imageopenpolygon()

(PHP 7 >= 7.2.0)

Draws an open polygon

说明

imageopenpolygon(resource $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.

参数

$image

由图象创建函数(例如imagecreatetruecolor())返回的图象资源。

$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.

$color

A color identifier created with imagecolorallocate().

返回值

成功时返回TRUE，或者在失败时返回FALSE。

范例

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);
?>

以上例程的输出类似于：

参见

• imagepolygon()画一个多边形

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);
?>