allow rect in add, clean up elem api

hui/src/element.rs

@@ -1,11 +1,11 @@
 //! element API and built-in elements like `Container`, `Button`, `Text`, etc.
 
-use std::any::Any;
 use crate::{
   draw::{atlas::ImageCtx, UiDrawCommandList},
   input::InputCtx,
   layout::{LayoutInfo, Size2d},
   measure::Response,
+  rect::Rect,
   signal::SignalStore,
   state::StateRepo,
   text::{FontHandle, TextMeasure},
@@ -50,27 +50,6 @@ pub trait UiElement {
   /// You should implement this function whenever possible, otherwise some features may not work at all, such as the `Remaining` size
   fn size(&self) -> Option<Size2d> { None }
 
-  /// Get the unique id used for internal state management\
-  /// This value must be unique for each instance of the element
-  ///
-  /// If the element is stateless, this function should return `None`
-  fn state_id(&self) -> Option<u64> { None }
-
-  /// Check if the element has state.\
-  /// Should not be overridden
-  fn is_stateful(&self) -> bool { self.state_id().is_some() }
-
-  /// Check if the element has no state\
-  /// Should not be overridden
-  fn is_stateless(&self) -> bool { !self.is_stateful() }
-
-  /// Initialize the state of the element\
-  /// This function should be called exactly once during the lifetime of the element,
-  /// or if the state gets reset
-  ///
-  /// This function will not get called for stateless elements
-  fn init_state(&self) -> Option<Box<dyn Any>> { None }
-
   /// Measure step, guaranteed to be called before the `process` step\
   /// May be called multiple times per single frame, so it should not contain any expensive calls\
   /// This function may not mutate any state.\
@@ -108,7 +87,7 @@ pub trait UiElementExt: UiElement {
   fn add_child(self, ui: &mut ElementList);
 
   /// Add element as a ui root.
-  fn add_root(self, ui: &mut UiInstance, max_size: glam::Vec2);
+  fn add_root(self, ui: &mut UiInstance, max_size: impl Into<Rect>);
 }
 
 impl<T: UiElement + 'static> UiElementExt for T {
@@ -116,7 +95,7 @@ impl<T: UiElement + 'static> UiElementExt for T {
     ui.add(self)
   }
 
-  fn add_root(self, ui: &mut UiInstance, max_size: glam::Vec2) {
+  fn add_root(self, ui: &mut UiInstance, rect: impl Into<Rect>) {
-    ui.add(self, max_size);
+    ui.add(self, rect);
   }
 }

hui/src/instance.rs

@@ -1,16 +1,20 @@
 use glam::Vec2;
 use crate::{
+  element::{MeasureContext, ProcessContext, UiElement},
+  layout::{Direction, LayoutInfo},
+  text::{FontHandle, TextRenderer},
   draw::{
-    ImageHandle, TextureFormat, UiDrawCall, UiDrawCommandList,
+    ImageHandle,
+    TextureFormat,
+    UiDrawCall,
+    UiDrawCommandList,
     atlas::{TextureAtlasManager, TextureAtlasMeta},
   },
-  element::{MeasureContext, ProcessContext, UiElement},
+  signal::{Signal, SignalStore},
   event::{EventQueue, UiEvent},
   input::UiInputState,
-  layout::{Direction, LayoutInfo},
+  rect::Rect,
-  signal::{SignalStore, Signal},
   state::StateRepo,
-  text::{FontHandle, TextRenderer}
 };
 
 /// The main instance of the UI system.
@@ -144,16 +148,17 @@ impl UiInstance {
 
   /// Add an element or an element tree to the UI
   ///
-  /// Use the `max_size` parameter to specify the maximum size of the element\
+  /// Use the `rect` parameter to specify the position and size of the element\
   /// (usually, the size of the window/screen)
   ///
   /// ## Panics:
   /// If called while the UI is not active (call [`UiInstance::begin`] first)
-  pub fn add<T: UiElement>(&mut self, element: T, max_size: Vec2) {
+  pub fn add(&mut self, element: impl UiElement, rect: impl Into<Rect>) {
     assert!(self.state, "must call UiInstance::begin before adding elements");
+    let rect: Rect = rect.into();
     let layout = LayoutInfo {
-      position: Vec2::ZERO,
+      position: rect.position,
-      max_size,
+      max_size: rect.size,
       direction: Direction::Vertical,
       remaining_space: None,
     };

hui/src/rect/rect.rs

@@ -11,6 +11,24 @@ pub struct Rect {
 }
 
 impl Rect {
+  pub const fn new(position: Vec2, size: Vec2) -> Self {
+    Self { position, size }
+  }
+
+  pub const fn from_position(position: Vec2) -> Self {
+    Self {
+      position,
+      size: Vec2::ZERO,
+    }
+  }
+
+  pub const fn from_size(size: Vec2) -> Self {
+    Self {
+      position: Vec2::ZERO,
+      size,
+    }
+  }
+
   /// 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()
@@ -63,3 +81,10 @@ impl Rect {
     }
   }
 }
+
+impl From<Vec2> for Rect {
+  /// Create a new `Rect` from a `Vec2`, where x and y are the width and height of the rect respectively.
+  fn from(size: Vec2) -> Self {
+    Self::from_size(size)
+  }
+}