一个强大的图片缩放类，支持填充缩放模式

我们在截图的时候，如果给定的尺寸比例与原图比例不等，那么情况就是缩略出来的图片总有一边是不理想的， 可能高度不够，也可能宽度不够，最近项目用到图片缩放，发现了这个问题，于是重写了框架里的图片缩放方法，大家可能都知道电脑设置壁纸模式的时候有一项为“填充”，这种模式保证了你的屏幕不会出现空白，图片会自动调整到填满屏幕大小，那么下面这个方法加入了这一种模式，保证你需要的尺寸一定会有图，而不是出现黑边或者尺寸不理想等情况。

启用填充模式需要设置：$scaleMode=false;

以下方法只是框架图片类中的一部分：

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         /**

         * 生成缩略图

         * @author Joychao<Joy#joychao.cc>

         * @static

         * @param string  $image         原图

         * @param string  $type          图像格式

         * @param string  $maxWidth      目标最大宽度

         * @param string  $maxHeight     目标最大高度

         * @param string  $prefix        目标后缀

         * @param boolean $scaleMode     按比例切割模式

         * @param boolean $saveImg       生成后是否保存文件

         * @param boolean $interlace     启用隔行扫描

         * @return void

         */

        static function thumbnail($image,$type='',$maxWidth=200,$maxHeight=50,$prefix='_thumb',$scaleMode=false,$saveImg=true,$interlace=true)

        {

            // 获取原图信息

            $info  = self::getInfo($image);

            if($info !== false) {

                $srcWidth  = $info['width'];

                $srcHeight = $info['height'];

                $type = empty($type)?$info['type']:$type;

                $type = strtolower($type);

                $interlace  =  $interlace? 1:0;

                unset($info);

                // 载入原图

                $createFun = 'Imagecreatefrom'.($type=='jpg'?'jpeg':$type);

                $srcImg     = $createFun($image);

                if($scaleMode){//按比例切图

                    $scale = min($maxWidth/$srcWidth, $maxHeight/$srcHeight); // 计算缩放比例

                    if($scale>=1) {

                        // 超过原图大小不再缩略

                        $width   =  $srcWidth;

                        $height  =  $srcHeight;

                    }else{

                        // 缩略图尺寸

                        $width  = (int)($srcWidth*$scale);

                        $height = (int)($srcHeight*$scale);

                    }

                }else{//不按比例切图

                    $newScale=$maxWidth/$maxHeight;

                    $srcScale=$srcWidth/$srcHeight;

                    if($srcScale>=$newScale){

                        $height=$maxHeight;

                        $width=intval($height*($srcWidth/$srcHeight));

                    }else{

                        $width=$maxWidth;

                        $height=intval($width/($srcWidth/$srcHeight));

                    }

                    $thumbImgFirst = imagecreatetruecolor($width, $height);

                    imagecopyresampled($thumbImgFirst, $srcImg, 0, 0, 0, 0, $width, $height, $srcWidth,$srcHeight);

                    if($srcScale>=$newScale){

                        //原图起点

                        $startX=intval(($width-$maxWidth)*0.5);

                        $startY=0;

                        $width=$maxWidth;

                    }else{

                        //原图起点

                        $startX=0;

                        $startY=intval(($height-$maxHeight)*0.5);

                        $height=$maxHeight;

                    }

                }

 

                //创建缩略图

                if($type!='gif' && function_exists('imagecreatetruecolor')){

                    $thumbImg = imagecreatetruecolor($width, $height);

                }else{

                    $thumbImg = imagecreate($width, $height);

                }

 

                // 复制图片

                if(!$scaleMode){

                    imagecopymerge($thumbImg, $thumbImgFirst, 0, 0, $startX, $startY, $width, $height, 100);

                }else{

                    if(function_exists("Imagecopyresampled")){

                        imagecopyresampled($thumbImg, $srcImg, 0, 0, 0, 0, $width, $height, $srcWidth,$srcHeight);

                    }else{

                        imagecopyresized($thumbImg, $srcImg, 0, 0, 0, 0, $width, $height,  $srcWidth,$srcHeight);

                   }

                }

 

                if('gif'==$type || 'png'==$type) {

                    $background_color = imagecolorallocate($thumbImg,  0,255,0);  //指派一个绿色

                    imagecolortransparent($thumbImg,$background_color);  //设置为透明色，若注释掉该行则输出绿色的图

                }

 

                // 对jpeg图形设置隔行扫描

                if('jpg'==$type || 'jpeg'==$type)

                    imageinterlace($thumbImg,$interlace);

                // 生成图片保存

                $imageFun = 'image'.($type=='jpg'?'jpeg':$type);

                $thumbName=preg_replace('/(.w+)$/', $prefix.'\1', $image);    //abs_thumb.jpg

                if($saveImg)//是否需要保存文件

                    $imageFun($thumbImg,$thumbName);

                else

                    $imageFun($thumbImg);

                imagedestroy($thumbImg);

                imagedestroy($srcImg);

                return $thumbName;

            }

            return false;

        }

 

      /**

         * 获取图片信息

         * @static

         * @param string $path 图片路径

         * @return array

         */

        static function getInfo($path){

            $arr=getimagesize($path);

            $info['width']=$arr[0];

            $info['height']=$arr[1];

            $info['mime']=$arr['mime'];

            return $info;

        }