Add gradient picker example

Author: matze

examples/gradients/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "gradients"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]
+iced = { path = "../.." }

examples/gradients/src/main.rs

@@ -0,0 +1,136 @@
+use iced::widget::{column, container, row, slider, text};
+use iced::{
+    gradient, Alignment, Background, BorderRadius, Color, Element, Length,
+    Radians, Sandbox, Settings,
+};
+
+pub fn main() -> iced::Result {
+    Gradient::run(Settings::default())
+}
+
+struct Gradient {
+    first: Color,
+    second: Color,
+    angle: f32,
+}
+
+#[derive(Debug, Clone, Copy)]
+enum Message {
+    FirstChanged(Color),
+    SecondChanged(Color),
+    AngleChanged(f32),
+}
+
+impl Sandbox for Gradient {
+    type Message = Message;
+
+    fn new() -> Self {
+        let first = Color::new(0.2784314, 0.0627451, 0.4117647, 1.0);
+        let second = Color::new(0.1882353, 0.772549, 0.8235294, 1.0);
+
+        Self {
+            first,
+            second,
+            angle: 0.0,
+        }
+    }
+
+    fn title(&self) -> String {
+        String::from("Color gradient")
+    }
+
+    fn update(&mut self, message: Message) {
+        match message {
+            Message::FirstChanged(color) => self.first = color,
+            Message::SecondChanged(color) => self.second = color,
+            Message::AngleChanged(angle) => self.angle = angle,
+        }
+    }
+
+    fn view(&self) -> Element<Message> {
+        let first = self.first;
+        let second = self.second;
+        let angle = self.angle;
+
+        let gradient_box = container(text(""))
+            .width(Length::Fill)
+            .height(Length::Fill)
+            .center_x()
+            .center_y()
+            .style(move |_: &_| {
+                let gradient = gradient::Linear::new(Radians(angle))
+                    .add_stop(0.0, first)
+                    .add_stop(1.0, second)
+                    .into();
+
+                container::Appearance {
+                    text_color: None,
+                    background: Some(Background::Gradient(gradient)),
+                    border_radius: BorderRadius::default(),
+                    border_width: 0.0,
+                    border_color: Color::new(0.0, 0.0, 0.0, 0.0),
+                }
+            });
+
+        let range = 0.0..=1.0;
+        let l = self.first;
+        let r = self.second;
+
+        let first_color_picker = row![
+            text("First").width(64),
+            slider(range.clone(), l.r, move |v| {
+                Message::FirstChanged(Color::new(v, l.g, l.b, l.a))
+            })
+            .step(0.01),
+            slider(range.clone(), l.g, move |v| {
+                Message::FirstChanged(Color::new(l.r, v, l.b, l.a))
+            })
+            .step(0.01),
+            slider(range.clone(), l.b, move |v| {
+                Message::FirstChanged(Color::new(l.r, l.g, v, l.a))
+            })
+            .step(0.01),
+        ]
+        .spacing(8)
+        .padding(8)
+        .align_items(Alignment::Center);
+
+        let second_color_picker = row![
+            text("Second").width(64),
+            slider(range.clone(), r.r, move |v| {
+                Message::SecondChanged(Color::new(v, r.g, r.b, r.a))
+            })
+            .step(0.01),
+            slider(range.clone(), r.g, move |v| {
+                Message::SecondChanged(Color::new(r.r, v, r.b, r.a))
+            })
+            .step(0.01),
+            slider(range.clone(), r.b, move |v| {
+                Message::SecondChanged(Color::new(r.r, r.g, v, r.a))
+            })
+            .step(0.01),
+        ]
+        .spacing(8)
+        .padding(8)
+        .align_items(Alignment::Center);
+
+        let angle_picker = row![
+            text("Angle").width(64),
+            slider(0.0..=std::f32::consts::PI * 2.0, self.angle, move |v| {
+                Message::AngleChanged(v)
+            })
+            .step(0.01)
+        ]
+        .spacing(8)
+        .padding(8)
+        .align_items(Alignment::Center);
+
+        column![
+            first_color_picker,
+            second_color_picker,
+            angle_picker,
+            gradient_box
+        ]
+        .into()
+    }
+}