Inspired by Backpackit.com’s image management, Image Snapshot can take a portion of an image (crop) to specific dimensions, from different areas of the original image.

This class has been created for the purpose of manipulating an uploaded image, and creating a Thumbnail image that does not alter the aspect ratio, and yet represents the contents of the original image. I’m sure other uses can be found for the Image Snapshot class, but I’ll leave that to you. I use it for Photo Galleries, and Shopping Cart systems.

This class supports:

* Jpg, Gif, Png files
* Output to Jpg
* Can resize images before applying the crop
* Can crop from any part of the image

An online manual exists for more customizations: http://blog.jc21.com/files/snapshot_manual.pdf

By : jc21com

<?php
/*
IMAGE SNAPSHOT CLASS - www.jc21.com
VERSION 1.3 ------------------------------------------------------

Can accept JPG, GIF and PNG files.
Refer to manual if you're confused:
http://blog.jc21.com/files/snapshot_manual.pdf

WARNING
------------------------------------------------------

Will save all images as JPG.

USAGE: ------------------------------------------------------

include('snapshot.class.php'); //this file
$myimage = new ImageSnapshot; //new instance
//if using this as an action to a form:
$myimage->ImageField = $_FILES['userfile']; //uploaded file array
//OR if you have the contents of the image as a variable:
$myimage->ImageContents = $the_image_contents; //image data
//OR if you want to use an image that is already saved:
$myimage->ImageFile = $_SERVER['DOCUMENT_ROOT'] . '/images/myimage.jpg'; //image file, as an example. Path can be relative or absolute.

$myimage->Width = 100; //width of output image
$myimage->Height = 100; //height of output image
$myimage->Resize = true; //resize image before crop
$myimage->ResizeScale = 50; //between 1 and 100, 0 for no resizing before crop, 100 to shrink image completely before crop
$myimage->Position = 'center'; //can be 'center' (default), 'random', 'topleft', 'topcenter', 'topright', 'bottomleft', 'bottomcenter', 'bottomright','custom'
$myimage->CustomPositionX = 25; //0 to 100. Only needed it Position is 'custom'. This specifies the position of the Snapshot along the X axis, in percentage. 25, is 25% from the left.
$myimage->CustomPositiony = 35; //0 to 100. Only needed it Position is 'custom'. This specifies the position of the Snapshot along the Y axis, in percentage. 35, is 35% from the top.
$myimage->Compression = 80; //jpg compression level

//if you want to save as a file:
if ($myimage->SaveImageAs('temp.jpg')) {
echo '<img src="temp.jpg" border="0" width="' . $myimage->ReturnedWidth . '" height="' . $myimage->ReturnedHeight . '" alt="test" />';
} else {
echo $myimage->Err;
}

//OR if you want to get the contents into a variable:
if ($myimage->ProcessImage() !== false) {
$img = $myimage->GetImageContents();
} else {
echo $myimage->Err;
}




CHANGE LOG:
------------------------------------------------------
05-12-2005 1.3 Release
05-12-2005 Added: ImageFile field, can now load image from saved file.
05-12-2005 Added: custom position type, specify by percentages. Read updated manual for help with this.
28-11-2005 1.2 Release
28-11-2005 Added: ReturnedWidth and ReturnedHeight variables, for more feedback.
28-11-2005 Fixed: if crop area was bigger than original image, mixed results occured.
28-11-2005 1.1 Release
28-11-2005 Added: support for Image input with a variable
27-11-2005 1.0 Release

*/




class ImageSnapshot {

var $ImageField; // should be: $_FILES['imagefield'] array, OR set the next var.
var $ImageFile; // location of an image file saved on the server.
var $ImageContents; // Contents of an image in a variable.
var $Compression; // JPG compression. Default is 75%

var $Resize; //either true or false. wether to resize image, if true the uses the next 3 vars
var $ResizeScale; //scale to resize the image to. 100 is as small as possible, 0 is effectively no resizing at all.

var $Position; //position of the snapshot: random, center (default), topleft, topright, bottomleft, bottomright

var $Width; // width (or max width) of image to output
var $Height; // height (or max height) of image to output

var $Err; // error if (and when) they occur

var $InternalImage; // Internal variable for working with the image

var $ReturnedWidth; //New in 1.2: this is the actual width of the image returned, will only differ to Width if the original image was smaller.
var $ReturnedHeight; //New in 1.2: this is the actual height of the image returned, will only differ to Height if the original image was smaller.

var $CustomPositionX; //New in 1.3: 0 to 100, this is the percentage of the custom position along the X scale. $Position must be 'custom' for this to apply.
var $CustomPositionY; //New in 1.3: 0 to 100, this is the percentage of the custom position along the Y scale. $Position must be 'custom' for this to apply.


function ImageSnapshot() {
//set up some defaults
$this->Width = '800';
$this->Height = '600';
$this->Resize = true;
$this->ResizeScale = 100;
$this->Position = 'center';
$this->Err = '';
$this->Compression = 75;
$this->InternalImage = '';
$this->ImageContents = '';
$this->ReturnedWidth = 0; // New in 1.2
$this->ReturnedHeight = 0; // New in 1.2
$this->CustomPositionX = 50; // New in 1.3
$this->CustomPositionY = 50; // New in 1.3
}



function SaveImageAs($destination) {
//Saves the image to the desination. Returns true if successful, or false with Err specifying the error.
//example: $myimage->SaveImageAs("/docroot/images/newimage.jpg
if ($this->ProcessImage()) {

if (!$handle = fopen($destination, 'w')) {
$this->Err = 'Cannot open file (' . $destination . ')';
return false;
} else {
if (fwrite($handle, $this->InternalImage) === FALSE) {
$this->Err = 'Cannot write to file (' . $destination . ')';
return false;
} else {
return true;
}
fclose($handle);
}
} else {
return false;
}
}

function GetImageContents() {
// If not already processed, calls process image, and returns the contents for other manipulations or database entry.
if (strlen($this->InternalImage) == 0) {
$this->ProcessImage();
}
//return the contents of the variable.
return $this->InternalImage;
}

function ProcessImage() {
//Processes the image. Resize if needed. fills the internal image with the contents of the changed image.
//Internal function

if (strlen($this->ImageContents) > 0) {
//LOAD FROM STRING!
$tmp_image = @imagecreatefromstring($this->ImageContents);
//END LOAD FROM STRING

} elseif (strlen($this->ImageFile) > 0) {
//LOAD FROM FILE
//check that file exists
if (file_exists($this->ImageFile)) {
//load it!
$data = getimagesize($this->ImageFile); //[0] = w, [1] = h, [2] = type, [3] = attr
switch ($data[2]) {
case 1:
$tmp_image = @imagecreatefromgif($this->ImageFile);
break;
case 2:
$tmp_image = @imagecreatefromjpeg($this->ImageFile);
break;
case 3:
$tmp_image = @imagecreatefrompng($this->ImageFile);
break;
default:
$this->Err = 'File is not a valid image type';
return false;
exit;
break;
}
} else {
$this->Err = 'File "' . $this->ImageFile . '" does not exist!';
return false;
}
//END LOAD FROM FILE

} elseif (count($this->ImageField) > 0) {
//LOAD FROM FIELD FILE
//check that file exists
if (file_exists($this->ImageField['tmp_name'])) {
//load it!
$data = getimagesize($this->ImageField['tmp_name']); //[0] = w, [1] = h, [2] = type, [3] = attr
switch ($data[2]) {
case 1:
$tmp_image = @imagecreatefromgif($this->ImageField['tmp_name']);
break;
case 2:
$tmp_image = @imagecreatefromjpeg($this->ImageField['tmp_name']);
break;
case 3:
$tmp_image = @imagecreatefrompng($this->ImageField['tmp_name']);
break;
default:
$this->Err = 'File is not a valid image type';
return false;
exit;
break;
}
} else {
$this->Err = 'File "' . $this->ImageField['tmp_name'] . '" does not exist!';
return false;
}
//END LOAD FROM FILE

} else {
$this->Err = 'No image was loaded, use ImageFile, ImageContents or ImageField before output';
return false;
exit;
}

$image_width = imagesx($tmp_image);
$image_height = imagesy($tmp_image);

//check a div by zero error.
if ($this->Resize == true && $this->ResizeScale == 0) {
//there is no point resizing, when the scale doesn't change the size anyway.
$this->Resize = false;
}


//check if image is meant to be resized...
if ($this->Resize == 'true' || $this->Resize == 1) {
//Yes resize
if ($image_width > $this->Width && $image_height > $this->Height) {
//have to resize..
//get the proportional dimensions, while allowing room for a snapshot, and according to the resizescale
$w_ratio = $this->Width / ($image_width * ($this->ResizeScale / 100)); //width ratio.. ie: 0.1 = 80 / 800
$h_ratio = $this->Height / ($image_height * ($this->ResizeScale / 100)); //height ratio. ie: 0.075 = 60 / 800
$maxwidth = $this->Width; //maxwidth is the max width of the final snapshot
$maxheight = $this->Height; //maxheight is the max height of the final snapshot
if ($w_ratio < $h_ratio) {
$maxheight = ceil($image_height * $h_ratio);
$maxwidth = ceil($image_width * $h_ratio);
} else {
$maxwidth = ceil($image_width * $w_ratio);
$maxheight = ceil($image_height * $w_ratio);
}

//now we either have a correctly sized image (compared to the thumb) or an oversized image, that has been shrink and waiting to be snaopshot'd

$final_width = $maxwidth;
$final_height = $maxheight;
//end maintain aspect

imagecopyresampled($tmp_image, $tmp_image,0,0,0,0, $final_width, $final_height, $image_width, $image_height);

$image_width = $final_width;
$image_height = $final_height;

}

// end resize
}

//SNAPSHOT
//at this stage, $tmp_image should contain the image ready for snapshot.

if ($image_width < $this->Width) {
$this->Width = $image_width;
}
if ($image_height < $this->Height) {
$this->Height = $image_height;
}

//create canvas
$new_photo = imagecreatetruecolor($this->Width,$this->Height);
//set return values.
$this->ReturnedWidth = $this->Width;
$this->ReturnedHeight = $this->Height;

$source_y = 0;
$source_x = 0;

//we shall compare the snapshot dimensions to the image dimensions

switch ($this->Position) {
case 'random':
//my favourite, random place on the image.
if ($image_height > $this->Height) {
// height is larger.
//get the min and max room to play with
$min = 0;
$max = $image_height - $this->Height;
$source_y = rand($min,$max);
}
if ($image_width > $this->Width) {
// width is larger.
$min = 0;
$max = $image_width - $this->Width;
$source_x = rand($min,$max);
}
break;

case 'topright':
//topright of the image
$source_y = 0;
if ($image_width > $this->Width) {
// width is larger.
$source_x = $image_width - $this->Width;
}
break;

case 'topleft':
//topleft of the image
$source_y = 0;
$source_x = 0;
break;

case 'topcenter':
//topleft of the image
$source_y = 0;
if ($image_width > $this->Width) {
// width is larger.
$source_x = (($image_width - $this->Width) / 2);
}
break;

case 'bottomright':
//bottomright of the image
if ($image_height > $this->Height) {
// height is larger.
$source_y = $image_height - $this->Height;
}
if ($image_width > $this->Width) {
// width is larger.
$source_x = $image_width - $this->Width;
}
break;

case 'bottomleft':
//bottom left of the image
if ($image_height > $this->Height) {
// height is larger.
$source_y = $image_height - $this->Height;
}
$source_x = 0;
break;

case 'bottomcenter':
//bottom left of the image
if ($image_height > $this->Height) {
// height is larger.
$source_y = $image_height - $this->Height;
}
if ($image_width > $this->Width) {
// width is larger.
$source_x = (($image_width - $this->Width) / 2);
}
break;

case 'custom':
//new in 1.3
//use custom positions as percentages to get the position.
if (round($this->CustomPositionX) < 0 || round($this->CustomPositionX) > 100) {
//x not a valid number. Reset:
$this->CustomPositionX = 50;
}
if (round($this->CustomPositionY) < 0 || round($this->CustomPositionY) > 100) {
//y not a valid number. Reset:
$this->CustomPositionY = 50;
}

//get the digits!
if (round($this->CustomPositionY) == 0 || $image_height <= $this->Height) {
//does not meet credentials
$source_y = 0;
} else {
//ok
$source_y = (($image_height - $this->Height) * (round($this->CustomPositionY) / 100)) ;
}
if (round($this->CustomPositionX) == 0 || $image_width <= $this->Width) {
//does not meet credentials
$source_x = 0;
} else {
//ok
$source_x = (($image_width - $this->Width) * (round($this->CustomPositionX) / 100)) ;
}
break;

default:
//center of the image
if ($image_height > $this->Height) {
// height is larger.
$source_y = (($image_height - $this->Height) / 2);
}
if ($image_width > $this->Width) {
// width is larger.
$source_x = (($image_width - $this->Width) / 2);
}
break;
}

//copy specific portions of the image
imagecopyresampled($new_photo, $tmp_image,0,0,$source_x,$source_y, $this->Width, $this->Height, $this->Width, $this->Height);
ob_start();
imagejpeg($new_photo,null,$this->Compression);
$this->InternalImage = ob_get_contents();
ob_end_clean();
return true;
//END SNAPSHOT

}
}
?>

DISCLAIMER: The content provided in this article is not warranted or guaranteed by Developer Shed, Inc. The content provided is intended for entertainment and/or educational purposes in order to introduce to the reader key ideas, concepts, and/or product reviews. As such it is incumbent upon the reader to employ real-world tactics for security and implementation of best practices. We are not liable for any negative consequences that may result from implementing any information covered in our articles or tutorials. If this is a hardware review, it is not recommended to open and/or modify your hardware.

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