php合并图片

在项目中需要把几张图片合并在一起，如下图

分别由头、身、腿三张图片合并起来

代码如下：

function combineImage($head_img,$middle_img,$footer_img,$save_path){
    $source_w = 400;
    $source_h = 1142;
    //取头部图片大小
    $head_size = getimagesize($head_img);
    $head_height = $head_size['1'];
    $head_width = $head_size['0'];
    $head_start_x = floor(($source_w-$head_width)/2);//头部开始位置
    //取中间图片大小
    $midd_size = getimagesize($middle_img);
    $midd_height = $midd_size['1'];
    $midd_width = $midd_size['0'];
    $midd_start_y = $head_height-15;//中间开始Y坐标，因为头部的图片底部有空白，所以减去15
    $midd_start_x = floor(($source_w-$midd_width)/2);
    
    //取底部图片大小
    $foot_size = getimagesize($footer_img);
    $foot_height = $foot_size[1];
    $foot_width = $foot_size[0];
    $foot_start_x = floor(($source_w-$foot_width)/2);//底部图片x坐标
    $foot_start_y = $source_h-$foot_height;//底部图片y坐标
    
    $head = imagecreatefrompng($head_img);
    $middle = imagecreatefrompng($middle_img);
    $footer = imagecreatefrompng($footer_img);
    
    $bg_img = imageCreatetruecolor($source_w,$source_h);//生成背景图片
    $color = imagecolorallocate($bg_img, 255, 255, 255); //设置白色背景
    imagefill($bg_img, 0, 0, $color);//背景色填充
    imageColorTransparent($bg_img, $color);//透明
    imagecopyresampled($bg_img,$head,$head_start_x,0,0,0,$head_width,$head_height,$head_width,$head_height);
    imagecopyresampled($bg_img,$middle,$midd_start_x , $midd_start_y,0,0,$midd_width,$midd_height,$midd_width,$midd_height);
    imagecopyresampled($bg_img,$footer,$foot_start_x , $foot_start_y,0,0,$foot_width,$foot_height,$foot_width,$foot_height);
    
    imagepng($bg_img,$save_path );
}
$head = dirname(__FILE__).'/public/images/head.png';
$midd = dirname(__FILE__).'/public/images/midd1.png';
$foot = dirname(__FILE__).'/public/images/foot1.png';
$save_path = dirname(__FILE__)."/public/images/testcomblie.png";
combineImage($head,$midd,$foot,$save_path);