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imagecolorallocate

Description

The imagecolorallocate of Image for PHP allocate a color for an image.

Syntax

imagecolorallocate(
    GdImage $image,
    int $red,
    int $green,
    int $blue
): int|false

Parameters

image

A GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().

red

Value of red component.

green

Value of green component.

blue

Value of blue component.

Return

A color identifier or false if the allocation failed.

Warning: This function may return Boolean false, but may also return a non-Boolean value which evaluates to false. Use the === operator for testing the return value of this function.

Examples

1 · red green blue · decimal

<?

$width = 100;
$height = 100;
$image = imagecreate($width, $height);

$red = 255;
$green = 255;
$blue = 255;

$return = imagecolorallocate($image, $red, $green, $blue);

echo $return;

?>
0

2 · red green blue · hexadecimal

<?

$width = 100;
$height = 100;
$image = imagecreate($width, $height);

$red = 0xff;
$green = 0xff;
$blue = 0xff;

$return = imagecolorallocate($image, $red, $green, $blue);

echo $return;

?>
0

3 · return

<?

$width = 100;
$height = 100;
$image = imagecreate($width, $height);

$red = 255;
$green = 255;
$blue = 255;
$background = imagecolorallocate($image, $red, $green, $blue);

$red = 255;
$green = 0;
$blue = 0;
$r = imagecolorallocate($image, $red, $green, $blue);

$red = 0;
$green = 255;
$blue = 0;
$g = imagecolorallocate($image, $red, $green, $blue);

$red = 0;
$green = 0;
$blue = 255;
$b = imagecolorallocate($image, $red, $green, $blue);

echo $background . $r . $g . $b;

?>
0123

4 · base64

<?

$width = 100;
$height = 100;
$image = imagecreate($width, $height);

$red = 255;
$green = 255;
$blue = 255;
$background = imagecolorallocate($image, $red, $green, $blue);

$x = 0;
$y = 0;
imagefill($image, $x, $y, $background);

$red = 255;
$green = 0;
$blue = 0;
$r = imagecolorallocate($image, $red, $green, $blue);

$x1 = 0;
$y1 = 0;
$x2 = 50;
$y2 = 50;
imagefilledrectangle($image, $x1, $y1, $x2, $y2, $r);

$red = 0;
$green = 255;
$blue = 0;
$g = imagecolorallocate($image, $red, $green, $blue);

$x1 = 25;
$y1 = 25;
$x2 = 75;
$y2 = 75;
imagefilledrectangle($image, $x1, $y1, $x2, $y2, $g);

$red = 0;
$green = 0;
$blue = 255;
$b = imagecolorallocate($image, $red, $green, $blue);

$x1 = 50;
$y1 = 50;
$x2 = 100;
$y2 = 100;
imagefilledrectangle($image, $x1, $y1, $x2, $y2, $b);

ob_start();

    imagepng($image);

$output = ob_get_clean();

echo '<!doctype html>
<html>
<body>
    <img src="data:image/png;base64,' . base64_encode($output) . '">
</body>
</html>';

?>
<!doctype html>
<html>
<body>
    <img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAGQAAABkAgMAAAANjH3HAAAADFBMVEX/////AAAA/wAAAP9WpSYHAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAANklEQVRIiWMIRQIhDMhgVGZUhv4yWauQwKjMqMwAy6z/jwSg8lqjMqMyg0IGAvhHZUZlaCsDAIspNRnrII7dAAAAAElFTkSuQmCC">
</body>
</html>
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