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Merged
merged 3 commits into from
Aug 14, 2022
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performance: implement growing sparkline #53

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8044efc
performance: implement growing sparkline
bablokb Jul 29, 2022
96c5246
fixed error + pylint-tweaks
bablokb Jul 29, 2022
25a1bc7
moved comment four blanks to the left to keep black happy
bablokb Jul 29, 2022
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206 changes: 117 additions & 89 deletions adafruit_display_shapes/sparkline.py
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Original file line number Diff line number Diff line change
Expand Up @@ -54,18 +54,25 @@ class Sparkline(displayio.Group):
:param width: Width of the sparkline graph in pixels
:param height: Height of the sparkline graph in pixels
:param max_items: Maximum number of values housed in the sparkline
:param dyn_xpitch: dynamically change xpitch (True)
:param y_min: Lower range for the y-axis. Set to None for autorange.
:param y_max: Upper range for the y-axis. Set to None for autorange.
:param x: X-position on the screen, in pixels
:param y: Y-position on the screen, in pixels
:param color: Line color, the default value is 0xFFFFFF (WHITE)

Note: If dyn_xpitch is True (default), the sparkline will allways span
the complete width. Otherwise, the sparkline will grow when you
add values. Once the line has reached the full width, the sparkline
will scroll to the left.
"""

def __init__(
self,
width: int,
height: int,
max_items: int,
dyn_xpitch: Optional[bool] = True, # True = dynamic pitch size
y_min: Optional[int] = None, # None = autoscaling
y_max: Optional[int] = None, # None = autoscaling
x: int = 0,
Expand All @@ -79,6 +86,9 @@ def __init__(
self.color = color #
self._max_items = max_items # maximum number of items in the list
self._spark_list = [] # list containing the values
self.dyn_xpitch = dyn_xpitch
if not dyn_xpitch:
self._xpitch = (width - 1) / (self._max_items - 1)
self.y_min = y_min # minimum of y-axis (None: autoscale)
self.y_max = y_max # maximum of y-axis (None: autoscale)
self.y_bottom = y_min
Expand All @@ -89,6 +99,8 @@ def __init__(
# updated if autorange
self._x = x
self._y = y
self._redraw = True # _redraw: redraw primitives
self._last = [] # _last: last point of sparkline

super().__init__(x=x, y=y) # self is a group of lines

Expand All @@ -98,6 +110,7 @@ def clear_values(self) -> None:
for _ in range(len(self)): # remove all items from the current group
self.pop()
self._spark_list = [] # empty the list
self._redraw = True

def add_value(self, value: float, update: bool = True) -> None:
"""Add a value to the sparkline.
Expand All @@ -114,7 +127,22 @@ def add_value(self, value: float, update: bool = True) -> None:
len(self._spark_list) >= self._max_items
): # if list is full, remove the first item
self._spark_list.pop(0)
self._redraw = True
self._spark_list.append(value)

if self.y_min is None:
self._redraw = self._redraw or value < self.y_bottom
self.y_bottom = (
value if not self.y_bottom else min(value, self.y_bottom)
)
if self.y_max is None:
self._redraw = self._redraw or value > self.y_top
self.y_top = value if not self.y_top else max(value, self.y_top)

# Guard for y_top and y_bottom being the same
if self.y_top == self.y_bottom:
self.y_bottom *= 0.99

if update:
self.update()

Expand Down Expand Up @@ -146,107 +174,107 @@ def _plotline(
last_value: float,
x_2: int,
value: float,
y_bottom: int,
y_top: int,
) -> None:

y_2 = int(self.height * (y_top - value) / (y_top - y_bottom))
y_1 = int(self.height * (y_top - last_value) / (y_top - y_bottom))
y_2 = int(self.height * (self.y_top - value) / (self.y_top - self.y_bottom))
y_1 = int(
self.height * (self.y_top - last_value) / (self.y_top - self.y_bottom)
)
self.append(Line(x_1, y_1, x_2, y_2, self.color)) # plot the line
self._last = [x_2, value]

# pylint: disable= too-many-branches, too-many-nested-blocks
# pylint: disable= too-many-branches, too-many-nested-blocks, too-many-locals, too-many-statements

def update(self) -> None:
"""Update the drawing of the sparkline."""

# get the y range
if self.y_min is None:
self.y_bottom = min(self._spark_list)
else:
self.y_bottom = self.y_min
# bail out early if we only have a single point
n_points = len(self._spark_list)
if n_points < 2:
self._last = [0, self._spark_list[0]]
return

if self.y_max is None:
self.y_top = max(self._spark_list)
if self.dyn_xpitch:
# this is a float, only make int when plotting the line
xpitch = (self.width - 1) / (n_points - 1)
self._redraw = True
else:
self.y_top = self.y_max

# Guard for y_top and y_bottom being the same
if self.y_top == self.y_bottom:
self.y_bottom -= 10
self.y_top += 10

if len(self._spark_list) > 2:
xpitch = (self.width - 1) / (
len(self._spark_list) - 1
) # this is a float, only make int when plotting the line

for _ in range(len(self)): # remove all items from the current group
self.pop()

for count, value in enumerate(self._spark_list):
if count == 0:
pass # don't draw anything for a first point
else:
x_2 = int(xpitch * count)
x_1 = int(xpitch * (count - 1))

if (self.y_bottom <= last_value <= self.y_top) and (
self.y_bottom <= value <= self.y_top
): # both points are in range, plot the line
self._plotline(
x_1, last_value, x_2, value, self.y_bottom, self.y_top
)

else: # at least one point is out of range, clip one or both ends the line
if ((last_value > self.y_top) and (value > self.y_top)) or (
(last_value < self.y_bottom) and (value < self.y_bottom)
):
# both points are on the same side out of range: don't draw anything
xpitch = self._xpitch

# only add new segment if redrawing is not necessary
if not self._redraw:
# end of last line (last point, read as "x(-1)")
x_m1 = self._last[0]
y_m1 = self._last[1]
# end of new line (new point, read as "x(0)")
x_0 = int(x_m1 + xpitch)
y_0 = self._spark_list[-1]
self._plotline(x_m1, y_m1, x_0, y_0)
return

self._redraw = False # reset, since we now redraw everything
for _ in range(len(self)): # remove all items from the current group
self.pop()

for count, value in enumerate(self._spark_list):
if count == 0:
pass # don't draw anything for a first point
else:
x_2 = int(xpitch * count)
x_1 = int(xpitch * (count - 1))

if (self.y_bottom <= last_value <= self.y_top) and (
self.y_bottom <= value <= self.y_top
): # both points are in range, plot the line
self._plotline(x_1, last_value, x_2, value)

else: # at least one point is out of range, clip one or both ends the line
if ((last_value > self.y_top) and (value > self.y_top)) or (
(last_value < self.y_bottom) and (value < self.y_bottom)
):
# both points are on the same side out of range: don't draw anything
pass
else:
xint_bottom = self._xintercept(
x_1, last_value, x_2, value, self.y_bottom
) # get possible new x intercept points
xint_top = self._xintercept(
x_1, last_value, x_2, value, self.y_top
) # on the top and bottom of range
if (xint_bottom is None) or (
xint_top is None
): # out of range doublecheck
pass
else:
xint_bottom = self._xintercept(
x_1, last_value, x_2, value, self.y_bottom
) # get possible new x intercept points
xint_top = self._xintercept(
x_1, last_value, x_2, value, self.y_top
) # on the top and bottom of range

if (xint_bottom is None) or (
xint_top is None
): # out of range doublecheck
pass
else:
# Initialize the adjusted values as the baseline
adj_x_1 = x_1
adj_last_value = last_value
adj_x_2 = x_2
adj_value = value

if value > last_value: # slope is positive
if xint_bottom >= x_1: # bottom is clipped
adj_x_1 = xint_bottom
adj_last_value = self.y_bottom # y_1
if xint_top <= x_2: # top is clipped
adj_x_2 = xint_top
adj_value = self.y_top # y_2
else: # slope is negative
if xint_top >= x_1: # top is clipped
adj_x_1 = xint_top
adj_last_value = self.y_top # y_1
if xint_bottom <= x_2: # bottom is clipped
adj_x_2 = xint_bottom
adj_value = self.y_bottom # y_2

self._plotline(
adj_x_1,
adj_last_value,
adj_x_2,
adj_value,
self.y_bottom,
self.y_top,
)

last_value = value # store value for the next iteration
# Initialize the adjusted values as the baseline
adj_x_1 = x_1
adj_last_value = last_value
adj_x_2 = x_2
adj_value = value

if value > last_value: # slope is positive
if xint_bottom >= x_1: # bottom is clipped
adj_x_1 = xint_bottom
adj_last_value = self.y_bottom # y_1
if xint_top <= x_2: # top is clipped
adj_x_2 = xint_top
adj_value = self.y_top # y_2
else: # slope is negative
if xint_top >= x_1: # top is clipped
adj_x_1 = xint_top
adj_last_value = self.y_top # y_1
if xint_bottom <= x_2: # bottom is clipped
adj_x_2 = xint_bottom
adj_value = self.y_bottom # y_2

self._plotline(
adj_x_1,
adj_last_value,
adj_x_2,
adj_value,
)

last_value = value # store value for the next iteration

def values(self) -> List[float]:
"""Returns the values displayed on the sparkline."""
Expand Down