You cannot select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
This repo is archived. You can view files and clone it, but cannot push or open issues/pull-requests.
ndg/lib/lvgl/examples/widgets/chart/lv_example_chart_8.py

125 lines
4.6 KiB
Python

import display_driver
import lvgl as lv
# A class is used to keep track of the series list because later we
# need to draw to the series in the reverse order to which they were initialised.
class StackedAreaChart:
def __init__(self):
self.obj = None
self.series_list = [None, None, None]
stacked_area_chart = StackedAreaChart()
#
# Callback which draws the blocks of colour under the lines
#
def draw_event_cb(e):
obj = e.get_target()
cont_a = lv.area_t()
obj.get_coords(cont_a)
#Add the faded area before the lines are drawn
dsc = e.get_draw_part_dsc()
if dsc.part == lv.PART.ITEMS:
if not dsc.p1 or not dsc.p2:
return
# Add a line mask that keeps the area below the line
line_mask_param = lv.draw_mask_line_param_t()
line_mask_param.points_init(dsc.p1.x, dsc.p1.y, dsc.p2.x, dsc.p2.y, lv.DRAW_MASK_LINE_SIDE.BOTTOM)
line_mask_id = lv.draw_mask_add(line_mask_param, None)
#Draw a rectangle that will be affected by the mask
draw_rect_dsc = lv.draw_rect_dsc_t()
draw_rect_dsc.init()
draw_rect_dsc.bg_opa = lv.OPA.COVER
draw_rect_dsc.bg_color = dsc.line_dsc.color
a = lv.area_t()
a.x1 = dsc.p1.x
a.x2 = dsc.p2.x
a.y1 = min(dsc.p1.y, dsc.p2.y)
a.y2 = cont_a.y2 - 13 # -13 cuts off where the rectangle draws over the chart margin. Without this an area of 0 doesn't look like 0
dsc.draw_ctx.rect(draw_rect_dsc, a)
# Remove the mask
lv.draw_mask_free_param(line_mask_param)
lv.draw_mask_remove_id(line_mask_id)
#
# Helper function to round a fixed point number
#
def round_fixed_point(n, shift):
# Create a bitmask to isolates the decimal part of the fixed point number
mask = 1
for bit_pos in range(shift):
mask = (mask << 1) + 1
decimal_part = n & mask
# Get 0.5 as fixed point
rounding_boundary = 1 << (shift - 1)
# Return either the integer part of n or the integer part + 1
if decimal_part < rounding_boundary:
return (n & ~mask)
return ((n >> shift) + 1) << shift
#
# Stacked area chart
#
def lv_example_chart_8():
#Create a stacked_area_chart.obj
stacked_area_chart.obj = lv.chart(lv.scr_act())
stacked_area_chart.obj.set_size(200, 150)
stacked_area_chart.obj.center()
stacked_area_chart.obj.set_type( lv.chart.TYPE.LINE)
stacked_area_chart.obj.set_div_line_count(5, 7)
stacked_area_chart.obj.add_event_cb( draw_event_cb, lv.EVENT.DRAW_PART_BEGIN, None)
# Set range to 0 to 100 for percentages. Draw ticks
stacked_area_chart.obj.set_range(lv.chart.AXIS.PRIMARY_Y,0,100)
stacked_area_chart.obj.set_axis_tick(lv.chart.AXIS.PRIMARY_Y, 3, 0, 5, 1, True, 30)
#Set point size to 0 so the lines are smooth
stacked_area_chart.obj.set_style_size(0, lv.PART.INDICATOR)
# Add some data series
stacked_area_chart.series_list[0] = stacked_area_chart.obj.add_series(lv.palette_main(lv.PALETTE.RED), lv.chart.AXIS.PRIMARY_Y)
stacked_area_chart.series_list[1] = stacked_area_chart.obj.add_series(lv.palette_main(lv.PALETTE.BLUE), lv.chart.AXIS.PRIMARY_Y)
stacked_area_chart.series_list[2] = stacked_area_chart.obj.add_series(lv.palette_main(lv.PALETTE.GREEN), lv.chart.AXIS.PRIMARY_Y)
for point in range(10):
# Make some random data
vals = [lv.rand(10, 20), lv.rand(20, 30), lv.rand(20, 30)]
fixed_point_shift = 5
total = vals[0] + vals[1] + vals[2]
draw_heights = [0, 0, 0]
int_sum = 0
decimal_sum = 0
# Fixed point cascade rounding ensures percentages add to 100
for series_index in range(3):
decimal_sum += int(((vals[series_index] * 100) << fixed_point_shift) // total)
int_sum += int((vals[series_index] * 100) / total)
modifier = (round_fixed_point(decimal_sum, fixed_point_shift) >> fixed_point_shift) - int_sum
# The draw heights are equal to the percentage of the total each value is + the cumulative sum of the previous percentages.
# The accumulation is how the values get "stacked"
draw_heights[series_index] = int(int_sum + modifier)
# Draw to the series in the reverse order to which they were initialised.
# Without this the higher values will draw on top of the lower ones.
# This is because the Z-height of a series matches the order it was initialised
stacked_area_chart.obj.set_next_value( stacked_area_chart.series_list[3 - series_index - 1], draw_heights[series_index])
stacked_area_chart.obj.refresh()
lv_example_chart_8()