phpday 2021 digital edition

imageopenpolygon

(PHP 7 >= 7.2.0, PHP 8)

imageopenpolygonDraws an open polygon

Descrição

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

Alternative signature (as of PHP 8.0.0)

imageopenpolygon ( resource $image , array $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.

Parâmetros

image

Um resource de imagem, retornado por funções de criação de imagens, como 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().

Valor Retornado

Retorna true em caso de sucesso ou false em caso de falha.

Exemplos

Exemplo #1 imageopenpolygon() example

<?php
// Create a blank image
$image imagecreatetruecolor(400300);

// Allocate a color for the polygon
$col_poly imagecolorallocate($image255255255);

// Draw the polygon
imageopenpolygon($image, array(
        
0,   0,
        
100200,
        
300200
    
),
    
3,
    
$col_poly);

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

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

O exemplo acima irá imprimir algo similar à:

Output of example : imageopenpolygon()

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User Contributed Notes 1 note

up
-1
marco at oostende dot nl
2 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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