(PHP 4 >= 4.0.6, PHP 5)
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: https://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);
}
小二苘 2015/01/12 19:17
这个有用，收藏了