Needle generator: one filled pointer per datum from the hub to its angle, as long as its length — a gauge's indicator, a compass needle (spec/04 §16, #392).
angle/2 is in the domain units of the radial scale given to scale/2 (radians without
one); length/2, inner_radius/2, width/2 and tail/2 are pixels. Each datum's
path is a tapered shape from the base at the hub to the tip, closed; hub_path/2 is
the hub circle the pointer turns about.
Examples
reading = Visualize.Scale.linear() |> Visualize.Scale.domain([0, 100]) |> Visualize.Scale.range([-2.0944, 2.0944])
needle =
Visualize.Shape.Needle.new()
|> Visualize.Shape.Needle.scale(reading)
|> Visualize.Shape.Needle.angle(:value)
|> Visualize.Shape.Needle.length(120)
|> Visualize.Shape.Needle.tail(12)
[path] = Visualize.Shape.Needle.generate_path(needle, [%{value: 42}])Summary
Functions
Sets the angle accessor, in the scale's domain units (radians without a scale)
Sets the tip: :point, :round or :flat
Returns the list of SVG path-data strings, one pointer per datum
Returns the list of IR.Path, one pointer per datum: from the base corner behind the
hub, round the tail, to the other corner, then to the tip as the cap says, closed.
Sets the hub circle's radius accessor; nil means the width
Returns the hub circle's IR.Path for a datum, radius hub (the width when nil)
Sets where the pointer starts, in pixels (default 0)
Sets the tip's radius accessor, in pixels
Creates a needle generator reading tuple elements 0 and 1 as angle and length
Sets the radial scale the angles map through; nil means radians
Sets how far the pointer extends behind the hub, in pixels (default 0)
Sets the base width accessor, in pixels (default 6)
Types
@type cap() :: :point | :round | :flat
@type t() :: %Visualize.Shape.Needle{ angle: Visualize.Shape.Line.accessor() | nil, cap: cap(), hub: Visualize.Shape.Line.accessor() | nil, inner_radius: Visualize.Shape.Line.accessor(), length: Visualize.Shape.Line.accessor() | nil, scale: struct() | nil, tail: Visualize.Shape.Line.accessor(), width: Visualize.Shape.Line.accessor() }
Functions
@spec angle(t(), Visualize.Shape.Line.accessor()) :: t()
Sets the angle accessor, in the scale's domain units (radians without a scale)
Sets the tip: :point, :round or :flat
@spec generate(t(), Visualize.Data.Table.source()) :: [String.t()]
Returns the list of SVG path-data strings, one pointer per datum
@spec generate_path(t(), Visualize.Data.Table.source()) :: [Visualize.IR.Path.t()]
Returns the list of IR.Path, one pointer per datum: from the base corner behind the
hub, round the tail, to the other corner, then to the tip as the cap says, closed.
@spec hub(t(), Visualize.Shape.Line.accessor() | nil) :: t()
Sets the hub circle's radius accessor; nil means the width
@spec hub_path(t(), term()) :: Visualize.IR.Path.t()
Returns the hub circle's IR.Path for a datum, radius hub (the width when nil)
@spec inner_radius(t(), Visualize.Shape.Line.accessor()) :: t()
Sets where the pointer starts, in pixels (default 0)
@spec length(t(), Visualize.Shape.Line.accessor()) :: t()
Sets the tip's radius accessor, in pixels
@spec new() :: t()
Creates a needle generator reading tuple elements 0 and 1 as angle and length
Sets the radial scale the angles map through; nil means radians
@spec tail(t(), Visualize.Shape.Line.accessor()) :: t()
Sets how far the pointer extends behind the hub, in pixels (default 0)
@spec width(t(), Visualize.Shape.Line.accessor()) :: t()
Sets the base width accessor, in pixels (default 6)