'''
Atlas
=====

.. versionadded:: 1.1.0

Atlas is a class for managing textures atlases: packing multiple texture into
one. With it, you are reducing the number of image to load and speedup the
application loading.

An Atlas is composed of:

    - a json file (.atlas) that contain all the information about the image
      contained inside the atlas.
    - one or multiple atlas image associated to the atlas definition.

Definition of .atlas
--------------------

A file with ``<basename>.atlas`` is a json file formatted like this::

    {
        "<basename>-<index>.png": {
            "id1": [ <x>, <y>, <width>, <height> ],
            "id2": [ <x>, <y>, <width>, <height> ],
            # ...
        },
        # ...
    }

Example of the Kivy ``defaulttheme.atlas``::

    {
        "defaulttheme-0.png": {
            "progressbar_background": [431, 224, 59, 24],
            "image-missing": [253, 344, 48, 48],
            "filechooser_selected": [1, 207, 118, 118],
            "bubble_btn": [83, 174, 32, 32],
            # ... and more ...
        }
    }

How to create an atlas
----------------------

.. warning::

    The atlas creation require Imaging/PIL. This will be removed in the future
    when Kivy core Image will be able to support loading / blitting / save
    operation.

You can directly use this module to create atlas file with this command::

    $ python -m kivy.atlas <basename> <size> <list of images...>

Let's say you have a list of image that you want to put into an Atlas. The
directory is named ``images`` with lot of png::

    $ ls
    images
    $ cd images
    $ ls
    bubble.png bubble-red.png button.png button-down.png

You can combine all the png into one, and generate the atlas file with::

    $ python -m kivy.atlas myatlas 256 *.png
    Atlas created at myatlas.atlas
    1 image have been created
    $ ls
    bubble.png bubble-red.png button.png button-down.png myatlas.atlas
    myatlas-0.png

As you can see, we got 2 new files: ``myatlas.atlas`` and ``myatlas-0.png``.

.. note::

    When using this script, the ids referenced in the atlas is the basename of
    the image, without the extension. So if you are going to give a filename
    ``../images/button.png``, the id for this image will be ``button``.

How to use an atlas
-------------------

Usually, you are doing something like this::

    a = Button(background_normal='images/button.png',
               background_down='images/button_down.png')

In our previous example, we have created the atlas containing both of them, and
put it in ``images/myatlas.atlas``. You can use the url notation to reference
them::

    atlas://path/to/myatlas/id
    # will search for the ``path/to/myatlas.atlas``, and get the image ``id``

In our case, it will be::

    atlas://images/myatlas/button

.. note::

    In the atlas url, their is no need to put the ``.atlas`` extension, it will
    be automatically append to the filename.

Manual usage of the Atlas
-------------------------

::

    >>> from kivy.atlas import Atlas
    >>> atlas = Atlas('path/to/myatlas.atlas')
    >>> print atlas.textures.keys()
    ['bubble', 'bubble-red', 'button', 'button-down']
    >>> print atlas['button']
    <kivy.graphics.texture.TextureRegion object at 0x2404d10>
'''

__all__ = ('Atlas', )

import json
from os.path import basename, dirname, join, splitext
from kivy.event import EventDispatcher
from kivy.logger import Logger
from kivy.properties import AliasProperty, DictProperty
import os


# late import to prevent recursion
CoreImage = None


class Atlas(EventDispatcher):
    '''Manage texture atlas. See module documentation for more information.
    '''

    textures = DictProperty({})
    '''List of available textures within the atlas.

    :data:`textures` is a :class:`~kivy.properties.DictProperty`, default to {}
    '''

    def _get_filename(self):
        return self._filename

    filename = AliasProperty(_get_filename, None)
    '''Filename of the current Atlas

    :data:`filename` is a :class:`~kivy.properties.AliasProperty`, default to
    None
    '''

    def __init__(self, filename):
        self._filename = filename
        super(Atlas, self).__init__()
        self._load()

    def __getitem__(self, key):
        return self.textures[key]

    def _load(self):
        # late import to prevent recursive import.
        global CoreImage
        if CoreImage is None:
            from kivy.core.image import Image as CoreImage

        # must be a name finished by .atlas ?
        filename = self._filename
        assert(filename.endswith('.atlas'))
        filename = filename.replace('/', os.sep)

        Logger.debug('Atlas: Load <%s>' % filename)
        with open(filename, 'r') as fd:
            meta = json.load(fd)

        Logger.debug('Atlas: Need to load %d images' % len(meta))
        d = dirname(filename)
        textures = {}
        for subfilename, ids in meta.iteritems():
            subfilename = join(d, subfilename)
            Logger.debug('Atlas: Load <%s>' % subfilename)

            # load the image
            ci = CoreImage(subfilename)

            # for all the uid, load the image, get the region, and put it in our
            # dict.
            for meta_id, meta_coords in ids.iteritems():
                x, y, w, h = meta_coords
                textures[meta_id] = ci.texture.get_region(*meta_coords)

        self.textures = textures

    @staticmethod
    def create(outname, filenames, size, padding=1):
        '''This method can be used to create manually an atlas from a set of
        images.

        :Parameters:
            `outname`: str
                Basename to use for ``.atlas`` creation and ``-<idx>.png``
                associated images.
            `filenames`: list
                List of filename to put in the atlas
            `size`: int
                Size of an atlas image
            `padding`: int, default to 1
                Padding to put around each image. Care, if you put 0, they might
                be some issues with OpenGL, because by default, Kivy texture are
                using GL_CLAMP_TO_EDGE, and the edge is another image than
                the image you'll want to display.
        '''
        # Thanks to
        # omnisaurusgames.com/2011/06/texture-atlas-generation-using-python/
        # for its initial implementation.
        try:
            import Image
        except ImportError:
            Logger.critical('Atlas: Imaging/PIL are missing')
            raise

        size = int(size)

        # open all of the images
        ims = [(f, Image.open(f)) for f in filenames]

        # sort by image area
        ims = sorted(ims, key=lambda im: im[1].size[0] * im[1].size[1],
                reverse=True)

        # free boxes are empty space in our output image set
        # the freebox tuple format is: outidx, x, y, w, h
        freeboxes = [(0, 0, 0, size, size)]
        numoutimages = 1
        padding = 1

        # full boxes are areas where we have placed images in the atlas
        # the full box tuple format is: image, outidx, x, y, w, h, filename
        fullboxes = []

        # do the actual atlasing by sticking the largest images we can have into
        # the smallest valid free boxes
        for imageinfo in ims:
            im = imageinfo[1]
            imw, imh = im.size
            imw += padding
            imh += padding
            if imw > size or imh > size:
                Logger.error('Atlas: image %s is larger than the atlas size!' %
                    imageinfo[0])
                return

            inserted = False
            while not inserted:
                for idx, fb in enumerate(freeboxes):
                    # find the smallest free box that will contain this image
                    if fb[3] >= imw and fb[4] >= imh:
                        # we found a valid spot! Remove the current freebox, and
                        # split the leftover space into (up to) two new
                        # freeboxes
                        del freeboxes[idx]
                        if fb[3] > imw:
                            freeboxes.append((
                                fb[0], fb[1] + imw, fb[2],
                                fb[3] - imw, imh))

                        if fb[4] > imh:
                            freeboxes.append((
                                fb[0], fb[1], fb[2] + imh,
                                fb[3], fb[4] - imh))

                        # keep this sorted!
                        freeboxes = sorted(freeboxes,
                                key=lambda fb: fb[3] * fb[4])
                        fullboxes.append((im,
                            fb[0], fb[1] + padding,
                            fb[2] + padding, imw - padding,
                            imh - padding, imageinfo[0]))
                        inserted = True
                        break

                if not inserted:
                    # oh crap - there isn't room in any of our free boxes, so we
                    # have to add a new output image
                    freeboxes.append((numoutimages, 0, 0, size, size))
                    numoutimages += 1

        # now that we've figured out where everything goes, make the output
        # images and blit the source images to the approriate locations
        Logger.info('Atlas: create an {0}x{0} rgba image'.format(size))
        outimages = [Image.new('RGBA', (size, size))
                for i in range(0, int(numoutimages))]
        for fb in fullboxes:
            outimages[fb[1]].paste(fb[0], (fb[2], fb[3]))

        # save the output images
        for idx, outimage in enumerate(outimages):
            outimage.save('%s-%d.png' % (outname, idx))

        # write out an json file that says where everything ended up
        meta = {}
        for fb in fullboxes:
            fn = '%s-%d.png' % (basename(outname), fb[1])
            if fn not in meta:
                d = meta[fn] = {}
            else:
                d = meta[fn]

            # fb[6] contain the filename aka '../apok.png'. just get only 'apok'
            # as the uniq id.
            uid = splitext(basename(fb[6]))[0]
            x, y, w, h = fb[2:6]
            d[uid] = x, size - y - h, w, h

        outfn = '%s.atlas' % outname
        with open(outfn, 'w') as fd:
            json.dump(meta, fd)

        return outfn, meta

if __name__ == '__main__':

    import sys
    argv = sys.argv[1:]
    if len(argv) < 3:
        print 'Usage: python -m kivy.atlas <outname> <size> <img1.png>' \
              '[<img2.png>, ...]'
        sys.exit(1)

    outname = argv[0]
    try:
        size = int(argv[1])
    except ValueError:
        print 'Error: size must be an integer'
        sys.exit(1)

    filenames = argv[2:]
    ret = Atlas.create(outname, filenames, size)
    if not ret:
        print 'Error while creating atlas!'
        sys.exit(1)

    fn, meta = ret
    print 'Atlas created at', fn
    print '%d image%s have been created' % (len(meta),
            's' if len(meta) > 1 else '')

