add pure version of color_palette example

examples/pure/color_palette/Cargo.toml

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+[package]
+name = "pure_color_palette"
+version = "0.1.0"
+authors = ["Clark Moody <clark@clarkmoody.com>"]
+edition = "2021"
+publish = false
+
+[dependencies]
+iced = { path = "../../..", features = ["pure", "canvas", "palette"] }
+palette = "0.6.0"

examples/pure/color_palette/README.md

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+## Color palette
+
+A color palette generator, based on a user-defined root color.
+
+<div align="center">
+  <a href="https://gfycat.com/dirtylonebighornsheep">
+    <img src="screenshot.png">
+  </a>
+</div>
+
+You can run it with `cargo run`:
+
+```
+cargo run --package pure_color_palette
+```

examples/pure/color_palette/src/main.rs

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+use iced::pure::{
+    column, row, text,
+    widget::canvas::{self, Canvas, Cursor, Frame, Geometry, Path},
+    widget::Slider,
+    Element, Sandbox,
+};
+use iced::{
+    alignment, Alignment, Color, Length, Point, Rectangle, Settings, Size,
+    Vector,
+};
+use palette::{self, convert::FromColor, Hsl, Srgb};
+use std::marker::PhantomData;
+use std::ops::RangeInclusive;
+
+pub fn main() -> iced::Result {
+    ColorPalette::run(Settings {
+        antialiasing: true,
+        ..Settings::default()
+    })
+}
+
+#[derive(Default)]
+pub struct ColorPalette {
+    theme: Theme,
+    rgb: ColorPicker<Color>,
+    hsl: ColorPicker<palette::Hsl>,
+    hsv: ColorPicker<palette::Hsv>,
+    hwb: ColorPicker<palette::Hwb>,
+    lab: ColorPicker<palette::Lab>,
+    lch: ColorPicker<palette::Lch>,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Message {
+    RgbColorChanged(Color),
+    HslColorChanged(palette::Hsl),
+    HsvColorChanged(palette::Hsv),
+    HwbColorChanged(palette::Hwb),
+    LabColorChanged(palette::Lab),
+    LchColorChanged(palette::Lch),
+}
+
+impl Sandbox for ColorPalette {
+    type Message = Message;
+
+    fn new() -> Self {
+        Self::default()
+    }
+
+    fn title(&self) -> String {
+        String::from("Color palette - Iced")
+    }
+
+    fn update(&mut self, message: Message) {
+        let srgb = match message {
+            Message::RgbColorChanged(rgb) => palette::Srgb::from(rgb),
+            Message::HslColorChanged(hsl) => palette::Srgb::from_color(hsl),
+            Message::HsvColorChanged(hsv) => palette::Srgb::from_color(hsv),
+            Message::HwbColorChanged(hwb) => palette::Srgb::from_color(hwb),
+            Message::LabColorChanged(lab) => palette::Srgb::from_color(lab),
+            Message::LchColorChanged(lch) => palette::Srgb::from_color(lch),
+        };
+
+        self.theme = Theme::new(srgb);
+    }
+
+    fn view(&self) -> Element<Message> {
+        let base = self.theme.base;
+
+        let srgb = palette::Srgb::from(base);
+        let hsl = palette::Hsl::from_color(srgb);
+        let hsv = palette::Hsv::from_color(srgb);
+        let hwb = palette::Hwb::from_color(srgb);
+        let lab = palette::Lab::from_color(srgb);
+        let lch = palette::Lch::from_color(srgb);
+
+        column()
+            .padding(10)
+            .spacing(10)
+            .push(self.rgb.view(base).map(Message::RgbColorChanged))
+            .push(self.hsl.view(hsl).map(Message::HslColorChanged))
+            .push(self.hsv.view(hsv).map(Message::HsvColorChanged))
+            .push(self.hwb.view(hwb).map(Message::HwbColorChanged))
+            .push(self.lab.view(lab).map(Message::LabColorChanged))
+            .push(self.lch.view(lch).map(Message::LchColorChanged))
+            .push(self.theme.view())
+            .into()
+    }
+}
+
+#[derive(Debug)]
+pub struct Theme {
+    lower: Vec<Color>,
+    base: Color,
+    higher: Vec<Color>,
+    canvas_cache: canvas::Cache,
+}
+
+impl Theme {
+    pub fn new(base: impl Into<Color>) -> Theme {
+        use palette::{Hue, Shade};
+
+        let base = base.into();
+
+        // Convert to HSL color for manipulation
+        let hsl = Hsl::from_color(Srgb::from(base));
+
+        let lower = [
+            hsl.shift_hue(-135.0).lighten(0.075),
+            hsl.shift_hue(-120.0),
+            hsl.shift_hue(-105.0).darken(0.075),
+            hsl.darken(0.075),
+        ];
+
+        let higher = [
+            hsl.lighten(0.075),
+            hsl.shift_hue(105.0).darken(0.075),
+            hsl.shift_hue(120.0),
+            hsl.shift_hue(135.0).lighten(0.075),
+        ];
+
+        Theme {
+            lower: lower
+                .iter()
+                .map(|&color| Srgb::from_color(color).into())
+                .collect(),
+            base,
+            higher: higher
+                .iter()
+                .map(|&color| Srgb::from_color(color).into())
+                .collect(),
+            canvas_cache: canvas::Cache::default(),
+        }
+    }
+
+    pub fn len(&self) -> usize {
+        self.lower.len() + self.higher.len() + 1
+    }
+
+    pub fn colors(&self) -> impl Iterator<Item = &Color> {
+        self.lower
+            .iter()
+            .chain(std::iter::once(&self.base))
+            .chain(self.higher.iter())
+    }
+
+    pub fn view(&self) -> Element<Message> {
+        Canvas::new(self)
+            .width(Length::Fill)
+            .height(Length::Fill)
+            .into()
+    }
+
+    fn draw(&self, frame: &mut Frame) {
+        let pad = 20.0;
+
+        let box_size = Size {
+            width: frame.width() / self.len() as f32,
+            height: frame.height() / 2.0 - pad,
+        };
+
+        let triangle = Path::new(|path| {
+            path.move_to(Point { x: 0.0, y: -0.5 });
+            path.line_to(Point { x: -0.5, y: 0.0 });
+            path.line_to(Point { x: 0.5, y: 0.0 });
+            path.close();
+        });
+
+        let mut text = canvas::Text {
+            horizontal_alignment: alignment::Horizontal::Center,
+            vertical_alignment: alignment::Vertical::Top,
+            size: 15.0,
+            ..canvas::Text::default()
+        };
+
+        for (i, &color) in self.colors().enumerate() {
+            let anchor = Point {
+                x: (i as f32) * box_size.width,
+                y: 0.0,
+            };
+            frame.fill_rectangle(anchor, box_size, color);
+
+            // We show a little indicator for the base color
+            if color == self.base {
+                let triangle_x = anchor.x + box_size.width / 2.0;
+
+                frame.with_save(|frame| {
+                    frame.translate(Vector::new(triangle_x, 0.0));
+                    frame.scale(10.0);
+                    frame.rotate(std::f32::consts::PI);
+
+                    frame.fill(&triangle, Color::WHITE);
+                });
+
+                frame.with_save(|frame| {
+                    frame.translate(Vector::new(triangle_x, box_size.height));
+                    frame.scale(10.0);
+
+                    frame.fill(&triangle, Color::WHITE);
+                });
+            }
+
+            frame.fill_text(canvas::Text {
+                content: color_hex_string(&color),
+                position: Point {
+                    x: anchor.x + box_size.width / 2.0,
+                    y: box_size.height,
+                },
+                ..text
+            });
+        }
+
+        text.vertical_alignment = alignment::Vertical::Bottom;
+
+        let hsl = Hsl::from_color(Srgb::from(self.base));
+        for i in 0..self.len() {
+            let pct = (i as f32 + 1.0) / (self.len() as f32 + 1.0);
+            let graded = Hsl {
+                lightness: 1.0 - pct,
+                ..hsl
+            };
+            let color: Color = Srgb::from_color(graded).into();
+
+            let anchor = Point {
+                x: (i as f32) * box_size.width,
+                y: box_size.height + 2.0 * pad,
+            };
+
+            frame.fill_rectangle(anchor, box_size, color);
+
+            frame.fill_text(canvas::Text {
+                content: color_hex_string(&color),
+                position: Point {
+                    x: anchor.x + box_size.width / 2.0,
+                    y: box_size.height + 2.0 * pad,
+                },
+                ..text
+            });
+        }
+    }
+}
+
+impl<Message> canvas::Program<Message> for Theme {
+    type State = ();
+
+    fn draw(
+        &self,
+        _state: &Self::State,
+        _theme: &iced::Theme,
+        bounds: Rectangle,
+        _cursor: Cursor,
+    ) -> Vec<Geometry> {
+        let theme = self.canvas_cache.draw(bounds.size(), |frame| {
+            self.draw(frame);
+        });
+
+        vec![theme]
+    }
+}
+
+impl Default for Theme {
+    fn default() -> Self {
+        Theme::new(Color::from_rgb8(75, 128, 190))
+    }
+}
+
+fn color_hex_string(color: &Color) -> String {
+    format!(
+        "#{:x}{:x}{:x}",
+        (255.0 * color.r).round() as u8,
+        (255.0 * color.g).round() as u8,
+        (255.0 * color.b).round() as u8
+    )
+}
+
+#[derive(Default)]
+struct ColorPicker<C: ColorSpace> {
+    color_space: PhantomData<C>,
+}
+
+trait ColorSpace: Sized {
+    const LABEL: &'static str;
+    const COMPONENT_RANGES: [RangeInclusive<f64>; 3];
+
+    fn new(a: f32, b: f32, c: f32) -> Self;
+
+    fn components(&self) -> [f32; 3];
+
+    fn to_string(&self) -> String;
+}
+
+impl<C: ColorSpace + Copy> ColorPicker<C> {
+    fn view(&self, color: C) -> Element<C> {
+        let [c1, c2, c3] = color.components();
+        let [cr1, cr2, cr3] = C::COMPONENT_RANGES;
+
+        fn slider<'a, C: Clone>(
+            range: RangeInclusive<f64>,
+            component: f32,
+            update: impl Fn(f32) -> C + 'a,
+        ) -> Slider<'a, f64, C, iced::Renderer> {
+            Slider::new(range, f64::from(component), move |v| update(v as f32))
+                .step(0.01)
+        }
+
+        row()
+            .spacing(10)
+            .align_items(Alignment::Center)
+            .push(text(C::LABEL).width(Length::Units(50)))
+            .push(slider(cr1, c1, move |v| C::new(v, c2, c3)))
+            .push(slider(cr2, c2, move |v| C::new(c1, v, c3)))
+            .push(slider(cr3, c3, move |v| C::new(c1, c2, v)))
+            .push(text(color.to_string()).width(Length::Units(185)).size(14))
+            .into()
+    }
+}
+
+impl ColorSpace for Color {
+    const LABEL: &'static str = "RGB";
+    const COMPONENT_RANGES: [RangeInclusive<f64>; 3] =
+        [0.0..=1.0, 0.0..=1.0, 0.0..=1.0];
+
+    fn new(r: f32, g: f32, b: f32) -> Self {
+        Color::from_rgb(r, g, b)
+    }
+
+    fn components(&self) -> [f32; 3] {
+        [self.r, self.g, self.b]
+    }
+
+    fn to_string(&self) -> String {
+        format!(
+            "rgb({:.0}, {:.0}, {:.0})",
+            255.0 * self.r,
+            255.0 * self.g,
+            255.0 * self.b
+        )
+    }
+}
+
+impl ColorSpace for palette::Hsl {
+    const LABEL: &'static str = "HSL";
+    const COMPONENT_RANGES: [RangeInclusive<f64>; 3] =
+        [0.0..=360.0, 0.0..=1.0, 0.0..=1.0];
+
+    fn new(hue: f32, saturation: f32, lightness: f32) -> Self {
+        palette::Hsl::new(
+            palette::RgbHue::from_degrees(hue),
+            saturation,
+            lightness,
+        )
+    }
+
+    fn components(&self) -> [f32; 3] {
+        [
+            self.hue.to_positive_degrees(),
+            self.saturation,
+            self.lightness,
+        ]
+    }
+
+    fn to_string(&self) -> String {
+        format!(
+            "hsl({:.1}, {:.1}%, {:.1}%)",
+            self.hue.to_positive_degrees(),
+            100.0 * self.saturation,
+            100.0 * self.lightness
+        )
+    }
+}
+
+impl ColorSpace for palette::Hsv {
+    const LABEL: &'static str = "HSV";
+    const COMPONENT_RANGES: [RangeInclusive<f64>; 3] =
+        [0.0..=360.0, 0.0..=1.0, 0.0..=1.0];
+
+    fn new(hue: f32, saturation: f32, value: f32) -> Self {
+        palette::Hsv::new(palette::RgbHue::from_degrees(hue), saturation, value)
+    }
+
+    fn components(&self) -> [f32; 3] {
+        [self.hue.to_positive_degrees(), self.saturation, self.value]
+    }
+
+    fn to_string(&self) -> String {
+        format!(
+            "hsv({:.1}, {:.1}%, {:.1}%)",
+            self.hue.to_positive_degrees(),
+            100.0 * self.saturation,
+            100.0 * self.value
+        )
+    }
+}
+
+impl ColorSpace for palette::Hwb {
+    const LABEL: &'static str = "HWB";
+    const COMPONENT_RANGES: [RangeInclusive<f64>; 3] =
+        [0.0..=360.0, 0.0..=1.0, 0.0..=1.0];
+
+    fn new(hue: f32, whiteness: f32, blackness: f32) -> Self {
+        palette::Hwb::new(
+            palette::RgbHue::from_degrees(hue),
+            whiteness,
+            blackness,
+        )
+    }
+
+    fn components(&self) -> [f32; 3] {
+        [
+            self.hue.to_positive_degrees(),
+            self.whiteness,
+            self.blackness,
+        ]
+    }
+
+    fn to_string(&self) -> String {
+        format!(
+            "hwb({:.1}, {:.1}%, {:.1}%)",
+            self.hue.to_positive_degrees(),
+            100.0 * self.whiteness,
+            100.0 * self.blackness
+        )
+    }
+}
+
+impl ColorSpace for palette::Lab {
+    const LABEL: &'static str = "Lab";
+    const COMPONENT_RANGES: [RangeInclusive<f64>; 3] =
+        [0.0..=100.0, -128.0..=127.0, -128.0..=127.0];
+
+    fn new(l: f32, a: f32, b: f32) -> Self {
+        palette::Lab::new(l, a, b)
+    }
+
+    fn components(&self) -> [f32; 3] {
+        [self.l, self.a, self.b]
+    }
+
+    fn to_string(&self) -> String {
+        format!("Lab({:.1}, {:.1}, {:.1})", self.l, self.a, self.b)
+    }
+}
+
+impl ColorSpace for palette::Lch {
+    const LABEL: &'static str = "Lch";
+    const COMPONENT_RANGES: [RangeInclusive<f64>; 3] =
+        [0.0..=100.0, 0.0..=128.0, 0.0..=360.0];
+
+    fn new(l: f32, chroma: f32, hue: f32) -> Self {
+        palette::Lch::new(l, chroma, palette::LabHue::from_degrees(hue))
+    }
+
+    fn components(&self) -> [f32; 3] {
+        [self.l, self.chroma, self.hue.to_positive_degrees()]
+    }
+
+    fn to_string(&self) -> String {
+        format!(
+            "Lch({:.1}, {:.1}, {:.1})",
+            self.l,
+            self.chroma,
+            self.hue.to_positive_degrees()
+        )
+    }
+}