372 lines
12 KiB
Python
372 lines
12 KiB
Python
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# -*- coding: utf-8 -*-
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# Copyright (c) 2016 Richard Hull and contributors
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# See LICENSE.rst for details.
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import time
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from PIL import Image, ImageDraw, ImageFont
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import oled.mixin as mixin
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from oled.threadpool import threadpool
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pool = threadpool(4)
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def calc_bounds(xy, entity):
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"""
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For an entity with width and height attributes, determine
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the bounding box if were positioned at (x, y).
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"""
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left, top = xy
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right, bottom = left + entity.width, top + entity.height
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return [left, top, right, bottom]
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def range_overlap(a_min, a_max, b_min, b_max):
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"""
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Neither range is completely greater than the other
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"""
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return (a_min < b_max) and (b_min < a_max)
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class viewport(mixin.capabilities):
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def __init__(self, device, width, height):
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self.capabilities(width, height, rotate=0, mode=device.mode)
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self._device = device
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self._backing_image = Image.new(self.mode, self.size)
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self._position = (0, 0)
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self._hotspots = []
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def display(self, image):
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assert(image.mode == self.mode)
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assert(image.size == self.size)
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self._backing_image.paste(image)
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self.refresh()
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def set_position(self, xy):
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self._position = xy
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self.refresh()
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def add_hotspot(self, hotspot, xy):
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"""
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Add the hotspot at (x, y). The hotspot must fit inside the bounds
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of the virtual device. If it does not then an AssertError is raised.
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"""
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(x, y) = xy
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assert(0 <= x <= self.width - hotspot.width)
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assert(0 <= y <= self.height - hotspot.height)
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# TODO: should it check to see whether hotspots overlap each other?
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# Is sensible to _allow_ them to overlap?
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self._hotspots.append((hotspot, xy))
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def remove_hotspot(self, hotspot, xy):
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"""
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Remove the hotspot at (x, y): Any previously rendered image where the
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hotspot was placed is erased from the backing image, and will be
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"undrawn" the next time the virtual device is refreshed. If the
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specified hotspot is not found (x, y), a ValueError is raised.
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"""
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self._hotspots.remove((hotspot, xy))
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eraser = Image.new(self.mode, hotspot.size)
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self._backing_image.paste(eraser, xy)
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def is_overlapping_viewport(self, hotspot, xy):
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"""
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Checks to see if the hotspot at position (x, y)
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is (at least partially) visible according to the
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position of the viewport
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"""
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l1, t1, r1, b1 = calc_bounds(xy, hotspot)
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l2, t2, r2, b2 = calc_bounds(self._position, self._device)
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return range_overlap(l1, r1, l2, r2) and range_overlap(t1, b1, t2, b2)
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def refresh(self):
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should_wait = False
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for hotspot, xy in self._hotspots:
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if hotspot.should_redraw() and self.is_overlapping_viewport(hotspot, xy):
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pool.add_task(hotspot.paste_into, self._backing_image, xy)
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should_wait = True
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if should_wait:
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pool.wait_completion()
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im = self._backing_image.crop(box=self._crop_box())
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self._device.display(im)
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del im
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def _crop_box(self):
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(left, top) = self._position
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right = left + self._device.width
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bottom = top + self._device.height
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assert(0 <= left <= right <= self.width)
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assert(0 <= top <= bottom <= self.height)
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return (left, top, right, bottom)
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class hotspot(mixin.capabilities):
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"""
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A hotspot (`a place of more than usual interest, activity, or popularity`)
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is a live display which may be added to a virtual viewport - if the hotspot
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and the viewport are overlapping, then the :func:`update` method will be
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automatically invoked when the viewport is being refreshed or its position
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moved (such that an overlap occurs).
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You would either:
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* create a ``hotspot`` instance, suppling a render function (taking an
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:py:mod:`PIL.ImageDraw` object, ``width`` & ``height`` dimensions. The
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render function should draw within a bounding box of (0, 0, width,
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height), and render a full frame.
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* sub-class ``hotspot`` and override the :func:``should_redraw`` and
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:func:`update` methods. This might be more useful for slow-changing
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values where it is not necessary to update every refresh cycle, or
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your implementation is stateful.
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"""
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def __init__(self, width, height, draw_fn=None):
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self.capabilities(width, height, rotate=0) # TODO: set mode?
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self._fn = draw_fn
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def paste_into(self, image, xy):
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im = Image.new(image.mode, self.size)
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draw = ImageDraw.Draw(im)
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self.update(draw)
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image.paste(im, xy)
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del draw
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del im
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def should_redraw(self):
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"""
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Override this method to return true or false on some condition
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(possibly on last updated member variable) so that for slow changing
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hotspots they are not updated too frequently.
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"""
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return True
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def update(self, draw):
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if self._fn:
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self._fn(draw, self.width, self.height)
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class snapshot(hotspot):
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"""
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A snapshot is a `type of` hotspot, but only updates once in a given
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interval, usually much less frequently than the viewport requests refresh
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updates.
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"""
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def __init__(self, width, height, draw_fn=None, interval=1.0):
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super(snapshot, self).__init__(width, height, draw_fn)
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self.interval = interval
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self.last_updated = 0.0
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def should_redraw(self):
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"""
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Only requests a redraw after ``interval`` seconds have elapsed
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"""
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return time.time() - self.last_updated > self.interval
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def paste_into(self, image, xy):
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super(snapshot, self).paste_into(image, xy)
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self.last_updated = time.time()
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class terminal(object):
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"""
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Provides a terminal-like interface to a device (or a device-like object
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that has :class:`mixin.capabilities` characteristics).
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"""
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def __init__(self, device, font=None, color="white", bgcolor="black", tabstop=4, line_height=None, animate=True):
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self._device = device
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self.font = font or ImageFont.load_default()
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self.color = color
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self.bgcolor = bgcolor
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self.animate = animate
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self.tabstop = tabstop
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self._cw, self._ch = (0, 0)
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for i in range(32, 128):
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w, h = self.font.getsize(chr(i))
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self._cw = max(w, self._cw)
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self._ch = max(h, self._ch)
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self._ch = line_height or self._ch
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self.width = device.width // self._cw
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self.height = device.height // self._ch
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self.size = (self.width, self.height)
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self._backing_image = Image.new(self._device.mode, self._device.size, self.bgcolor)
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self._canvas = ImageDraw.Draw(self._backing_image)
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self.clear()
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def clear(self):
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"""
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Clears the display and resets the cursor position to (0, 0).
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"""
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self._cx, self._cy = (0, 0)
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self._canvas.rectangle(self._device.bounding_box, fill=self.bgcolor)
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self.flush()
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def println(self, text=""):
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"""
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Prints the supplied text to the device, scrolling where necessary.
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The text is always followed by a newline.
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"""
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self.puts(text)
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self.newline()
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def puts(self, text):
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"""
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Prints the supplied text, handling special character codes for carriage
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return (\\r), newline (\\n), backspace (\\b) and tab (\\t).
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If the ``animate`` flag was set to True (default), then each character
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is flushed to the device, giving the effect of 1970's teletype device.
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"""
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for line in str(text).split("\n"):
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for char in line:
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if char == '\r':
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self.carriage_return()
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elif char == '\n':
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self.newline()
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elif char == '\b':
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self.backspace()
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elif char == '\t':
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self.tab()
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else:
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self.putch(char, flush=self.animate)
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def putch(self, ch, flush=True):
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"""
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Prints the specific character, which must be a valid printable ASCII
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value in the range 32..127 only.
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"""
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assert(32 <= ord(ch) <= 127)
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w = self.font.getsize(ch)[0]
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if self._cx + w >= self._device.width:
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self.newline()
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self.erase()
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self._canvas.text((self._cx, self._cy), text=ch, font=self.font, fill=self.color)
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self._cx += w
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if flush:
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self.flush()
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def carriage_return(self):
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"""
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Returns the cursor position to the left-hand side without advancing
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downwards.
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"""
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self._cx = 0
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def tab(self):
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"""
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Advances the cursor position to the next (soft) tabstop.
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"""
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soft_tabs = self.tabstop - ((self._cx // self._cw) % self.tabstop)
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for _ in range(soft_tabs):
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self.putch(" ", flush=False)
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def newline(self):
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"""
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Advances the cursor position ot the left hand side, and to the next
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line. If the cursor is on the lowest line, the displayed contents are
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scrolled, causing the top line to be lost.
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"""
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self.carriage_return()
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if self._cy + (2 * self._ch) >= self._device.height:
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# Simulate a vertical scroll
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copy = self._backing_image.crop((0, self._ch, self._device.width, self._device.height))
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self._backing_image.paste(copy, (0, 0))
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self._canvas.rectangle((0, copy.height, self._device.width, self._device.height), fill=self.bgcolor)
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else:
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self._cy += self._ch
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self.flush()
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if self.animate:
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time.sleep(0.2)
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def backspace(self):
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"""
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Moves the cursor one place to the left, erasing the character at the
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current position. Cannot move beyound column zero, nor onto the
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previous line
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"""
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if self._cx + self._cw >= 0:
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self.erase()
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self._cx -= self._cw
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self.flush()
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def erase(self):
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"""
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Erase the contents of the cursor's current postion without moving the
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cursor's position.
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"""
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self._canvas.rectangle((self._cx, self._cy, self._cx + self._cw, self._cy + self._ch), fill=self.bgcolor)
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def flush(self):
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"""
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Cause the current backing store to be rendered on the nominated device.
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"""
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self._device.display(self._backing_image)
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class history(mixin.capabilities):
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"""
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Wraps a device (or emulator) to provide a facility to be able to make a
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savepoint (a point at which the screen display can be "rolled-back" to).
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This is mostly useful for displaying transient error/dialog messages
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which could be subsequently dismissed, reverting back to the previous
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display.
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"""
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def __init__(self, device):
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self.capabilities(device.width, device.height, rotate=0, mode=device.mode)
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self._savepoints = []
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self._device = device
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self._last_image = None
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def display(self, image):
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self._last_image = image.copy()
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self._device.display(image)
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def savepoint(self):
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"""
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Copies the last displayed image.
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"""
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if self._last_image:
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self._savepoints.append(self._last_image)
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self._last_image = None
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def restore(self, drop=0):
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"""
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Restores the last savepoint. If ``drop`` is supplied and greater than
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zero, then that many savepoints are dropped, and the next savepoint is
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restored.
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"""
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assert(drop >= 0)
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while drop > 0:
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self._savepoints.pop()
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drop -= 1
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img = self._savepoints.pop()
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self.display(img)
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def __len__(self):
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"""
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Indication of the number of savepoints retained.
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"""
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return len(self._savepoints)
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