原因
最近在做网页拖拽验证码的开源项目，需要在服务端生成图片对应的可移动的色块，但是网上的资源都是做缩略图，对整个图片进行缩放的，所以自己动手，完成了对图片进行裁剪小块的工具
CODE
<?php
namespace App\Libs;
/**
* 2016-01-07 15:54:58
* Lixiaoyu
*
* mode 1 : 强制裁剪，生成图片严格按照需要，不足放大，超过裁剪，图片始终铺满
* mode 2 : 和1类似，但不足的时候 不放大 会产生补白，可以用png消除。
* mode 3 : 只缩放，不裁剪，保留全部图片信息，会产生补白，
* mode 4 : 只缩放，不裁剪，保留全部图片信息，生成图片大小为最终缩放后的图片有效信息的实际大小，不产生补白
* 默认补白为白色，如果要使补白成透明像素，请使用SaveAlpha()方法代替SaveImage()方法
*/
class ImageCrop{
var $sImage;
var $dImage;
var $src_file;
var $dst_file;
var $src_width;
var $src_height;
var $src_ext;
var $src_type;
function __construct($src_file,$dst_file=''){
$this->src_file=$src_file;
$this->dst_file=$dst_file;
$this->LoadImage();
}
function SetSrcFile($src_file){
$this->src_file=$src_file;
}
function SetDstFile($dst_file){
$this->dst_file=$dst_file;
}
function LoadImage(){
list($this->src_width, $this->src_height, $this->src_type) = getimagesize($this->src_file);
switch($this->src_type) {
case IMAGETYPE_JPEG :
$this->sImage=imagecreatefromjpeg($this->src_file);
$this->ext='jpg';
break;
case IMAGETYPE_PNG :
$this->sImage=imagecreatefrompng($this->src_file);
$this->ext='png';
break;
case IMAGETYPE_GIF :
$this->sImage=imagecreatefromgif($this->src_file);
$this->ext='gif';
break;
default:
exit();
}
}
function SaveImage($fileName=''){
$this->dst_file=$fileName ? $fileName : $this->dst_file;
switch($this->src_type) {
case IMAGETYPE_JPEG :
imagejpeg($this->dImage,$this->dst_file,100);
break;
case IMAGETYPE_PNG :
imagepng($this->dImage,$this->dst_file);
break;
case IMAGETYPE_GIF :
imagegif($this->dImage,$this->dst_file);
break;
default:
break;
}
}
function OutImage(){
switch($this->src_type) {
case IMAGETYPE_JPEG :
header('Content-type: image/jpeg');
imagejpeg($this->dImage);
break;
case IMAGETYPE_PNG :
header('Content-type: image/png');
imagepng($this->dImage);
break;
case IMAGETYPE_GIF :
header('Content-type: image/gif');
imagegif($this->dImage);
break;
default:
break;
}
}
function SaveAlpha($fileName=''){
$this->dst_file=$fileName ? $fileName . '.png' : $this->dst_file .'.png';
imagesavealpha($this->dImage, true);
imagepng($this->dImage,$this->dst_file);
}
function OutAlpha(){
imagesavealpha($this->dImage, true);
header('Content-type: image/png');
imagepng($this->dImage);
}
function destory(){
imagedestroy($this->sImage);
imagedestroy($this->dImage);
}
function Crop($dst_width,$dst_height,$mode=1,$dst_file=''){
if($dst_file) $this->dst_file=$dst_file;
$this->dImage = imagecreatetruecolor($dst_width,$dst_height);
$bg = imagecolorallocatealpha($this->dImage,255,255,255,127);
imagefill($this->dImage, 0, 0, $bg);
imagecolortransparent($this->dImage,$bg);
$ratio_w=1.0 * $dst_width / $this->src_width;
$ratio_h=1.0 * $dst_height / $this->src_height;
$ratio=1.0;
switch($mode){
case 1: // always crop
if( ($ratio_w < 1 && $ratio_h < 1) || ($ratio_w > 1 && $ratio_h > 1)){
$ratio = $ratio_w < $ratio_h ? $ratio_h : $ratio_w;
$tmp_w = (int)($dst_width / $ratio);
$tmp_h = (int)($dst_height / $ratio);
$tmp_img=imagecreatetruecolor($tmp_w , $tmp_h);
$src_x = (int) (($this->src_width-$tmp_w)/2) ;
$src_y = (int) (($this->src_height-$tmp_h)/2) ;
imagecopy($tmp_img, $this->sImage, 0,0,$src_x,$src_y,$tmp_w,$tmp_h);
imagecopyresampled($this->dImage,$tmp_img,0,0,0,0,$dst_width,$dst_height,$tmp_w,$tmp_h);
imagedestroy($tmp_img);
}else{
$ratio = $ratio_w < $ratio_h ? $ratio_h : $ratio_w;
$tmp_w = (int)($this->src_width * $ratio);
$tmp_h = (int)($this->src_height * $ratio);
$tmp_img=imagecreatetruecolor($tmp_w ,$tmp_h);
imagecopyresampled($tmp_img,$this->sImage,0,0,0,0,$tmp_w,$tmp_h,$this->src_width,$this->src_height);
$src_x = (int)($tmp_w - $dst_width) / 2 ;
$src_y = (int)($tmp_h - $dst_height) / 2 ;
imagecopy($this->dImage, $tmp_img, 0,0,$src_x,$src_y,$dst_width,$dst_height);
imagedestroy($tmp_img);
}
break;
case 2: // only small
if($ratio_w < 1 && $ratio_h < 1){
$ratio = $ratio_w < $ratio_h ? $ratio_h : $ratio_w;
$tmp_w = (int)($dst_width / $ratio);
$tmp_h = (int)($dst_height / $ratio);
$tmp_img=imagecreatetruecolor($tmp_w , $tmp_h);
$src_x = (int) ($this->src_width-$tmp_w)/2 ;
$src_y = (int) ($this->src_height-$tmp_h)/2 ;
imagecopy($tmp_img, $this->sImage, 0,0,$src_x,$src_y,$tmp_w,$tmp_h);
imagecopyresampled($this->dImage,$tmp_img,0,0,0,0,$dst_width,$dst_height,$tmp_w,$tmp_h);
imagedestroy($tmp_img);
}elseif($ratio_w > 1 && $ratio_h > 1){
$dst_x = (int) abs($dst_width - $this->src_width) / 2 ;
$dst_y = (int) abs($dst_height -$this->src_height) / 2;
imagecopy($this->dImage, $this->sImage,$dst_x,$dst_y,0,0,$this->src_width,$this->src_height);
}else{
$src_x=0;$dst_x=0;$src_y=0;$dst_y=0;
if(($dst_width - $this->src_width) < 0){
$src_x = (int) ($this->src_width - $dst_width)/2;
$dst_x =0;
}else{
$src_x =0;
$dst_x = (int) ($dst_width - $this->src_width)/2;
}
if( ($dst_height -$this->src_height) < 0){
$src_y = (int) ($this->src_height - $dst_height)/2;
$dst_y = 0;
}else{
$src_y = 0;
$dst_y = (int) ($dst_height - $this->src_height)/2;
}
imagecopy($this->dImage, $this->sImage,$dst_x,$dst_y,$src_x,$src_y,$this->src_width,$this->src_height);
}
break;
case 3: // keep all image size and create need size
if($ratio_w > 1 && $ratio_h > 1){
$dst_x = (int)(abs($dst_width - $this->src_width )/2) ;
$dst_y = (int)(abs($dst_height- $this->src_height)/2) ;
imagecopy($this->dImage, $this->sImage, $dst_x,$dst_y,0,0,$this->src_width,$this->src_height);
}else{
$ratio = $ratio_w > $ratio_h ? $ratio_h : $ratio_w;
$tmp_w = (int)($this->src_width * $ratio);
$tmp_h = (int)($this->src_height * $ratio);
$tmp_img=imagecreatetruecolor($tmp_w ,$tmp_h);
imagecopyresampled($tmp_img,$this->sImage,0,0,0,0,$tmp_w,$tmp_h,$this->src_width,$this->src_height);
$dst_x = (int)(abs($tmp_w -$dst_width )/2) ;
$dst_y = (int)(abs($tmp_h -$dst_height)/2) ;
imagecopy($this->dImage, $tmp_img, $dst_x,$dst_y,0,0,$tmp_w,$tmp_h);
imagedestroy($tmp_img);
}
break;
case 4: // keep all image but create actually size
if($ratio_w > 1 && $ratio_h > 1){
$this->dImage = imagecreatetruecolor($this->src_width,$this->src_height);
imagecopy($this->dImage, $this->sImage,0,0,0,0,$this->src_width,$this->src_height);
}else{
$ratio = $ratio_w > $ratio_h ? $ratio_h : $ratio_w;
$tmp_w = (int)($this->src_width * $ratio);
$tmp_h = (int)($this->src_height * $ratio);
$this->dImage = imagecreatetruecolor($tmp_w ,$tmp_h);
imagecopyresampled($this->dImage,$this->sImage,0,0,0,0,$tmp_w,$tmp_h,$this->src_width,$this->src_height);
}
break;
}
}// end Crop
/**
*
* 裁切方法
* 2016-01-07 15:05:44
* Lixiaoyu
*
* @param $dst_width 目标长
* @param $dst_height 目标高
* @param $dst_x 裁剪部分和原图左侧的距离
* @param $dst_y 裁剪部分和原图右侧的距离
* @param int $mode 模式
* @param string $dst_file 目标文件路径
*/
function Cut($dst_width,$dst_height,$dst_x,$dst_y,$dst_file='')
{
if ($dst_file) $this->dst_file = $dst_file; //设置目标文件位置
$this->dImage = imagecreatetruecolor($dst_width, $dst_height); //创建了目标文件的大小的画布
$bg = imagecolorallocatealpha($this->dImage, 255, 255, 255, 127); //给画布分配颜色
imagefill($this->dImage, 0, 0, $bg); //给图像用颜色进行填充
imagecolortransparent($this->dImage, $bg); //背景定义成透明色
$ratio_w = 1.0 * $dst_width / $this->src_width; //横向缩放的比例
$ratio_h = 1.0 * $dst_height / $this->src_height; //纵向缩放的比例
//var_dump($this);
//不进行缩放,直接对图像进行裁剪
$ratio = 1.0;
$tmp_w = (int)($dst_width / $ratio);
$tmp_h = (int)($dst_height / $ratio);
$tmp_img = imagecreatetruecolor($dst_width, $dst_height); //创建暂时保存的画布
imagecopy($tmp_img, $this->sImage, 0,0,$dst_x,$dst_y,$dst_width,$dst_height); //拷贝出图像的一部分,进行裁切
imagecopyresampled($this->dImage,$tmp_img,0,0,0,0,$dst_width,$dst_height,$tmp_w,$tmp_h); //把暂时缓存的图片,放到目标文件里面
imagedestroy($tmp_img);
}
}
?>
Use
裁剪图像
$ic=new ImageCrop($pathToFile,'./pic/afterCrop'.time().'.jpg');
$ic->Cut(40,30,120,130);
$ic->SaveImage();
//$ic->SaveAlpha();将补白变成透明像素保存
$ic->destory();
实现效果
原图
裁剪之后的图
缩放图像
原图
缩略图
重点难点
重点在于使用图像处理函数 imagecopy 和 imagecopyresampled
bool imagecopy ( resource dstim,resourcesrc_im , int dstx,intdst_y , int srcx,intsrc_y , int srcw,intsrc_h )
将 src_im 图像中坐标从 src_x，src_y 开始，宽度为 src_w，高度为 src_h 的一部分拷贝到 dst_im 图像中坐标为 dst_x 和 dst_y 的位置上。
