[RESOLVED] How do you zoom up on an image using PHP?

ppowell

re: http://www.phpbuilder.com/columns/pablo19990729.php3

I tried recreating his code (with some modernity considering he's using PHP 3 and I'm using PHP 4.3.2 - PHP 5.0.4):

<?
	if ($_POST['blah']) {
	 list($image_width, $image_height) = @getimagesize('http://valsignalandet.com/images/stave.jpg');
	 $zoomImgObj = @imagecreatefromjpeg('http://valsignalandet.com/images/stave.jpg');
	 $imageObj = @imagecreatetruecolor($image_width, $image_height);
	 $factor=3.75;
	 $posx = floor($_POST['val_x'] * $factor - floor((int)($image_width / 2)));
	 $posy = floor($_POST['val_y'] * $factor - floor((int)($image_height / 2)));
	 $copia = @imagecopyresized($zoomImgObj, $imageObj, 0, 0, $posx, $posy, $image_width, $image_height, $image_width, $image_height);
         @imagejpeg($imageObj, '/tmp/val.jpg');
         @imagedestroy($imageObj);
	 @imagedestroy($zoomImgObj);
         $contents = @file_get_contents('/tmp/val.jpg');
 	 require_once('/var/www/html/tools/tools_globals/client_globals.inc.php');
	 require_once('/var/www/html/tools/ivc/ivc_globals/project_globals.inc.php');
	 require_once('/var/www/html/tools/ivc/include/classes.inc.php');
	 require_once('/var/www/html/tools/ivc/include/db_action.inc.php');
	 DownloadGenerator::generateForceDownloadHeaders('/tmp/val.jpg', $contents);
	} else {

?>
<html>
<head>
<title>asdf</title>
</head>
<body>
<form method="post" action="<?= $_SERVER['PHP_SELF'] ?>">
 <input type="hidden" id="blah" name="blah" value="foo">
 <input type="image" id="val" name="val" src="http://valsignalandet.com/images/stave.jpg" alt="V&auml;lsignalandet" value="val">
</form>
</body>
</html>
<?	}	?>

However, each time I run this script, the resulting downloaded "image" is a black graphic, same width and height as the original image.

What I want is the ability to zoom in on an image based upon the place where the user clicks (thus capturing the positions via $_POST)

Any suggestions?

Thanx
Phil

ppowell

UPDATE:

I think this is the culprit, because if I click on the upper left hand corner of the image, I get something LIKE a zoomed-in image but terribly offset, otherwise, nuthin' but black:

	 $factor=3.75;
	 $posx = floor($_POST['val_x'] * $factor - (int)($image_width / 2));
	 $posy = floor($_POST['val_y'] * $factor - (int)($image_height / 2));

I suspect the calculations for $posx and $posy are causing it to happen.. but I don't have any idea how to fix that.

Phil

ppowell

UPDATE:

This works to an extent, however, the image is very pixelated the larger the magnification, and it doesn't seem to center the coordinates too well either:

<?
	$imageURL = 'http://valsignalandet.com/images/london_bobfest4/chapel_at_abney_park_cemetery_in_london_2.jpg';

if ($_POST['blah']) {
 $factor = (is_numeric($_POST['zoom']) && (int)$_POST['zoom'] > 0) ? (double)($_POST['zoom'] / 100) : 1;
 list($image_width, $image_height) = @getimagesize($imageURL);
 $zoomImgObj = @imagecreatefromjpeg($imageURL);
 $imageObj = @imagecreatetruecolor($image_width, $image_height);
 @imagealphablending($zoomImgObj, true);
 list($srcWidth, $srcHeight) = array(50, 50);		// 50 x 50 ZOOMING SQUARE "PIXELAGE" AROUND THE CENTER OF THE X-Y COORDINATE YOU SELECTED TO ZOOM IN ON
 $posx = (int)$_POST['val_x'] - floor($srcWidth / 2);
 $posy = (int)$_POST['val_y'] - floor($srcHeight / 2);
 if ($posx < 0) $posx = 0;
 if ($posy < 0) $posy = 0;
 if ($posx + $srcWdith > $image_width) $posx = $image_width - $srcWidth;
 if ($posy + $srcHeight > $image_height) $posy = $image_height - $srcHeight;
//print_r("posx = $posx and posy = $posy and $image_width * $factor = " . ($image_width * $factor) . " and $image_height * $factor = " . ($image_height * $factor) . "<P>");
 $junk = @imagecopyresampled($imageObj, $zoomImgObj, 0, 0, $posx, $posy, floor($image_width * $factor), floor($image_height * $factor), $image_width, $image_height);
     @imagejpeg($imageObj, '/tmp/val.jpg');
     @imagedestroy($imageObj);
 @imagedestroy($zoomImgObj);
     $contents = @file_get_contents('/tmp/val.jpg');
 require_once('/var/www/html/tools/tools_globals/client_globals.inc.php');
 require_once('/var/www/html/tools/ivc/ivc_globals/project_globals.inc.php');
 require_once('/var/www/html/tools/ivc/include/classes.inc.php');
 require_once('/var/www/html/tools/ivc/include/db_action.inc.php');
 DownloadGenerator::generateForceDownloadHeaders('/tmp/val.jpg', $contents);
} else {

?>
<html>
<head>
<title>asdf</title>
</head>
<body>
<form method="post" action="<?= $_SERVER['PHP_SELF'] ?>">
 <input type="hidden" id="blah" name="blah" value="foo">
 <input type="image" id="val" name="val" src="<?= $imageURL ?>" alt="V&auml;lsignalandet" value="val">
 <br clear="all">Select a percentage and then click onto the image, else it will default to the minimum percentage (100%)
 <select name="zoom">
<?	 for ($i = 100; $i <= 500; $i += 50) echo "\n  <option value=\"$i\">$i%</option>";	?>
 </select>
</form>
</body>
</html>
<?	}	?>

ppowell

GOT IT!

<?
	$imageURL = 'http://valsignalandet.com/images/london_bobfest4/chapel_at_abney_park_cemetery_in_london_2.jpg';

if ($_POST['blah']) {
 $factor = (is_numeric($_POST['zoom']) && (int)$_POST['zoom'] > 0) ? (double)($_POST['zoom'] / 100) : 1;
 list($image_width, $image_height) = @getimagesize($imageURL);
 $zoomImgObj = @imagecreatefromjpeg($imageURL);
 $imageObj = @imagecreatetruecolor($image_width, $image_height);
 @imagealphablending($zoomImgObj, true);
 // ZOOMING SQUARE "PIXELAGE" AROUND THE CENTER OF THE X-Y COORDINATE YOU SELECTED TO ZOOM IN ON
 list($srcWidth, $srcHeight) = array(floor($image_width / $factor), floor($image_height / $factor));
 $posx = (int)$_POST['val_x'] - floor($srcWidth / 2);
 $posy = (int)$_POST['val_y'] - floor($srcHeight / 2);
 if ($posx < 0) $posx = 0;
 if ($posy < 0) $posy = 0;
 if ($posx + $srcWdith > $image_width) $posx = $image_width - $srcWidth;
 if ($posy + $srcHeight > $image_height) $posy = $image_height - $srcHeight;
 $junk = @imagecopyresampled($imageObj, $zoomImgObj, 0, 0, $posx, $posy, floor($image_width * $factor), floor($image_height * $factor), $image_width, $image_height);
     @imagejpeg($imageObj, '/tmp/val.jpg');
     @imagedestroy($imageObj);
 @imagedestroy($zoomImgObj);
     $contents = @file_get_contents('/tmp/val.jpg');
 require_once('/var/www/html/tools/tools_globals/client_globals.inc.php');
 require_once('/var/www/html/tools/ivc/ivc_globals/project_globals.inc.php');
 require_once('/var/www/html/tools/ivc/include/classes.inc.php');
 require_once('/var/www/html/tools/ivc/include/db_action.inc.php');
 DownloadGenerator::generateForceDownloadHeaders('/tmp/val.jpg', $contents);
} else {

?>
<html>
<head>
<title>asdf</title>
</head>
<body>
<form method="post" action="<?= $_SERVER['PHP_SELF'] ?>">
 <input type="hidden" id="blah" name="blah" value="foo">
 <input type="image" id="val" name="val" src="<?= $imageURL ?>" alt="V&auml;lsignalandet" value="val">
 <br clear="all">Select a percentage and then click onto the image, else it will default to the minimum percentage (100%)
 <select name="zoom">
<?	 for ($i = 100; $i <= 500; $i += 50) echo "\n  <option value=\"$i\">$i%</option>";	?>
 </select>
</form>
</body>
</html>
<?	}	?>