<reponame>4gbag/ssd1306
#!/usr/bin/env python
# -*- coding: utf-8 -*-

# The MIT License (MIT)
#
# Copyright (c) 2016 <NAME>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

import time
from PIL import Image, ImageDraw
import oled.mixin as mixin
from oled.threadpool import threadpool

pool = threadpool(4)


def calc_bounds(xy, entity):
    """
    For an entity with width and height attributes, determine
    the bounding box if were positioned at (x, y).
    """
    left, top = xy
    right, bottom = left + entity.width, top + entity.height
    return [left, top, right, bottom]


def range_overlap(a_min, a_max, b_min, b_max):
    """
    Neither range is completely greater than the other
    """
    return (a_min < b_max) and (b_min < a_max)


class viewport(mixin.capabilities):

    def __init__(self, device, width, height):
        self.capabilities(width, height, mode=device.mode)
        self._device = device
        self._backing_image = Image.new(self.mode, self.size)
        self._position = (0, 0)
        self._hotspots = []

    def display(self, image):
        assert(image.mode == self.mode)
        assert(image.size[0] == self.width)
        assert(image.size[1] == self.height)

        self._backing_image.paste(image)
        self.refresh()

    def set_position(self, xy):
        self._position = xy
        self.refresh()

    def add_hotspot(self, hotspot, xy):
        """
        Add the hotspot at (x, y). The hotspot must fit inside the bounds
        of the virtual device. If it does not then an AssertError is raised.
        """
        (x, y) = xy
        assert(x >= 0)
        assert(y >= 0)
        assert(x <= self.width - hotspot.width)
        assert(y <= self.height - hotspot.height)

        # TODO: should it check to see whether hotspots overlap each other?
        # Is sensible to _allow_ them to overlap?
        self._hotspots.append((hotspot, xy))

    def remove_hotspot(self, hotspot, xy):
        """
        Remove the hotspot at (x, y): Any previously rendered image where the
        hotspot was placed is erased from the backing image, and will be
        "undrawn" the next time the virtual device is refreshed. If the
        specified hotspot is not found (x, y), a ValueError is raised.
        """
        self._hotspots.remove((hotspot, xy))
        eraser = Image.new(self.mode, hotspot.size)
        self._backing_image.paste(eraser, xy)

    def is_overlapping_viewport(self, hotspot, xy):
        """
        Checks to see if the hotspot at position (x, y)
        is (at least partially) visible according to the
        position of the viewport
        """
        l1, t1, r1, b1 = calc_bounds(xy, hotspot)
        l2, t2, r2, b2 = calc_bounds(self._position, self._device)
        return range_overlap(l1, r1, l2, r2) and range_overlap(t1, b1, t2, b2)

    def refresh(self):
        should_wait = False
        for hotspot, xy in self._hotspots:
            if hotspot.should_redraw() and self.is_overlapping_viewport(hotspot, xy):
                pool.add_task(hotspot.paste_into, self._backing_image, xy)
                should_wait = True

        if should_wait:
            pool.wait_completion()

        im = self._backing_image.crop(box=self._crop_box())
        self._device.display(im)
        del im

    def _crop_box(self):
        (left, top) = self._position
        right = left + self._device.width
        bottom = top + self._device.height

        assert(left >= 0)
        assert(top >= 0)
        assert(right <= self.width)
        assert(bottom <= self.height)

        return (left, top, right, bottom)


class hotspot(mixin.capabilities):
    """
    A hotspot (`a place of more than usual interest, activity, or popularity`)
    is a live display which may be added to a virtual viewport - if the hotspot
    and the viewport are overlapping, then the :func:`update` method will be
    automatically invoked when the viewport is being refreshed or its position
    moved (such that an overlap occurs).

    You would either:

        * create a ``hotspot`` instance, suppling a render function (taking an
          :py:mod:`PIL.ImageDraw` object, ``width`` & ``height`` dimensions. The
          render function should draw within a bounding box of (0, 0, width,
          height), and render a full frame.

        * sub-class ``hotspot`` and override the :func:``should_redraw`` and
          :func:`update` methods. This might be more useful for slow-changing
          values where it is not necessary to update every refresh cycle, or
          your implementation is stateful.
    """
    def __init__(self, width, height, draw_fn=None):
        self.capabilities(width, height)  # TODO: set mode?
        self._fn = draw_fn

    def paste_into(self, image, xy):
        im = Image.new(image.mode, self.size)
        draw = ImageDraw.Draw(im)
        self.update(draw)
        image.paste(im, xy)
        del draw
        del im

    def should_redraw(self):
        """
        Override this method to return true or false on some condition
        (possibly on last updated member variable) so that for slow changing
        hotspots they are not updated too frequently.
        """
        return True

    def update(self, draw):
        if self._fn:
            self._fn(draw, self.width, self.height)


class snapshot(hotspot):
    """
    A snapshot is a `type of` hotspot, but only updates once in a given
    interval, usually much less frequently than the viewport requests refresh
    updates.
    """
    def __init__(self, width, height, draw_fn=None, interval=1.0):
        super(snapshot, self).__init__(width, height, draw_fn)
        self.interval = interval
        self.last_updated = 0.0

    def should_redraw(self):
        """
        Only requests a redraw after ``interval`` seconds have elapsed
        """
        return time.time() - self.last_updated > self.interval

    def paste_into(self, image, xy):
        super(snapshot, self).paste_into(image, xy)
        self.last_updated = time.time()
