NAME
Term::Fabulous::Chart::Palette - Color palettes and color arithmetic for the chart widgets
SYNOPSIS
use Term::Fabulous::Chart::Palette qw(palette_colors mix_rgb contrast_rgb chart_color);
my @dark_steps = palette_colors( default => 'dark' ); # 0x3987e5, 0xd95926, ...
my $faded = mix_rgb( $dark_steps[0], 0x141923, 0.6 ); # 60 % of the way to the background
my $on_slice = contrast_rgb(0xeda100); # dark text on yellow
my ( $rgb, $opacity ) = chart_color( $widget, color => '#3987e580' );DESCRIPTION
The functions the chart widgets (Term::Fabulous::Widget::Chart and its subclasses) use to pick, check and mix colors. Colors are passed around as packed 0xRRGGBB integers, the fastest form a canvas cell takes. All functions are exported on request. To choose a palette for a chart, pass its name (or an array of colors of your own) as the chart's palette; see "Colors and themes" in Term::Fabulous::Widget::Chart and the recipe "Light backgrounds, palettes and colors of your own" in Term::Fabulous::Cookbook::ChartStyles. You need the functions below only for charts or widgets of your own.
Palettes
A palette is an ordered list of eight colors. A chart gives its first series (or its first slice) the first color, the second series the second, and so on, and a series keeps its color when other series are removed. Each palette has steps for dark and for light backgrounds; a chart chooses the steps that suit its background (see "theme" in Term::Fabulous::Widget::Chart).
default-
Blue, orange, aqua, yellow, magenta, green, violet, red: the palette a chart uses unless you choose another. The order keeps neighbors apart for readers with the common color vision deficiencies. On a dark background every color has at least 3:1 contrast to the background; on a light one, aqua, yellow and magenta have less (about 2:1 to 2.7:1), so use them there for fills and bars rather than for thin lines. Use this palette unless you have a reason not to.
classic-
The colors of popular dark and light editor themes: softer blue, red, green, yellow and purple. They match the colors of the Term::Fabulous examples.
pastel-
Light, soft colors; good for large fills such as pie slices and stacked areas on a dark background.
vivid-
Saturated, bright colors for thin lines on a dark background.
Only default was checked for color vision deficiencies. With the other palettes, and in general with more than four series, help readers with labels: the legend, value labels, or different line styles and point glyphs.
FUNCTIONS
palette_colors
my @colors = palette_colors( $name, $mode );The eight colors of a palette as packed integers. $mode is dark or light. Dies for an unknown name or mode.
palette_names
The names of all palettes, sorted: classic, default, pastel, vivid.
is_palette_name
True for the name of a palette.
chart_color
my ( $rgb, $opacity ) = chart_color( $owner, $name, $color );Reads a color in any format a canvas cell takes (see "Colors" in Term::Fabulous::Widget::Canvas): a packed 0xRRGGBB integer, a string such as '#ff8800', '#ff880080', 'rgb(255, 136, 0)' or 'hsl(32, 100%, 50%)', an array or hash reference, or a Term::Fabulous::Color (such as Term::Fabulous::Enum::WebColor->Tomato). Returns the color as a packed integer and its alpha as an opacity from 0 to 1. Dies with $owner and $name in the message for anything else.
mix_rgb
my $mixed = mix_rgb( $from, $to, $amount );The color $amount (0 to 1) of the way from $from to $to, channel by channel. This is how translucent fills are drawn: the fill color mixed into what is below it.
luminance
The relative luminance of a color as WCAG 2 defines it, from 0 (black) to 1 (white).
is_light_rgb
True when dark text has more contrast on the color than light text.
contrast_rgb
Near black (0x111111) for a light color, near white (0xF5F5F5) for a dark one: the color of text written on it.
ink_colors
my $ink = ink_colors( $background, $mode );
# { title => ..., text => ..., label => ..., axis => ..., grid => ... }The colors of a chart's chrome on a background: the title, the legend text, the tick labels and axis titles, the axis lines and the grid lines. They are mixed from the background and the ink of the mode (white on dark, near black on light), so grid lines are always one shade off the background and labels are recessive, whatever background the chart has.
rgb_hex
The #rrggbb string of a packed color.
SEE ALSO
Term::Fabulous::Widget::Chart, "CHARTS" in Term::Fabulous::Manual::Charts, Term::Fabulous::Color.