如何在PHP中绘制图形？

<?php
// 创建一个空白图像
$image = imagecreatetruecolor(400, 300);

// 为图像分配颜色
$red = imagecolorallocate($image, 255, 0, 0);
$green = imagecolorallocate($image, 0, 255, 0);
$blue = imagecolorallocate($image, 0, 0, 255);

// 绘制矩形
imagefilledrectangle($image, 50, 50, 250, 150, $red);
imagefilledrectangle($image, 300, 50, 400, 150, $green);
imagefilledrectangle($image, 50, 200, 250, 300, $blue);

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

<?php
// 创建一个空白图像
$image = new Imagick();
$image->newImage(400, 300, 'none');

// 为图像分配颜色
$red = new ImagickPixel('red');
$green = new ImagickPixel('green');
$blue = new ImagickPixel('blue');

// 绘制矩形
$draw = new ImagickDraw();
$draw->setFillColor($red);
$draw->rectangle(50, 50, 250, 150);
$draw->setFillColor($green);
$draw->rectangle(300, 50, 400, 150);
$draw->setFillColor($blue);
$draw->rectangle(50, 200, 250, 300);

$image->drawImage($draw);

// 输出图像
header('Content-Type: image/png');
echo $image->getImageBlob();
?>