Resize images on upload - silverstripe

Question

How it would be possible to resize the images when uploading them?
There exists i.e. the function:
$image->resizeByWidth(width)
Where it can be implemented for having a resizing of the images
which are uploaded?
How could it be added to the following example of upload:
class GalleryPage extends Page {
private static $many_many = array(
'GalleryImages' => 'Image'
);
function getCMSFields() {
$fields = parent::getCMSFields();
$fields->addFieldToTab(
'Root.Upload',
$uploadField = new UploadField(
$name = 'GalleryImages',
$title = 'Upload one or more images (max 10 in total)'
)
);
$uploadField->setAllowedMaxFileNumber(10);
return $fields;
}
Thank you

Answer 1

It's done automatically by the CMS. When you go to use the image in your template, you tell it the dimensions, and it will be resized as soon as you save or publish (if it hasn't been already)

Answer 2

If you're concerned about disk space from your CMS users uploading RAW files e.g. 5MB JPGs, then you can actually resample on upload as asked in your question and then further resize as needed within your templates.
If you're using SilverStripe 2.4+ then you could use this ResampleUpload extension. It resamples the image on upload and deletes the original.
If you're using SilverStripe 3+ then you'd need to change the above extension to extend DataExtension instead of DataObjectDecorator. I've not used this under SS3 myself so there may be other minor tweaks required but looking at it I can't see any changes needed as it's modifying the onAfterUpload and onAfterWrite methods which still exist on the Image class in SS 3.

Answer 3

As stated before, no out of box functionality for this in SS 3. This mod offers the solution you're looking for though: https://github.com/heyday/silverstripe-optimisedimage
First Install the mod in root.
Then write the code below in your mysite/_config/config.yml to activate image resampling (resizing).
Image:
extensions:
- ResampleImage
In the same config.yml file, write the max resolution (x = width, y = height obviously). If user uploads a bigger res photo, it will be scaled down (maintaining aspect ratio) to fit within the given max res dimensions.
ResampleImage:
max_x: 2000
max_y: 2000