Image Manipulation Class
************************

CodeIgniter’s Image Manipulation class lets you perform the following
actions:

* Image Resizing

* Thumbnail Creation

* Image Cropping

* Image Rotating

* Image Watermarking

All three major image libraries are supported: GD/GD2, NetPBM, and
ImageMagick

Note:

  Watermarking is only available using the GD/GD2 library. In
  addition, even though other libraries are supported, GD is required
  in order for the script to calculate the image properties. The image
  processing, however, will be performed with the library you specify.

* Initializing the Class

  * Processing an Image

  * Processing Methods

  * Preferences

  * Setting preferences in a config file

* Image Watermarking

  * Two Types of Watermarking

  * Watermarking an Image

  * Watermarking Preferences

    * Text Preferences

    * Overlay Preferences

* Class Reference


Initializing the Class
======================

Like most other classes in CodeIgniter, the image class is initialized
in your controller using the $this->load->library function:

   $this->load->library('image_lib');

Once the library is loaded it will be ready for use. The image library
object you will use to call all functions is: "$this->image_lib"


Processing an Image
-------------------

Regardless of the type of processing you would like to perform
(resizing, cropping, rotation, or watermarking), the general process
is identical. You will set some preferences corresponding to the
action you intend to perform, then call one of four available
processing functions. For example, to create an image thumbnail you’ll
do this:

   $config['image_library'] = 'gd2';
   $config['source_image'] = '/path/to/image/mypic.jpg';
   $config['create_thumb'] = TRUE;
   $config['maintain_ratio'] = TRUE;
   $config['width']         = 75;
   $config['height']       = 50;

   $this->load->library('image_lib', $config);

   $this->image_lib->resize();

The above code tells the image_resize function to look for an image
called *mypic.jpg* located in the source_image folder, then create a
thumbnail that is 75 X 50 pixels using the GD2 image_library. Since
the maintain_ratio option is enabled, the thumb will be as close to
the target width and height as possible while preserving the original
aspect ratio. The thumbnail will be called *mypic_thumb.jpg* and
located at the same level as *source_image*.

Note:

  In order for the image class to be allowed to do any processing, the
  folder containing the image files must have write permissions.

Note:

  Image processing can require a considerable amount of server memory
  for some operations. If you are experiencing out of memory errors
  while processing images you may need to limit their maximum size,
  and/or adjust PHP memory limits.


Processing Methods
------------------

There are four available processing methods:

* $this->image_lib->resize()

* $this->image_lib->crop()

* $this->image_lib->rotate()

* $this->image_lib->watermark()

These methods return boolean TRUE upon success and FALSE for failure.
If they fail you can retrieve the error message using this function:

   echo $this->image_lib->display_errors();

A good practice is to use the processing function conditionally,
showing an error upon failure, like this:

   if ( ! $this->image_lib->resize())
   {
           echo $this->image_lib->display_errors();
   }

Note:

  You can optionally specify the HTML formatting to be applied to the
  errors, by submitting the opening/closing tags in the function, like
  this:

     $this->image_lib->display_errors('<p>', '</p>');


Preferences
-----------

The preferences described below allow you to tailor the image
processing to suit your needs.

Note that not all preferences are available for every function. For
example, the x/y axis preferences are only available for image
cropping. Likewise, the width and height preferences have no effect on
cropping. The “availability” column indicates which functions support
a given preference.

Availability Legend:

* R - Image Resizing

* C - Image Cropping

* X - Image Rotation

* W - Image Watermarking

+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| Preference              | Default Value           | Options                         | Description                                                                 | Availability  |
|=========================|=========================|=================================|=============================================================================|===============|
| **image_library**       | GD2                     | GD, GD2, ImageMagick, NetPBM    | Sets the image library to be used.                                          | R, C, X, W    |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **library_path**        | None                    | None                            | Sets the server path to your ImageMagick or NetPBM library. If you use      | R, C, X R, C, |
|                         |                         |                                 | either of those libraries you must supply the path.                         | S, W          |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **source_image**        | None                    | None                            | Sets the source image name/path. The path must be a relative or absolute    |               |
|                         |                         |                                 | server path, not a URL.                                                     |               |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **dynamic_output**      | FALSE                   | TRUE/FALSE (boolean)            | Determines whether the new image file should be written to disk or          | R, C, X, W    |
|                         |                         |                                 | generated dynamically. Note: If you choose the dynamic setting, only one    |               |
|                         |                         |                                 | image can be shown at a time, and it can’t be positioned on the page. It    |               |
|                         |                         |                                 | simply outputs the raw image dynamically to your browser, along with image  |               |
|                         |                         |                                 | headers.                                                                    |               |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **file_permissions**    | 0644                    | (integer)                       | File system permissions to apply on the resulting image file, writing it to | R, C, X, W    |
|                         |                         |                                 | the disk. WARNING: Use octal integer notation!                              |               |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **quality**             | 90%                     | 1 - 100%                        | Sets the quality of the image. The higher the quality the larger the file   | R, C, X, W    |
|                         |                         |                                 | size.                                                                       |               |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **new_image**           | None                    | None                            | Sets the destination image name/path. You’ll use this preference when       | R, C, X, W    |
|                         |                         |                                 | creating an image copy. The path must be a relative or absolute server      |               |
|                         |                         |                                 | path, not a URL.                                                            |               |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **width**               | None                    | None                            | Sets the width you would like the image set to.                             | R, C          |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **height**              | None                    | None                            | Sets the height you would like the image set to.                            | R, C          |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **create_thumb**        | FALSE                   | TRUE/FALSE (boolean)            | Tells the image processing function to create a thumb.                      | R             |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **thumb_marker**        | _thumb                  | None                            | Specifies the thumbnail indicator. It will be inserted just before the file | R             |
|                         |                         |                                 | extension, so mypic.jpg would become mypic_thumb.jpg                        |               |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **maintain_ratio**      | TRUE                    | TRUE/FALSE (boolean)            | Specifies whether to maintain the original aspect ratio when resizing or    | R, C          |
|                         |                         |                                 | use hard values.                                                            |               |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **master_dim**          | auto                    | auto, width, height             | Specifies what to use as the master axis when resizing or creating thumbs.  | R             |
|                         |                         |                                 | For example, let’s say you want to resize an image to 100 X 75 pixels. If   |               |
|                         |                         |                                 | the source image size does not allow perfect resizing to those dimensions,  |               |
|                         |                         |                                 | this setting determines which axis should be used as the hard value. “auto” |               |
|                         |                         |                                 | sets the axis automatically based on whether the image is taller than       |               |
|                         |                         |                                 | wider, or vice versa.                                                       |               |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **rotation_angle**      | None                    | 90, 180, 270, vrt, hor          | Specifies the angle of rotation when rotating images. Note that PHP rotates | X             |
|                         |                         |                                 | counter-clockwise, so a 90 degree rotation to the right must be specified   |               |
|                         |                         |                                 | as 270.                                                                     |               |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **x_axis**              | None                    | None                            | Sets the X coordinate in pixels for image cropping. For example, a setting  | C             |
|                         |                         |                                 | of 30 will crop an image 30 pixels from the left.                           |               |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+
| **y_axis**              | None                    | None                            | Sets the Y coordinate in pixels for image cropping. For example, a setting  | C             |
|                         |                         |                                 | of 30 will crop an image 30 pixels from the top.                            |               |
+-------------------------+-------------------------+---------------------------------+-----------------------------------------------------------------------------+---------------+


Setting preferences in a config file
------------------------------------

If you prefer not to set preferences using the above method, you can
instead put them into a config file. Simply create a new file called
image_lib.php, add the $config array in that file. Then save the file
in *config/image_lib.php* and it will be used automatically. You will
NOT need to use the "$this->image_lib->initialize()" method if you
save your preferences in a config file.


Image Watermarking
==================

The Watermarking feature requires the GD/GD2 library.


Two Types of Watermarking
-------------------------

There are two types of watermarking that you can use:

* **Text**: The watermark message will be generated using text, either
  with a True Type font that you specify, or using the native text
  output that the GD library supports. If you use the True Type
  version your GD installation must be compiled with True Type support
  (most are, but not all).

* **Overlay**: The watermark message will be generated by overlaying
  an image (usually a transparent PNG or GIF) containing your
  watermark over the source image.


Watermarking an Image
---------------------

Just as with the other methods (resizing, cropping, and rotating) the
general process for watermarking involves setting the preferences
corresponding to the action you intend to perform, then calling the
watermark function. Here is an example:

   $config['source_image'] = '/path/to/image/mypic.jpg';
   $config['wm_text'] = 'Copyright 2006 - John Doe';
   $config['wm_type'] = 'text';
   $config['wm_font_path'] = './system/fonts/texb.ttf';
   $config['wm_font_size'] = '16';
   $config['wm_font_color'] = 'ffffff';
   $config['wm_vrt_alignment'] = 'bottom';
   $config['wm_hor_alignment'] = 'center';
   $config['wm_padding'] = '20';

   $this->image_lib->initialize($config);

   $this->image_lib->watermark();

The above example will use a 16 pixel True Type font to create the
text “Copyright 2006 - John Doe”. The watermark will be positioned at
the bottom/center of the image, 20 pixels from the bottom of the
image.

Note:

  In order for the image class to be allowed to do any processing, the
  image file must have “write” file permissions For example, 777.


Watermarking Preferences
------------------------

This table shows the preferences that are available for both types of
watermarking (text or overlay)

+-------------------------+---------------------+-------------------------+----------------------------------------------------------------------------+
| Preference              | Default Value       | Options                 | Description                                                                |
|=========================|=====================|=========================|============================================================================|
| **wm_type**             | text                | text, overlay           | Sets the type of watermarking that should be used.                         |
+-------------------------+---------------------+-------------------------+----------------------------------------------------------------------------+
| **source_image**        | None                | None                    | Sets the source image name/path. The path must be a relative or absolute   |
|                         |                     |                         | server path, not a URL.                                                    |
+-------------------------+---------------------+-------------------------+----------------------------------------------------------------------------+
| **dynamic_output**      | FALSE               | TRUE/FALSE (boolean)    | Determines whether the new image file should be written to disk or         |
|                         |                     |                         | generated dynamically. Note: If you choose the dynamic setting, only one   |
|                         |                     |                         | image can be shown at a time, and it can’t be positioned on the page. It   |
|                         |                     |                         | simply outputs the raw image dynamically to your browser, along with image |
|                         |                     |                         | headers.                                                                   |
+-------------------------+---------------------+-------------------------+----------------------------------------------------------------------------+
| **quality**             | 90%                 | 1 - 100%                | Sets the quality of the image. The higher the quality the larger the file  |
|                         |                     |                         | size.                                                                      |
+-------------------------+---------------------+-------------------------+----------------------------------------------------------------------------+
| **wm_padding**          | None                | A number                | The amount of padding, set in pixels, that will be applied to the          |
|                         |                     |                         | watermark to set it away from the edge of your images.                     |
+-------------------------+---------------------+-------------------------+----------------------------------------------------------------------------+
| **wm_vrt_alignment**    | bottom              | top, middle, bottom     | Sets the vertical alignment for the watermark image.                       |
+-------------------------+---------------------+-------------------------+----------------------------------------------------------------------------+
| **wm_hor_alignment**    | center              | left, center, right     | Sets the horizontal alignment for the watermark image.                     |
+-------------------------+---------------------+-------------------------+----------------------------------------------------------------------------+
| **wm_hor_offset**       | None                | None                    | You may specify a horizontal offset (in pixels) to apply to the watermark  |
|                         |                     |                         | position. The offset normally moves the watermark to the right, except if  |
|                         |                     |                         | you have your alignment set to “right” then your offset value will move    |
|                         |                     |                         | the watermark toward the left of the image.                                |
+-------------------------+---------------------+-------------------------+----------------------------------------------------------------------------+
| **wm_vrt_offset**       | None                | None                    | You may specify a vertical offset (in pixels) to apply to the watermark    |
|                         |                     |                         | position. The offset normally moves the watermark down, except if you have |
|                         |                     |                         | your alignment set to “bottom” then your offset value will move the        |
|                         |                     |                         | watermark toward the top of the image.                                     |
+-------------------------+---------------------+-------------------------+----------------------------------------------------------------------------+


Text Preferences
~~~~~~~~~~~~~~~~

This table shows the preferences that are available for the text type
of watermarking.

+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+
| Preference              | Default Value       | Options             | Description                                                                |
|=========================|=====================|=====================|============================================================================|
| **wm_text**             | None                | None                | The text you would like shown as the watermark. Typically this will be a   |
|                         |                     |                     | copyright notice.                                                          |
+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+
| **wm_font_path**        | None                | None                | The server path to the True Type Font you would like to use. If you do not |
|                         |                     |                     | use this option, the native GD font will be used.                          |
+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+
| **wm_font_size**        | 16                  | None                | The size of the text. Note: If you are not using the True Type option      |
|                         |                     |                     | above, the number is set using a range of 1 - 5. Otherwise, you can use    |
|                         |                     |                     | any valid pixel size for the font you’re using.                            |
+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+
| **wm_font_color**       | ffffff              | None                | The font color, specified in hex. Both the full 6-length (ie, 993300) and  |
|                         |                     |                     | the short three character abbreviated version (ie, fff) are supported.     |
+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+
| **wm_shadow_color**     | None                | None                | The color of the drop shadow, specified in hex. If you leave this blank a  |
|                         |                     |                     | drop shadow will not be used. Both the full 6-length (ie, 993300) and the  |
|                         |                     |                     | short three character abbreviated version (ie, fff) are supported.         |
+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+
| **wm_shadow_distance**  | 3                   | None                | The distance (in pixels) from the font that the drop shadow should appear. |
+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+


Overlay Preferences
~~~~~~~~~~~~~~~~~~~

This table shows the preferences that are available for the overlay
type of watermarking.

+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+
| Preference              | Default Value       | Options             | Description                                                                |
|=========================|=====================|=====================|============================================================================|
| **wm_overlay_path**     | None                | None                | The server path to the image you wish to use as your watermark. Required   |
|                         |                     |                     | only if you are using the overlay method.                                  |
+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+
| **wm_opacity**          | 50                  | 1 - 100             | Image opacity. You may specify the opacity (i.e. transparency) of your     |
|                         |                     |                     | watermark image. This allows the watermark to be faint and not completely  |
|                         |                     |                     | obscure the details from the original image behind it. A 50% opacity is    |
|                         |                     |                     | typical.                                                                   |
+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+
| **wm_x_transp**         | 4                   | A number            | If your watermark image is a PNG or GIF image, you may specify a color on  |
|                         |                     |                     | the image to be “transparent”. This setting (along with the next) will     |
|                         |                     |                     | allow you to specify that color. This works by specifying the “X” and “Y”  |
|                         |                     |                     | coordinate pixel (measured from the upper left) within the image that      |
|                         |                     |                     | corresponds to a pixel representative of the color you want to be          |
|                         |                     |                     | transparent.                                                               |
+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+
| **wm_y_transp**         | 4                   | A number            | Along with the previous setting, this allows you to specify the coordinate |
|                         |                     |                     | to a pixel representative of the color you want to be transparent.         |
+-------------------------+---------------------+---------------------+----------------------------------------------------------------------------+


Class Reference
===============

class CI_Image_lib

   initialize([$props = array()])

      Parameters:
         * **$props** ("array") – Image processing preferences

      Returns:
         TRUE on success, FALSE in case of invalid settings

      Return type:
         "bool"

      Initializes the class for processing an image.

   resize()

      Returns:
         TRUE on success, FALSE on failure

      Return type:
         "bool"

      The image resizing method lets you resize the original image,
      create a copy (with or without resizing), or create a thumbnail
      image.

      For practical purposes there is no difference between creating a
      copy and creating a thumbnail except a thumb will have the
      thumbnail marker as part of the name (i.e. mypic_thumb.jpg).

      All preferences listed in the Preferences table are available
      for this method except these three: *rotation_angle*, *x_axis*
      and *y_axis*.

      **Creating a Thumbnail**

      The resizing method will create a thumbnail file (and preserve
      the original) if you set this preference to TRUE:

         $config['create_thumb'] = TRUE;

      This single preference determines whether a thumbnail is created
      or not.

      **Creating a Copy**

      The resizing method will create a copy of the image file (and
      preserve the original) if you set a path and/or a new filename
      using this preference:

         $config['new_image'] = '/path/to/new_image.jpg';

      Notes regarding this preference:

      * If only the new image name is specified it will be placed in
        the same folder as the original

      * If only the path is specified, the new image will be placed in
        the destination with the same name as the original.

      * If both the path and image name are specified it will placed
        in its own destination and given the new name.

      **Resizing the Original Image**

      If neither of the two preferences listed above (create_thumb,
      and new_image) are used, the resizing method will instead target
      the original image for processing.

   crop()

      Returns:
         TRUE on success, FALSE on failure

      Return type:
         "bool"

      The cropping method works nearly identically to the resizing
      function except it requires that you set preferences for the X
      and Y axis (in pixels) specifying where to crop, like this:

         $config['x_axis'] = 100;
         $config['y_axis'] = 40;

      All preferences listed in the Preferences table are available
      for this method except these: *rotation_angle*, *create_thumb*
      and *new_image*.

      Here’s an example showing how you might crop an image:

         $config['image_library'] = 'imagemagick';
         $config['library_path'] = '/usr/X11R6/bin/';
         $config['source_image'] = '/path/to/image/mypic.jpg';
         $config['x_axis'] = 100;
         $config['y_axis'] = 60;

         $this->image_lib->initialize($config);

         if ( ! $this->image_lib->crop())
         {
                 echo $this->image_lib->display_errors();
         }

      Note:

        Without a visual interface it is difficult to crop images, so
        this method is not very useful unless you intend to build such
        an interface. That’s exactly what we did using for the photo
        gallery module in ExpressionEngine, the CMS we develop. We
        added a JavaScript UI that lets the cropping area be selected.

   rotate()

      Returns:
         TRUE on success, FALSE on failure

      Return type:
         "bool"

      The image rotation method requires that the angle of rotation be
      set via its preference:

         $config['rotation_angle'] = '90';

      There are 5 rotation options:

      1. 90 - rotates counter-clockwise by 90 degrees.

      2. 180 - rotates counter-clockwise by 180 degrees.

      3. 270 - rotates counter-clockwise by 270 degrees.

      4. hor - flips the image horizontally.

      5. vrt - flips the image vertically.

      Here’s an example showing how you might rotate an image:

         $config['image_library'] = 'netpbm';
         $config['library_path'] = '/usr/bin/';
         $config['source_image'] = '/path/to/image/mypic.jpg';
         $config['rotation_angle'] = 'hor';

         $this->image_lib->initialize($config);

         if ( ! $this->image_lib->rotate())
         {
                 echo $this->image_lib->display_errors();
         }

   watermark()

      Returns:
         TRUE on success, FALSE on failure

      Return type:
         "bool"

      Creates a watermark over an image, please refer to the
      Watermarking an Image section for more info.

   clear()

      Return type:
         "void"

      The clear method resets all of the values used when processing
      an image. You will want to call this if you are processing
      images in a loop.

         $this->image_lib->clear();

   display_errors([$open = '
[, $close = '
']])

      Parameters:
         * **$open** ("string") – Error message opening tag

         * **$close** ("string") – Error message closing tag

      Returns:
         Error messages

      Return type:
         "string"

      Returns all detected errors formatted as a string.

         echo $this->image_lib->display_errors();
