前言：业务需要，进行两张图片的合成。

PHP图片合成类

/**
 * 图片合成
 * @param array  参数,包括图片和文字
 * @param string  $filename 生成文件名,不传此参数则不生成文件,直接输出图片
 * @return [type] [description]
 */
function createPoster($config = array(), $filename = "")
{
    //如果要看报什么错，可以先注释调这个header
    // if(empty($filename)) header("content-type: image/png");
    $imageDefault = array(
        'left' => 0,
        'top' => 0,
        'right' => 0,
        'bottom' => 0,
        'width' => 100,
        'height' => 100,
        'opacity' => 100
    );

    $textDefault = array(
        'text' => '',
        'left' => 0,
        'top' => 0,
        'fontSize' => 32,       //字号
        'fontColor' => '255,255,255', //字体颜色
        'angle' => 0,
    );
    $background = $config['background']; //最底层得背景
    //背景方法
    $backgroundInfo = getimagesize($background);
    $backgroundFun = 'imagecreatefrom' . image_type_to_extension($backgroundInfo[2], false);
    $background = $backgroundFun($background);
    $backgroundWidth = imagesx($background);  //背景宽度
    $backgroundHeight = imagesy($background);  //背景高度
    $imageRes = imageCreatetruecolor($backgroundWidth, $backgroundHeight);
    $color = imagecolorallocate($imageRes, 0, 0, 0);
    imagefill($imageRes, 0, 0, $color);
    // imageColorTransparent($imageRes, $color);  //颜色透明
    imagecopyresampled($imageRes, $background, 0, 0, 0, 0, imagesx($background), imagesy($background), imagesx($background), imagesy($background));
    //处理了图片
    if (!empty($config['image'])) {
        foreach ($config['image'] as $key => $val) {
            $val = array_merge($imageDefault, $val);
            $info = getimagesize($val['url']);

            $function = 'imagecreatefrom' . image_type_to_extension($info[2], false);
            if ($val['stream']) {   //如果传的是字符串图像流
                $info = getimagesizefromstring($val['url']);
                $function = 'imagecreatefromstring';
            }
            $res = $function($val['url']);
            $resWidth = $info[0];
            $resHeight = $info[1];
            //建立画板 ，缩放图片至指定尺寸
            $canvas = imagecreatetruecolor($val['width'], $val['height']);
            imagefill($canvas, 0, 0, $color);
            //关键函数，参数（目标资源，源，目标资源的开始坐标x,y, 源资源的开始坐标x,y,目标资源的宽高w,h,源资源的宽高w,h）
            imagecopyresampled($canvas, $res, 0, 0, 0, 0, $val['width'], $val['height'], $resWidth, $resHeight);
            $val['left'] = $val['left'] < 0 ? $backgroundWidth - abs($val['left']) - $val['width'] : $val['left'];
            $val['top'] = $val['top'] < 0 ? $backgroundHeight - abs($val['top']) - $val['height'] : $val['top'];
            //放置图像
            imagecopymerge($imageRes, $canvas, $val['left'], $val['top'], $val['right'], $val['bottom'], $val['width'], $val['height'], $val['opacity']); //左，上，右，下，宽度，高度，透明度
        }
    }
    
    //处理文字
    if (!empty($config['text'])) {
        foreach ($config['text'] as $key => $val) {
            $val = array_merge($textDefault, $val);
            list($R, $G, $B) = explode(',', $val['fontColor']);
            $fontColor = imagecolorallocate($imageRes, $R, $G, $B);
            $val['left'] = $val['left'] < 0 ? $backgroundWidth - abs($val['left']) : $val['left'];
            $val['top'] = $val['top'] < 0 ? $backgroundHeight - abs($val['top']) : $val['top'];
            imagettftext($imageRes, $val['fontSize'], $val['angle'], $val['left'], $val['top'], $fontColor, $val['fontPath'], $val['text']);
        }
    }

    //生成图片
    if (!empty($filename)) {
        $res = imagejpeg($imageRes, $filename, 90); //保存到本地
        imagedestroy($imageRes);
        if (!$res) return false;
        return $filename;
    } else {
        imagejpeg($imageRes);     //在浏览器上显示
        imagedestroy($imageRes);
    }
}

调用方法：

            $configPost = array(
                //要加上的图
                'image' => array(
                    array(
                        'url'     => CMF_ROOT . "public/static/images/msk3.png",       //图片资源路径
                        // 'left'    => 352,
                        // 'top'     => -116,
                        'stream'  => 0,             //图片资源是否是字符串图像流
                        'right'   => 0,
                        'bottom'  => 0,
                        'width'   => 800,
                        'height'  => 800,
                        'opacity' => 70
                    ),
                ),
                //底图
                'background' => $data['info']['image'],
            );

            $getSaveName = CMF_ROOT . "public/upload/goodsTime/" . $goodsTime . "goodsTime" . '.jpg';
            createPoster($configPost, $getSaveName);