Creating directories( folders ) for the application
- Create a directory named myWebApp in your server root directory eg. in www directory (for windows).
- Create subdirectories named css and myServer inside your myWebApp directory.
- Create a subdirectory named resizedImages inside your myServer directory. Here all the resized images will be stored.
HTML markup
<!DOCTYPE html>
<html>
<head>
<title>Resizing image using PHP</title>
<link rel="stylesheet" href="css/my_styles.css">
</head>
<body>
<form method="post" action="myServer/resize_image.php" id="myForm" enctype="multipart/form-data" required="required">
<div class="label">Pick a jpg on png image</div>
<input type="file" name="img" accept="image/jpeg,image/png" required="required">
<div class="label">New width & new height</div>
<div id="tb">
<div class="td" id="w">
<input type="number" name="new_width" placeholder="New width">
</div>
<div class="td" id="h">
<input type="number" name="new_height" placeholder="New height">
</div>
</div>
<input type="submit" value="Submit form">
</form>
</body>
</html>Save this html as image_picker.html file in myWebApp directory.
CSS rules
body
{
margin:0px;
font-size:14px;
background-color:#fff;
}
body,input[type="number"],input[type="submit"]
{
font-family:Helvetica,arial,sans-serif;
}
form
{
width:270px;
margin:0 auto;
margin-top:170px;
padding:0px 20px 20px 20px;
border:1px solid #af111c;
}
input[type="submit"]
{
display: block;
width:100%;
padding: 10px;
margin-top:20px;
color: #fff;
background-color: #af111c;
border-width:0px;
text-align: center;
outline:none;
cursor:pointer;
}
input[type="number"]
{
border-width:0px;
border-bottom:1px solid #ccc;
width:100%;
height:20px;
outline:none;
}
.label
{
font-weight:bold;
font-size:15px;
padding:20px 0px;
}
#tb
{
display:table;
width:100%;
}
.td
{
display:table-cell;
}
#w
{
padding-right:10px;
}
#h
{
padding-left:10px;
}Save this css as my_styles.css file in css directory.
PHP code
php.ini file directives required for this application.
Set the following directives to appropriate values in your php.ini file.
- file_uploads must be set to On.
- upload_max_filesize must be greater than the size of image that you are uploading. i.e if you are uploading an image of size 10M(Mega bytes) then upload_max_filesize value must be greater than 10M eg. 11M
- post_max_size should be greater than upload_max_filesize value.
- memory_limit must be set to appropriate value (Needed in case when there is Fatal error: Allowed memory size of ******** bytes exhausted while processing the image).
But memory limit should not be set to a high number as this may affect the execution of other functionalities of server.
<?php
$image = $_FILES['img'];
// 1. Check if image is provided or not
if( empty($image['tmp_name']) )
exit();
// 2. Check if valid image is provided or not
$size = getimagesize($image['tmp_name']);
if( $size === false )
{
// Invalid image
echo 'Invalid image !';
exit();
}
else
{
// Get width and height of uploaded image
$dimensions = array($size[0],$size[1]); // array(image width, image height)
}
// 3. Now check type of uploaded image [ jpg and png only ]
// Checking file type based on content of image
$fileType = exif_imagetype($image['tmp_name']);
$allowedTypes = array(IMAGETYPE_PNG,IMAGETYPE_JPEG);
if( !in_array($fileType,$allowedTypes) )
{
// File type not supported
echo 'File type not supported ! try jpg or png image.';
exit();
}
else
{
// Set the image file extension
if($fileType == IMAGETYPE_JPEG) // JPG image
{
$extension = '.jpg';
}
else // PNG image
{
$extension = '.png';
}
}
// 4. Create file name
$fileName = SHA1(time().mt_rand(0,20000).$image['name']);
// 5. Path to store resized images
$path = 'resizedImages'.DIRECTORY_SEPARATOR.$fileName.$extension;
// 6. Resizing the image
$imgContent = file_get_contents($image['tmp_name']); // Get content of the uploaded image file
$old_image = imagecreatefromstring($imgContent);
$old_width = $dimensions[0];
$old_height = $dimensions[1];
$ratio = $old_width / $old_height;
// 7. Get new width and height for the image
$new_width = (int)trim($_POST['new_width']); // New width
$new_height = (int)trim($_POST['new_height']); // New height
if( !empty($new_width) && empty($new_height) ) // If only new width is provided
{
if( !is_integer($new_width) || $new_width <= 0 )
exit();
// Set the new height maintaining width:height ratio of image
$new_height = $new_width / $ratio;
}
else if( empty($new_width) && !empty($new_height) ) // If only new height is provided
{
if( !is_integer($new_height) || $new_height <= 0 )
exit();
// Set the new width maintaining width:height ratio of image
$new_width = $new_height * $ratio;
}
else if( empty($new_width) && empty($new_height) )
{
// If new width and new height are not provided then use dimensions of uploaded image
$new_width = $old_width;
$new_height = $old_height;
}
// 8. Create a new image with the new dimensions ( default background color is black )
$new_image = imagecreatetruecolor($new_width,$new_height);
if( $new_image === false ) // Could not create new image
exit();
// 9. Setting the background color of new image ( created in previous step )
if( $fileType == IMAGETYPE_JPEG ) // JPG image
{
// Make the black background to white
$bg = imagecolorallocate($new_image,255,255,255);
// 255,255,255 is RGB code for white color
}
else // PNG image
{
// Make the black background to transparent
$alpha = imagesavealpha($new_image, true);
$bg = imagecolorallocatealpha($new_image, 255, 255, 255, 127);
// Last parameter is alpha value, it's value is set to 127 means full transparency
}
$filled = imagefill($new_image,0,0,$bg); // paint the new image with new background color
// 10. Copy old image to new image
imagecopyresampled($new_image,$old_image,0,0,0,0,$new_width,$new_height,$old_width,$old_height);
// 0,0,0,0 in above function parameters are x-coordinate of new image, y-coordinate of new image, x-coordinate of old image, y-coordinate of old image respectively.
// These coordinates means that -> Copy content from (0,0) coordinates of old image and start pasting it from (0,0) coordinates in the new image.
// 11. Save the new resized image file to the "processed_images" directory
if( $fileType == IMAGETYPE_JPEG ) // JPG image
{
imagejpeg($new_image,$path);
}
else // PNG image
{
imagepng($new_image,$path);
}
// 12. Free any memory associated with the new image
imagedestroy($new_image);
echo "<a href='$path' target='_blank'>View the image</a>";
?>Save this php code as resize_image.php file in myServer directory.
Execution of the application
- Start your wamp / lamp / xampp server.
- Open image_picker.html HTML file in your web browser.
- Select an image file and provide the dimensions.
- If only width or height is provided, image will be resized maintaining the width:height ratio.
- If both width & height are provided then resized image will have the exact provided dimensions.
- If nothing is provided then the output image will have the exact dimensions of the original image.
- Submit the form.
- Go to resizedImages directory ( inside myServer directory ) there you will find your resized images.
Plus point
If no width & and height are provided then the size of output image may reduce to a lower or greater extent depending on the image ( above PHP code also works as image size reducer ), but for some images size may increase.
Notice
If you dont't have access to exif_imagetype() function ( as this may be the case with some web-hosting providers ) then you can use pathinfo() function to get the image extension.
$extension = pathinfo($_FILES['img']['name'],PATHINFO_EXTENSION);
// If jpg image is uploaded then $extension will have value jpg, and png in case of png image.
For further readings check out these links
