imagefilledpolygon

(PHP 4, PHP 5, PHP 7)

imagefilledpolygon — 画一多边形并填充

说明

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

imagefilledpolygon() 在 image 图像中画一个填充了的多边形。

points 参数是一个按顺序包含有多边形各顶点的 x 和 y 坐标的数组。

num_points 参数是顶点的总数，必须大于 3。

Example #1 imagefilledpolygon() 例子

  <?php
 // 建立多边形各顶点坐标的数组
 $values  = array(
             40 ,   50 ,   // Point 1 (x, y)
             20 ,   240 ,  // Point 2 (x, y)
             60 ,   60 ,   // Point 3 (x, y)
             240 ,  20 ,   // Point 4 (x, y)
             50 ,   40 ,   // Point 5 (x, y)
             10 ,   10    // Point 6 (x, y)
             );

 // 创建图像
 $image  =  imagecreatetruecolor ( 250 ,  250 );

 // 设定颜色
 $bg    =  imagecolorallocate ( $image ,  200 ,  200 ,  200 );
 $blue  =  imagecolorallocate ( $image ,  0 ,  0 ,  255 );

 // 画一个多边形
 imagefilledpolygon ( $image ,  $values ,  6 ,  $blue );

 // 输出图像
 header ( 'Content-type: image/png' );
 imagepng ( $image );
 imagedestroy ( $image );
 ?>

用户评论:

[#1] rbenheidorn at gmail dot com [2015-02-01 21:20:05]

Discovered while working on printing geographical boundaries to an image: if you provide floating point vertices, then the decimal value is automatically truncated. This can cause images drawn with floating point vertices to shift slightly towards the top-left corner. My personal resolution is to round all of the vertices to their nearest whole values, which eliminates this shift.

[#2] austinoblouk at yahoo dot com [2009-09-05 20:28:18]

Actually the minimum it allows is 3. It says "Total number of vertices, which must be bigger than 3." but it allows 3...

[#3] Arnapou [2007-10-29 06:49:00]

I discovered that the GD imagefilledpolygon function is incorrect for some drawing with transparent color (for example red 50% : RGBA = 255, 0, 0, 64).

I tried to draw a complex form with lots of points really near (1 pixel of distance) and a transparent red.

The problem was : some border pixels were not drawn by the imagefilledpolygon but were drawn with imagepolygon !?!?

So I wrote my own imagefilledpolygon function which work very well in all case I tested.

<?php // $points should be an array of coordinates like that : $points = array( array(0, 0), array(100, 50), array(90, 100), array(50, 50), array(70, 30), array(10, 10), ); ?>

<?php function myimagefilledpolygon(& $img, $points, $color) { $scanline = 99999; // compute edges $all_edges = array(); $n = count($points); for($i=0; $i<$n; $i++) { $p1 = $points[$i]; if ($i == $n-1) { $p2 = $points[0]; } else { $p2 = $points[$i+1]; } $x1 = $p1[0]; $y1 = $p1[1]; $x2 = $p2[0]; $y2 = $p2[1]; if ($y1 != $y2) { $invslope = ($x2 - $x1)/($y2 - $y1); if ($y1 < $y2 ) { $ymin = $y1; $xval = $x1; $ymax = $y2; } else { $ymin = $y2; $xval = $x2; $ymax = $y1; } $all_edges[] = array($ymin, $ymax, $xval, $invslope); if ($ymin < $scanline) { $scanline = $ymin; } } else { if ($y1 < $scanline) { $scanline = $y1; } if ($y2 < $scanline) { $scanline = $y2; } } } // draw $active = array(); do { // add edges to active array $tmp = array(); $n = count($all_edges); for($i=0; $i<$n; $i++) { if ($all_edges[$i][0] == $scanline) { $active[] = $all_edges[$i]; } else { $tmp[] = $all_edges[$i]; } } $all_edges = $tmp; // remove previous edges from active array $tmp = array(); $n = count($active); for($i=0; $i<$n; $i++) { if ($active[$i][1] > $scanline) { $tmp[] = $active[$i]; } } $active = $tmp; // sort active tab $n = count($active); for($i=0; $i<$n-1; $i++) { $min = $i; for($k=$i+1; $k<$n; $k++) { if ($active[$k][2] < $active[$min][2]) { $min = $k; } } if ($i != $min) { $tmp = $active[$i]; $active[$i] = $active[$min]; $active[$min] = $tmp; } } // draw $n = count($active); for($i=0; $i<$n; $i+=2) { if ($i+1 < $n) { if ($tmp[$i][2] == $active[$i+1][2]) { imagesetpixel($img, round($active[$i][2]), $scanline, $color); } else { imageline($img, round($active[$i][2]), $scanline, round($active[$i+1][2]), $scanline, $color); } } } // increment x values $n = count($active); for($i=0; $i<$n; $i++) { $active[$i][2] += $active[$i][3]; } $scanline++; } while (count($all_edges) + count($active) > 0); } ?>

[#4] webmaster at mywebsolution dot de [2007-10-22 14:24:53]

Just thought that 'tatlar at yahoo dot com's function has some redundant code in it, so I tried to "improve" it. Now you can choose a variable number of spikes.

<?php error_reporting(E_ALL); function drawStar($x, $y, $radius, $spikes=5) { // $x, $y -> Position in the image // $radius -> Radius of the star // $spikes -> Number of spikes $coordinates = array(); $angel = 360 / $spikes ; // Get the coordinates of the outer shape of the star $outer_shape = array(); for($i=0; $i<$spikes; $i++){ $outer_shape[$i]['x'] = $x + ($radius * cos(deg2rad(270 - $angel*$i))); $outer_shape[$i]['y'] = $y + ($radius * sin(deg2rad(270 - $angel*$i))); } // Get the coordinates of the inner shape of the star $inner_shape = array(); for($i=0; $i<$spikes; $i++){ $inner_shape[$i]['x'] = $x + (0.5*$radius * cos(deg2rad(270-180 - $angel*$i))); $inner_shape[$i]['y'] = $y + (0.5*$radius * sin(deg2rad(270-180 - $angel*$i))); } // Bring the coordinates in the right order foreach($inner_shape as $key => $value){ if($key == (floor($spikes/2)+1)) break; $inner_shape[] = $value; unset($inner_shape[$key]); } // Reset the keys $i=0; foreach($inner_shape as $value){ $inner_shape[$i] = $value; $i++; } // "Merge" outer and inner shape foreach($outer_shape as $key => $value){ $coordinates[] = $outer_shape[$key]['x']; $coordinates[] = $outer_shape[$key]['y']; $coordinates[] = $inner_shape[$key]['x']; $coordinates[] = $inner_shape[$key]['y']; } // Return the coordinates return $coordinates ; } // Example $spikes = 5; $values = drawStar(250, 250, 200, $spikes); $im = imagecreate(500,500); imagecolorallocate($im,0,0,0); $w = imagecolorallocate($im, 255, 255, 255); imagefilledpolygon($im, $values, $spikes*2, $w); imageGIF($im); imagedestroy($im); ?>

[#5] jylyn at hotmail dot com [2006-10-16 17:11:12]

In spite of what it says about requiring more than 3 vertices, it is possible to draw a triangle with this function!

[#6] tatlar at yahoo dot com [2006-09-11 17:08:22]

<?php function _makeFiveSidedStar( $x, $y, $radius, $shape='polygon', $spiky=NULL ) {
    // $x, $y co-ords of origin (in pixels), $radius (in pixels), $shape - 'polygon' or 'star', $spikiness - ratio between 0 and 1
    $point = array() ;
    $angle = 360 / 5 ;
    $point[0]['x'] = $x ;
    $point[0]['y'] = $y - $radius ;
    $point[2]['x'] = $x + ( $radius * cos( deg2rad( 90 - $angle ) ) ) ;
    $point[2]['y'] = $y - ( $radius * sin( deg2rad( 90 - $angle ) ) ) ;
    $point[4]['x'] = $x + ( $radius * sin( deg2rad( 180 - ( $angle*2 ) ) ) ) ;
    $point[4]['y'] = $y + ( $radius * cos( deg2rad( 180 - ( $angle*2 ) ) ) ) ;
    $point[6]['x'] = $x - ( $radius * sin( deg2rad( 180 - ( $angle*2 ) ) ) ) ;
    $point[6]['y'] = $y + ( $radius * cos( deg2rad( 180 - ( $angle*2 ) ) ) ) ;
    $point[8]['x'] = $x - ( $radius * cos( deg2rad( 90 - $angle ) ) ) ;
    $point[8]['y'] = $y - ( $radius * sin( deg2rad( 90 - $angle ) ) ) ;
    if( $shape == 'star' ) {
        if( $spiky == NULL ) $spiky = 0.5 ;  // default to 0.5
        $indent = $radius * $spiky ;
        $point[1]['x'] = $x + ( $indent * cos( deg2rad( 90 - $angle/2 ) ) ) ;
        $point[1]['y'] = $y - ( $indent * sin( deg2rad( 90 - $angle/2 ) ) ) ;
        $point[3]['x'] = $x + ( $indent * sin( deg2rad( 180 - $angle ) ) ) ;
        $point[3]['y'] = $y - ( $indent * cos( deg2rad( 180 - $angle ) ) ) ;
        $point[5]['x'] = $x ;
        $point[5]['y'] = $y + ( $indent * sin( deg2rad( 180 - $angle ) ) ) ;
        $point[7]['x'] = $x - ( $indent * sin( deg2rad( 180 - $angle ) ) ) ;
        $point[7]['y'] = $y - ( $indent * cos( deg2rad( 180 - $angle ) ) ) ;
        $point[9]['x'] = $x - ( $indent * cos( deg2rad( 90 - $angle/2 ) ) ) ;
        $point[9]['y'] = $y - ( $indent * sin( deg2rad( 90 - $angle/2 ) ) ) ;
    }
    ksort( $point ) ;
    $coords = array() ;  // new array
    foreach( $point as $pKey=>$pVal ) {
        if( is_array( $pVal ) ) {
            foreach( $pVal as $pSubKey=>$pSubVal ) {
                if( !empty( $pSubVal ) ) array_push( $coords, $pSubVal ) ;
            }
        }
    }
    return $coords ;
}
$values = _makeFiveSidedStar( 100, 100, 50, 'star' ) ;
// Put values into imagepolygon function. You need to define the $image and $color, and flush it out to an image type.?>

[#7] etnekor at tar dot hu [2006-01-22 13:18:16]

There is a simple function to draw a filled point with a chosen radius and color.

<?php function drawPoint($img, $radius, $origo_x, $origo_y, $pointColor) { for ($i=0;$i<=360;$i++) { $pont[] = $origo_x + ($radius * sin(deg2rad($i))); $pont[] = $origo_y - ($radius * cos(deg2rad($i))); } reset($pont); ImageFilledPolygon ($img, $pont, (sizeof($pont)/2), $pointColor); } ?>