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Aspect Ratios with .jpg Files - Help!

I'm trying to figure out how to write some php code that will allow me to resize a .jpg image and maintain it's aspect ratio - I'd like to change it's width and height yet not make it look too streched in one direction or the other - any help or idea's would be appreciated.

Thanks...

DoppyNL

If you only want to display the image smaller (ie: not create a new image) then this code can be informing:

$size = get_image_size('filename'); // manualpage: http://www.php.net/get_image_size

$size[0] contains width of the image (200)
$size[1] contains height of the image (300)
$size[2] contains flag for imagetype (see manual page)
$size[3] contains string you can use in html (height="yyy" width="xxx")

using the info from $size[0] and $size[1] you can set the width and height in your html.

if you want to actually create a new image; you will have to use the GD library, in wich case someone else will have to help you :-/

intrwrks

Here is a function that will resize your images for you.

$image_file_path = path and name to the image you are wanting to resize.
$new_image_file_path = path and name that you want to save the image to. This directory will need write permissions.
$max_width = the maximum size you want the width to be.
$max_height = the maximum size you want the height to be.

Specify either the width or the height and it will adjust the other one to the size it should be.

function resize_jpeg( $image_file_path, $new_image_file_path, $max_width=1600, $max_height=1600 )
{

$return_val = 1;

$return_val = ( ($img = ImageCreateFromJPEG ( $image_file_path )) && $return_val == 1 ) ? "1" : "0";

$FullImage_width = imagesx ($img); // Original image width
$FullImage_height = imagesy ($img); // Original image height

// now we check for over-sized images and pare them down
// to the dimensions we need for display purposes
$ratio = ( $FullImage_width > $max_width ) ? (real)($max_width / $FullImage_width) : 1 ;
$new_width = ((int)($FullImage_width * $ratio)); //full-size width
$new_height = ((int)($FullImage_height * $ratio)); //full-size height
//check for images that are still too high
$ratio = ( $new_height > $max_height ) ? (real)($max_height / $new_height) : 1 ;
$new_width = ((int)($new_width * $ratio)); //mid-size width
$new_height = ((int)($new_height * $ratio)); //mid-size height

// --Start Full Creation, Copying--
// now, before we get silly and 'resize' an image that doesn't need it...
if ( $new_width == $FullImage_width && $new_height == $FullImage_height )
copy ( $image_file_path, $new_image_file_path );

$full_id = ImageCreateTrueColor( $new_width , $new_height ); //create an image
ImageCopyResized( $full_id, $img,
0,0, 0,0, //starting points
$new_width, $new_height,
$FullImage_width, $FullImage_height );
$return_val = ( $full = ImageJPEG( $full_id, $new_image_file_path, 80 )
&& $return_val == 1 ) ? "1" : "0";
ImageDestroy( $full_id );
// --End Creation, Copying--

return ($return_val) ? TRUE : FALSE ;

}

rfresh

ASKER

intrwrks -

Can you give me an example of how I would call this function? It looks like I need to be using some kind of image object to receive the function value? How would this syntax look in PHP?

Thanks...

intrwrks

You can use any image that is accessible by your webserver. In the example below I have a JPEG in an images directory called img1.jpg. I want to create a thumbnail of that image that is no wider or higher than 50. I am going to save that image to the images directory as img_thumb.jpg.

The original file that I used as an example was 1152 x 1767. The new thumbnail image that was output was 32 x 50.

// the file to be created
$imgthumb = "images/img_thumb.jpg";

// call the function and get the return value... either true or false
$result = resize_jpeg("images/img1.jpg", $imgthumb, 50, 50);
?>

<html>
<head>
<title>Image Resized</title>
</head>

<body>

<?php
// if the image was successfully resized... show it.
if($result)
echo "<img src=\"$imgthumb\">";
?>

</body>
</html>

intrwrks

BTW: The newer version of PHP has more security and the above function will not over-write a file that already exists. You will need to add something like this to the above example before you call the resize_jpeg() function:

if (file_exists($imgthumb))
unlink($imgthumb);

rfresh

ASKER

I see - I'm sorry I didn't clarify in my orignal post - I don't want to actually create a new file on the sever, I need to reduce the size of the image so I can use it as a small 'thumbnail' image on an html page inside <TR><TD> tags - so in other words, the smaller image is a temp just for the thumbnail display on the web page - while the original image *is* on the server, I don't want to write additonal images on the server for this thumbnail purpose - I'd prefer to just generate the smaller image on the fly - I think we're very close eh?

Thanks...

intrwrks

Try this... Instead of using a function, like above, you will need to have the code that resizes the jpeg in its own file.

+++++ Code to resize jpeg - makethumb.php
<?php
$max_height = 100;
$max_width = 100;
$image_file_path = $file;

$img = ImageCreateFromJPEG ( $image_file_path );

$FullImage_width = imagesx ($img); // Original image width
$FullImage_height = imagesy ($img); // Original image height

// now we check for over-sized images and pare them down
// to the dimensions we need for display purposes
$ratio = ( $FullImage_width > $max_width ) ? (real)($max_width / $FullImage_width) : 1 ;
$new_width = ((int)($FullImage_width * $ratio)); //full-size width
$new_height = ((int)($FullImage_height * $ratio)); //full-size height

//check for images that are still too high
$ratio = ( $new_height > $max_height ) ? (real)($max_height / $new_height) : 1 ;
$new_width = ((int)($new_width * $ratio)); //mid-size width
$new_height = ((int)($new_height * $ratio)); //mid-size height

$full_id = ImageCreateTrueColor( $new_width , $new_height ); //create an image
ImageCopyResized( $full_id, $img,
0,0, 0,0, //starting points
$new_width, $new_height,
$FullImage_width, $FullImage_height );
ImageJPEG( $full_id );
ImageDestroy( $full_id );
ImageDestroy( $img );
?>

++++ PHP File that will show the image - index.php
<html>
<head>
<title>Image Resized</title>
</head>

<body>

<?php
echo "<img src=\"makethumb.php?file=images/img1.jpg\" border=\"0\">";
?>

</body>
</html>

rfresh

ASKER

I can't get the <img tag line to work:

echo "<img src=\"makethumb.php?file=images/img1.jpg\" border=\"0\">";

In your makethumb.php file don't you have to use $_GET[] to grab the filename argument? How does makethumb.php know what '$file' is in makethumb.php:

$image_file_path = $file;

I tried adding the $_GET["file"] statement and put a print statement below it but it printed nothing so the filename isn't getting passed to makethumb.php for some reason. I'm calling it from a different .php file which is OK I think. I checked the name of my image on the sever and the filename is correct and I added a print statement in my calling .php file just before the <img tag and the filename is OK - I'm using a folder called 'uploads' but I made that change so that should not matter.

I'm sorry I can't follow your code that well - I've been programming in PHP for only 6 months.

Thanks...

intrwrks

Yes, it is appropriate and recommended that you use $_GET[]. Make sure you use single quotes $_GET['file'] and not the double quotes.

$image_file_path = $_GET['file'];

rfresh

ASKER

This line is not being called for some reason - I have a print statement in makethumb.php and it's not displaying the test message - so that means makethumb.php is not getting called -

echo "<img src=\"makethumb.php?file=uploads/ferris wheel.jpg\" border=\"0\">";

Other than a different image folder and filename, it's the same line as what you provided in your makethumb.php file.

Got any idea why it isn't callng makethumb.php ?

Thanks....

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intrwrks

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