在我们的工作的项目中,有时候我们需要显示规定尺寸的图片,虽然可以通过css来控制显示大小。但是如果图片过大,会造成加载的延迟,影响网站整体性能。因此,我们需要一个服务器来帮助我们进行图片的裁剪。流程大致是,首先我们传给服务器原图像和裁剪的尺寸,然后服务器进行裁剪,生成对应的裁剪图片,下次我们再访问相同图像和相同的裁剪尺寸的时候,我们就不需要裁剪,直接进行图片的访问就行。
Talk is cheap, show me the code.
<?php // ①构建图片请求地址比如 http://xxx.com/resize.php?site=www&width=300&height=200&mode=2&path=uploadfile/helloworld.png // ②配置nginx重写规则 rewrite /s/(.*)/(\d+)x(\d+)-(\d)/(.*) /s/resize.php?site=$1&width=$2&height=$3&mode=$4&path=$5 last; //③进行裁剪图片的处理 $path = trim($_GET['path']); $mode = intval($_GET['mode']); $site = trim($_GET['site']); $width = intval($_GET['width']); $height = intval($_GET['height']); $site_list = array('crop' => '.'); $orig_dir = dirname(__FILE__); if (!array_key_exists($site, $site_list)) { header('HTTP/1.1 400 Bad Request'); exit(); } if ($mode > 3 || $mode < 0) { header('HTTP/1.1 400 Bad Request'); exit(); } $orig_file = $site_list[$site] . $path; if (!file_exists($orig_file)) { header('HTTP/1.1 404 Not Found'); exit(); } $file_ext = '.' . pathinfo($path, PATHINFO_EXTENSION); $file_name = basename($path, $file_ext); $save_path = "{$orig_dir}/{$site}/{$width}x{$height}-{$mode}{$path}"; $save_dir = dirname($save_path); if (!file_exists($save_dir)) { wpx_mkdir($save_dir); } $target_width = $width; $target_height = $height; $save_image = $save_dir . '/' . $file_name . '.jpg'; if (file_exists($save_image)) { header('Content-Type: image/jpeg'); header('Last-Modified: ' . gmdate('D, d M Y H:i:s') . ' GMT'); echo file_get_contents($save_image); } imagecropper2($orig_file, $target_width, $target_height, $save_image); die; //原图像对应缩放裁剪,会拉伸图片 function imagecropper2($source_path, $width, $height, $save_image) { //获取原图像$filename的宽度$width_orig和高度$height_orig $info = getimagesize($source_path); $width_orig = $info[0]; $height_orig = $info[1]; $mime = $info['mime']; //根据参数$width和$height值,换算出等比例缩放的高度和宽度 if ($width && ($width_orig<$height_orig)){ $width = ($height/$height_orig)*$width_orig; }else{ $height = ($width / $width_orig)*$height_orig; } //将原图缩放到这个新创建的图片资源中 $image_p = imagecreatetruecolor($width, $height); //获取原图的图像资源 if($mime=='image/jpeg'){ $image = imagecreatefromjpeg($source_path); }elseif($mime=='image/png'){ $image = imagecreatefrompng($source_path); }elseif($mime=='image/gif'){ $image = imagecreatefromgif($source_path); } //使用imagecopyresampled()函数进行缩放设置 imagecopyresampled($image_p,$image,0,0,0,0,$width,$height,$width_orig,$height_orig); //将缩放后的图片$image_p保存,100(质量最佳,文件最大) if($mime=='image/jpeg'){ imagejpeg($image_p,$save_image); header('Content-Type: image/jpeg'); imagejpeg($image_p); }elseif($mime=='image/png'){ imagepng($image_p,$save_image); header('Content-Type: image/jpeg'); imagepng($image_p); }else{ imagegif($image_p,$save_image); header('Content-Type: image/jpeg'); imagegif($image_p); } } //进行比例保存裁剪,会丢失图像部分像素 function imagecropper($source_path, $target_width, $target_height, $save_image) { $source_info = getimagesize($source_path); $source_width = $source_info[0]; $source_height = $source_info[1]; $source_mime = $source_info['mime']; $source_ratio = $source_height / $source_width; $target_ratio = $target_height / $target_width; // 源图过高 if ($source_ratio > $target_ratio) { $cropped_width = $source_width; $cropped_height = $source_width * $target_ratio; $source_x = 0; $source_y = ($source_height – $cropped_height) / 2; } // 源图过宽 elseif ($source_ratio < $target_ratio) { $cropped_width = $source_height / $target_ratio; $cropped_height = $source_height; $source_x = ($source_width – $cropped_width) / 2; $source_y = 0; } // 源图适中 else { $cropped_width = $source_width; $cropped_height = $source_height; $source_x = 0; $source_y = 0; } switch ($source_mime) { case 'image/gif': $source_image = imagecreatefromgif($source_path); break; case 'image/jpeg': $source_image = imagecreatefromjpeg($source_path); break; case 'image/png': $source_image = imagecreatefrompng($source_path); break; default: return false; break; } $target_image = imagecreatetruecolor($target_width, $target_height); $cropped_image = imagecreatetruecolor($cropped_width, $cropped_height); // 裁剪 $bool = imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height); // 缩放 $bool = imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $target_width, $target_height, $cropped_width, $cropped_height); imagejpeg($target_image, $save_image); header('Content-Type: image/jpeg'); imagejpeg($target_image); imagedestroy($source_image); imagedestroy($target_image); imagedestroy($cropped_image); } // 循环生成目录 function wpx_mkdir($dir, $mode = 0777) { if (is_dir($dir) || @mkdir($dir, $mode)) { return true; } if (!wpx_mkdir(dirname($dir), $mode)) { return false; } return @mkdir($dir, $mode); }
通过上面的处理,我们就将图片按照我们设置的尺寸进行了裁剪。我们还可以定期对裁剪图片进行清理,这样就不需要占用太多服务器空间。只有经常访问的图片才会一直保存。
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