imageellipse

(PHP 4 >= 4.0.6, PHP 5, PHP 7)

imageellipse — 画一个椭圆

说明

bool imageellipse ( resource $image , int $cx , int $cy , int $width , int $height , int $color )

在指定的坐标上画一个椭圆。

参数

image

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

cx

中间的 X 坐标。

cy

中间的 Y 坐标。

width

椭圆的宽度。

height

椭圆的高度。

color

椭圆的颜色。颜色标识符由 imagecolorallocate() 创建。

返回值

成功时返回 TRUE， 或者在失败时返回 FALSE。

范例

Example #1 imageellipse() 例子

<?php

// 新建一个空白图像
$image = imagecreatetruecolor(400, 300);

// 填充背景色
$bg = imagecolorallocate($image, 0, 0, 0);

// 选择椭圆的颜色
$col_ellipse = imagecolorallocate($image, 255, 255, 255);

// 画一个椭圆
imageellipse($image, 200, 150, 300, 200, $col_ellipse);

// 输出图像
header("Content-type: image/png");
imagepng($image);


?>

以上例程的输出类似于：

例子输出： imageellipse()

注释

Note:

本函数需要 GD 2.0.2 或更高版本。

参见

User Contributed Notes

simon_nuttall at hotmail dot com 07-Jun-2006 10:36
This is an optimised and bug fixed version of nojer at yahoo dot com's rotatedellipse function. I've changed it so that the arguments are compatible with imageellipse. See notes on imagearc for original version.

<?php

function rotatedellipse($im, $cx, $cy, $width, $height, $rotateangle, $colour, $filled=false) {
  // modified here from nojer's version
  // Rotates from the three o-clock position clockwise with increasing angle.
  // Arguments are compatible with imageellipse.

  $width=$width/2;
  $height=$height/2;

  // This affects how coarse the ellipse is drawn.
  $step=3;

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

  // $px and $py are initialised to values corresponding to $angle=0.
  $px=$width * $cosangle;
  $py=$width * $sinangle;
 
  for ($angle=$step; $angle<=(180+$step); $angle+=$step) {
   
    $ox = $width * cos(deg2rad($angle));
    $oy = $height * sin(deg2rad($angle));
   
    $x = ($ox * $cosangle) - ($oy * $sinangle);
    $y = ($ox * $sinangle) + ($oy * $cosangle);
 
    if ($filled) {
      triangle($im, $cx, $cy, $cx+$px, $cy+$py, $cx+$x, $cy+$y, $colour);
      triangle($im, $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;
  }
}

function triangle($im, $x1,$y1, $x2,$y2, $x3,$y3, $colour) {
   $coords = array($x1,$y1, $x2,$y2, $x3,$y3);
   imagefilledpolygon($im, $coords, 3, $colour);
}

?>
julian 16-Jan-2005 03:23
if you want to display an ellipse in the upper left corner of an image, you can easily calculate the corresponding cx and cy values. this example will draw an ellipse having the same width and height as the image.

<?php

$ellipse_width = 100;
$ellipse_height = 200;

$ellipse_cx = ($ellipse_width / 2);
$ellipse_cy = ($ellipse_height / 2);

$img_x = $ellipse_width;
$img_y = $ellipse_height;

$img = imagecreate($img_x, $img_y);
$bg = imagecolorallocate($img, 255,255,255);

$ellipse_color = imagecolorallocate($img, 0, 0, 0);

imageellipse($img, $ellipse_cx, $ellipse_cy, $ellipse_width, $ellipse_height, $ellipse_color);

header("Content-type: image/png");
imagepng($img);
imagedestroy($img);

?>
agentyoungsoo at hanmail dot net 05-Dec-2002 05:56
When you wana use "ImageEllipse" function
in under GD 2.0.2 version, you can use "ImageArc" like bellow

----------------------------------------------------
$file_name = "test.png";

$screen_x = 300;
$screen_y = 200;

$x1 = $screen_x / 2;
$y1 = $screen_y / 2;

$radius = 30;

$image = ImageCreate($screen_x, $screen_y);
$black = ImageColorAllocate($image, 0,0,0);

ImageArc($image, $x1, $y1, $radius , $radius , 0, 360, $black);

ImagePng($image, $file_name);
ImageDestroy($image);
----------------------------------------------------