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Merge pull request #14 from kmatch98/master
Add example using line for a moving sparkline graph
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‎adafruit_display_shapes/sparkline.py

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# class of sparklines in CircuitPython
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# created by Kevin Matocha - Copyright 2020 (C)
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# See the bottom for a code example using the `sparkline` Class.
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# # File: display_shapes_sparkline.py
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# A sparkline is a scrolling line graph, where any values added to sparkline using `
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# add_value` are plotted.
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#
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# The `sparkline` class creates an element suitable for adding to the display using
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# `display.show(mySparkline)`
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# or adding to a `displayio.Group` to be displayed.
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#
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# When creating the sparkline, identify the number of `max_items` that will be
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# included in the graph. When additional elements are added to the sparkline and
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# the number of items has exceeded max_items, any excess values are removed from
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# the left of the graph, and new values are added to the right.
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"""
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`sparkline`
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================================================================================
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Various common shapes for use with displayio - Sparkline!
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* Author(s): Kevin Matocha
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Implementation Notes
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--------------------
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**Software and Dependencies:**
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* Adafruit CircuitPython firmware for the supported boards:
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https://github.com/adafruit/circuitpython/releases
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"""
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import displayio
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from adafruit_display_shapes.line import Line
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class Sparkline(displayio.Group):
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# pylint: disable=too-many-arguments
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""" A sparkline graph.
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: param width: Width of the sparkline graph in pixels
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: param height: Height of the sparkline graph in pixels
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: param max_items: Maximum number of values housed in the sparkline
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: param y_min: Lower range for the y-axis. Set to None for autorange.
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: param y_max: Upper range for the y-axis. Set to None for autorange.
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: param x: X-position on the screen, in pixels
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: param y: Y-position on the screen, in pixels
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: param color: Line color, the default value is 0xFFFFFF (WHITE)
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"""
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def __init__(
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self,
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width,
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height,
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max_items,
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y_min=None, # None = autoscaling
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y_max=None, # None = autoscaling
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x=0,
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y=0,
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color=0xFFFFFF, # line color, default is WHITE
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):
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# define class instance variables
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self.width = width # in pixels
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self.height = height # in pixels
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self.color = color #
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self._max_items = max_items # maximum number of items in the list
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self._spark_list = [] # list containing the values
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self.y_min = y_min # minimum of y-axis (None: autoscale)
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self.y_max = y_max # maximum of y-axis (None: autoscale)
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self.y_bottom = y_min
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# y_bottom: The actual minimum value of the vertical scale, will be
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# updated if autorange
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self.y_top = y_max
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# y_top: The actual minimum value of the vertical scale, will be
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# updated if autorange
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self._x = x
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self._y = y
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super().__init__(
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max_size=self._max_items - 1, x=x, y=y
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) # self is a group of lines
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def add_value(self, value):
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""" Add a value to the sparkline.
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: param value: The value to be added to the sparkline
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"""
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if value is not None:
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if (
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len(self._spark_list) >= self._max_items
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): # if list is full, remove the first item
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self._spark_list.pop(0)
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self._spark_list.append(value)
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self.update()
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# pylint: disable=no-else-return
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@staticmethod
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def _xintercept(
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x_1, y_1, x_2, y_2, horizontal_y
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): # finds intercept of the line and a horizontal line at horizontalY
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slope = (y_2 - y_1) / (x_2 - x_1)
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b = y_1 - slope * x_1
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if slope == 0 and y_1 != horizontal_y: # does not intercept horizontalY
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return None
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else:
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xint = (
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horizontal_y - b
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) / slope # calculate the x-intercept at position y=horizontalY
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return int(xint)
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def _plotline(self, x_1, last_value, x_2, value, y_bottom, y_top):
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y_2 = int(self.height * (y_top - value) / (y_top - y_bottom))
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y_1 = int(self.height * (y_top - last_value) / (y_top - y_bottom))
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self.append(Line(x_1, y_1, x_2, y_2, self.color)) # plot the line
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# pylint: disable= too-many-branches, too-many-nested-blocks
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def update(self):
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"""Update the drawing of the sparkline
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"""
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# get the y range
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if self.y_min is None:
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self.y_bottom = min(self._spark_list)
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else:
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self.y_bottom = self.y_min
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if self.y_max is None:
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self.y_top = max(self._spark_list)
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else:
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self.y_top = self.y_max
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if len(self._spark_list) > 2:
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xpitch = self.width / (
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len(self._spark_list) - 1
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) # this is a float, only make int when plotting the line
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for _ in range(len(self)): # remove all items from the current group
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self.pop()
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for count, value in enumerate(self._spark_list):
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if count == 0:
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pass # don't draw anything for a first point
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else:
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x_2 = int(xpitch * count)
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x_1 = int(xpitch * (count - 1))
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if (self.y_bottom <= last_value <= self.y_top) and (
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self.y_bottom <= value <= self.y_top
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): # both points are in range, plot the line
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self._plotline(
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x_1, last_value, x_2, value, self.y_bottom, self.y_top
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)
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else: # at least one point is out of range, clip one or both ends the line
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if ((last_value > self.y_top) and (value > self.y_top)) or (
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(last_value < self.y_bottom) and (value < self.y_bottom)
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):
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# both points are on the same side out of range: don't draw anything
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pass
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else:
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xint_bottom = self._xintercept(
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x_1, last_value, x_2, value, self.y_bottom
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) # get possible new x intercept points
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xint_top = self._xintercept(
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x_1, last_value, x_2, value, self.y_top
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) # on the top and bottom of range
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if (xint_bottom is None) or (
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xint_top is None
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): # out of range doublecheck
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pass
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else:
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# Initialize the adjusted values as the baseline
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adj_x_1 = x_1
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adj_last_value = last_value
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adj_x_2 = x_2
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adj_value = value
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if value > last_value: # slope is positive
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if xint_bottom >= x_1: # bottom is clipped
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adj_x_1 = xint_bottom
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adj_last_value = self.y_bottom # y_1
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if xint_top <= x_2: # top is clipped
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adj_x_2 = xint_top
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adj_value = self.y_top # y_2
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else: # slope is negative
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if xint_top >= x_1: # top is clipped
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adj_x_1 = xint_top
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adj_last_value = self.y_top # y_1
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if xint_bottom <= x_2: # bottom is clipped
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adj_x_2 = xint_bottom
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adj_value = self.y_bottom # y_2
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self._plotline(
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adj_x_1,
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adj_last_value,
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adj_x_2,
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adj_value,
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self.y_bottom,
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self.y_top,
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)
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last_value = value # store value for the next iteration
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def values(self):
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"""Returns the values displayed on the sparkline
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"""
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return self._spark_list

‎examples/display_shapes_sparkline_simpletest.py

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# class of sparklines in CircuitPython
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# created by Kevin Matocha - Copyright 2020 (C)
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# See the bottom for a code example using the `sparkline` Class.
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# # File: display_shapes_sparkline.py
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# A sparkline is a scrolling line graph, where any values added to sparkline using
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# `add_value` are plotted.
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#
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# The `sparkline` class creates an element suitable for adding to the display using
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# `display.show(mySparkline)`
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# or adding to a `displayio.Group` to be displayed.
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#
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# When creating the sparkline, identify the number of `max_items` that will be
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# included in the graph.
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# When additional elements are added to the sparkline and the number of items has
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# exceeded max_items, any excess values are removed from the left of the graph,
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# and new values are added to the right.
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# The following is an example that shows the
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# setup display
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# instance sparklines
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# add to the display
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# Loop the following steps:
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# add new values to sparkline `add_value`
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# update the sparklines `update`
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import time
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import random
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import board
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import displayio
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from adafruit_display_shapes.sparkline import Sparkline
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if "DISPLAY" not in dir(board):
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# Setup the LCD display with driver
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# You may need to change this to match the display driver for the chipset
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# used on your display
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from adafruit_ili9341 import ILI9341
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displayio.release_displays()
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# setup the SPI bus
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spi = board.SPI()
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tft_cs = board.D9 # arbitrary, pin not used
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tft_dc = board.D10
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tft_backlight = board.D12
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tft_reset = board.D11
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while not spi.try_lock():
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spi.configure(baudrate=32000000)
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spi.unlock()
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display_bus = displayio.FourWire(
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spi,
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command=tft_dc,
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chip_select=tft_cs,
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reset=tft_reset,
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baudrate=32000000,
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polarity=1,
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phase=1,
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)
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print("spi.frequency: {}".format(spi.frequency))
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# Number of pixels in the display
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DISPLAY_WIDTH = 320
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DISPLAY_HEIGHT = 240
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# create the display
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display = ILI9341(
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display_bus,
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width=DISPLAY_WIDTH,
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height=DISPLAY_HEIGHT,
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rotation=180, # The rotation can be adjusted to match your configuration.
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auto_refresh=True,
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native_frames_per_second=90,
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)
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# reset the display to show nothing.
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display.show(None)
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else:
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# built-in display
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display = board.DISPLAY
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##########################################
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# Create background bitmaps and sparklines
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##########################################
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# Baseline size of the sparkline chart, in pixels.
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chart_width = display.width
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chart_height = display.height
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# sparkline1 uses a vertical y range between 0 to 10 and will contain a
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# maximum of 40 items
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sparkline1 = Sparkline(
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width=chart_width, height=chart_height, max_items=40, y_min=0, y_max=10, x=0, y=0
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)
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# Create a group to hold the sparkline and append the sparkline into the
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# group (my_group)
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#
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# Note: In cases where display elements will overlap, then the order the elements
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# are added to the group will set which is on top. Latter elements are displayed
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# on top of former elemtns.
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my_group = displayio.Group(max_size=1)
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# add the sparkline into my_group
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my_group.append(sparkline1)
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# Add my_group (containing the sparkline) to the display
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display.show(my_group)
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# Start the main loop
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while True:
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# turn off the auto_refresh of the display while modifying the sparkline
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display.auto_refresh = False
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# add_value: add a new value to a sparkline
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# Note: The y-range for mySparkline1 is set to 0 to 10, so all these random
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# values (between 0 and 10) will fit within the visible range of this sparkline
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sparkline1.add_value(random.uniform(0, 10))
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# turn the display auto_refresh back on
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display.auto_refresh = True
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# The display seems to be less jittery if a small sleep time is provided
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# You can adjust this to see if it has any effect
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time.sleep(0.01)

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