Architecture

Diagram shows basic architecture of Crop.

Components

Entity

• Crop is entity that stores various information related to the crop area.
• CropType is Crop entity bundle.

Plugin

• CropEffect applies crop to the image using information from the crop entity.

The "Manual Crop Effect" effect uses two parameters, uri and crop_type to get crop associated with the image.

• "uri" is an important property because it is the only contextual information available when you apply the effect (manual crop) to the image.
• "crop_type" makes linking between Crop entity and image possible, and it makes the difference between several crop types on the same image.

Limitation: Due to limitations in Drupal core we're currently not able to handle the case where one image would have several crops of the same crop type. The oldest crop will be used in such case.

See Crop API supports multiple issues for more information.

Focus on properties of crop entity

Crop entity base fields (explained):

• type This is the machine name of the corresponding crop type used by this entity, it works exactly like as "Node" and "NodeType".
• entity_id ID of the entity crop relates to. "fid" when entity is a file.
• entity_type This is the type of crop on which the entity is linked.
• uri URI of the image that is cropped.
• x Position of top left corner of the crop area on x-axis.
• y Position of top left corner of the crop area on y-axis.
• width Width of the crop area.
• height Height of the crop area.