fix containers defaulting to black color

hui-examples/examples/align_test.rs

@@ -10,7 +10,7 @@ use winit::{
 use hui::{
   element::{
     container::Container, progress_bar::ProgressBar, fill_rect::FillRect, ElementList, UiElement
-  }, layout::{Alignment, Direction, Size}, rectangle::{Corners, Sides}, UiInstance
+  }, layout::{Alignment, Direction, Size}, rect::{Corners, Sides}, UiInstance
 };
 use hui_glium::GliumUiRenderer;
 

hui-examples/examples/rounded_rect.rs

@@ -12,7 +12,7 @@ use hui::{
     text::Text, ElementList
   },
   layout::{Alignment, Direction, Size},
-  rectangle::{Corners, Sides},
+  rect::{Corners, Sides},
   UiInstance
 };
 use hui_glium::GliumUiRenderer;

hui-examples/examples/ui_test_2_loading.rs

@@ -3,7 +3,7 @@ use hui::{
   color, size,
   element::{container::Container, progress_bar::ProgressBar, text::Text, UiElementExt},
   layout::Alignment,
-  rectangle::Corners,
+  rect::Corners,
   text::FontHandle,
 };
 

hui-examples/examples/ui_test_3_transform.rs

@@ -9,7 +9,7 @@ use hui::{
     UiElementExt
   },
   layout::Alignment,
-  rectangle::Corners,
+  rect::Corners,
   text::FontHandle,
   size,
 };

hui-examples/examples/ui_test_5_input.rs

@@ -1,7 +1,7 @@
 use hui::{
   color, size,
   draw::TextureFormat,
-  signal::UiSignal,
+  signal::Signal,
   layout::{Alignment, Direction},
   element::{
     container::Container,
@@ -17,7 +17,7 @@ enum CounterSignal {
   Increment,
   Decrement,
 }
-impl UiSignal for CounterSignal {}
+impl Signal for CounterSignal {}
 
 #[path = "../boilerplate.rs"]
 #[macro_use]

hui-examples/examples/ui_test_6_slider.rs

@@ -1,23 +1,22 @@
 use hui::{
-  color, size,
   draw::TextureFormat,
-  signal::UiSignal,
+  signal::Signal,
   layout::{Alignment, Direction},
   element::{
     container::Container,
     text::Text,
     image::Image,
     br::Br,
-    interactable::ElementInteractableExt,
     slider::Slider,
     UiElementExt,
   },
+  size,
 };
 
 enum CounterSignal {
   ChangeValue(u32)
 }
-impl UiSignal for CounterSignal {}
+impl Signal for CounterSignal {}
 
 #[path = "../boilerplate.rs"]
 #[macro_use]
@@ -41,7 +40,7 @@ ui_main!(
       .with_background((0.1, 0.1, 0.1))
       .with_wrap(true)
       .with_children(|ui| {
-        Text::new("Number of images:")
+        Text::new(format!("Number of images: {counter}"))
           .with_text_size(24)
           .add_child(ui);
         Br.add_child(ui);

hui/Cargo.toml

@@ -24,6 +24,7 @@ rect_packer = "0.2"
 log = "0.4"
 document-features = "0.2"
 derive_setters = "0.1"
+derive_more = "0.99"
 tinyset = "0.4"
 
 [features]

hui/src/background.rs

@@ -1,105 +0,0 @@
-//! background color, gradient and texturing
-
-use glam::{vec4, Vec3, Vec4};
-use crate::rectangle::Corners;
-
-//TODO: use this
-// pub struct Background {
-//   pub color: BackgroundColor,
-//   pub texture: Option<TextureH>
-// }
-
-//TODO: move this into the color module?
-#[derive(Clone, Copy, Default, Debug, PartialEq)]
-pub enum BackgroundColor {
-  #[default]
-  Transparent,
-  Solid(Vec4),
-  Gradient(Corners<Vec4>),
-}
-
-impl From<(f32, f32, f32, f32)> for BackgroundColor {
-  fn from(color: (f32, f32, f32, f32)) -> Self {
-    Self::Solid(vec4(color.0, color.1, color.2, color.3))
-  }
-}
-
-impl From<Corners<Vec4>> for BackgroundColor {
-  fn from(corners: Corners<Vec4>) -> Self {
-    Self::Gradient(corners)
-  }
-}
-
-impl From<Option<Vec4>> for BackgroundColor {
-  fn from(color: Option<Vec4>) -> Self {
-    match color {
-      Some(color) => Self::Solid(color),
-      None => Self::Transparent,
-    }
-  }
-}
-
-impl From<Vec4> for BackgroundColor {
-  fn from(color: Vec4) -> Self {
-    Self::Solid(color)
-  }
-}
-
-impl From<(f32, f32, f32)> for BackgroundColor {
-  fn from(color: (f32, f32, f32)) -> Self {
-    Self::Solid(vec4(color.0, color.1, color.2, 1.))
-  }
-}
-
-impl From<Corners<Vec3>> for BackgroundColor {
-  fn from(corners: Corners<Vec3>) -> Self {
-    Self::Gradient(Corners {
-      top_left: corners.top_left.extend(1.),
-      top_right: corners.top_right.extend(1.),
-      bottom_left: corners.bottom_left.extend(1.),
-      bottom_right: corners.bottom_right.extend(1.),
-    })
-  }
-}
-
-impl From<Option<Vec3>> for BackgroundColor {
-  fn from(color: Option<Vec3>) -> Self {
-    match color {
-      Some(color) => Self::Solid(color.extend(1.)),
-      None => Self::Transparent,
-    }
-  }
-}
-
-impl From<Vec3> for BackgroundColor {
-  fn from(color: Vec3) -> Self {
-    Self::Solid(color.extend(1.))
-  }
-}
-
-impl BackgroundColor {
-  /// Returns the colors of individual corners
-  pub fn corners(&self) -> Corners<Vec4> {
-    match *self {
-      Self::Transparent => Corners::all(Vec4::ZERO),
-      Self::Solid(color) => Corners::all(color),
-      Self::Gradient(corners) => corners,
-    }
-  }
-
-  /// Returns `true` if the background is `Transparent` or all corners have an alpha value of `0`.
-  pub fn is_transparent(&self) -> bool {
-    match *self {
-      Self::Transparent => true,
-      Self::Solid(color) => color.w == 0.,
-      Self::Gradient(corners) => {
-        let max_alpha =
-          corners.top_left.w
-            .max(corners.top_right.w)
-            .max(corners.bottom_left.w)
-            .max(corners.bottom_right.w);
-          max_alpha == 0.
-      },
-    }
-  }
-}

hui/src/draw.rs

@@ -3,7 +3,7 @@
 //TODO: 9-slice draw command
 
 use crate::{
-  rectangle::Corners,
+  rect::Corners,
   text::{FontHandle, TextRenderer}
 };
 

hui/src/draw/atlas.rs

@@ -2,7 +2,7 @@ use glam::{uvec2, vec2, UVec2, Vec2};
 use hashbrown::HashMap;
 use nohash_hasher::BuildNoHashHasher;
 use rect_packer::DensePacker;
-use crate::rectangle::Corners;
+use crate::rect::Corners;
 
 const RGBA_CHANNEL_COUNT: u32 = 4;
 //TODO make this work

hui/src/draw/corner_radius.rs

@@ -1,5 +1,5 @@
 use std::num::NonZeroU16;
-use crate::rectangle::Corners;
+use crate::rect::Corners;
 
 //TODO uneven corners (separate width/height for each corner)
 

hui/src/element/builtin/container.rs

@@ -3,12 +3,11 @@
 use derive_setters::Setters;
 use glam::{Vec2, vec2};
 use crate::{
-  background::BackgroundColor,
   draw::{ImageHandle, RoundedCorners, UiDrawCommand},
   element::{ElementList, MeasureContext, ProcessContext, UiElement},
   layout::{Alignment, Alignment2d, Direction, LayoutInfo, Size, Size2d},
   measure::{Hints, Response},
-  rectangle::{Corners, Sides},
+  rect::{Corners, FillColor, Sides},
 };
 
 // pub struct Border {
@@ -59,7 +58,7 @@ pub struct Container {
   ///
   /// If the container has a background texture, it will be multiplied by this color
   #[setters(into)]
-  pub background: BackgroundColor,
+  pub background: FillColor,
 
   /// Background texture of the container
   ///
@@ -104,7 +103,7 @@ impl Default for Container {
       gap: 0.,
       padding: Sides::all(0.),
       align: Alignment2d::default(),
-      background: Default::default(),
+      background: FillColor::transparent(),
       background_image: None,
       children: ElementList(Vec::new()),
       wrap: false,

hui/src/element/builtin/fill_rect.rs

@@ -3,12 +3,11 @@
 use derive_setters::Setters;
 use glam::{vec2, Vec4};
 use crate::{
-  background::BackgroundColor,
-  draw::{UiDrawCommand, RoundedCorners},
-  element::{UiElement, MeasureContext, ProcessContext},
+  draw::{RoundedCorners, UiDrawCommand},
+  element::{MeasureContext, ProcessContext, UiElement},
   layout::{Size, Size2d},
   measure::Response,
-  rectangle::Corners,
+  rect::{Corners, FillColor},
   size,
 };
 
@@ -22,7 +21,7 @@ pub struct FillRect {
 
   /// Background color of the rectangle
   #[setters(into)]
-  pub background: BackgroundColor,
+  pub background: FillColor,
 
   /// Corner radius of the rectangle
   #[setters(into)]

hui/src/element/builtin/image.rs

@@ -1,12 +1,11 @@
 use derive_setters::Setters;
 use glam::vec2;
 use crate::{
-  background::BackgroundColor,
   draw::{ImageHandle, RoundedCorners, UiDrawCommand},
   element::{MeasureContext, ProcessContext, UiElement},
   layout::{compute_size, Size, Size2d},
   measure::Response,
-  rectangle::Corners,
+  rect::{Corners, FillColor},
 };
 
 #[derive(Setters)]
@@ -29,7 +28,7 @@ pub struct Image {
   ///
   /// Image will get multiplied/tinted by this color or gradient
   #[setters(into)]
-  pub color: BackgroundColor,
+  pub color: FillColor,
 
   /// Corner radius of the image
   #[setters(into)]
@@ -44,7 +43,7 @@ impl Image {
         width: Size::Auto,
         height: Size::Auto,
       },
-      color: BackgroundColor::from((1., 1., 1., 1.)),
+      color: (1., 1., 1.).into(),
       corner_radius: Corners::all(0.),
     }
   }

hui/src/element/builtin/interactable.rs

@@ -5,7 +5,7 @@
 
 use crate::{
   element::{MeasureContext, ProcessContext, UiElement},
-  signal::UiSignal,
+  signal::Signal,
 };
 use std::cell::RefCell;
 
@@ -18,7 +18,7 @@ pub enum InteractableEvent {
 }
 
 /// Wrapper that allows adding click and hover events to any element
-pub struct Interactable<C: UiSignal + 'static> {
+pub struct Interactable<C: Signal + 'static> {
   /// The wrapped element that will be interactable
   pub element: Box<dyn UiElement>,
 
@@ -29,7 +29,7 @@ pub struct Interactable<C: UiSignal + 'static> {
   pub signal: RefCell<Option<C>>,
 }
 
-impl<C: UiSignal + 'static> Interactable<C> {
+impl<C: Signal + 'static> Interactable<C> {
   pub fn new(element: Box<dyn UiElement>, event: InteractableEvent, signal: C) -> Self {
     Self {
       element,
@@ -39,7 +39,7 @@ impl<C: UiSignal + 'static> Interactable<C> {
   }
 }
 
-impl<C: UiSignal + 'static> UiElement for Interactable<C> {
+impl<C: Signal + 'static> UiElement for Interactable<C> {
   fn name(&self) -> &'static str {
     "Interactable"
   }
@@ -71,25 +71,25 @@ impl<C: UiSignal + 'static> UiElement for Interactable<C> {
 /// Extension trait for [`UiElement`] that adds methods to wrap the element in an [`Interactable`]
 pub trait ElementInteractableExt: UiElement {
   /// Wrap the element in an [`Interactable`] that will call the given signal when the specified event occurs
-  fn into_interactable<C: UiSignal + 'static>(self, event: InteractableEvent, signal: C) -> Interactable<C>;
+  fn into_interactable<C: Signal + 'static>(self, event: InteractableEvent, signal: C) -> Interactable<C>;
 
   /// Wrap the element in an [`Interactable`] that will call the given signal when clicked
-  fn on_click<C: UiSignal + 'static>(self, signal: C) -> Interactable<C>;
+  fn on_click<C: Signal + 'static>(self, signal: C) -> Interactable<C>;
 
   /// Wrap the element in an [`Interactable`] that will call the given signal while hovered
-  fn on_hover<C: UiSignal + 'static>(self, signal: C) -> Interactable<C>;
+  fn on_hover<C: Signal + 'static>(self, signal: C) -> Interactable<C>;
 }
 
 impl<T: UiElement + 'static> ElementInteractableExt for T {
-  fn into_interactable<C: UiSignal + 'static>(self, event: InteractableEvent, signal: C) -> Interactable<C> {
+  fn into_interactable<C: Signal + 'static>(self, event: InteractableEvent, signal: C) -> Interactable<C> {
     Interactable::new(Box::new(self), event, signal)
   }
 
-  fn on_click<C: UiSignal + 'static>(self, signal: C) -> Interactable<C> {
+  fn on_click<C: Signal + 'static>(self, signal: C) -> Interactable<C> {
     self.into_interactable(InteractableEvent::Click, signal)
   }
 
-  fn on_hover<C: UiSignal + 'static>(self, signal: C) -> Interactable<C> {
+  fn on_hover<C: Signal + 'static>(self, signal: C) -> Interactable<C> {
     self.into_interactable(InteractableEvent::Hover, signal)
   }
 }

hui/src/element/builtin/progress_bar.rs

@@ -1,12 +1,11 @@
 use derive_setters::Setters;
 use glam::{vec2, vec4};
 use crate::{
-  background::BackgroundColor,
   draw::{RoundedCorners, UiDrawCommand},
   element::{MeasureContext, ProcessContext, UiElement},
   layout::{compute_size, Size, Size2d},
   measure::Response,
-  rectangle::Corners
+  rect::{Corners, FillColor}
 };
 
 #[derive(Debug, Clone, Copy, Setters)]
@@ -21,11 +20,11 @@ pub struct ProgressBar {
 
   /// Foreground (bar) color
   #[setters(into)]
-  pub foreground: BackgroundColor,
+  pub foreground: FillColor,
 
   /// Background color
   #[setters(into)]
-  pub background: BackgroundColor,
+  pub background: FillColor,
 
   /// Corner radius of the progress bar
   #[setters(into)]

hui/src/element/builtin/slider.rs

@@ -1,30 +1,80 @@
-//! work in progress
+//! a slider element that allows selecting a value in a range
 
 use derive_setters::Setters;
-use glam::{vec2, Vec2};
+use glam::{Vec2, vec2};
 
 use crate::{
-  draw::{RoundedCorners, UiDrawCommand},
+  draw::UiDrawCommand,
   element::{MeasureContext, ProcessContext, UiElement},
-  layout::{compute_size, Size2d},
+  layout::{Size2d, compute_size},
   measure::Response,
-  rectangle::Corners,
-  signal::{SignalStore, UiSignal},
+  rect::FillColor,
+  signal::{trigger::SignalTriggerArg, Signal},
 };
 
-/// work in progress
-#[derive(Default, Setters)]
+/// Follow mode for the slider
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Default)]
+pub enum SliderFollowMode {
+  /// Slider will change based on the absolute mouse position in the slider
+  ///
+  /// This is the default mode and is recommended for most use cases
+  #[default]
+  Absolute,
+
+  /// Slider will change based on the difference between the current and starting mouse position
+  ///
+  /// This is an experimental option and does not currently work well for sliders with large step sizes
+  Relative,
+}
+
+/// A slider element that allows selecting a value in a range
+#[derive(Setters)]
 #[setters(prefix = "with_")]
 pub struct Slider {
+  /// Value of the slider, should be in range 0..1
+  ///
+  /// Out of range values will be clamped
   pub value: f32,
+
+  /// Size of the element
+  #[setters(into)]
   pub size: Size2d,
 
+  /// Color of the slider handle
+  #[setters(into)]
+  pub handle_color: FillColor,
+
+  /// Color of the slider track
+  #[setters(into)]
+  pub track_color: FillColor,
+
+  /// Color of the "active" part of the slider
+  #[setters(into)]
+  pub track_active_color: FillColor,
+
+  /// Follow mode
+  pub follow_mode: SliderFollowMode,
+
   #[setters(skip)]
-  fire_on_shit: Option<Box<dyn Fn(&mut SignalStore, f32)>>,
+  pub on_change: Option<SignalTriggerArg<f32>>,
+}
+
+impl Default for Slider {
+  fn default() -> Self {
+    Self {
+      value: 0.0,
+      size: Size2d::default(),
+      handle_color: (0.0, 0.0, 1.0).into(),
+      track_color: (0.5, 0.5, 0.5).into(),
+      track_active_color: (0.0, 0.0, 0.75).into(),
+      follow_mode: SliderFollowMode::default(),
+      on_change: None
+    }
+  }
 }
 
 impl Slider {
-  pub const DEFAULT_HEIGHT: f32 = 20.0;
+  pub const DEFAULT_HEIGHT: f32 = 21.0;
 
   pub fn new(value: f32) -> Self {
     Self {
@@ -33,11 +83,9 @@ impl Slider {
     }
   }
 
-  pub fn on_change<S: UiSignal + 'static, T: Fn(f32) -> S + 'static>(self, f: T) -> Self {
+  pub fn on_change<S: Signal, T: Fn(f32) -> S + 'static>(self, f: T) -> Self {
     Self {
-      fire_on_shit: Some(Box::new(move |s: &mut SignalStore, x| {
-        s.add::<S>(f(x));
-      })),
+      on_change: Some(SignalTriggerArg::new(f)),
       ..self
     }
   }
@@ -56,36 +104,69 @@ impl UiElement for Slider {
   }
 
   fn process(&self, ctx: ProcessContext) {
-    let bgrect_height_ratio = 0.25;
-    ctx.draw.add(UiDrawCommand::Rectangle {
-      position: ctx.layout.position + ctx.measure.size * vec2(0., 0.5 - bgrect_height_ratio / 2.),
-      size: ctx.measure.size * vec2(1., bgrect_height_ratio),
-      color: Corners::all((1., 1., 1., 0.7).into()),
-      texture: None,
-      rounded_corners: None,
-      //Some(RoundedCorners::from_radius(Corners::all(bgrect_height_ratio * ctx.measure.size.y * 0.4))),
-    });
+    //TODO: unhardcode this
+    let bgrect_height_ratio = 0.33;
 
-    let value = self.value.clamp(0., 1.);
-    let handle_size = vec2(15., ctx.measure.size.y);
-    ctx.draw.add(UiDrawCommand::Rectangle {
-      position: ctx.layout.position + (ctx.measure.size.x * value - handle_size.x / 2.) * Vec2::X,
-      size: handle_size,
-      color: Corners::all((1., 1., 1., 1.).into()),
-      texture: None,
-      rounded_corners: None,
-      //Some(RoundedCorners::from_radius(Corners::all(handle_size.x / 3.))),
-    });
+    //XXX: some of these assumptions are wrong if the  corners are rounded
 
-    //handle click etc
+    //Draw the track
+    //If the active part is opaque and value >= 1., we don't need to draw the background as the active part will cover it
+    //Of corse, if it's fully transparent, we don't need to draw it either
+    if !(self.track_color.is_transparent() || (self.track_active_color.is_opaque() && self.value >= 1.)) {
+      ctx.draw.add(UiDrawCommand::Rectangle {
+        position: ctx.layout.position + ctx.measure.size * vec2(0., 0.5 - bgrect_height_ratio / 2.),
+        size: ctx.measure.size * vec2(1., bgrect_height_ratio),
+        color: self.track_color.into(),
+        texture: None,
+        rounded_corners: None,
+      });
+    }
+
+    //"Active" part of the track
+    //We can skip drawing it if it's fully transparent or value <= 0.
+    if !(self.track_active_color.is_transparent() || self.value <= 0.) {
+      ctx.draw.add(UiDrawCommand::Rectangle {
+        position: ctx.layout.position + ctx.measure.size * vec2(0., 0.5 - bgrect_height_ratio / 2.),
+        size: ctx.measure.size * vec2(self.value, bgrect_height_ratio),
+        color: self.track_active_color.into(),
+        texture: None,
+        rounded_corners: None,
+      });
+    }
+
+    // The handle
+    // This is kinda counter-intuitive, but if the handle is transparent, we treat it as completely disabled
+    // To prevent confusing offset from the edge of the slider, we set the handle size to 0
+    let handle_size = if self.handle_color.is_transparent() {
+      Vec2::ZERO
+    } else {
+      vec2(15., ctx.measure.size.y)
+    };
+    if handle_size.x != 0. {
+      let value = self.value.clamp(0., 1.);
+      ctx.draw.add(UiDrawCommand::Rectangle {
+        position: ctx.layout.position + ((ctx.measure.size.x - handle_size.x) * value) * Vec2::X,
+        size: handle_size,
+        color: self.handle_color.into(),
+        texture: None,
+        rounded_corners: None,
+      });
+    }
+
+    //handle events
     if let Some(res) = ctx.input.check_active(ctx.measure.rect(ctx.layout.position)) {
-      let new_value = (res.position_in_rect.x / ctx.measure.size.x).clamp(0., 1.);
-      if let Some(fire) = &self.fire_on_shit {
-        fire(ctx.signal, new_value);
+      let new_value = match self.follow_mode {
+        SliderFollowMode::Absolute => ((res.position_in_rect.x - handle_size.x / 2.) / (ctx.measure.size.x - handle_size.x)).clamp(0., 1.),
+        SliderFollowMode::Relative => {
+          let delta = res.position_in_rect.x - res.last_position_in_rect.x;
+          let delta_ratio = delta / (ctx.measure.size.x - handle_size.x);
+          (self.value + delta_ratio).clamp(0., 1.)
+        }
+      };
+      if let Some(signal) = &self.on_change {
+        signal.fire(ctx.signal, new_value);
       }
       //TODO call signal with new value
     }
   }
 }
-
-//TODO

hui/src/input.rs

@@ -3,9 +3,9 @@
 use std::hash::{Hash, Hasher};
 use glam::Vec2;
 use hashbrown::HashMap;
-use nohash_hasher::{BuildNoHashHasher, NoHashHasher};
-use tinyset::{Fits64, Set64, SetU32};
-use crate::{event::{EventQueue, UiEvent}, rectangle::Rect};
+use nohash_hasher::BuildNoHashHasher;
+use tinyset::{Fits64, Set64};
+use crate::{event::{EventQueue, UiEvent}, rect::Rect};
 
 /// Represents a mouse button.
 ///
@@ -144,6 +144,9 @@ pub struct MouseState {
   /// Current position of the mouse pointer
   pub current_position: Vec2,
 
+  /// Position of the mouse pointer on the previous frame
+  pub prev_position: Vec2,
+
   /// Current state of each mouse button (if down)
   pub buttons: HashMap<MouseButton, MouseButtonMeta, BuildNoHashHasher<u16>>,
 
@@ -184,6 +187,7 @@ impl UiInputState {
   ///
   /// This function should be called exactly once per frame
   pub fn update_state(&mut self, event_queue: &mut EventQueue) {
+    self.mouse_pointer.prev_position = self.mouse_pointer.current_position;
     self.mouse_pointer.released_buttons.clear();
     self.just_happened.clear();
     self.just_happened.extend(event_queue.drain());
@@ -234,9 +238,17 @@ impl UiInputState {
   }
 }
 
+/// Response for checks that involve an active pointer
 #[derive(Clone, Copy, Debug)]
-pub struct ClickCheckResponse {
+pub struct ActiveCheckResponse {
+  /// Current position of the pointer inside the target rectangle's coordinate space
   pub position_in_rect: Vec2,
+
+  /// Position of the pointer at the time the start of the input inside the target rectangle's coordinate space
+  pub start_position_in_rect: Vec2,
+
+  /// Position of the pointer on the previous frame inside the target rectangle's coordinate space
+  pub last_position_in_rect: Vec2,
 }
 
 #[derive(Clone, Copy)]
@@ -297,23 +309,27 @@ impl<'a> InputCtx<'a> {
   /// By default, this function only checks for the primary mouse button\
   /// This is a limitation of the current API and may change in the future\
   /// (as the current implementation of this function checks for both mouse and touch input, and the touch input quite obviously only supports one "button")
-  pub fn check_click(&self, rect: Rect) -> Option<ClickCheckResponse> {
+  pub fn check_click(&self, rect: Rect) -> Option<ActiveCheckResponse> {
     let pos = self.0.mouse_pointer.current_position;
-    self.0.mouse_pointer.released_buttons.get(&MouseButton::Primary).map_or(false, |meta| {
+    self.0.mouse_pointer.released_buttons.get(&MouseButton::Primary).filter(|meta| {
       rect.contains_point(meta.start_position) && rect.contains_point(pos)
-    }).then_some(ClickCheckResponse {
+    }).map(|mi| ActiveCheckResponse {
       position_in_rect: pos - rect.position,
+      start_position_in_rect: mi.start_position - rect.position,
+      last_position_in_rect: self.0.mouse_pointer.prev_position - rect.position,
     })
   }
 
   // TODO: write better docs
 
   /// Check if a rect is being actively being interacted with (e.g. dragged)
-  pub fn check_active(&self, rect: Rect) -> Option<ClickCheckResponse> {
+  pub fn check_active(&self, rect: Rect) -> Option<ActiveCheckResponse> {
     self.0.mouse_pointer.buttons.get(&MouseButton::Primary).filter(|mi| {
       rect.contains_point(mi.start_position)
-    }).map(|_| ClickCheckResponse {
+    }).map(|mi| ActiveCheckResponse {
       position_in_rect: self.0.mouse_pointer.current_position - rect.position,
+      start_position_in_rect: mi.start_position - rect.position,
+      last_position_in_rect: self.0.mouse_pointer.prev_position - rect.position,
     })
   }
 }

hui/src/instance.rs

@@ -8,7 +8,7 @@ use crate::{
   event::{EventQueue, UiEvent},
   input::UiInputState,
   layout::{Direction, LayoutInfo},
-  signal::{SignalStore, UiSignal},
+  signal::{SignalStore, Signal},
   state::StateRepo,
   text::{FontHandle, TextRenderer}
 };
@@ -244,7 +244,7 @@ impl UiInstance {
   }
 
   /// Push a "fake" signal to the UI signal queue
-  pub fn push_signal<T: UiSignal + 'static>(&mut self, signal: T) {
+  pub fn push_signal<T: Signal + 'static>(&mut self, signal: T) {
     self.signal.add(signal);
   }
 
@@ -253,7 +253,7 @@ impl UiInstance {
   /// Process all signals of a given type
   ///
   /// This clears the signal queue for the given type and iterates over all signals
-  pub fn process_signals<T: UiSignal + 'static>(&mut self, f: impl FnMut(T)) {
+  pub fn process_signals<T: Signal + 'static>(&mut self, f: impl FnMut(T)) {
     self.signal.drain::<T>().for_each(f);
   }
 }

hui/src/lib.rs

@@ -12,8 +12,7 @@
 mod instance;
 mod macros;
 pub mod layout;
-pub mod rectangle;
-pub mod background;
+pub mod rect;
 pub mod element;
 pub mod event;
 pub mod input;

hui/src/measure.rs

@@ -1,7 +1,7 @@
 //! element measurement, hints and responses
 
 use glam::Vec2;
-use crate::rectangle::Rect;
+use crate::rect::Rect;
 
 // #[non_exhaustive]
 #[derive(Default)]

hui/src/rect.rs

@@ -0,0 +1,15 @@
+//! contains types which represent the sides and corners of a rectangular shape.
+
+//XXX: this is kinda a mess, either move the rect struct here or come up with a better name for this module
+#[allow(clippy::module_inception)]
+mod rect;
+pub use rect::Rect;
+
+mod sides;
+pub use sides::Sides;
+
+mod corners;
+pub use corners::Corners;
+
+mod color;
+pub use color::FillColor;

hui/src/rect/color.rs

@@ -0,0 +1,187 @@
+use super::Corners;
+use glam::{Vec3, Vec4, vec4};
+
+/// Represents the fill color of a rectangle
+///
+/// Can be a single color or a simple gradient with different colors for each corner
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct FillColor(Corners<Vec4>);
+
+impl FillColor {
+  pub const fn new(corners: Corners<Vec4>) -> Self {
+    Self(corners)
+  }
+
+  /// Transparent background (alpha = 0)
+  pub const TRANSPARENT: Self = Self::rgba(0., 0., 0., 0.);
+
+  /// Transparent background (alpha = 0)
+  pub const fn transparent() -> Self {
+    Self::TRANSPARENT
+  }
+
+  /// Check if the fill color is completely transparent
+  ///
+  /// (i.e. all corners have an alpha value of 0.0)
+  pub fn is_transparent(&self) -> bool {
+    self.0.top_left.w == 0. &&
+    self.0.top_right.w == 0. &&
+    self.0.bottom_left.w == 0. &&
+    self.0.bottom_right.w == 0.
+  }
+
+  /// Check if the fill color is completely opaque
+  ///
+  /// (i.e. all corners have an alpha value of 1.0)
+  pub fn is_opaque(&self) -> bool {
+    self.0.top_left.w == 1. &&
+    self.0.top_right.w == 1. &&
+    self.0.bottom_left.w == 1. &&
+    self.0.bottom_right.w == 1.
+  }
+
+  /// Construct a solid color fill from values representing the red, green, blue and alpha channels
+  pub const fn rgba(r: f32, g: f32, b: f32, a: f32) -> Self {
+    Self(Corners {
+      top_left: vec4(r, g, b, a),
+      top_right: vec4(r, g, b, a),
+      bottom_left: vec4(r, g, b, a),
+      bottom_right: vec4(r, g, b, a),
+    })
+  }
+
+  /// Construct a solid color fill from three values representing the red, green and blue channels
+  pub const fn rgb(r: f32, g: f32, b: f32) -> Self {
+    Self(Corners {
+      top_left: vec4(r, g, b, 1.0),
+      top_right: vec4(r, g, b, 1.0),
+      bottom_left: vec4(r, g, b, 1.0),
+      bottom_right: vec4(r, g, b, 1.0),
+    })
+  }
+
+  /// Construct a solid color fill from colors for each corner
+  pub const fn from_corners(corners: Corners<Vec4>) -> Self {
+    Self(corners)
+  }
+
+  /// Get a list of the colors for each corner
+  pub const fn corners(&self) -> Corners<Vec4> {
+    self.0
+  }
+}
+
+impl Default for FillColor {
+  fn default() -> Self {
+    Self(Corners::all(vec4(0.0, 0.0, 0.0, 1.0)))
+  }
+}
+
+impl From<Corners<Vec4>> for FillColor {
+  fn from(corners: Corners<Vec4>) -> Self {
+    Self(corners)
+  }
+}
+
+impl From<FillColor> for Corners<Vec4> {
+  fn from(corners: FillColor) -> Self {
+    corners.0
+  }
+}
+
+impl From<Vec4> for FillColor {
+  fn from(value: Vec4) -> Self {
+    Self(Corners::all(value))
+  }
+}
+
+impl From<(f32, f32, f32, f32)> for FillColor {
+  fn from((r, g, b, a): (f32, f32, f32, f32)) -> Self {
+    Self(Corners::all(vec4(r, g, b, a)))
+  }
+}
+
+impl From<[f32; 4]> for FillColor {
+  fn from([r, g, b, a]: [f32; 4]) -> Self {
+    Self(Corners::all(vec4(r, g, b, a)))
+  }
+}
+
+impl From<Vec3> for FillColor {
+  fn from(value: Vec3) -> Self {
+    Self(Corners::all(vec4(value.x, value.y, value.z, 1.0)))
+  }
+}
+
+impl From<(f32, f32, f32)> for FillColor {
+  fn from((r, g, b): (f32, f32, f32)) -> Self {
+    Self(Corners::all(vec4(r, g, b, 1.0)))
+  }
+}
+
+impl From<[f32; 3]> for FillColor {
+  fn from([r, g, b]: [f32; 3]) -> Self {
+    Self(Corners::all(vec4(r, g, b, 1.0)))
+  }
+}
+
+impl From<(Vec4, Vec4, Vec4, Vec4)> for FillColor {
+  fn from((top_left, top_right, bottom_left, bottom_right): (Vec4, Vec4, Vec4, Vec4)) -> Self {
+    Self(Corners { top_left, top_right, bottom_left, bottom_right })
+  }
+}
+
+impl From<((f32, f32, f32, f32), (f32, f32, f32, f32), (f32, f32, f32, f32), (f32, f32, f32, f32))> for FillColor {
+  fn from(value: ((f32, f32, f32, f32), (f32, f32, f32, f32), (f32, f32, f32, f32), (f32, f32, f32, f32))) -> Self {
+    Self(Corners {
+      top_left: vec4(value.0.0, value.0.1, value.0.2, value.0.3),
+      top_right: vec4(value.1.0, value.1.1, value.1.2, value.1.3),
+      bottom_left: vec4(value.2.0, value.2.1, value.2.2, value.2.3),
+      bottom_right: vec4(value.3.0, value.3.1, value.3.2, value.3.3),
+    })
+  }
+}
+
+impl From<[[f32; 4]; 4]> for FillColor {
+  fn from(value: [[f32; 4]; 4]) -> Self {
+    Self(Corners {
+      top_left: vec4(value[0][0], value[0][1], value[0][2], value[0][3]),
+      top_right: vec4(value[1][0], value[1][1], value[1][2], value[1][3]),
+      bottom_left: vec4(value[2][0], value[2][1], value[2][2], value[2][3]),
+      bottom_right: vec4(value[3][0], value[3][1], value[3][2], value[3][3]),
+    })
+  }
+}
+
+impl From<(Vec3, Vec3, Vec3, Vec3)> for FillColor {
+  fn from((top_left, top_right, bottom_left, bottom_right): (Vec3, Vec3, Vec3, Vec3)) -> Self {
+    Self(Corners {
+      top_left: vec4(top_left.x, top_left.y, top_left.z, 1.0),
+      top_right: vec4(top_right.x, top_right.y, top_right.z, 1.0),
+      bottom_left: vec4(bottom_left.x, bottom_left.y, bottom_left.z, 1.0),
+      bottom_right: vec4(bottom_right.x, bottom_right.y, bottom_right.z, 1.0),
+    })
+  }
+}
+
+impl From<((f32, f32, f32), (f32, f32, f32), (f32, f32, f32), (f32, f32, f32))> for FillColor {
+  fn from(value: ((f32, f32, f32), (f32, f32, f32), (f32, f32, f32), (f32, f32, f32))) -> Self {
+    Self(Corners {
+      top_left: vec4(value.0.0, value.0.1, value.0.2, 1.0),
+      top_right: vec4(value.1.0, value.1.1, value.1.2, 1.0),
+      bottom_left: vec4(value.2.0, value.2.1, value.2.2, 1.0),
+      bottom_right: vec4(value.3.0, value.3.1, value.3.2, 1.0),
+    })
+  }
+}
+
+impl From<[[f32; 3]; 4]> for FillColor {
+  fn from(value: [[f32; 3]; 4]) -> Self {
+    Self(Corners {
+      top_left: vec4(value[0][0], value[0][1], value[0][2], 1.0),
+      top_right: vec4(value[1][0], value[1][1], value[1][2], 1.0),
+      bottom_left: vec4(value[2][0], value[2][1], value[2][2], 1.0),
+      bottom_right: vec4(value[3][0], value[3][1], value[3][2], 1.0),
+    })
+  }
+}

hui/src/rect/corners.rs

@@ -0,0 +1,85 @@
+/// Represents 4 corners of a rectangular shape.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
+pub struct Corners<T> {
+  pub top_left: T,
+  pub top_right: T,
+  pub bottom_left: T,
+  pub bottom_right: T,
+}
+
+impl<T: Clone> Corners<T> {
+  #[inline]
+  pub fn all(value: T) -> Self {
+    Self {
+      top_left: value.clone(),
+      top_right: value.clone(),
+      bottom_left: value.clone(),
+      bottom_right: value,
+    }
+  }
+
+  #[inline]
+  pub fn top_bottom(top: T, bottom: T) -> Self {
+    Self {
+      top_left: top.clone(),
+      top_right: top,
+      bottom_left: bottom.clone(),
+      bottom_right: bottom,
+    }
+  }
+
+  #[inline]
+  pub fn left_right(left: T, right: T) -> Self {
+    Self {
+      top_left: left.clone(),
+      top_right: right.clone(),
+      bottom_left: left,
+      bottom_right: right,
+    }
+  }
+}
+
+impl <T: Ord + Clone> Corners<T> {
+  pub fn max(&self) -> T {
+    self.top_left.clone()
+      .max(self.top_right.clone())
+      .max(self.bottom_left.clone())
+      .max(self.bottom_right.clone())
+      .clone()
+  }
+}
+
+impl Corners<f32> {
+  pub fn max_f32(&self) -> f32 {
+    self.top_left
+      .max(self.top_right)
+      .max(self.bottom_left)
+      .max(self.bottom_right)
+  }
+}
+
+impl Corners<f64> {
+  pub fn max_f64(&self) -> f64 {
+    self.top_left
+      .max(self.top_right)
+      .max(self.bottom_left)
+      .max(self.bottom_right)
+  }
+}
+
+impl<T: Clone> From<T> for Corners<T> {
+  fn from(value: T) -> Self {
+    Self::all(value)
+  }
+}
+
+impl<T> From<(T, T, T, T)> for Corners<T> {
+  fn from((top_left, top_right, bottom_left, bottom_right): (T, T, T, T)) -> Self {
+    Self {
+      top_left,
+      top_right,
+      bottom_left,
+      bottom_right,
+    }
+  }
+}

hui/src/rect/rect.rs

@@ -0,0 +1,65 @@
+use glam::Vec2;
+use super::Corners;
+
+/// Represents a rectangle/AABB with specified position and size
+#[derive(Clone, Copy, Debug, PartialEq, Default)]
+pub struct Rect {
+  /// Position of the top-left corner of the rect.
+  pub position: Vec2,
+  /// Size of the rect, should not be negative.
+  pub size: Vec2,
+}
+
+impl Rect {
+  /// Check if the rect contains a point.
+  pub fn contains_point(&self, point: Vec2) -> bool {
+    point.cmpge(self.position).all() && point.cmple(self.position + self.size).all()
+  }
+
+  //TODO: return intersect rect
+  /// Check if the rect intersects with another rect.
+  pub fn intersects_rect(&self, other: Rect) -> bool {
+    self.position.x < other.position.x + other.size.x
+      && self.position.x + self.size.x > other.position.x
+      && self.position.y < other.position.y + other.size.y
+      && self.position.y + self.size.y > other.position.y
+  }
+
+  /// Get width of the rectangle.
+  ///
+  /// To get both width and height, use the `size` property instead.
+  pub fn width(&self) -> f32 {
+    self.size.x
+  }
+
+  /// Get height of the rectangle.
+  ///
+  /// To get both width and height, use the `size` property instead.
+  pub fn height(&self) -> f32 {
+    self.size.y
+  }
+
+  /// Get position of the top-left corner of the rectangle on the x-axis.
+  ///
+  /// To get both x and y, use the `position` property instead.
+  pub fn x(&self) -> f32 {
+    self.position.x
+  }
+
+  /// Get position of the top-left corner of the rectangle on the y-axis.
+  ///
+  /// To get both x and y, use the `position` property instead.
+  pub fn y(&self) -> f32 {
+    self.position.y
+  }
+
+  /// Get positions of all 4 corners of the rectangle.
+  pub fn corners(&self) -> Corners<Vec2> {
+    Corners {
+      top_left: self.position,
+      top_right: self.position + Vec2::new(self.size.x, 0.0),
+      bottom_left: self.position + Vec2::new(0.0, self.size.y),
+      bottom_right: self.position + self.size,
+    }
+  }
+}

hui/src/rect/sides.rs

@@ -0,0 +1,49 @@
+
+/// Represents 4 sides of a rectangular shape.
+#[derive(Default, Clone, Copy, PartialEq, Eq, Debug)]
+pub struct Sides<T> {
+  pub top: T,
+  pub bottom: T,
+  pub left: T,
+  pub right: T,
+}
+
+impl<T: Clone> Sides<T> {
+  #[inline]
+  pub fn all(value: T) -> Self {
+    Self {
+      top: value.clone(),
+      bottom: value.clone(),
+      left: value.clone(),
+      right: value,
+    }
+  }
+
+  #[inline]
+  pub fn horizontal_vertical(horizontal: T, vertical: T) -> Self {
+    Self {
+      top: vertical.clone(),
+      bottom: vertical,
+      left: horizontal.clone(),
+      right: horizontal,
+    }
+  }
+}
+
+impl<T: Clone> From<T> for Sides<T> {
+  fn from(value: T) -> Self {
+    Self::all(value)
+  }
+}
+
+impl<T: Clone> From<(T, T)> for Sides<T> {
+  fn from((horizontal, vertical): (T, T)) -> Self {
+    Self::horizontal_vertical(horizontal, vertical)
+  }
+}
+
+impl<T> From<(T, T, T, T)> for Sides<T> {
+  fn from((top, bottom, left, right): (T, T, T, T)) -> Self {
+    Self { top, bottom, left, right }
+  }
+}

hui/src/rectangle.rs

@@ -1,201 +0,0 @@
-//! Contains types which represent the sides and corners of a rectangular shape.
-
-use glam::Vec2;
-
-/// Represents a rectangle/AABB with specified position and size
-#[derive(Clone, Copy, Debug, PartialEq, Default)]
-pub struct Rect {
-  /// Position of the top-left corner of the rect.
-  pub position: Vec2,
-  /// Size of the rect, should not be negative.
-  pub size: Vec2,
-}
-
-impl Rect {
-  /// Check if the rect contains a point.
-  pub fn contains_point(&self, point: Vec2) -> bool {
-    point.cmpge(self.position).all() && point.cmple(self.position + self.size).all()
-  }
-
-  //TODO: return intersect rect
-  /// Check if the rect intersects with another rect.
-  pub fn intersects_rect(&self, other: Rect) -> bool {
-    self.position.x < other.position.x + other.size.x
-      && self.position.x + self.size.x > other.position.x
-      && self.position.y < other.position.y + other.size.y
-      && self.position.y + self.size.y > other.position.y
-  }
-
-  /// Get width of the rectangle.
-  ///
-  /// To get both width and height, use the `size` property instead.
-  pub fn width(&self) -> f32 {
-    self.size.x
-  }
-
-  /// Get height of the rectangle.
-  ///
-  /// To get both width and height, use the `size` property instead.
-  pub fn height(&self) -> f32 {
-    self.size.y
-  }
-
-  /// Get position of the top-left corner of the rectangle on the x-axis.
-  ///
-  /// To get both x and y, use the `position` property instead.
-  pub fn x(&self) -> f32 {
-    self.position.x
-  }
-
-  /// Get position of the top-left corner of the rectangle on the y-axis.
-  ///
-  /// To get both x and y, use the `position` property instead.
-  pub fn y(&self) -> f32 {
-    self.position.y
-  }
-
-  /// Get positions of all 4 corners of the rectangle.
-  pub fn corners(&self) -> Corners<Vec2> {
-    Corners {
-      top_left: self.position,
-      top_right: self.position + Vec2::new(self.size.x, 0.0),
-      bottom_left: self.position + Vec2::new(0.0, self.size.y),
-      bottom_right: self.position + self.size,
-    }
-  }
-}
-
-/// Represents 4 sides of a rectangular shape.
-#[derive(Default, Clone, Copy, PartialEq, Eq, Debug)]
-pub struct Sides<T> {
-  pub top: T,
-  pub bottom: T,
-  pub left: T,
-  pub right: T,
-}
-
-impl<T: Clone> Sides<T> {
-  #[inline]
-  pub fn all(value: T) -> Self {
-    Self {
-      top: value.clone(),
-      bottom: value.clone(),
-      left: value.clone(),
-      right: value,
-    }
-  }
-
-  #[inline]
-  pub fn horizontal_vertical(horizontal: T, vertical: T) -> Self {
-    Self {
-      top: vertical.clone(),
-      bottom: vertical,
-      left: horizontal.clone(),
-      right: horizontal,
-    }
-  }
-}
-
-impl<T: Clone> From<T> for Sides<T> {
-  fn from(value: T) -> Self {
-    Self::all(value)
-  }
-}
-
-impl<T: Clone> From<(T, T)> for Sides<T> {
-  fn from((horizontal, vertical): (T, T)) -> Self {
-    Self::horizontal_vertical(horizontal, vertical)
-  }
-}
-
-impl<T> From<(T, T, T, T)> for Sides<T> {
-  fn from((top, bottom, left, right): (T, T, T, T)) -> Self {
-    Self { top, bottom, left, right }
-  }
-}
-
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
-pub struct Corners<T> {
-  pub top_left: T,
-  pub top_right: T,
-  pub bottom_left: T,
-  pub bottom_right: T,
-}
-
-impl<T: Clone> Corners<T> {
-  #[inline]
-  pub fn all(value: T) -> Self {
-    Self {
-      top_left: value.clone(),
-      top_right: value.clone(),
-      bottom_left: value.clone(),
-      bottom_right: value,
-    }
-  }
-
-  #[inline]
-  pub fn top_bottom(top: T, bottom: T) -> Self {
-    Self {
-      top_left: top.clone(),
-      top_right: top,
-      bottom_left: bottom.clone(),
-      bottom_right: bottom,
-    }
-  }
-
-  #[inline]
-  pub fn left_right(left: T, right: T) -> Self {
-    Self {
-      top_left: left.clone(),
-      top_right: right.clone(),
-      bottom_left: left,
-      bottom_right: right,
-    }
-  }
-}
-
-impl <T: Ord + Clone> Corners<T> {
-  pub fn max(&self) -> T {
-    self.top_left.clone()
-      .max(self.top_right.clone())
-      .max(self.bottom_left.clone())
-      .max(self.bottom_right.clone())
-      .clone()
-  }
-}
-
-/// Represents 4 corners of a rectangular shape.
-impl Corners<f32> {
-  pub fn max_f32(&self) -> f32 {
-    self.top_left
-      .max(self.top_right)
-      .max(self.bottom_left)
-      .max(self.bottom_right)
-  }
-}
-
-impl Corners<f64> {
-  pub fn max_f64(&self) -> f64 {
-    self.top_left
-      .max(self.top_right)
-      .max(self.bottom_left)
-      .max(self.bottom_right)
-  }
-}
-
-impl<T: Clone> From<T> for Corners<T> {
-  fn from(value: T) -> Self {
-    Self::all(value)
-  }
-}
-
-impl<T> From<(T, T, T, T)> for Corners<T> {
-  fn from((top_left, top_right, bottom_left, bottom_right): (T, T, T, T)) -> Self {
-    Self {
-      top_left,
-      top_right,
-      bottom_left,
-      bottom_right,
-    }
-  }
-}

hui/src/signal.rs

@@ -1,15 +1,21 @@
+//! signal handling for UI events
+
 use std::any::{Any, TypeId};
 use hashbrown::HashMap;
 use nohash_hasher::BuildNoHashHasher;
 
-/// A marker trait for signals
-pub trait UiSignal: Any {}
+pub mod trigger;
+
+/// A marker trait for UI Signals
+pub trait Signal: Any {}
 
 // #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, Default)]
 // pub(crate) struct DummySignal;
 // impl UiSignal for DummySignal {}
 
+/// Internal storage for signals
 pub struct SignalStore {
+  //TODO use a multithreaded queue instead, to allow easily offloading ui processing to a different thread
   ///XXX: is this truly the most efficient structure?
   sig: HashMap<TypeId, Vec<Box<dyn Any>>, BuildNoHashHasher<u64>>
 }
@@ -23,7 +29,7 @@ impl SignalStore {
   }
 
   /// Ensure that store for given signal type exists and return a mutable reference to it
-  fn internal_store<T: UiSignal + 'static>(&mut self) -> &mut Vec<Box<dyn Any>> {
+  fn internal_store<T: Signal + 'static>(&mut self) -> &mut Vec<Box<dyn Any>> {
     let type_id = TypeId::of::<T>();
     self.sig.entry(type_id).or_default()
   }
@@ -31,7 +37,7 @@ impl SignalStore {
   /// Add a signal to the store
   ///
   /// Signals are stored in the order they are added
-  pub fn add<T: UiSignal + 'static>(&mut self, sig: T) {
+  pub fn add<T: Signal + 'static>(&mut self, sig: T) {
     let type_id = TypeId::of::<T>();
     if let Some(v) = self.sig.get_mut(&type_id) {
       v.push(Box::new(sig));
@@ -41,7 +47,7 @@ impl SignalStore {
   }
 
   /// Drain all signals of a given type
-  pub(crate) fn drain<T: UiSignal + 'static>(&mut self) -> impl Iterator<Item = T> + '_ {
+  pub(crate) fn drain<T: Signal + 'static>(&mut self) -> impl Iterator<Item = T> + '_ {
     self.internal_store::<T>()
       .drain(..)
       .map(|x| *x.downcast::<T>().unwrap()) //unchecked?
@@ -54,7 +60,6 @@ impl SignalStore {
   }
 }
 
-//TODO this, simplifies handling signals
 
 // pub trait Signal {
 //   type Arg;

hui/src/signal/trigger.rs

@@ -0,0 +1,71 @@
+//! Contains the implementation of signal triggers, which simplify creation of custom elements
+
+use super::{Signal, SignalStore};
+//use crate::element::UiElement;
+
+/// Signal trigger that does not take any arguments
+#[allow(clippy::complexity)]
+pub struct SignalTrigger(Box<dyn Fn(&mut SignalStore)>);
+
+impl SignalTrigger {
+  /// Create a new signal trigger from a function or a constructor
+  pub fn new<S: Signal + 'static, F: Fn() -> S + 'static>(f: F) -> Self {
+    Self(Box::new(move |s: &mut SignalStore| {
+      s.add::<S>(f());
+    }))
+  }
+
+  /// Fire the signal
+  pub fn fire(&self, s: &mut SignalStore) {
+    (self.0)(s);
+  }
+}
+
+/// Signal trigger that takes a single argument and passes it to the signal
+#[allow(clippy::complexity)]
+pub struct SignalTriggerArg<T>(Box<dyn Fn(&mut SignalStore, T)>);
+
+impl<T> SignalTriggerArg<T> {
+  /// Create a new signal trigger from a function or a constructor
+  pub fn new<S: Signal, F: Fn(T) -> S + 'static>(f: F) -> Self {
+    Self(Box::new(move |s: &mut SignalStore, x| {
+      s.add::<S>(f(x));
+    }))
+  }
+
+  /// Fire the signal with the given argument
+  pub fn fire(&self, s: &mut SignalStore, x: T) {
+    (self.0)(s, x);
+  }
+}
+
+
+// #[allow(clippy::complexity)]
+// pub struct SignalTriggerElement<E: UiElement>(Box<dyn Fn(&mut SignalStore, &mut E)>);
+
+// impl<E: UiElement> SignalTriggerElement<E> {
+//   pub fn new<S: Signal, F: Fn(&mut E) -> S + 'static>(f: F) -> Self {
+//     Self(Box::new(move |s: &mut SignalStore, e: &mut E| {
+//       s.add::<S>(f(e));
+//     }))
+//   }
+
+//   pub fn fire(&self, s: &mut SignalStore, e: &mut E) {
+//     (self.0)(s, e);
+//   }
+// }
+
+// #[allow(clippy::complexity)]
+// pub struct SignalTriggerElementArg<E: UiElement, T>(Box<dyn Fn(&mut SignalStore, &mut E, T)>);
+
+// impl<E: UiElement, T> SignalTriggerElementArg<E, T> {
+//   pub fn new<S: Signal, F: Fn(T, &mut E) -> S + 'static>(f: F) -> Self {
+//     Self(Box::new(move |s: &mut SignalStore, e: &mut E, x| {
+//       s.add::<S>(f(x, e));
+//     }))
+//   }
+
+//   pub fn fire(&self, s: &mut SignalStore, e: &mut E, x: T) {
+//     (self.0)(s, e, x);
+//   }
+// }