Image toolkits
Drupal's image toolkits provide an abstraction layer for common image file manipulations like scaling, cropping, and rotating. The abstraction frees module authors from the need to support multiple image libraries, and it allows site administrators to choose the library that's best for them.
PHP includes the GD library by default so a GD toolkit is installed with Drupal. Other toolkits like ImageMagic are available from contrib modules. GD works well for small images, but using it with larger files may cause PHP to run out of memory. In contrast the ImageMagick library does not suffer from this problem, but it requires the ISP to have installed additional software.
Image toolkits are discovered based on the associated module's hook_image_toolkits. Additionally the image toolkit include file must be identified in the files array in the module.info file. The toolkit must then be enabled using the admin/settings/image-toolkit form.
Only one toolkit may be selected at a time. If a module author wishes to call a specific toolkit they can check that it is installed by calling image_get_available_toolkits(), and then calling its functions directly.
Functions
Name | Location | Description |
|---|---|---|
| image_crop | includes/image.inc | Crop an image to the rectangle specified by the given rectangle. |
| image_get_available_toolkits | includes/image.inc | Return a list of available toolkits. |
| image_get_info | includes/image.inc | Get details about an image. |
| image_get_toolkit | includes/image.inc | Retrieve the name of the currently used toolkit. |
| image_resize | includes/image.inc | Resize an image to the given dimensions (ignoring aspect ratio). |
| image_rotate | includes/image.inc | Rotate an image by the given number of degrees. |
| image_scale | includes/image.inc | Scales an image to the given width and height while maintaining aspect ratio. |
| image_scale_and_crop | includes/image.inc | Scales an image to the exact width and height given. Achieves the target aspect ratio by cropping the original image equally on both sides, or equally on the top and bottom. This function is, for example, useful to create uniform sized avatars from... |
| image_toolkit_invoke | includes/image.inc | Invokes the given method using the currently selected toolkit. |