/******************************
*      折线图生成函数
******************************/
function line_stats_pic ( $value_y,$width,$high,$strong=1,$fix=0 )
{
//y值处理函数
	function line_point_y ( $num,$width,$high,$max_num_add,$min_num_add,$y_pxdensity )
	{
		$return=$high-floor ( ( $num-$min_num_add+$y_pxdensity ) / ( ( $max_num_add-$min_num_add ) /$high ) );
		return $return;
	}

//参数处理
	$allnum=sizeof ( $value_y );
	$max_num=max ( $value_y );           //最大值
	$min_num=min ( $value_y );           //最小值
	$limit_m=$max_num-$min_num;            //极差
	$max_num_add=$max_num+$limit_m*0.1;        //轴最大值
	$min_num_add=$min_num-$limit_m*0.1;        //轴最小值
	$limit=$max_num_add-$min_num_add;         //极差-坐标轴y
	$y_pxdensity= ( $max_num_add-$min_num_add ) /$high;  //y轴密度
	$x_pxdensity=floor ( $width/$allnum );     //x轴密度
	reset ( $value_y );              //将数组指针归零
	$i=0;
	foreach ( $value_y as $val )
	{
		$point_y[$i]=line_point_y ( $val,$width,$high,$max_num_add,$min_num_add,$y_pxdensity );
		$i++;
	}
	$zero_y=line_point_y ( 0,$width,$high,$max_num_add,$min_num_add,$y_pxdensity );  //零点的y值
	$empty_size_x= ( strlen ( $max_num ) > strlen ( $min_num ) ? strlen ( $max_num ) : strlen ( $min_num ) ) *5+3;          //左边空白

//图片流开始
	header ( "Content-type:image/png" );
	$pic=imagecreate ( $width+$empty_size_x+10,$high+13 );
	imagecolorallocate ( $pic,255,255,255 );  //背景色
	$color_1=imagecolorallocate ( $pic,30,144,255 ); //线条色
	$color_2=imagecolorallocate ( $pic,0,0,0 );   //黑色
	$color_3=imagecolorallocate ( $pic,194,194,194 );//灰色
//绘制网格
	imagesetthickness ( $pic,1 );       //网格线宽
	$y_line_width=floor ( $width/100 );    //纵网格线数目
	$y_line_density=$y_line_width==0 ? 0 :floor ( $width/$y_line_width ); //纵网格线密度
	$point_zero_y=$zero_y > $high ? $high : $zero_y;
	imagestring ( $pic,1,$empty_size_x-1,$high+4,"0",$color_2 ); //零点数轴标记
	for ( $i=1; $i <= $y_line_width; $i++ )  //绘制纵网格线
	{
		imagesetthickness ( $pic,1 );      //网格线宽
		imageline ( $pic,$y_line_density*$i+$empty_size_x,0,$y_line_density*$i+$empty_size_x,$high,$color_3 );
		imagesetthickness ( $pic,2 );      //轴点线宽
		imageline ( $pic,$y_line_density*$i+$empty_size_x,$point_zero_y-4,$y_line_density*$i+$empty_size_x,$point_zero_y,$color_2 );
		imagestring ( $pic,1,100*$i+$empty_size_x-5,$high+4,$allnum/$y_line_width*$i,$color_2 );  //数轴标记
	}
	$x_line_width=floor ( $high/30 );     //横网格线数目
	$x_line_density=$x_line_width==0 ? 0 :floor ( $high/$y_line_width );  //横网格线密度
	if ( $zero_y > $high )           //绘制横网格线
	{
		imagestring ( $pic,1,0,$high-3,round ( $min_num_add,$fix ),$color_2 ); //零点数轴标记
		for ( $i=1; $i <= $x_line_width; $i++ )
		{
			imagesetthickness ( $pic,1 );     //网格线宽
			imageline ( $pic,0+$empty_size_x,$high-$x_line_density*$i,$width+$empty_size_x,$high-$x_line_density*$i,$color_3 );
			imagesetthickness ( $pic,2 );     //轴点线宽
			imageline ( $pic,0+$empty_size_x,$high-$x_line_density*$i,3+$empty_size_x,$high-$x_line_density*$i,$color_2 );
			imagestring ( $pic,1,0,$high-$x_line_density*$i-3,round ( $limit/$x_line_width*$i+$min_num_add,$fix ),$color_2 );  //数轴标记
		}
	}
	else
	{
		imagestring ( $pic,1,$empty_size_x-8,$zero_y,"0",$color_2 ); //零点数轴标记
		for ( $i=1; $i <= ceil ( $x_line_width/2 ); $i++ )
		{
			imagesetthickness ( $pic,1 );     //网格线宽
			imageline ( $pic,0+$empty_size_x,$zero_y-$x_line_density*$i,$width+$empty_size_x,$zero_y-$x_line_density*$i,$color_3 );
			if ( $zero_y+$x_line_density*$i < $high )
			{
				imageline ( $pic,0+$empty_size_x,$zero_y+$x_line_density*$i,$width+$empty_size_x,$zero_y+$x_line_density*$i,$color_3 );
			}
			imagesetthickness ( $pic,2 );     //轴点线宽
			imageline ( $pic,0+$empty_size_x,$zero_y-$x_line_density*$i,3+$empty_size_x,$zero_y-$x_line_density*$i,$color_2 );
			if ( $zero_y+$x_line_density*$i < $high )
			{
				imageline ( $pic,0+$empty_size_x,$zero_y+$x_line_density*$i,3+$empty_size_x,$zero_y+$x_line_density*$i,$color_2 );
			}
			imagestring ( $pic,1,0,$zero_y-$x_line_density*$i-3,round ( $limit/$x_line_width*$i,$fix ),$color_2 );   //数轴标记
			if ( $zero_y+$x_line_density*$i < $high )
			{
				imagestring ( $pic,1,0,$zero_y+$x_line_density*$i-3,round ( -$limit/$x_line_width*$i,$fix ),$color_2 );  //数轴标记
			}
		}
	}
//绘制轴线
	imagesetthickness ( $pic,2 );       //轴线宽
	imageline ( $pic,1+$empty_size_x,0,1+$empty_size_x,$high,$color_2 );
	if ( $zero_y > $high )           //x轴位置
	{
		imageline ( $pic,0+$empty_size_x,$high,$width+$empty_size_x,$high,$color_2 );
	}
	else
	{
		imageline ( $pic,0+$empty_size_x,$zero_y,$width+$empty_size_x,$zero_y,$color_2 );
	}
//产生折线
	$point_x=0;
	$j=0;
	imagesetthickness ( $pic,$strong );    //线条粗细
	while ( $j+1 < $allnum )
	{
		imageline ( $pic,$point_x+2+$empty_size_x,$point_y[$j],$point_x+$x_pxdensity+2+$empty_size_x,$point_y[$j+1],$color_1 );
		$point_x+=$x_pxdensity;
		$j++;
	}
	imagepng ( $pic );
	imagedestroy ( $pic );
}

/*
函数描述及例子
参数说明：
$value_y -------- 包含你想生成折线图的数组，要求键值从0开始递增。
$width--------生成的折线图的网格宽度（不算白边）
$high--------高度
$strong-------线条粗细（默认为1）
$fix-------数据保留的位数（默认为取整）
*/

for ( $i=0; $i<100; $i++ )
{
	$value = rand ( 1,200 );
	$value_y[]=$value;
}
line_stats_pic ( $value_y,500,100,1,1 );
?>