在photoshop中我们常用的一个功能就是选择区域，用魔法棒选择工具点击图片上的一个点就会选中跟该点颜色一样的连续或非连续区域。这是怎么做到的呢？下面是我用php实生的区域生长算法。

<?php/***找到生长区域**@paramarray$arr数据数组*@paramarray$seed种子点*@returnarray*/functiongetGrowRegion($arr,$seed,$mode=4){$seed_value=$seed['value'];$queue=array();$label=array();if($arr[$seed['y']][$seed['x']]==$seed_value){$queue[]=$seed;$label[$seed['y']][$seed['x']]=1;//标记}//判断该点4或8个方向上的值,如果未被标记就标记，并加入到队列中switch($mode){case4:default:$directions=array(array(-1,0),array(1,0),array(0,-1),array(0,1));break;case8:$directions=array(array(-1,0),array(1,0),array(0,-1),array(0,1),array(-1,-1),array(-1,1),array(1,-1),array(1,1),);break;}while(!empty($queue)){$current=array_shift($queue);foreach($directionsas$key=>$val){$y_idx=$current['y']+$val[0];$x_idx=$current['x']+$val[1];if(isset($arr[$y_idx][$x_idx])&&$arr[$y_idx][$x_idx]==$seed_value&&!isset($label[$y_idx][$x_idx])){$label[$y_idx][$x_idx]=1;$queue[]=array('y'=>$y_idx,'x'=>$x_idx);}}}return$label;}//生长区域测试$str=<<<EOT000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000011100000000000000000000000000011100000000000000000000000000011110000000000000000000000000111110000000000000000000000000110111000000000000000000000000110111000000000000000000000001110011000000000000000000000001111111100000000000000000000011111111100000000000000000000011111111110000000000000000000011000001110000000000000000000111000000110000000000000000000111000000111000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000EOT;$data=preg_split('/[\r\n]+/',$str);//切分成行数组//处理成二维坐标数组$arr=array();foreach($dataas$y=>$val){$x_len=strlen($val);for($x=0;$x<$x_len;$x++){$arr[$y][$x]=$val{$x};}}//设置种子点，这里取左上角，value是要匹配的值//这里的意思就是以左上角为起点，所有值为0的点全部作为要匹配的区域$seed=array('y'=>0,'x'=>0,'value'=>'0');$result=getGrowRegion($arr,$seed);//输出反转之后的字符串foreach($arras$y=>$rows){foreach($rowsas$x=>$val){if(isset($result[$y][$x])){echo$result[$y][$x];}else{echo$val==1?0:2;//非生长点}}echo"\n";}

运行后的输出结果如下：

111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111100011111111111111111111111111100011111111111111111111111111100001111111111111111111111111000001111111111111111111111111002000111111111111111111111111002000111111111111111111111110002200111111111111111111111110000000011111111111111111111100000000011111111111111111111100000000001111111111111111111100111110001111111111111111111000111111001111111111111111111000111111000111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111

可以看到原来为0的点全换成了1，但图形中间的点不受影响，我将其标记成了2。