imageopenpolygon

(PHP 7 >= 7.2.0, PHP 8)

imageopenpolygon — Draws an open polygon

Description

Signature as of PHP 8.0.0 (not supported with named arguments)

imageopenpolygon(GdImage $image, array $points, int $color): bool

Alternative signature (deprecated as of PHP 8.1.0)

imageopenpolygon(
    GdImage $image,
    array $points,
    int $num_points,
    int $color
): bool

imageopenpolygon() draws an open polygon on the given image. Contrary to imagepolygon(), no line is drawn between the last and the first point.

Parameters

image

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

points

An array containing the polygon's vertices, e.g.:

points[0]	= x0
points[1]	= y0
points[2]	= x1
points[3]	= y1

num_points

Total number of points (vertices), which must be at least 3.

If this parameter is omitted as per the second signature, points must have an even number of elements, and num_points is assumed to be count($points)/2.

color

A color identifier created with imagecolorallocate().

Return Values

Returns true on success or false on failure.

Changelog

Version	Description
8.1.0	The parameter `num_points` has been deprecated.
8.0.0	`image` expects a GdImage instance now; previously, a valid `gd` resource was expected.

Examples

Example #1 imageopenpolygon() example

<?php
// Create a blank image
$image = imagecreatetruecolor(400, 300);

// Allocate a color for the polygon
$col_poly = imagecolorallocate($image, 255, 255, 255);

// Draw the polygon
imageopenpolygon($image, array(
        0,   0,
        100, 200,
        300, 200
    ),
    3,
    $col_poly);

// Output the picture to the browser
header('Content-type: image/png');

imagepng($image);
imagedestroy($image);
?>

The above example will output something similar to:

User Contributed Notes 1 note

down

marco at oostende dot nl ¶

6 years ago


In case you want to use an open polygon but are stuck with a PHP version prior to 7.2, a solution may be to 'backplot' your array to its original start. Say you have an array of pixels (below seperated by commas)

<?php
$arr = array();
for ($i = 0; $i < count($pixels); $i++) {
    $pixel = explode(',', $pixels[$i]);
    if (($pixel[0] > 0) && ($pixel[1] > 0)) {
        $arr[] = $pixel[0];
        $arr[] = $pixel[1];
    }
}
imagepolygon($im, $arr, (count($arr) / 2), $otcolor);
?>

you can replace this by something like

<?php
$arr = array();
for ($i = 0; $i < count($pixels); $i++) {
    $pixel = explode(',', $pixels[$i]);
    $arr[] = $pixel[0];
    $arr[] = $pixel[1];
}
// imageopenpolygon($im, $arr, (count($arr) / 2), $otcolor) is not possible, so...
for ($i = (count($pixels)-1); $i >= 0; $i--) {
    $pixel = explode(',', $pixels[$i]);
    $arr[] = $pixel[0];
    $arr[] = $pixel[1];
}
imagepolygon($im, $arr, (count($arr) / 2), $otcolor);
?>

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