Merge pull request #293 from hecrj/improvement/canvas-ergonomics

Improve `Canvas` ergonomics

7 files changed, 118 insertions, 85 deletions

diff --git a/examples/clock/src/main.rs b/examples/clock/src/main.rs
index a85a964c..827379fa 100644
--- a/examples/clock/src/main.rs
+++ b/examples/clock/src/main.rs
@@ -95,68 +95,57 @@ impl From<chrono::DateTime<chrono::Local>> for LocalTime {
 
 impl canvas::Drawable for LocalTime {
     fn draw(&self, frame: &mut canvas::Frame) {
+        use canvas::Path;
+
         let center = frame.center();
         let radius = frame.width().min(frame.height()) / 2.0;
-        let offset = Vector::new(center.x, center.y);
 
-        let clock = canvas::Path::new(|path| path.circle(center, radius));
+        let clock = Path::circle(center, radius);
+        frame.fill(&clock, Color::from_rgb8(0x12, 0x93, 0xD8));
 
-        frame.fill(
-            &clock,
-            canvas::Fill::Color(Color::from_rgb8(0x12, 0x93, 0xD8)),
-        );
+        let short_hand =
+            Path::line(Point::ORIGIN, Point::new(0.0, -0.5 * radius));
 
-        fn draw_hand(
-            n: u32,
-            total: u32,
-            length: f32,
-            offset: Vector,
-            path: &mut canvas::path::Builder,
-        ) {
-            let turns = n as f32 / total as f32;
-            let t = 2.0 * std::f32::consts::PI * (turns - 0.25);
+        let long_hand =
+            Path::line(Point::ORIGIN, Point::new(0.0, -0.8 * radius));
 
-            let x = length * t.cos();
-            let y = length * t.sin();
+        let thin_stroke = canvas::Stroke {
+            width: radius / 100.0,
+            color: Color::WHITE,
+            line_cap: canvas::LineCap::Round,
+            ..canvas::Stroke::default()
+        };
 
-            path.line_to(Point::new(x, y) + offset);
-        }
+        let wide_stroke = canvas::Stroke {
+            width: thin_stroke.width * 3.0,
+            ..thin_stroke
+        };
 
-        let hour_and_minute_hands = canvas::Path::new(|path| {
-            path.move_to(center);
-            draw_hand(self.hour, 12, 0.5 * radius, offset, path);
+        frame.translate(Vector::new(center.x, center.y));
 
-            path.move_to(center);
-            draw_hand(self.minute, 60, 0.8 * radius, offset, path)
+        frame.with_save(|frame| {
+            frame.rotate(hand_rotation(self.hour, 12));
+            frame.stroke(&short_hand, wide_stroke);
         });
 
-        frame.stroke(
-            &hour_and_minute_hands,
-            canvas::Stroke {
-                width: radius / 100.0 * 3.0,
-                color: Color::WHITE,
-                line_cap: canvas::LineCap::Round,
-                ..canvas::Stroke::default()
-            },
-        );
-
-        let second_hand = canvas::Path::new(|path| {
-            path.move_to(center);
-            draw_hand(self.second, 60, 0.8 * radius, offset, path)
+        frame.with_save(|frame| {
+            frame.rotate(hand_rotation(self.minute, 60));
+            frame.stroke(&long_hand, wide_stroke);
         });
 
-        frame.stroke(
-            &second_hand,
-            canvas::Stroke {
-                width: radius / 100.0,
-                color: Color::WHITE,
-                line_cap: canvas::LineCap::Round,
-                ..canvas::Stroke::default()
-            },
-        );
+        frame.with_save(|frame| {
+            frame.rotate(hand_rotation(self.second, 60));
+            frame.stroke(&long_hand, thin_stroke);
+        });
     }
 }
 
+fn hand_rotation(n: u32, total: u32) -> f32 {
+    let turns = n as f32 / total as f32;
+
+    2.0 * std::f32::consts::PI * turns
+}
+
 mod time {
     use iced::futures;
 
diff --git a/examples/solar_system/src/main.rs b/examples/solar_system/src/main.rs
index 963f047b..bcd1dc71 100644
--- a/examples/solar_system/src/main.rs
+++ b/examples/solar_system/src/main.rs
@@ -128,14 +128,12 @@ impl State {
 
 impl canvas::Drawable for State {
     fn draw(&self, frame: &mut canvas::Frame) {
-        use canvas::{Fill, Path, Stroke};
+        use canvas::{Path, Stroke};
         use std::f32::consts::PI;
 
         let center = frame.center();
 
-        let space = Path::new(|path| {
-            path.rectangle(Point::new(0.0, 0.0), frame.size())
-        });
+        let space = Path::rectangle(Point::new(0.0, 0.0), frame.size());
 
         let stars = Path::new(|path| {
             for (p, size) in &self.stars {
@@ -143,12 +141,12 @@ impl canvas::Drawable for State {
             }
         });
 
-        let sun = Path::new(|path| path.circle(center, Self::SUN_RADIUS));
-        let orbit = Path::new(|path| path.circle(center, Self::ORBIT_RADIUS));
+        let sun = Path::circle(center, Self::SUN_RADIUS);
+        let orbit = Path::circle(center, Self::ORBIT_RADIUS);
 
-        frame.fill(&space, Fill::Color(Color::BLACK));
-        frame.fill(&stars, Fill::Color(Color::WHITE));
-        frame.fill(&sun, Fill::Color(Color::from_rgb8(0xF9, 0xD7, 0x1C)));
+        frame.fill(&space, Color::BLACK);
+        frame.fill(&stars, Color::WHITE);
+        frame.fill(&sun, Color::from_rgb8(0xF9, 0xD7, 0x1C));
         frame.stroke(
             &orbit,
             Stroke {
@@ -170,21 +168,13 @@ impl canvas::Drawable for State {
             );
             frame.translate(Vector::new(Self::ORBIT_RADIUS, 0.0));
 
-            let earth = Path::new(|path| {
-                path.circle(Point::ORIGIN, Self::EARTH_RADIUS)
-            });
-
-            let shadow = Path::new(|path| {
-                path.rectangle(
-                    Point::new(0.0, -Self::EARTH_RADIUS),
-                    Size::new(
-                        Self::EARTH_RADIUS * 4.0,
-                        Self::EARTH_RADIUS * 2.0,
-                    ),
-                )
-            });
+            let earth = Path::circle(Point::ORIGIN, Self::EARTH_RADIUS);
+            let shadow = Path::rectangle(
+                Point::new(0.0, -Self::EARTH_RADIUS),
+                Size::new(Self::EARTH_RADIUS * 4.0, Self::EARTH_RADIUS * 2.0),
+            );
 
-            frame.fill(&earth, Fill::Color(Color::from_rgb8(0x6B, 0x93, 0xD6)));
+            frame.fill(&earth, Color::from_rgb8(0x6B, 0x93, 0xD6));
 
             frame.with_save(|frame| {
                 frame.rotate(
@@ -193,19 +183,16 @@ impl canvas::Drawable for State {
                 );
                 frame.translate(Vector::new(0.0, Self::MOON_DISTANCE));
 
-                let moon = Path::new(|path| {
-                    path.circle(Point::ORIGIN, Self::MOON_RADIUS)
-                });
-
-                frame.fill(&moon, Fill::Color(Color::WHITE));
+                let moon = Path::circle(Point::ORIGIN, Self::MOON_RADIUS);
+                frame.fill(&moon, Color::WHITE);
             });
 
             frame.fill(
                 &shadow,
-                Fill::Color(Color {
+                Color {
                     a: 0.7,
                     ..Color::BLACK
-                }),
+                },
             );
         });
     }
diff --git a/wgpu/src/widget/canvas/fill.rs b/wgpu/src/widget/canvas/fill.rs
index 5ce24cf3..a2010e45 100644
--- a/wgpu/src/widget/canvas/fill.rs
+++ b/wgpu/src/widget/canvas/fill.rs
@@ -12,3 +12,9 @@ impl Default for Fill {
         Fill::Color(Color::BLACK)
     }
 }
+
+impl From<Color> for Fill {
+    fn from(color: Color) -> Fill {
+        Fill::Color(color)
+    }
+}
diff --git a/wgpu/src/widget/canvas/frame.rs b/wgpu/src/widget/canvas/frame.rs
index 940be402..de4717f1 100644
--- a/wgpu/src/widget/canvas/frame.rs
+++ b/wgpu/src/widget/canvas/frame.rs
@@ -89,14 +89,14 @@ impl Frame {
     ///
     /// [`Path`]: path/struct.Path.html
     /// [`Frame`]: struct.Frame.html
-    pub fn fill(&mut self, path: &Path, fill: Fill) {
+    pub fn fill(&mut self, path: &Path, fill: impl Into<Fill>) {
         use lyon::tessellation::{
             BuffersBuilder, FillOptions, FillTessellator,
         };
 
         let mut buffers = BuffersBuilder::new(
             &mut self.buffers,
-            FillVertex(match fill {
+            FillVertex(match fill.into() {
                 Fill::Color(color) => color.into_linear(),
             }),
         );
@@ -127,11 +127,13 @@ impl Frame {
     ///
     /// [`Path`]: path/struct.Path.html
     /// [`Frame`]: struct.Frame.html
-    pub fn stroke(&mut self, path: &Path, stroke: Stroke) {
+    pub fn stroke(&mut self, path: &Path, stroke: impl Into<Stroke>) {
         use lyon::tessellation::{
             BuffersBuilder, StrokeOptions, StrokeTessellator,
         };
 
+        let stroke = stroke.into();
+
         let mut buffers = BuffersBuilder::new(
             &mut self.buffers,
             StrokeVertex(stroke.color.into_linear()),
@@ -173,9 +175,11 @@ impl Frame {
     /// [`Text`]: struct.Text.html
     /// [`Frame`]: struct.Frame.html
     /// [`Canvas`]: struct.Canvas.html
-    pub fn fill_text(&mut self, text: Text) {
+    pub fn fill_text(&mut self, text: impl Into<Text>) {
         use std::f32;
 
+        let text = text.into();
+
         let position = if self.transforms.current.is_identity {
             text.position
         } else {
diff --git a/wgpu/src/widget/canvas/path.rs b/wgpu/src/widget/canvas/path.rs
index e7ff47f3..c26bf187 100644
--- a/wgpu/src/widget/canvas/path.rs
+++ b/wgpu/src/widget/canvas/path.rs
@@ -7,6 +7,8 @@ mod builder;
 pub use arc::Arc;
 pub use builder::Builder;
 
+use iced_native::{Point, Size};
+
 /// An immutable set of points that may or may not be connected.
 ///
 /// A single [`Path`] can represent different kinds of 2D shapes!
@@ -33,6 +35,33 @@ impl Path {
         builder.build()
     }
 
+    /// Creates a new [`Path`] representing a line segment given its starting
+    /// and end points.
+    ///
+    /// [`Path`]: struct.Path.html
+    pub fn line(from: Point, to: Point) -> Self {
+        Self::new(|p| {
+            p.move_to(from);
+            p.line_to(to);
+        })
+    }
+
+    /// Creates a new [`Path`] representing a rectangle given its top-left
+    /// corner coordinate and its `Size`.
+    ///
+    /// [`Path`]: struct.Path.html
+    pub fn rectangle(top_left: Point, size: Size) -> Self {
+        Self::new(|p| p.rectangle(top_left, size))
+    }
+
+    /// Creates a new [`Path`] representing a circle given its center
+    /// coordinate and its radius.
+    ///
+    /// [`Path`]: struct.Path.html
+    pub fn circle(center: Point, radius: f32) -> Self {
+        Self::new(|p| p.circle(center, radius))
+    }
+
     #[inline]
     pub(crate) fn raw(&self) -> &lyon::path::Path {
         &self.raw
diff --git a/wgpu/src/widget/canvas/path/builder.rs b/wgpu/src/widget/canvas/path/builder.rs
index a013149e..6511fa52 100644
--- a/wgpu/src/widget/canvas/path/builder.rs
+++ b/wgpu/src/widget/canvas/path/builder.rs
@@ -133,11 +133,14 @@ impl Builder {
     ///
     /// [`Path`]: struct.Path.html
     #[inline]
-    pub fn rectangle(&mut self, p: Point, size: Size) {
-        self.move_to(p);
-        self.line_to(Point::new(p.x + size.width, p.y));
-        self.line_to(Point::new(p.x + size.width, p.y + size.height));
-        self.line_to(Point::new(p.x, p.y + size.height));
+    pub fn rectangle(&mut self, top_left: Point, size: Size) {
+        self.move_to(top_left);
+        self.line_to(Point::new(top_left.x + size.width, top_left.y));
+        self.line_to(Point::new(
+            top_left.x + size.width,
+            top_left.y + size.height,
+        ));
+        self.line_to(Point::new(top_left.x, top_left.y + size.height));
         self.close();
     }
 
diff --git a/wgpu/src/widget/canvas/text.rs b/wgpu/src/widget/canvas/text.rs
index d1cf1a0f..c4cae30e 100644
--- a/wgpu/src/widget/canvas/text.rs
+++ b/wgpu/src/widget/canvas/text.rs
@@ -32,3 +32,18 @@ impl Default for Text {
         }
     }
 }
+
+impl From<String> for Text {
+    fn from(content: String) -> Text {
+        Text {
+            content,
+            ..Default::default()
+        }
+    }
+}
+
+impl From<&str> for Text {
+    fn from(content: &str) -> Text {
+        String::from(content).into()
+    }
+}