Merge pull request #138 from hecrj/feature/empty-widget

`Space` widget

10 files changed, 202 insertions, 3 deletions

diff --git a/examples/tour.rs b/examples/tour.rs
index da05b396..91b75296 100644
--- a/examples/tour.rs
+++ b/examples/tour.rs
@@ -1,7 +1,7 @@
 use iced::{
     button, scrollable, slider, text_input, Button, Checkbox, Color, Column,
     Container, Element, HorizontalAlignment, Image, Length, Radio, Row,
-    Sandbox, Scrollable, Settings, Slider, Text, TextInput,
+    Sandbox, Scrollable, Settings, Slider, Space, Text, TextInput,
 };
 
 pub fn main() {
@@ -67,7 +67,7 @@ impl Sandbox for Tour {
             );
         }
 
-        controls = controls.push(Column::new());
+        controls = controls.push(Space::with_width(Length::Fill));
 
         if steps.can_continue() {
             controls = controls.push(
diff --git a/native/src/mouse_cursor.rs b/native/src/mouse_cursor.rs
index a4740a27..c7297e0e 100644
--- a/native/src/mouse_cursor.rs
+++ b/native/src/mouse_cursor.rs
@@ -22,3 +22,9 @@ pub enum MouseCursor {
     /// The cursor is over a text widget.
     Text,
 }
+
+impl Default for MouseCursor {
+    fn default() -> MouseCursor {
+        MouseCursor::OutOfBounds
+    }
+}
diff --git a/native/src/widget.rs b/native/src/widget.rs
index 26889280..dcc99645 100644
--- a/native/src/widget.rs
+++ b/native/src/widget.rs
@@ -29,6 +29,7 @@ pub mod radio;
 pub mod row;
 pub mod scrollable;
 pub mod slider;
+pub mod space;
 pub mod svg;
 pub mod text;
 pub mod text_input;
@@ -52,6 +53,8 @@ pub use scrollable::Scrollable;
 #[doc(no_inline)]
 pub use slider::Slider;
 #[doc(no_inline)]
+pub use space::Space;
+#[doc(no_inline)]
 pub use svg::Svg;
 #[doc(no_inline)]
 pub use text::Text;
diff --git a/native/src/widget/space.rs b/native/src/widget/space.rs
new file mode 100644
index 00000000..2029c52f
--- /dev/null
+++ b/native/src/widget/space.rs
@@ -0,0 +1,104 @@
+//! Distribute content vertically.
+use std::hash::Hash;
+
+use crate::{
+    layout, Element, Hasher, Layout, Length, Point, Rectangle, Size, Widget,
+};
+
+/// An amount of empty space.
+///
+/// It can be useful if you want to fill some space with nothing.
+#[derive(Debug)]
+pub struct Space {
+    width: Length,
+    height: Length,
+}
+
+impl Space {
+    /// Creates an amount of empty [`Space`] with the given width and height.
+    ///
+    /// [`Space`]: struct.Space.html
+    pub fn new(width: Length, height: Length) -> Self {
+        Space { width, height }
+    }
+
+    /// Creates an amount of horizontal [`Space`].
+    ///
+    /// [`Space`]: struct.Space.html
+    pub fn with_width(width: Length) -> Self {
+        Space {
+            width,
+            height: Length::Shrink,
+        }
+    }
+
+    /// Creates an amount of vertical [`Space`].
+    ///
+    /// [`Space`]: struct.Space.html
+    pub fn with_height(height: Length) -> Self {
+        Space {
+            width: Length::Shrink,
+            height,
+        }
+    }
+}
+
+impl<'a, Message, Renderer> Widget<Message, Renderer> for Space
+where
+    Renderer: self::Renderer,
+{
+    fn width(&self) -> Length {
+        self.width
+    }
+
+    fn height(&self) -> Length {
+        self.height
+    }
+
+    fn layout(
+        &self,
+        _renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        let limits = limits.width(self.width).height(self.height);
+
+        layout::Node::new(limits.resolve(Size::ZERO))
+    }
+
+    fn draw(
+        &self,
+        renderer: &mut Renderer,
+        layout: Layout<'_>,
+        _cursor_position: Point,
+    ) -> Renderer::Output {
+        renderer.draw(layout.bounds())
+    }
+
+    fn hash_layout(&self, state: &mut Hasher) {
+        std::any::TypeId::of::<Space>().hash(state);
+        self.width.hash(state);
+        self.height.hash(state);
+    }
+}
+
+/// The renderer of an amount of [`Space`].
+///
+/// [`Space`]: struct.Space.html
+pub trait Renderer: crate::Renderer {
+    /// Draws an amount of empty [`Space`].
+    ///
+    /// You should most likely return an empty primitive here.
+    ///
+    /// [`Space`]: struct.Space.html
+    fn draw(&mut self, bounds: Rectangle) -> Self::Output;
+}
+
+impl<'a, Message, Renderer> From<Space> for Element<'a, Message, Renderer>
+where
+    Renderer: self::Renderer,
+    Message: 'static,
+{
+    fn from(space: Space) -> Element<'a, Message, Renderer> {
+        Element::new(space)
+    }
+}
diff --git a/src/native.rs b/src/native.rs
index f06f1c99..cf48a391 100644
--- a/src/native.rs
+++ b/src/native.rs
@@ -1,6 +1,6 @@
 pub use iced_winit::{
     Align, Background, Color, Command, Font, HorizontalAlignment, Length,
-    Subscription, VerticalAlignment,
+    Space, Subscription, VerticalAlignment,
 };
 
 pub mod widget {
diff --git a/web/src/widget.rs b/web/src/widget.rs
index b0e16692..0ac536bd 100644
--- a/web/src/widget.rs
+++ b/web/src/widget.rs
@@ -28,6 +28,7 @@ mod container;
 mod image;
 mod radio;
 mod row;
+mod space;
 mod text;
 
 #[doc(no_inline)]
@@ -47,6 +48,7 @@ pub use container::Container;
 pub use image::Image;
 pub use radio::Radio;
 pub use row::Row;
+pub use space::Space;
 
 /// A component that displays information and allows interaction.
 ///
diff --git a/web/src/widget/space.rs b/web/src/widget/space.rs
new file mode 100644
index 00000000..baf4c80b
--- /dev/null
+++ b/web/src/widget/space.rs
@@ -0,0 +1,69 @@
+use crate::{style, Bus, Element, Length, Widget};
+use dodrio::bumpalo;
+
+/// An amount of empty space.
+///
+/// It can be useful if you want to fill some space with nothing.
+#[derive(Debug)]
+pub struct Space {
+    width: Length,
+    height: Length,
+}
+
+impl Space {
+    /// Creates an amount of empty [`Space`] with the given width and height.
+    ///
+    /// [`Space`]: struct.Space.html
+    pub fn new(width: Length, height: Length) -> Self {
+        Space { width, height }
+    }
+
+    /// Creates an amount of horizontal [`Space`].
+    ///
+    /// [`Space`]: struct.Space.html
+    pub fn with_width(width: Length) -> Self {
+        Space {
+            width,
+            height: Length::Shrink,
+        }
+    }
+
+    /// Creates an amount of vertical [`Space`].
+    ///
+    /// [`Space`]: struct.Space.html
+    pub fn with_height(height: Length) -> Self {
+        Space {
+            width: Length::Shrink,
+            height,
+        }
+    }
+}
+
+impl<'a, Message> Widget<Message> for Space {
+    fn node<'b>(
+        &self,
+        bump: &'b bumpalo::Bump,
+        _publish: &Bus<Message>,
+        _style_sheet: &mut style::Sheet<'b>,
+    ) -> dodrio::Node<'b> {
+        use dodrio::builder::*;
+
+        let width = style::length(self.width);
+        let height = style::length(self.height);
+
+        let style = bumpalo::format!(
+            in bump,
+            "width: {}; height: {};",
+            width,
+            height
+        );
+
+        div(bump).attr("style", style.into_bump_str()).finish()
+    }
+}
+
+impl<'a, Message> From<Space> for Element<'a, Message> {
+    fn from(space: Space) -> Element<'a, Message> {
+        Element::new(space)
+    }
+}
diff --git a/wgpu/src/primitive.rs b/wgpu/src/primitive.rs
index 958cc17f..6c61f800 100644
--- a/wgpu/src/primitive.rs
+++ b/wgpu/src/primitive.rs
@@ -64,3 +64,9 @@ pub enum Primitive {
         content: Box<Primitive>,
     },
 }
+
+impl Default for Primitive {
+    fn default() -> Primitive {
+        Primitive::None
+    }
+}
diff --git a/wgpu/src/renderer/widget.rs b/wgpu/src/renderer/widget.rs
index 91f107e8..f82631d5 100644
--- a/wgpu/src/renderer/widget.rs
+++ b/wgpu/src/renderer/widget.rs
@@ -6,6 +6,7 @@ mod radio;
 mod row;
 mod scrollable;
 mod slider;
+mod space;
 mod text;
 mod text_input;
 
diff --git a/wgpu/src/renderer/widget/space.rs b/wgpu/src/renderer/widget/space.rs
new file mode 100644
index 00000000..28e05437
--- /dev/null
+++ b/wgpu/src/renderer/widget/space.rs
@@ -0,0 +1,8 @@
+use crate::{Primitive, Renderer};
+use iced_native::{space, MouseCursor, Rectangle};
+
+impl space::Renderer for Renderer {
+    fn draw(&mut self, _bounds: Rectangle) -> Self::Output {
+        (Primitive::None, MouseCursor::OutOfBounds)
+    }
+}