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
<?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 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); }}?>$ic=new ImageCrop($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();
原图
裁剪之后的图
原图
缩略图
重点在于使用图像处理函数 imagecopy 和 imagecopyresampled
bool imagecopy ( resource dstim,resource src_im , int dstx,int dst_y , int srcx,int src_y , int srcw,int src_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。
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