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jonaspleyerjonaspleyer
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also add struct for dynamic creation of colormaps
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‎plotters/src/style/colors/colormaps.rs

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@@ -14,6 +14,96 @@ where
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}
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/// This struct is used to dynamically construct colormaps by giving it a slice of colors.
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/// It can then be used when being intantiated, but not with associated functions.
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/// ```
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/// use plotters::prelude::{BLACK,BLUE,WHITE,DerivedColorMap,ColorMap};
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///
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/// let derived_colormap = DerivedColorMap::new(
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/// &[BLACK,
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/// BLUE,
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/// WHITE]
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/// );
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///
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/// assert_eq!(derived_colormap.get_color(0.0), BLACK);
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/// assert_eq!(derived_colormap.get_color(0.5), BLUE);
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/// assert_eq!(derived_colormap.get_color(1.0), WHITE);
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/// ```
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pub struct DerivedColorMap<ColorType> {
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colors: Vec<ColorType>,
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}
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impl<ColorType: crate::style::Color + Clone> DerivedColorMap<ColorType> {
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pub fn new(colors: &[ColorType]) -> Self {
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DerivedColorMap { colors: colors.iter().map(|color| color.clone()).collect::<Vec<_>>() }
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}
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}
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macro_rules! calculate_new_color_value(
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($relative_difference:expr, $colors:expr, $index_upper:expr, $index_lower:expr, RGBColor) => {
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RGBColor(
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// These equations are a very complicated way of writing a simple linear extrapolation with lots of casting between numerical values
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// In principle every cast should be safe which is why we choose to unwrap
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// (1.0 - r) * color_value_1 + r * color_value_2
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((FloatType::one() - $relative_difference) * FloatType::from_u8($colors[$index_upper].0).unwrap() + $relative_difference * FloatType::from_u8($colors[$index_lower].0).unwrap()).round().to_u8().unwrap(),
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((FloatType::one() - $relative_difference) * FloatType::from_u8($colors[$index_upper].1).unwrap() + $relative_difference * FloatType::from_u8($colors[$index_lower].1).unwrap()).round().to_u8().unwrap(),
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((FloatType::one() - $relative_difference) * FloatType::from_u8($colors[$index_upper].2).unwrap() + $relative_difference * FloatType::from_u8($colors[$index_lower].2).unwrap()).round().to_u8().unwrap()
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)
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};
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($relative_difference:expr, $colors:expr, $index_upper:expr, $index_lower:expr, RGBAColor) => {
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RGBAColor(
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// These equations are a very complicated way of writing a simple linear extrapolation with lots of casting between numerical values
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// In principle every cast should be safe which is why we choose to unwrap
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// (1.0 - r) * color_value_1 + r * color_value_2
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((FloatType::one() - $relative_difference) * FloatType::from_u8($colors[$index_upper].0).unwrap() + $relative_difference * FloatType::from_u8($colors[$index_lower].0).unwrap()).round().to_u8().unwrap(),
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((FloatType::one() - $relative_difference) * FloatType::from_u8($colors[$index_upper].1).unwrap() + $relative_difference * FloatType::from_u8($colors[$index_lower].1).unwrap()).round().to_u8().unwrap(),
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((FloatType::one() - $relative_difference) * FloatType::from_u8($colors[$index_upper].2).unwrap() + $relative_difference * FloatType::from_u8($colors[$index_lower].2).unwrap()).round().to_u8().unwrap(),
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((FloatType::one() - $relative_difference) * FloatType::from_f64($colors[$index_upper].3).unwrap() + $relative_difference * FloatType::from_f64($colors[$index_lower].3).unwrap()).to_f64().unwrap()
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)
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};
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($relative_difference:expr, $colors:expr, $index_upper:expr, $index_lower:expr, HSLColor) => {
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HSLColor(
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// These equations are a very complicated way of writing a simple linear extrapolation with lots of casting between numerical values
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// In principle every cast should be safe which is why we choose to unwrap
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// (1.0 - r) * color_value_1 + r * color_value_2
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((FloatType::one() - $relative_difference) * FloatType::from_f64($colors[$index_upper].0).unwrap() + $relative_difference * FloatType::from_f64($colors[$index_lower].0).unwrap()).to_f64().unwrap(),
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((FloatType::one() - $relative_difference) * FloatType::from_f64($colors[$index_upper].1).unwrap() + $relative_difference * FloatType::from_f64($colors[$index_lower].1).unwrap()).to_f64().unwrap(),
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((FloatType::one() - $relative_difference) * FloatType::from_f64($colors[$index_upper].2).unwrap() + $relative_difference * FloatType::from_f64($colors[$index_lower].2).unwrap()).to_f64().unwrap(),
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)
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};
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);
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macro_rules! implement_color_scale_for_derived_ColorMap{
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($($color_type:tt),+) => {
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$(
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impl<FloatType: Float + FromPrimitive + ToPrimitive> ColorMap<$color_type, FloatType> for DerivedColorMap<$color_type> {
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fn get_color_normalized(&self, h: FloatType, min: FloatType, max: FloatType) -> $color_type {
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// Ensure that we do have a value in bounds
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let h = h.max(min).min(max);
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// Make sure that we really have a minimal value which is smaller than the maximal value
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assert_eq!(min<max, true);
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// Next calculate a normalized value between 0.0 and 1.0
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let t = (h - min)/(max-min);
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let approximate_index = t * (FloatType::from_usize(self.colors.len()).unwrap() - FloatType::one()).max(FloatType::zero());
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// Calculate which index are the two most nearest of the supplied value
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let index_lower = approximate_index.floor().to_usize().unwrap();
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let index_upper = approximate_index.ceil().to_usize().unwrap();
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// Calculate the relative difference, ie. is the actual value more towards the color of index_upper or index_lower?
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let relative_difference = approximate_index.ceil() - approximate_index;
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// Interpolate the final color linearly
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calculate_new_color_value!(relative_difference, self.colors, index_upper, index_lower, $color_type)
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}
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}
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)+
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}
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}
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implement_color_scale_for_derived_ColorMap!{RGBAColor, RGBColor, HSLColor}
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macro_rules! count {
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() => (0usize);
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($x:tt $($xs:tt)* ) => (1usize + count!($($xs)*));

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