Class: Flightdeck::Metrics::Chart

Inherits:
Object
  • Object
show all
Defined in:
app/models/flightdeck/metrics/chart.rb

Overview

Geometry for the server-rendered SVG charts.

All the arithmetic lives here so the ERB partials stay readable: they place elements and nothing else. Colours are never computed here either — the partials reference the CSS custom properties, so charts re-theme with the rest of the page and there is no inline colour to get out of step.

Direct Known Subclasses

BarChart, LineChart

Constant Summary collapse

WIDTH = 
720
HEIGHT = 
190
PAD_LEFT = 
40
PAD_RIGHT = 
10
PAD_TOP = 
12
PAD_BOTTOM = 
22
GRID_INTERVALS = 
3

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(points:, window:) ⇒ Chart

Returns a new instance of Chart.



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# File 'app/models/flightdeck/metrics/chart.rb', line 22

def initialize(points:, window:)
  @points = points
  @window = window
end

Instance Attribute Details

#points ⇒ Object (readonly)

Returns the value of attribute points.



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# File 'app/models/flightdeck/metrics/chart.rb', line 20

def points
  @points
end

#window ⇒ Object (readonly)

Returns the value of attribute window.



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# File 'app/models/flightdeck/metrics/chart.rb', line 20

def window
  @window
end

Instance Method Details

#axis_max ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 56

def axis_max
  @axis_max ||= nice_ceiling(raw_max)
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'app/models/flightdeck/metrics/chart.rb', line 35

def empty? = points.empty?

#format_time(time, pattern) ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 60

def format_time(time, pattern)
  time.in_time_zone(Flightdeck.config.display_timezone).strftime(pattern)
end

#full_time(time) ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 64

def full_time(time)
  format_time(time, "%Y-%m-%d %H:%M")
end

#gridlines ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 37

def gridlines
  (0..GRID_INTERVALS).map do |i|
    value = axis_max * (GRID_INTERVALS - i) / GRID_INTERVALS.to_f
    { y: round(plot_top + (plot_height * i / GRID_INTERVALS.to_f)), value: value, label: format_value(value) }
  end
end

#height ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 28

def height = HEIGHT

#plot_bottom ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 32

def plot_bottom = HEIGHT - PAD_BOTTOM

#plot_height ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 34

def plot_height = plot_bottom - plot_top

#plot_left ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 29

def plot_left = PAD_LEFT

#plot_right ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 30

def plot_right = WIDTH - PAD_RIGHT

#plot_top ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 31

def plot_top = PAD_TOP

#plot_width ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 33

def plot_width = plot_right - plot_left

#width ⇒ Object 



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# File 'app/models/flightdeck/metrics/chart.rb', line 27

def width = WIDTH

#x_ticks ⇒ Object

Ticks are placed on bucket boundaries so a label always names a bucket that is actually on screen.



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# File 'app/models/flightdeck/metrics/chart.rb', line 46

def x_ticks
  every = [ window.tick_every.to_i, 1 ].max

  points.each_with_index.filter_map do |point, index|
    next unless (index % every).zero?

    { x: round(tick_x(index)), label: format_time(point.at, window.tick_format) }
  end
end