php代码：

// ==================== 合成图片 begin ====================
$bg_width = 480;
$bg_height = 384;
$bg = imagecreatetruecolor($bg_width, $bg_height);
$white = imagecolorallocate($bg, 255, 255, 255);
// imagecolortransparent($bg, $white);
imagefill($bg, 0, 0, $white);

// 字体文件
$font_file = 'SourceHanSansCN-Light.otf';
$font_size = 14;

// 绘制作者
$title = ‘测试';

$box = imagettfbbox($font_size, 0, $font_file, $title); // 取得使用 TrueType 字体的文本的范围 x-y
$title_width = abs($box[2] - $box[0]); // 右下角x - 左下角x  = 计算出title占用的宽度

$color = imagecolorallocate($bg, 192,192,192); // 灰色
imagettftext($bg, $font_size, 0, 10, 26, $color, $font_file, $title);

// 绘制发布时间
$title = date("Y-m-d H:i", time());
imagettftext($bg, $font_size, 0, $title_width+20, 26, $color, $font_file, $title);

// 绘制一行描述
$title = "景区-推荐 九寨沟：重建将探索“世遗”抢救...";
$color = imagecolorallocate($bg, 56, 56, 56); // 灰色
imagettftext($bg, $font_size+1, 0, 10, 66, $color, $font_file, $title);
        
// 绘制第一张图  
// $bg = imagecreatefromstring (  file_get_contents($bg)  ); //open picture source

$item_imagessize = getimagesize('0208_b.png');
$item_width = $item_imagessize[0];
$item_height = $item_imagessize[1];

// $thumb1 = imagecreatefrompng('0208_b.png');

$precent = $item_height / $item_width;
$thumb1 = imagecreatefromstring (  file_get_contents('0208_b.png')  );   //open picture source 
        
//x轴430 y轴670 宽175高175
imagecopyresampled ( $bg, $thumb1, 10, 86, 0, 0, $bg_width-20, ((($bg_width-20)*$item_height)/$item_width), $item_width, $item_height ); // 这里是背景图与二维码的合成

$result_png = "share_pic.png"; // file name
$file = $result_png; // 绘制完成的图片
// header('content-type:image/png'); 
imagepng ( $bg, $file ); //output picture
imagedestroy($bg);  
imagedestroy($thumb1);

最终生成的图片：

share_pic.png