
<?php  session_start(); //must be at beginning 





//read-only of width and height after frist GET

function sendGetPage ($sizeReadonly="") {

  //too many ' and " in heredoc?

  $serverNamePhpSelf = $_SERVER['SERVER_NAME'].$_SERVER['PHP_SELF'];

  $width = $_POST['width'];

  $height = $_POST['height'];

  $x1 = $_POST['x1'];

  $y1 = $_POST['y1'];

  $x2 = $_POST['x2'];

  $y2 = $_POST['y2'];



  //  $getpage = <<< endOfGetPage

 echo <<< endOfGetPage

<html>

<head>

<title>PHP Drawing images</title>

</head>

<!-- presents generic image creator in browser -->

<body>

<form name="drawingForm" 

action="http://$serverNamePhpSelf";

method="post">

<input name="shape" value="rectangle" type="radio" checked>Rectangle

<input name="shape" value="ellipse" type="radio" >Ellipse

<input name="shape" value="line" type="radio" >Line

<input name="shape" value="point" type="radio">Point

<br>

X1

<input type="text" size="3" maxlength="4"  name="x1" value="$x1">

Y1

<input type="text" size="3" maxlength="4"  name="y1" value="$y1">

X2/Width

<input type="text" size="3" maxlength="4"  name="x2" value="$x2">

Y2/Height

<input type="text" size="3" maxlength="4"  name="y2" value="$y2">

Image size: Width

<input type="text" size="3" maxlength="4"  name="width" value="$width" $sizeReadonly>

Height

<input type="text" size="3" maxlength="4"  name="height" value="$height" $sizeReadonly>

  Color: 

<select name="color">

<option>white</option>

<option selected>black</option>

<option>red</option>

<option>blue</option>

<option>green</option>

<option>yellow</option>

<option>cyan</option>

<option>magenta</option>

</select>

<input value="Draw it" type="submit">

</form>

endOfGetPage;

}



//initial page load.  display form

if ($_SERVER['REQUEST_METHOD'] == 'GET') {

  sendGetPage();

  echo "</body>\n</html>";

  unlink("drawingfile.png");

  //$_SESSION['firstposting'] = true;  //HTTP_SESSION_VARS is pre 4.1

  exit();  

}







if ($_SESSION['firstposting']) {

  $_SESSION['queryHistory'] = "";     // \0 delimited fields

  $_SESSION['firstposting'] = false;

}





$width = $_POST['width'];

$height = $_POST['height'];

$x1 = $_POST['x1'];

$y1 = $_POST['y1'];

$w = $x2 = $_POST['x2'];

$h = $y2 = $_POST['y2'];

$shape = $_POST['shape'];

$color = $_POST['color'];

//echo "color: ".$color."\n";



//type check and range check here...

//form input is always string!!!  must use is-numeric, not is-int

if (!is_numeric($width) || !is_numeric($height) || !is_numeric($x1) || !is_numeric($y1) || 

    !is_numeric($x2) || !is_numeric($y2) ||

    $width<1 || $width>1000 || $height<1 || $height>1000) {

  echo "BAD INPUT. width: $width h: $height x1: $x1 y1: $y1 x2: $x2 y2: $y2\n"; 

  sendGetPage();

  echo "</body>\n</html>";

  exit();

}  





if (file_exists("drawingfile.png") && is_readable("drawingfile.png")) {

  $im = ImageCreateFromPNG("drawingfile.png");

}

else {

  $im = ImageCreateTrueColor($width, $height);



  ImageAlphaBlending($im, false);

  ImageFilledRectangle($im, 0, 0, $width, $height, ImageColorAllocate($im, 255, 255, 255));

}



//could probably do only one each call

$colors['white'] = ImageColorAllocate($im, 255, 255, 255);

$colors['black'] = ImageColorAllocate($im, 0, 0, 0);

$colors['red'] = ImageColorAllocate($im, 255, 0, 0);

$colors['blue'] = ImageColorAllocate($im, 0, 0, 255);

$colors['green'] = ImageColorAllocate($im, 0, 255, 0);

$colors['yellow'] = ImageColorAllocate($im, 255, 255, 0);

$colors['cyan'] = ImageColorAllocate($im, 0, 255, 255);

$colors['magenta'] = ImageColorAllocate($im, 255, 0, 255);



$color = $colors[$color];   //user's color choice



switch ($shape) {

 case "line": 

   ImageLine($im, $x1, $y1, $x2, $y2, $color);

   break;

 case "point": 

   ImageSetPixel($im, $x1, $y1, $color);

   break;

 case "ellipse": 

   ImageFilledEllipse($im, $x1, $y1, $w, $h, $color);

   break;

 case "rectangle": 

   ImageFilledRectangle($im, $x1, $y1, $x2, $y2, $color);

   break;

}





//$gray = ImageColorResolveAlpha($im, 70, 70, 70, 63);

//  ImageAlphaBlending($im, true);

//ImageFilledRectangle($im, 60, 60, 120, 120, $gray);





/*  can only send one part to browser.  multipart stuff is for uploading to server???

$boundary_string = "\n" . "--End" . "\n";

##$end_of_data = "\n" . "--End--" . "\n";



header("Content-type: multipart/form-data; boundary=--End");

header("Content-type: text/html");

echo $boundary_string;

*/



sendGetPage("readonly");



//echo $boundary_string;



/*changed to write to file and use img tag:

header('Content-Type: image/png');

ImagePNG($im);

*/



//my directory needs to be 777 for apache to write to it:

if (($fp = fopen("drawingfile.png","w")) == false) {

  echo "<p>file open failed!</p>";

  exit();

}

ImagePNG($im,"drawingfile.png");



echo "<hr>\n<img src=\"drawingfile.png\">\n";

echo "</body>\n</html>";

?>