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

<?phpnamespace 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($mode){case 1: // always cropif( ($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 smallif($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,$this->src_height);}break;case 3: // keep all image size and create need sizeif($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($tmp_img);}break;case 4: // keep all image but create actually sizeif($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

本文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。