sorl-watermark 1.0.0

Image based watermarks for sorl-thumbnail

# sorl-watermark

As of 12th July 2013, *vbazhin* will be taking over development and take care of implementing all the
mentioned features. Everybody welcome him with a warm applause :D!

sorl-watermark offers drop-in engines for sorl-thumbnail, which automagically
insert a specified image as watermark on top of the original thumbnail.

Of course everything is configurable, from watermark image to the position and
the opacity.

If you are looking for a sorl engine to dynamically create text watermarks,
you might want to have a look at [zeus/watermark](https://bitbucket.org/zeus/watermarker/overview).

_Note_: This project uses [Semantic Versioning](http://semver.org/) as it's
versioning scheme.

## Setup
Install sorl-watermark, either by cloning from the [github repository]() or
by installing it via `pip`:

pip install sorl_watermarker

Change sorl's thumbnail engine to the fitting one from sorl-watermark.
By now PIL and pgmagick engines are implemented.

PIL:

THUMBNAIL_ENGINE = 'sorl_watermarker.engines.pil_engine.Engine'

Pgmagick:

THUMBNAIL_ENGINE = 'sorl_watermarker.engines.pgmagick_engine.Engine'


Next up you tell it which image should be used as a watermark. Note that this
file has to live somewhere inside STATIC\_ROOT.

THUMBNAIL_WATERMARK = 'my_watermark.png'

That's it for a simple setup. The engine will only apply the watermark
if the thumbnail size is big enough.

See _Advanced Usage_ for ways to dynamically change the watermark itself,
it's size or ways to selectively apply watermarks.

## Engines
sorl-watermark supports two of sorl-thumbnails backends:

* PIL (sorl_watermarker.engines.pil)
* GraphicsMagick (Magick++) via pgmagick (sorl_watermarker.engines.magick)

## Advanced Usage
sorl-watermark also _enhances_ the default `thumbnail` templatetag with some
more options. (Well, actually it does not really enhance it, since the templatetag
itself passes the options through to the engine itself by default)

By default, the templatetag syntax is:

{% thumbnail image key1=var1 key2=var2 %}

The following new options are available:

* `watermark=imagefile`
This options takes an ImageFile and uses this one instead of the default
watermark file, set via `THUMBNAIL_WATERMARK`
* `watermark_size="x200"`
Changes the watermark's size. Takes the same options as the
`THUMBNAIL_WATERMARK_SIZE` option.
* `watermark_pos="north east"`
Specifies where the watermark shall be put. Accepts the same options as the
`THUMBNAIL_WATERMARK_POSITION` setting.
* `watermark_alpha=0.9`
Sets the watermark's opacity. Has to be a value between 0 and 1.

## Settings Reference
The following settings are available

* `THUMBNAIL_WATERMARK`
Sets the image to be used as a watermark. The file must live within
`STATIC_ROOT`.

* `THUMBNAIL_WATERMARK_ALWAYS`
Stamp a watermark on every image.
Default is `True`.

* `THUMBNAIL_WATERMARK_SIZE`
Change the size of the watermark. This can either be a geometry string, as
is usual with sorl-thumbnail ("x200", "200x200"), or a percentage.
If given a percentage, the watermark will always be the given percentage
of the thumbnail size.

* `THUMBNAIL_WATERMARK_OPACITY`
An integer from 0 to 1, specifying the opacity of the watermark.
Default is `0` (opaque).

* `THUMBNAIL_WATERMARK_POSITION`
Specifies the position of the watermark. You can either pass this a gravity
like

* "north"
* "south"
* "west"
* "east"
* "north east"
* "south east"
* "north west"
* "south west"
* "center"

If you want to tile your image completely with a watermark, you should set

THUMBNAIL_WATERMARK_POSITION = 'tile'


or with a pair of values in pixels ("20 20" would place watermark near the left-top corner,
"-20 -20" - near the right-bottom corner).
Default: `"south east"`