)

In your code, you can utilized the #channel(int) function or color space specific names: 

 PiiColor<> clr(255, 127, 0);
 QCOMPARE(clr.channel(1), clr.rgbG);
 QCOMPARE(clr.rgbG, static_cast<unsigned char>(127));
 QCOMPARE(clr.channel(2), clr.hsvV);
 QCOMPARE(clr.c2, clr.rgbaB);

The syntax is <space><Channel>, where <space> is any of the following: rgb, hsv, hsi, yuv, yiq, xyz, lab, luv, cmyk, rgba. <Channel> is the name of the color channel as a capital letter, e.g. R, G, B, or Y. The R channel of the RGB color space is denoted by rgbR. Furthermore, the channels are aliased with generic names c0, c1 and c2. If possible, the color channel names should be preferred over the channel array for code readability.

NOTE! The order of color channels in the channel array is opposite to what you probably expect. For example, rgbR corresponds to channel[2], and rgbB to channel[0]. This allows one to use PiiColor4<unsigned char> and int interchangeably on little-endian hardware (such as the PC). It also makes it possible to use the colors with QRgb. You can, however, use the channel(int) function to access the channels in the "natural" order.

See also

Public types

typedef PiiColorBaseTraits< T >::Type
Type

The content type.

Constructors and destructor

PiiColorBase
(
  • T value = 0
)

Create a new color with the same value on each color channel.

PiiColorBase
(
  • T channel0
  • T channel1
  • T channel2
)

Create a new color with the given values for each color channel.

Public member functions

PiiColorBaseTraits< T >::ConstIterator
begin
( )

An stl-style const iterator to the first color channel.

PiiColorBaseTraits< T >::Iterator
begin
( )

An stl-style iterator to the first color channel.

T
channel
(
  • int channelIndex
)

Return the value of the channel denoted by channelIndex.

operator char
( )

Return the average of all color channels as a char.

operator double
( )

Return the average of all color channels as a double.

operator float
( )

Return the average of all color channels as a float.

operator int
( )

Return the average of all color channels as an int.

operator short
( )

Return the average of all color channels as a short.

operator unsigned char
( )

Return the average of all color channels as an unsigned char.

operator unsigned int
( )

Return the average of all color channels as an unsigned int.

operator unsigned short
( )

Return the average of all color channels as an unsigned short.

void
setChannel
(
  • int channelIndex
  • T value
)

Set the value of a color channel.

Function details

  • PiiColorBase

    (
    • T value = 0
    )
    [inline]

    Create a new color with the same value on each color channel.

  • PiiColorBase

    (
    • T channel0
    • T channel1
    • T channel2
    )
    [inline]

    Create a new color with the given values for each color channel.

    Note that the order of channels in the channel array is reversed. When you initialize a PiiColor with RGB values, B will be the first channel. 

     // Parameters:       R, G, B
 PiiColorBase<> pureRed(255, 0, 0);
 QVERIFY(pureRed.rgbR == 255);
 QVERIFY(pureRed.c0 == 255);
 QVERIFY(pureRed.channels[0] == 0); // !

  • PiiColorBaseTraits< T >::ConstIterator begin

    ()
    [inline]

    An stl-style const iterator to the first color channel.

    Note that the first color channel in the RGB space is B.

  • PiiColorBaseTraits< T >::Iterator begin

    ()
    [inline]

    An stl-style iterator to the first color channel.

    Note that the first color channel in the RGB space is B.

  • T channel

    (
    • int channelIndex
    )
    [inline]

    Return the value of the channel denoted by channelIndex.

    This is a convenience function that returns the channels in "traditional" order (channel(0) returns the R channel etc.)

  • operator char

    ()
    [inline]

    Return the average of all color channels as a char.

  • operator double

    ()
    [inline]

    Return the average of all color channels as a double.

  • operator float

    ()
    [inline]

    Return the average of all color channels as a float.

  • operator int

    ()
    [inline]

    Return the average of all color channels as an int.

  • operator short

    ()
    [inline]

    Return the average of all color channels as a short.

  • operator unsigned char

    ()
    [inline]

    Return the average of all color channels as an unsigned char.

  • operator unsigned int

    ()
    [inline]

    Return the average of all color channels as an unsigned int.

  • operator unsigned short

    ()
    [inline]

    Return the average of all color channels as an unsigned short.

  • void setChannel

    (
    • int channelIndex
    • T value
    )
    [inline]

    Set the value of a color channel.

    This is a convenience function that allows one to index the channels in "traditional" order.

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