php绘图

$size = 300;

$image = imagecreatetruecolor($size,$size);

//用白色背景，黑色边框画方框

$back = imagecolorallocate($image,255,255,255);

$border = imagecolorallocate($image,0,0,0);

imagefilledrectangle($image,0,0,$size,$size,$back); //画出白色背景

imagerectangle($image,0,0,$size-1,$size-1,$border); //画出黑色边框

$yellow_x = 150;

$yellow_y = 75;

$red_x = 100;

$red_y = 160;

$blue_x = 200;

$blue_y = 160;

$radius = 150;

$yellow = imagecolorallocatealpha($image,255,255,0,75); //此函数将黄色的alpha值调为75，就是透明度

$red = imagecolorallocatealpha($image,255,0,0,75);

$blue = imagecolorallocatealpha($image,0,0,255,75);

//画三个交叠的圆

imagefilledellipse($image,$yellow_x,$yellow_y,$radius,$radius,$yellow); //此函数就是我要在$image上画一个圆心（$yellow_x,$yellow_y）半径为$radius/2颜色为$yellow的圆

imagefilledellipse($image,$red_x,$red_y,$radius,$radius,$red);

imagefilledellipse($image,$blue_x,$blue_y,$radius,$radius,$blue);

//输出正确的header

header(“Content-type: image/png”);

//输出结果

imagepng($image);