php生成图片与验证码图片生成原理

class chart{

var $a; //椭圆长半轴
var $b; //椭圆短半轴
var $DataArray;  //每个扇形的数据
var $ColorArray; //每个扇形的颜色 要求按照十六进制书写但前面不加0x
//为边缘及阴影为黑色

function chart($pa=100,$pb=60,$sData="100,200,300,400,500,300", $sColor="ee00ff,dd0000,cccccc,ccff00,00ccff,ccff00")
{
    $this->a=$pa;
    $this->b=$pb;
    $this->DataArray=split(",",$sData);
    $this->ColorArray=split(",",$sColor);
}

function setA($v){
    $this->a=$v;
}

function getA(){
    return $this->a;
}

function setB($v){
    $this->b=$v; 
}

function getB(){
    return $this->b;
}

function setDataArray($v){
    $this->DataArray=split(",",$v);
}

function getDataArray($v){
    return $this->DataArray;
}

function setColorArray($v){
    $this->ColorArray=split(",",$v);
}

function getColorArray(){
    return  $this->ColorArray;
}

 
function  DrawPie(){
    $image=imagecreate($this->a*2+40,$this->b*2+40);
    $PieCenterX=$this->a+10;
    $PieCenterY=$this->b+10;
    $DoubleA=$this->a*2;
    $DoubleB=$this->b*2;
    list($R,$G,$B)=getRGB(0);
    $colorBorder=imagecolorallocate($image,$R,$G,$B);
    $DataNumber=count($this->DataArray);
    
    //$DataTotal
    for($i=0;$i<$DataNumber;$i++)      $DataTotal+=$this->DataArray[$i]; //算出数据和
    
    //填充背境
    imagefill($image, 0, 0, imagecolorallocate($image, 0xFF, 0xFF, 0xFF));

    /*
    ** 画每一个扇形
    */
    $Degrees = 0;
    for($i = 0; $i < $DataNumber; $i++){
        $StartDegrees = round($Degrees);
        $Degrees += (($this->DataArray[$i]/$DataTotal)*360);
        $EndDegrees = round($Degrees);
        $percent = number_format($this->DataArray[$i]/$DataTotal*100, 1); 
        list($R,$G,$B)=getRGB(hexdec($this->ColorArray[$i]));
        $CurrentColor=imagecolorallocate($image,$R,$G,$B);
        if ($R>60 and $R<256)            $R=$R-60;
        if ($G>60 and $G<256)            $G=$G-60;
        if ($B>60 and $B<256)            $B=$B-60;
        $CurrentDarkColor=imagecolorallocate($image,$R,$G,$B);
        //画扇形弧
        imagearc($image,$PieCenterX,$PieCenterY,$DoubleA,$DoubleB,$StartDegrees,$EndDegrees,$CurrentColor);
        //画直线
        list($ArcX, $ArcY) = pie_point($StartDegrees , $this->a , $this->b);
        imageline($image,$PieCenterX,$PieCenterY,floor($PieCenterX + $ArcX),floor($PieCenterY + $ArcY),$CurrentColor);
        //画直线
        list($ArcX, $ArcY) = pie_point($EndDegrees,$this->a , $this->b);
        imageline($image,$PieCenterX,$PieCenterY,ceil($PieCenterX + $ArcX),ceil($PieCenterY + $ArcY),$CurrentColor);
        //填充扇形
        $MidPoint = round((($EndDegrees - $StartDegrees)/2) + $StartDegrees);
        list($ArcX, $ArcY) = Pie_point($MidPoint, $this->a*3/4 , $this->b*3/4);
        
        imagefilltoborder($image,floor($PieCenterX + $ArcX),floor($PieCenterY + $ArcY), $CurrentColor,$CurrentColor);
        imagestring($image,2,floor($PieCenterX + $ArcX-5),floor($PieCenterY + $ArcY-5),$percent."%",$colorBorder);

        //画阴影
        if ($StartDegrees>=0 and $StartDegrees<=180){
           if($EndDegrees<=180){    
               for($k = 1; $k < 15; $k++)
                imagearc($image,$PieCenterX, $PieCenterY+$k,$DoubleA, $DoubleB, $StartDegrees, $EndDegrees, $CurrentDarkColor);
           }else{
               for($k = 1; $k < 15; $k++)
                imagearc($image,$PieCenterX, $PieCenterY+$k,$DoubleA, $DoubleB, $StartDegrees, 180, $CurrentDarkColor);
           }

        }
   }
        
    /*到此脚本已经生了一幅图像了
    **现在需要的是把它发到浏览器上，重要的一点是要将标头发给浏览器，让它知道是一个GIF文件。不然的话你只能看到一堆奇怪的乱码
    */ 
    //输出生成的图片    
    header("Content-type: image/gif");
    imagegif($image);
    imagedestroy($image);
}//End drawPie()
}//End class

//实现

$objp = new chart();
$objp->DrawPie();

<?php教程
header("Content-type: image/jpeg");
// 载入图像
$imagen1 = imagecreatefromjpeg("imagen1.jpg");
$imagen2 = imagecreatefromjpeg("imagen2.jpg");

// 复制图像www.111cn.net
imagecopy($imagen1,$imagen2,0,0,0,0,200,150);

// 输出jpeg图像
imagejpeg($imagen1);

//释放内存
imagedestroy($imagen2);
imagedestroy($imagen1);

?>

<?php
$info = getimagesize("imagen2.jpg");
print_r($info);

?>

<?php
//PNG格式图像处理函数
function Loadpng ($imgname) {
    $im = @ImageCreateFromPNG ($imgname);
    if (!$im) {    //载入图像失败                     
        $im = ImageCreate (400, 30);     
        $bgc = ImageColorAllocate ($im, 255, 255, 255);
        $tc  = ImageColorAllocate ($im, 0, 0, 0);
       ImageFilledRectangle ($im, 0, 0, 150, 30, $bgc);
       ImageString($im, 4, 5, 5, "Error loading: $imgname", $tc);
    }
    return $im;
 }
 $imgPng=Loadpng("./karte.png");
   /* 输出图像到浏览器 */
 header("Content-type: image/png");
 imagePng($imgPng);
 ?>