You can have multiple dragonfly apps, each with their own configuration. Each app has a name, and is referred to by that name.
Dragonfly[:images] # ===> Creates an app called 'images' Dragonfly[:images] # ===> Refers to the already created app 'images' app = Dragonfly[:images]
A number of methods can be used to get content:
app.fetch('some_uid') # Fetch from datastore (default filesystem) app.fetch_file('~/path/to/file.png') # Fetch from a local file app.fetch_url('somewhere.com/img.png') # Fetch from a url (will work with http, https) app.generate(:plasma, 400, 300) # Generates using a method from the configured # generator (in this case a plasma image) app.create("CONTENT") # Can pass in a String, Pathname, File or Tempfile
These all returnobjects. These objects are lazy - they don't do any fetching/generating until some other method is called on them.
Using the content
Once we have aobject:
image = app.fetch('some_uid')
We can get the data a number of ways...
image.data # => "\377???JFIF\000\..." image.to_file('out.png') # writes to file 'out.png' and returns a readable file object image.tempfile # => #<File:/var/folders/st/strHv74sH044JPabSiODz... a closed Tempfile object image.file # => #<File:/var/folders/st/strHv74sH044JPabSiODz... a readable (open) File object image.file do |f| # Yields an open file object, returns the return value of data = f.read(256) # the block, and closes the file object end image.path # => '/var/folders/st/strHv74sH044JPabSiODz...' i.e. the path of the tempfile image.size # => 134507 (size in bytes)
We can get its url...
image.url # => "/media/BAhbBlsHOgZmIg9hc..." # this won't work if we've used create to get the content
We can analyse it (see Analysers for more info) ...
image.width # => 280
We can process it (see Processing for more info) ...
new_image = image.process(:thumb, '40x30') # returns another 'Job' object
We can encode it (see Encoding for more info) ...
new_image = image.encode(:gif) # returns another 'Job' object
Because the methods
all return objects, we can chain them as much as we want...
image = app.fetch('some_uid').process(:greyscale).process(:thumb, '40x20#').encode(:gif)
... and because they're lazy, we don't actually do any processing/encoding until either
apply is called
image.apply # actually 'does' the processing and returns self
... or a method is called like
This means we can cheaply generate urls for processed data without doing any fetching or processing:
url = app.fetch('some_uid').process(:thumb, '40x20#').encode(:gif).url
and then visit that url in a browser to get the actual processed image.
Commonly used processing/encoding steps can be shortened, so instead of
we could use something like
This does exactly the same, returning aobject.
To define this shortcut:
app.configure do |c| c.job :grey do |size| process :greyscale process :thumb, size encode :jpg end # ... end