imageline

imageline

(PHP 3, PHP 4, PHP 5)

imageline -- Draw a line

Description

bool imageline ( resource image, int x1, int y1, int x2, int y2, int color )

imageline() draws a line from x1, y1 to x2, y2 (top left is 0, 0) in image image of color color.

Example 1. Drawing a thick line

<?php

function imagelinethick($image, $x1, $y1, $x2, $y2, $color, $thick = 1)
{
    
/* this way it works well only for orthogonal lines
    imagesetthickness($image, $thick);
    return imageline($image, $x1, $y1, $x2, $y2, $color);
    */
    
if ($thick == 1) {
        return
imageline($image, $x1, $y1, $x2, $y2, $color);
    }
    
$t = $thick / 2 - 0.5;
    if (
$x1 == $x2 || $y1 == $y2) {
        return
imagefilledrectangle($image, round(min($x1, $x2) - $t), round(min($y1, $y2) - $t), round(max($x1, $x2) + $t), round(max($y1, $y2) + $t), $color);
    }
    
$k = ($y2 - $y1) / ($x2 - $x1); //y = kx + q
    
$a = $t / sqrt(1 + pow($k, 2));
    
$points = array(
        
round($x1 - (1+$k)*$a), round($y1 + (1-$k)*$a),
        
round($x1 - (1-$k)*$a), round($y1 - (1+$k)*$a),
        
round($x2 + (1+$k)*$a), round($y2 - (1-$k)*$a),
        
round($x2 + (1-$k)*$a), round($y2 + (1+$k)*$a),
    );    
    
imagefilledpolygon($image, $points, 4, $color);
    return
imagepolygon($image, $points, 4, $color);
}

?>

See also imagecreatetruecolor() and imagecolorallocate().

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