RGBAColor

This utility class is used to hold information on an RGB based color, with optional opacity / alpha channel.

Overview

Supported color value ranges

To easily work with the many possible color value ranges, each color can be specified using a special ColorChannel class, which allows specifying the color value the way you prefer:

• 8-Bit integer: 0-255 (Standard color values)
• 7-Bit integer: 0-127 (PHP GD style alpha channel)
• Decimal: 0.00-1.00 (CSS opacity, for example)
• Percent: 0-100 (General purpose)

Color components

• Red
• Green
• Blue
• Opacity
• Transparency (Inverted opacity)

Usage examples

Creating from different formats

From a hexadecimal string

use AppUtils\RGBAColor\ColorFactory;

$red = ColorFactory::createFromHEX('CC0000');

// Shorthand syntax
$gray = ColorFactory::createFromHEX('CCC');

// With opacity
$overlay = ColorFactory::createFromHEX('00000066');

From 8-Bit values

use AppUtils\RGBAColor\ColorFactory;

$white = ColorFactory::create8Bit(255, 255, 255, 255);

From an array of 8-Bit values

use AppUtils\RGBAColor\ColorFactory;

// Indexed array
$white = ColorFactory::createPercent(array(100, 100, 100, 100));

// Associative array
$white = ColorFactory::createPercent(array(
    'red' => 100, 
    'green' => 100, 
    'blue' => 100, 
    'alpha' => 100
));

From GD-compatible values

PHP's GD library uses 8-Bit values for the color channels, and 7-Bit for the opacity.

use AppUtils\RGBAColor\ColorFactory;

$white = ColorFactory::createGD(255, 255, 255, 127);

From percentages

use AppUtils\RGBAColor\ColorFactory;

$white = ColorFactory::createPercent(100, 100, 100, 100);

From CSS-compatible values

In style sheets, the color channels are 8-Bit values, and the opacity is a decimal from 0-1.

use AppUtils\RGBAColor\ColorFactory;

$white = ColorFactory::createCSS(255, 255, 255, 1);

From individual channels

Each color is specified using a color channel instance, giving the most flexibility in the type of value per channel.

In the following example, every color uses a different value:

use AppUtils\RGBAColor\ColorFactory;
use AppUtils\RGBAColor\ColorChannel;

$white = ColorFactory::create(
    ColorChannel::eightBit(255),
    ColorChannel::sevenBit(127),
    ColorChannel::percent(100),
    ColorChannel::decimal(1)
);

Automatic value detection

While it is not possible to automatically detect the type from numeric color values, some other formats can be used:

• An empty or NULL value
• A HEX color string
• An 8-Bit color array
• An existing RGBAColor instance
• A preset name

Comparing colors

Ignoring the opacity

The match() method compares two colors, ignoring the opacity. Two colors that have the same RGB values but different opacity values will be considered the same.

use AppUtils;

$colorA = ColorFactory::createFromHEX('CCC');
$colorB = ColorFactory::createFromHEX('CCC');

if($colorA->matches($colorB))
{
    echo 'Colors match.';
}
else
{
    echo 'Colors do not match.';
}

Output:

Colors match.

With opacity

The matchAlpha() method compares two colors, including their opacity. To match, colors must both have the same RGB values and opacity value.

use AppUtils;

$colorA = ColorFactory::createFromHEX('CCCCCCDD');
$colorB = ColorFactory::createFromHEX('CCCCCCEE');

if($colorA->matchesAlpha($colorB))
{
    echo 'Colors match.';
}
else
{
    echo 'Colors do not match.';
}

Output:

Colors do not match.