PHP 图片合成常涉及到以下几个问题

1、多张图合成
2、png透明问题
3、多行文字
4、文字居中

常用到的php函数

imagecreatefrompng 创建一块画布并载入一张png图片
imagecreatefromjpeg 创建一块画布并载入一张jpg图片
imagesx 获取图片宽
imagesy 获取图片高
imagecreatetruecolor 创建画布
imagecopy 拷贝图片，用于png透明
imagefontwidth 获取文字宽度
ImageColorAllocate 文字颜色
imagettftext 文字
Imagepng 显示或保存
ImageDestroy 销毁图像

123.png

<?php

class hb
{

    function make($arr)
    {
        $file_name = './hb/a' . uniqid() . '.png';

// picture
        $file_bg = './data/img/bg.png';
        $file_head = './data/img/head.png';
        $file_code = './data/img/wx.png';
        $file_bgcard = './data/img/bg_card.png';

        $text_title = $arr['title'];
        $text = $arr['info'];
        $tag_name = $arr['name'];
        $tag_content = $arr['content'];
        $tag_a = $arr['shui'];
        $tag_b = $arr['gj'];
        $tag_c = $arr['xue'];

// font type
        $font_msyh = './data/fonts/msyh.ttc';
        $font_simhei = './data/fonts/simhei.ttf';

        $img_bg = imagecreatefrompng($file_bg);//背景,如果是jpg就用imagecreatefromjpeg
        $img_star = imagecreatefrompng($file_head);//卡片
        $img_bgcard = imagecreatefrompng($file_bgcard);//背景卡
        $img_code = imagecreatefrompng($file_code);//二维码


        $width = imagesx($img_bg);
        $height = imagesy($img_bg);

//$im = $img_bg;
        $im = imagecreatetruecolor($width, $height);  //创建一张与背景图同样大小的真彩色图像
        imagecopy($im, $img_bg, 0, 0, 0, 0, $width, $height);


//加载head图片
        $width_code = imagesx($img_star);
        $height_code = imagesy($img_star);
        imagecopymerge($im, $img_star, 110, 20, 0, 0, $width_code, $height_code, 100);

//加载bg_card
        $width_code = imagesx($img_bgcard);
        $height_code = imagesy($img_bgcard);
//imagecopymerge($im, $img_bgcard, 0, 0, 0, 0, $width_code, $height_code, 100);
//png透明用法
        imagecopy($im, $img_bgcard, 0, 0, 0, 0, $width_code, $height_code);

//加载二维码图片
        $width_code = 120;
        $height_code = 120;
        imagecopymerge($im, $img_code, $width - $width_code - 15, $height - $height_code - 15, 0, 0, $width_code, $height_code, 50);


//字体颜色
        $color_grey = ImageColorAllocate($im, 139, 139, 139);
        $color_white = ImageColorAllocate($im, 255, 255, 255);
        $color_red = ImageColorAllocate($im, 21, 124, 175);
        $color_black = ImageColorAllocate($im, 000, 000, 000);

        $fontSize = 16; //18号字体
        $fontWidth = imagefontwidth($fontSize);//获取文字宽度
        $textWidth = $fontWidth * mb_strlen($tag_name);
        if (mb_strlen($tag_name) < 6) {
            $top = 293;
            $left = 395;
        } else {
            $top = 300;
            $left = 325;
        }
        $x = ceil(($left - $textWidth) / 2); //计算文字的水平位置

        //卡片名称
        imagettftext($im, $fontSize, 6, $x, $top, $color_black, $font_msyh, $tag_name);

        //标题
        imagettftext($im, 16, 0, 35, 590, $color_red, $font_msyh, $text_title);


        $left_a = mb_strlen($tag_a) > 1 ? 35 : 53;
        $left_b = mb_strlen($tag_b) > 1 ? 35 : 53;
        $left_c = mb_strlen($tag_c) > 1 ? 310 : 330;

        imagettftext($im, 58, 0, $left_a, 95, $color_white, $font_msyh, $tag_a);
        imagettftext($im, 58, 0, $left_b, 510, $color_white, $font_msyh, $tag_b);
        imagettftext($im, 58, 0, $left_c, 510, $color_white, $font_msyh, $tag_c);

        //卡片描述--多行文本渲染
        $h = 390;
        $font_row = 11;    //一行显示多少字
        $fontSize = 14; //18号字体
        foreach (str_split($tag_content, $font_row * 3) as $key => $val) {
            $tmp_h = $h + $key * 20;
            imagettftext($im, 14, 0, 120, $tmp_h, $color_black, $font_simhei, $val);
        }


        //广告--多行文本渲染
        $font_row = 12;    //一行显示多少字
        $h = 620;
        foreach (str_split($text, $font_row * 3) as $key => $val) {
            $tmp_h = $h + $key * 20;
            imagettftext($im, 12, 0, 30, $tmp_h, $color_grey, $font_simhei, $val);
        }


    //最后处理 输出、销毁
        //Imagepng($im, $file_name);//保存到服务器
    header('Content-Type: image/png');
    Imagepng($im);      //浏览器直接显示
        ImageDestroy($img_code);
        ImageDestroy($img_star);
        ImageDestroy($img_bg);
        ImageDestroy($img_bgcard);
        ImageDestroy($im);

        return $file_name;
    }
}
$arr=[];
$arr['name'] = '阿里山';
$arr['content'] = "冲锋、突袭";
$arr['shui']='20';
$arr['xue']='19';
$arr['gj']='33';
$arr['title'] = '你想要的标题';
$arr['info'] = '这里就是传说中的描述吧，看这里看这里...';
echo (new hb)->make($arr);