Image

Image files can be stored either through the [api:Image] dataobject, or though [api:DBFile] fields. In either case, the same image resizing and manipulation functionality is available though the common [api:ImageManipulation] trait.

Usage

Managing images through form fields

Images can be uploaded like any other file, through [api:FileField]. Allows upload of images through limiting file extensions with setAllowedExtensions().

Inserting images into the WYSIWYG editor

Images can be inserted into [api:HTMLValue] database fields through the built-in WYSIWYG editor. In order to retain a relationship to the underlying [api:Image] records, images are saved as shortcodes. The shortcode ([image id="<id>" alt="My text" ...]) will be converted into an <img> tag on your website automatically.

See HTMLEditorField.

Manipulating images in Templates

You can manipulate images directly from templates to create images that are resized and cropped to suit your needs. This doesn't affect the original image or clutter the CMS with any additional files, and any images you create in this way are cached for later use. In most cases the pixel aspect ratios of images are preserved (meaning images are not stretched).

Here are some examples, assuming the $Image object has dimensions of 200x100px:

:::ss
// Scaling functions
$Image.ScaleWidth(150) // Returns a 150x75px image
$Image.ScaleMaxWidth(100) // Returns a 100x50px image (like ScaleWidth but prevents up-sampling)
$Image.ScaleHeight(150) // Returns a 300x150px image (up-sampled. Try to avoid doing this)
$Image.ScaleMaxHeight(150) // Returns a 200x100px image (like ScaleHeight but prevents up-sampling)
$Image.Fit(300,300) // Returns an image that fits within a 300x300px boundary, resulting in a 300x150px image (up-sampled)
$Image.FitMax(300,300) // Returns a 200x100px image (like Fit but prevents up-sampling)

// Warning: This method can distort images that are not the correct aspect ratio
$Image.ResizedImage(200, 300) // Forces dimensions of this image to the given values.

// Cropping functions
$Image.Fill(150,150) // Returns a 150x150px image resized and cropped to fill specified dimensions (up-sampled)
$Image.FillMax(150,150) // Returns a 100x100px image (like Fill but prevents up-sampling)
$Image.CropWidth(150) // Returns a 150x100px image (trims excess pixels off the x axis from the center)
$Image.CropHeight(50) // Returns a 200x50px image (trims excess pixels off the y axis from the center)

// Padding functions (add space around an image)
$Image.Pad(100,100) // Returns a 100x100px padded image, with white bars added at the top and bottom
$Image.Pad(100, 100, CCCCCC) // Same as above but with a grey background

// Metadata
$Image.Width // Returns width of image
$Image.Height // Returns height of image
$Image.Orientation // Returns Orientation
$Image.Title // Returns the friendly file name
$Image.Name // Returns the actual file name
$Image.FileName // Returns the actual file name including directory path from web root
$Image.Link // Returns relative URL path to image
$Image.AbsoluteLink // Returns absolute URL path to image

Image methods are chainable. Example:

:::ss
<body style="background-image:url($Image.ScaleWidth(800).CropHeight(800).Link)">

Padded Image Resize

The Pad method allows you to resize an image with existing ratio and will pad any surplus space. You can specify the color of the padding using a hex code such as FFFFFF or 000000.

You can also specify a level of transparency to apply to the padding color in a fourth param. This will only effect png images.

:::php
$Image.Pad(80, 80, FFFFFF, 50) // white padding with 50% transparency
$Image.Pad(80, 80, FFFFFF, 100) // white padding with 100% transparency
$Image.Pad(80, 80, FFFFFF) // white padding with no transparency

Manipulating images in PHP

The image manipulation functions can be used in your code with the same names, example: $image->Fill(150,150).

Some of the MetaData functions need to be prefixed with 'get', example getHeight(), getOrientation() etc.

Please refer to the [api:ImageManipulation] API documentation for specific functions.

Creating custom image functions

You can also create your own functions by decorating the Image class.

:::php
class MyImage extends DataExtension {
	
	public function Landscape()	{
		return $this->owner->getWidth() > $this->owner->getHeight();
	}
	
	public function Portrait() {
		return $this->owner->getWidth() < $this->owner->getHeight();
	}
	
	public function PerfectSquare()	{
		$variant = $this->owner->variantName(__FUNCTION__);
		return $this->owner->manipulateImage($variant, function(Image_Backend $backend) {
		return $backend->croppedResize(100,100);
		});
	}
	
	public function Exif(){
		//http://www.v-nessa.net/2010/08/02/using-php-to-extract-image-exif-data
		$mime = $this->owner->getMimeType();
		$content = $this->owner->getAsString();
		$image = "data://{$mime};base64," . base64_encode($content);
		$d=new ArrayList();	
		$exif = exif_read_data($image, 0, true);
		foreach ($exif as $key => $section) {
			$a=new ArrayList();	
			foreach ($section as $name => $val) {
				$a->push(new ArrayData(array(
					"Title"=>$name,
					"Content"=>$val
				)));
		}
			$d->push(new ArrayData(array(
				"Title"=>strtolower($key),
				"Content"=>$a
			)));
		}
		return $d;
	}
}

:::yml
Image:
  extensions:
    - MyImage
SilverStripe\Filesystem\Storage\DBFile:
  extensions:
    - MyImage

Form Upload

For usage on a website form, see [api:FileField].

Image Quality

To adjust the quality of the generated images when they are resized add the following to your mysite/config/config.yml file:

:::yml
GDBackend:
  default_quality: 90
# or
ImagickBackend:
  default_quality: 90

The default value is 75.

By default SilverStripe image functions will not resample an image if no cropping or resizing is taking place. You can tell SilverStripe to always to always produce resampled output by adding this to your mysite/config/config.yml file:

:::yml
# Configure resampling for File dataobject
File:
  force_resample: true
# DBFile can be configured independently
SilverStripe\Filesystem\Storage\DBFile:
  force_resample: true

If you are intending to resample images with SilverStripe it is good practice to upload high quality (minimal compression) images as these will produce better results when resampled. Very high resolution images may cause GD to crash so a good size for website images is around 2000px on the longest edge.

API Documentation

[api:File]
[api:Image]
[api:DBFile]
[api:ImageManipulation]

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