Image resize on the fly

  1. Requirements.
  2. How it’s works.
  3. Code
  4. What was it?


How it’s works.

For example have folder with image resources which are public accessible


Ordinary image displaying would be

<?php echo CHtml::image("/resoures/images/photos/album1/gh53.jpg"); ?>

If we want to get thumbnail of this picture we just have to change a bit url

<?php echo CHtml::image("/resources/thumbs/images/photos/album1/gh53.jpg_200x300.jpg"); ?>

Pretty simple? Isn't it?


To get this working we have to create new Controller with id resources and here is its code.

class ResourcesController extends Controller {
    public function actionThumbs() {
        $request = str_replace(DIRECTORY_SEPARATOR . 'thumbs', '', Yii::app()->request->requestUri);
        $resourcesPath = Yii::getPathOfAlias('webroot') . $request;
        $targetPath = Yii::getPathOfAlias('webroot') . Yii::app()->request->requestUri;
        if (preg_match('/_(\d+)x(\d+).*\.(jpg|jpeg|png|gif)/i', $resourcesPath, $matches)) {
            if (!isset($matches[0]) || !isset($matches[1]) || !isset($matches[2]) || !isset($matches[3]))
                throw new CHttpException(400, 'Non valid params');
            if (!$matches[1] || !$matches[2]) {
                throw new CHttpException(400, 'Invalid dimensions');
            $originalFile = str_replace($matches[0], '', $resourcesPath);
            if (!file_exists($originalFile))
                throw new CHttpException(404, 'File not found');
            $dirname = dirname($targetPath);
            if (!is_dir($dirname))
                mkdir($dirname, 0775, true);
            $image = Yii::app()->image->load($originalFile);
            $image->resize($matches[1], $matches[2]);
            if ($image->save($targetPath)) {
                if (Yii::app()->request->urlReferrer != Yii::app()->request->requestUri)
            throw new CHttpException(500, 'Server error');
        } else {
            throw new CHttpException(400, 'Wrong params');

What was it?

After first attempt to thumbnail /resources/thumbs/images/photos/album1/gh53.jpg_200x300.jpg — thumb action will be triggered because file won’t found on disk.

Script will try to find location of the original source file here /resources/images/photos/album1/gh53.jpg

If source file exists it will be resized and stored here /resources/thumbs/images/photos/album1/gh53.jpg_200x300.jpg

Then script will refresh the url page and after that browser will open newly created thumbnail file directly from disk!

Quite easy!

You can extend this script to support only list of dimensions to avoid disk overflow.

That is all.

Comments are appreciated. Thanks.

PS If you are using Nginx and you want to encrease speed of this script you could use

header("X-Accel-Redirect: /resources/images****");

instead of refresh.