Set of Tornado request handlers that allows on-the-fly conversion of images according to a request's query string options. Ectyper, by default, provides a way to resize, reflect and reformat images.
from ectyper.handlers import ImageHandler import os from tornado import web, ioloop class StreamLocal(ImageHandler): """ Trivial local file handler. It loads files in images directory, converts it and streams it to the client. Example calls: Resize: http://host:8888/images/hulu.jpg?size=200x96 Reformat: http://host:8888/images/hulu.jpg?format=png Reflect: http://host:8888/images/hulu.jpg?size=200x96&format=png&reflection_height=60 """ def calculate_options(self): super(StreamLocal, self).calculate_options() # By default Ectyper uses "convert" as found in the PATH of the running # python process, use this to override. if self.magick: self.magick.convert_path = "/path/to/imagemagick/convert" def handler(self, *args): self.convert_image(os.path.join("/path/to/images", args)) app = web.Application([ ('/images/(.*)', StreamLocal), ]) if __name__ == "__main__": app.listen(8888) ioloop.IOLoop.instance().start()
Ectyper provides a primary ImageHandler class (extending Tornado's RequestHandler class). This class parses each request's query string and converts it into a command-line call into ImageMagick's convert. This class is wrapped by ectyper.magick.ImageMagick which can be overridden to provide other options.
A request into an ImageHandler will automatically generate an ImageMagick object based on standard options (see help(ectyper.handlers.ImageHandler) for more). Once your handler calls convert_image() with a local file path or a remote URL, ImageHandler kicks off an ImageMagick convert process with the calculated options and streams the result to the browser. You can optionally extend CachingImageHandler or FileCachingImageHandler to stream the output elsewhere for caching purposes.
Full list of options supported by default:
size=NxM Resize the source image to N pixels wide and M pixels high. maintain_ratio=1 Maintain aspect ratio when resizing (ignored if size is not provided). If requested size is a different aspect ratio than the source image, the resize will scale to fit the width or height, whichever is reached first. The other dimension will be centered vertically or horizontally as necessary. Defaults to 0. reflection_height=N Flip the image upside down and apply a gradient to mimic a reflected image. reflection_alpha_top and reflection_alpha_bottom can be used to set the gradient parameters. reflection_alpha_top=N The top value to use when generating the gradient for reflection_height, ignored if that parameter is not set. Should be between 0 and 1. Defaults to 1. Note that reflection alpha only works properly with format=png output. reflection_alpha_bottom=N The bottom value to use when generating the gradient for reflection_height, ignored if that parameter is not set. Should be between 0 and 1. Defaults to 0. format=(jpeg|png|png16) Format to convert the image into. png16 is 24-bit png pre-dithered for 16-bit (RGB555) screens. Defaults to jpeg.
See example.py for more.
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