Implement Geometry2D primitive

core/src/geometry.rs

@@ -0,0 +1,20 @@
+/// A two-dimensional vertex which has a color
+#[repr(C)]
+#[derive(Copy, Clone, Debug)]
+pub struct Vertex2D {
+    /// The vertex position
+    pub position: [f32; 2],
+    /// The vertex color in rgba
+    pub color: [f32; 4],
+}
+
+/// A set of [`Vertex2D`] and indices for drawing some 2D geometry on the GPU.
+///
+/// [`Vertex2D`]: struct.Vertex2D.html
+#[derive(Clone, Debug)]
+pub struct Geometry2D {
+    /// The vertices for this geometry
+    pub vertices: Vec<Vertex2D>,
+    /// The indices for this geometry
+    pub indices: Vec<u16>,
+}

core/src/lib.rs

@@ -23,6 +23,7 @@ mod length;
 mod point;
 mod rectangle;
 mod vector;
+mod geometry;
 
 pub use align::{Align, HorizontalAlignment, VerticalAlignment};
 pub use background::Background;
@@ -32,6 +33,7 @@ pub use length::Length;
 pub use point::Point;
 pub use rectangle::Rectangle;
 pub use vector::Vector;
+pub use geometry::{Vertex2D, Geometry2D};
 
 #[cfg(feature = "command")]
 mod command;

examples/geometry.rs

@@ -0,0 +1,227 @@
+//! This example showcases a simple native custom widget that renders using
+//! arbitrary low-level geometry.
+mod rainbow {
+    // For now, to implement a custom native widget you will need to add
+    // `iced_native` and `iced_wgpu` to your dependencies.
+    //
+    // Then, you simply need to define your widget type and implement the
+    // `iced_native::Widget` trait with the `iced_wgpu::Renderer`.
+    //
+    // Of course, you can choose to make the implementation renderer-agnostic,
+    // if you wish to, by creating your own `Renderer` trait, which could be
+    // implemented by `iced_wgpu` and other renderers.
+    use iced_native::{
+        layout,  Element, Geometry2D, Hasher, Layout, Length,
+        MouseCursor, Point, Size, Vertex2D, Widget,
+    };
+    use iced_wgpu::{Primitive, Renderer};
+
+    pub struct Rainbow {
+        dimen: u16,
+    }
+
+    impl Rainbow {
+        pub fn new(dimen: u16) -> Self {
+            Self { dimen }
+        }
+    }
+
+    impl<Message> Widget<Message, Renderer> for Rainbow {
+        fn width(&self) -> Length {
+            Length::Shrink
+        }
+
+        fn height(&self) -> Length {
+            Length::Shrink
+        }
+
+        fn layout(
+            &self,
+            _renderer: &Renderer,
+            _limits: &layout::Limits,
+        ) -> layout::Node {
+            layout::Node::new(Size::new(
+                f32::from(self.dimen),
+                f32::from(self.dimen),
+            ))
+        }
+
+        fn hash_layout(&self, state: &mut Hasher) {
+            use std::hash::Hash;
+
+            self.dimen.hash(state);
+        }
+
+        fn draw(
+            &self,
+            _renderer: &mut Renderer,
+            layout: Layout<'_>,
+            cursor_position: Point,
+        ) -> (Primitive, MouseCursor) {
+            let b = layout.bounds();
+
+            // R O Y G B I V
+            let color_r = [1.0, 0.0, 0.0, 1.0];
+            let color_o = [1.0, 0.5, 0.0, 1.0];
+            let color_y = [1.0, 1.0, 0.0, 1.0];
+            let color_g = [0.0, 1.0, 0.0, 1.0];
+            let color_gb = [0.0, 1.0, 0.5, 1.0];
+            let color_b = [0.0, 0.2, 1.0, 1.0];
+            let color_i = [0.5, 0.0, 1.0, 1.0];
+            let color_v = [0.75, 0.0, 0.5, 1.0];
+
+            let posn_center = {
+                if b.contains(cursor_position) {
+                    [cursor_position.x, cursor_position.y]
+                } else {
+                    [b.x + (b.width / 2.0), b.y + (b.height / 2.0)]
+                }
+            };
+
+            let posn_tl = [b.x, b.y];
+            let posn_t = [b.x + (b.width / 2.0), b.y];
+            let posn_tr = [b.x + b.width, b.y];
+            let posn_r = [b.x + b.width, b.y + (b.height / 2.0)];
+            let posn_br = [b.x + b.width, b.y + b.height];
+            let posn_b = [b.x + (b.width / 2.0), b.y + b.height];
+            let posn_bl = [b.x, b.y + b.height];
+            let posn_l = [b.x, b.y + (b.height / 2.0)];
+
+            (
+                Primitive::Geometry2D {
+                    geometry: Geometry2D {
+                        vertices: vec![
+                            Vertex2D {
+                                position: posn_center,
+                                color: [1.0, 1.0, 1.0, 1.0],
+                            },
+                            Vertex2D {
+                                position: posn_tl,
+                                color: color_r,
+                            },
+                            Vertex2D {
+                                position: posn_t,
+                                color: color_o,
+                            },
+                            Vertex2D {
+                                position: posn_tr,
+                                color: color_y,
+                            },
+                            Vertex2D {
+                                position: posn_r,
+                                color: color_g,
+                            },
+                            Vertex2D {
+                                position: posn_br,
+                                color: color_gb,
+                            },
+                            Vertex2D {
+                                position: posn_b,
+                                color: color_b,
+                            },
+                            Vertex2D {
+                                position: posn_bl,
+                                color: color_i,
+                            },
+                            Vertex2D {
+                                position: posn_l,
+                                color: color_v,
+                            },
+                        ],
+                        indices: vec![
+                            0, 1, 2, // TL
+                            0, 2, 3, // T
+                            0, 3, 4, // TR
+                            0, 4, 5, // R
+                            0, 5, 6, // BR
+                            0, 6, 7, // B
+                            0, 7, 8, // BL
+                            0, 8, 1, // L
+                        ],
+                    },
+                },
+                MouseCursor::OutOfBounds,
+            )
+        }
+    }
+
+    impl<'a, Message> Into<Element<'a, Message, Renderer>> for Rainbow {
+        fn into(self) -> Element<'a, Message, Renderer> {
+            Element::new(self)
+        }
+    }
+}
+
+use iced::{
+    scrollable, settings::Window,  Align, Column, Container, Element,
+    Length, Sandbox, Scrollable, Settings,  Text,
+};
+use rainbow::Rainbow;
+
+pub fn main() {
+    Example::run(Settings {
+        window: Window {
+            size: (660, 660),
+            resizable: true,
+            decorations: true,
+        },
+    })
+}
+
+struct Example {
+    dimen: u16,
+    scroll: scrollable::State,
+}
+
+#[derive(Debug, Clone, Copy)]
+enum Message {}
+
+impl Sandbox for Example {
+    type Message = Message;
+
+    fn new() -> Self {
+        Example {
+            dimen: 500,
+            scroll: scrollable::State::new(),
+        }
+    }
+
+    fn title(&self) -> String {
+        String::from("Custom 2D geometry - Iced")
+    }
+
+    fn update(&mut self, _: Message) {}
+
+    fn view(&mut self) -> Element<Message> {
+        let content = Column::new()
+            .padding(20)
+            .spacing(20)
+            .max_width(500)
+            .align_items(Align::Start)
+            .push(Rainbow::new(self.dimen))
+            .push(
+                Text::new(String::from("In this example we draw a custom widget Rainbow, using the \
+                Geometry2D primitive. This primitive supplies a list of triangles, expressed as vertices and indices."))
+                    .width(Length::Shrink),
+            )
+            .push(
+                Text::new(String::from("Move your cursor over it, and see the center vertex follow you!"))
+                    .width(Length::Shrink),
+            )
+            .push(
+                Text::new(String::from("Every Vertex2D defines its own color. You could use the \
+                Geometry2D primitive to render virtually any two-dimensional geometry for your widget."))
+                    .width(Length::Shrink),
+            );
+
+        let scrollable =
+            Scrollable::new(&mut self.scroll).push(Container::new(content));
+
+        Container::new(scrollable)
+            .width(Length::Fill)
+            .height(Length::Fill)
+            .center_x()
+            .center_y()
+            .into()
+    }
+}

native/src/lib.rs

@@ -55,7 +55,7 @@ mod user_interface;
 
 pub use iced_core::{
     Align, Background, Color, Command, Font, HorizontalAlignment, Length,
-    Point, Rectangle, Vector, VerticalAlignment,
+    Point, Rectangle, Vector, VerticalAlignment, Geometry2D, Vertex2D,
 };
 
 pub use clipboard::Clipboard;