PHP: imagefilledellipse

Description

bool imagefilledellipse ( resource image, int cx, int cy, int w, int h, int color )

imagefilledellipse() draws an ellipse centered at cx, cy (top left is 0, 0) in the image represented by image. W and h specifies the ellipse's width and height respectively. The ellipse is filled using color. Returns TRUE on success or FALSE on failure.

Note: This function was added in PHP 4.0.6 and requires GD 2.0.1 or later

Example 1. imagefilledellipse() example

<?php // create a blank image $image = imagecreate(400, 300); // fill the background color $bg = imagecolorallocate($image, 0, 0, 0); // choose a color for the ellipse $col_ellipse = imagecolorallocate($image, 255, 255, 255); // draw the white ellipse imagefilledellipse($image, 200, 150, 300, 200, $col_ellipse); // output the picture header("Content-type: image/png"); imagepng($image); ?>

Note: This function requires GD 2.0.1 or later.

User Contributed Notes
imagefilledellipse

richard at mf2fm dot co dot uk
09-Feb-2005 04:25


Here is a piece of code using imagefilledellipse which creates a simulation of the current phase of the moon...



Usage is <img src="moon.php?size=100"> which produces an image 100px by 100px wide.  If size is left out, the default is 24px by 24px.



<?php



$mps=2551442.8; // moon phase in seconds (29 days, 12 hours, 44 mins, 2.8 secs)

$position=time()-mktime(10, 32, 0, 1, 25, 2005); // seconds since full moon at 10:32GMT on 25 Jan 2005

$position=($position-$mps*intval($position/$mps))/$mps; // phase from 0 to 1



$position=2*(0.5-$position);

## revised to produce easier to work with...

## $position=1 - full moon

## $position=0 - new moon

## $position=-1 - full moon



$size=$_GET['size'];

if (!is_numeric($size)) $size=24; // width/height in pixels

$moon=imagecreate($size, $size);

$dark=imagecolorallocate($moon, 0, 34, 68); // background colour for moon

$light=imagecolorallocate($moon, 238, 238, 255); // foreground colour for moon

$corona=imagecolorallocatealpha($moon, 153, 153, 153, 64); // edge of moon (semi-transparent)



##

## Make transparent background

##

$background=imagecolorallocatealpha($moon, 0, 0, 0, 127);

imagefill($moon, 0, 0, $background); 



##

## Make the moon!

##

imagefilledellipse($moon, round($size/2), round($size/2), $size, $size, $corona);

if ($position>-1/$size AND $position<1/$size) imagefilledellipse($moon, round($size/2), round($size/2), $size-2, $size-2, $dark); // new moon

elseif (abs($position)>1-1/$size) imagefilledellipse($moon, round($size/2), round($size/2), $size-2, $size-2, $light); // full moon

elseif ($position>0) {

    imagefilledellipse($moon, round($size/2), round($size/2), $size-2, $size-2, $light);

    for ($i=0; $i<$size-2; $i++) {

        $xpos=($size-2)/2;

        $xpos=1-($i/$xpos);

        $xpos=sqrt(1-($xpos*$xpos));

        $xpos=($size/2)+($position-0.5)*$xpos*($size-2);

        imagesetpixel($moon, round($xpos), $i+1, $dark);

    }

    for ($i=0; $i<$size; $i++) {

        $set=0;

        for ($j=0; $j<$size; $j++) {

            if (!$set AND imagecolorat($moon, $j, $i)==$dark) $set=1;

            elseif ($set AND imagecolorat($moon, $j, $i)==$light) imagesetpixel($moon, $j, $i, $dark); 

        }

    }

}

else {

    imagefilledellipse($moon, round($size/2), round($size/2), $size-2, $size-2, $dark);

    for ($i=0; $i<$size-2; $i++) {

        $xpos=($size-2)/2;

        $xpos=1-($i/$xpos);

        $xpos=sqrt(1-($xpos*$xpos));

        $xpos=($size/2)+($position+0.5)*$xpos*($size-2);

        imagesetpixel($moon, round($xpos), $i+1, $light);

    }

    for ($i=0; $i<$size; $i++) {

        $set=0;

        for ($j=0; $j<$size; $j++) {

            if (!$set AND imagecolorat($moon, $j, $i)==$light) $set=1;

            elseif ($set AND imagecolorat($moon, $j, $i)==$dark) imagesetpixel($moon, $j, $i, $light); 

        }

    }

}



##

## And output the picture

##

header ("Content-Type: image/png");

imagepng($moon);

imagedestroy($moon);

?>

dave at corecommunications dot us
10-Oct-2002 08:56


I needed to draw translucent circles on an existing image, using imagealphablending($image,true);. Turns out that imagefilledellipse seems to do the ellipse by drawing a series of lines from the centroid out to the circumference. Problem with this is that pixels near the center very visibly get drawn multiple times, producing a kind of moire effect. Also, the 0-degree (center to right) line is drawn twice and so is twice as dark the pixel below it.



My workaround was to draw the ellipse solid in a copy of the source image and do an imagecopymerge back into the original.

ivank at 2xtreme dot net
30-Mar-2002 06:31


Sometimes, you have x1, y1, x2, y2 parameters, but not the center, width, and height. Use this to draw a filled ellipse from your x1, y1, x2, and y2:



ImageFilledEllipse(

$im, 

($x1 + round(($x2 - $x1) / 2)), 

($y1 + round(($y2 - $y1) / 2)), 

($x2 - $x1), 

($y2 - $y1), 

$color);

harry dot wood at ic dot ac dot uk
19-Jun-2001 06:09


This draws a rotated ellipse. If you don't want filled ellipses, then you don't need the triangle function.





function triangle($x1,$y1, $x2,$y2, $x3,$y3, $colour) {


   global $im;


   $coords = array($x1,$y1, $x2,$y2, $x3,$y3);


   imagefilledpolygon($im, $coords, 3, $colour); 


}





function rotatedellipse($cx, $cy, $width, $height, $rotateangle, $colour, $filled=true) {


   global $im;


   $step=15;


   $cosangle=cos(deg2rad($rotateangle));


   $sinangle=sin(deg2rad($rotateangle));





   $squishratio = $height/$width;


   $nopreviouspoint = true;


   for ($angle=0; $angle<=(180+$step); $angle+=$step) {


       


      $ox = ($width * cos(deg2rad($angle)));


      $oy = ($width * sin(deg2rad($angle))) * $squishratio;





      $x = ($ox * $cosangle) - ($oy * $sinangle);


      $y = ($ox * $sinangle) + ($oy * $cosangle);


  


      if ($nopreviouspoint) {


        $px=$x;


        $py=$y;


        $nopreviouspoint=false;


      }





      if ($filled) {


         triangle($cx, $cy, $cx+$px, $cy+$py, $cx+$x, $cy+$y, $colour);


         triangle($cx, $cy, $cx-$px, $cy-$py, $cx-$x, $cy-$y, $colour);


      } else {


         imageline($im, $cx+$px, $cy+$py, $cx+$x, $cy+$y, $colour); 


         imageline($im, $cx-$px, $cy-$py, $cx-$x, $cy-$y, $colour); 


      }


      $px=$x;


      $py=$y;


   } 


}