imagecopyresampled — 重采样拷贝部分图像并调整大小
imagecopyresampled() 将一幅图像中的一块正方形区域拷贝到另一个图像中，平滑地插入像素值，减小了图像的大小而仍然保持了极大的清晰度。如果源和目标的宽度和高度不同，则会进行相应的图像收缩和拉伸。坐标指的是左上角。本函数可用来在同一幅图内部拷贝（如果 dst_image 和src_image 相同的话）区域，但如果区域交迭的话则结果不可预知。
函数参数如下：
- bool imagecopyresampled ( resource $dst_image , resource $src_image , int $dst_x , int $dst_y , int $src_x , int $src_y , int $dst_w , int $dst_h , int $src_w , int $src_h )
今天根据这个函数写了个方法，能够等比缩放图片的大小，并且可以设置宽度固定高度等比缩放，或者高度固定宽度等比缩放，或者设置最大宽和最大高。具体代码如下：
- /**
- * 图片缩放函数（可设置高度固定，宽度固定或者最大宽高，支持gif/jpg/png三种类型）
- * Author : Specs
- * Homepage: http://9iphp.com
- *
- * @param string $source_path 源图片
- * @param int $target_width 目标宽度
- * @param int $target_height 目标高度
- * @param string $fixed_orig 锁定宽高（可选参数 width、height或者空值）
- * @return string
- */
- function myImageResize($source_path, $target_width = 200, $target_height = 200, $fixed_orig = ''){
- $source_info = getimagesize($source_path);
- $source_width = $source_info[0];
- $source_height = $source_info[1];
- $source_mime = $source_info['mime'];
- $ratio_orig = $source_width / $source_height;
- if ($fixed_orig == 'width'){
- //宽度固定
- $target_height = $target_width / $ratio_orig;
- }elseif ($fixed_orig == 'height'){
- //高度固定
- $target_width = $target_height * $ratio_orig;
- }else{
- //最大宽或最大高
- if ($target_width / $target_height > $ratio_orig){
- $target_width = $target_height * $ratio_orig;
- }else{
- $target_height = $target_width / $ratio_orig;
- }
- }
- switch ($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, $target_height);
- imagecopyresampled($target_image, $source_image, 0, 0, 0, 0, $target_width, $target_height, $source_width, $source_height);
- //header('Content-type: image/jpeg');
- $imgArr = explode('.', $source_path);
- $target_path = $imgArr[0] . '_new.' . $imgArr[1];
- imagejpeg($target_image, $target_path, 100);
- }
用法如下：
- myImageResize($filename, 200, 200); //最大宽高
- myImageResize($filename, 200, 200, 'width'); //宽度固定
- myImageResize($filename, 200, 200, 'height'); //高度固定
宽图结果如下：
（原图）
最大宽高
固定高
固定宽
高图结果如下：
原图
最大宽高
固定高
固定宽
附：把图片剪切为固定大小的函数：
- function imagecropper($source_path, $target_width, $target_height){
- $source_info = getimagesize($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 - $cropped_height) / 2;
- }elseif ($source_ratio < $target_ratio){ // 源图过宽
- $cropped_width = $source_height / $target_ratio;
- $cropped_height = $source_height;
- $source_x = ($source_width - $cropped_width) / 2;
- $source_y = 0;
- }else{ // 源图适中
- $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, $cropped_height);
- // 裁剪
- imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height);
- // 缩放
- imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $target_width, $target_height, $cropped_width, $cropped_height);
- $dotpos = strrpos($source_path, '.');
- $imgName = substr($source_path, 0, $dotpos);
- $suffix = substr($source_path, $dotpos);
- $imgNew = $imgName . '_small' . $suffix;
- imagejpeg($target_image, $imgNew, 100);
- imagedestroy($source_image);
- imagedestroy($target_image);
- imagedestroy($cropped_image);
- }
- 来自 http://9iphp.com/web/php/1208.html