alignment!!!

src/layout/pos.rs

@@ -1,5 +1,5 @@
 use crate::{
-    layout::{Axis, Corner, Vec2, vec2},
+    layout::{Align, Axis, Vec2},
     util::{F32Util, impl_op},
 };
 
@@ -20,10 +20,6 @@ impl UiPos {
         }
     }
 
-    pub const fn center() -> Self {
-        Self::anchor(vec2(0.5, 0.5))
-    }
-
     pub const fn anchor(anchor: Vec2) -> Self {
         Self {
             anchor,
@@ -38,10 +34,6 @@ impl UiPos {
         }
     }
 
-    pub const fn corner(corner: Corner) -> Self {
-        Self::anchor(corner.anchor())
-    }
-
     pub const fn shift(&mut self, offset: impl const Into<Vec2>) {
         self.offset += offset.into();
     }
@@ -90,6 +82,18 @@ impl UiPos {
     }
 }
 
+impl const From<Align> for UiPos {
+    fn from(align: Align) -> Self {
+        Self::anchor(align.anchor())
+    }
+}
+
+impl Align {
+    pub fn pos(self) -> UiPos {
+        UiPos::from(self)
+    }
+}
+
 #[derive(Clone, Copy, Debug)]
 pub struct UIScalar {
     pub anchor: f32,
@@ -137,8 +141,8 @@ pub struct UiRegion {
 impl UiRegion {
     pub const fn full() -> Self {
         Self {
-            top_left: UiPos::corner(Corner::TopLeft),
-            bot_right: UiPos::corner(Corner::BotRight),
+            top_left: Align::TopLeft.into(),
+            bot_right: Align::BotRight.into(),
         }
     }
     pub fn anchor(anchor: Vec2) -> Self {
@@ -153,9 +157,6 @@ impl UiRegion {
             bot_right: self.bot_right.within(parent),
         }
     }
-    pub fn select(&mut self, inner: &Self) {
-        *self = inner.within(self);
-    }
     pub fn axis_mut(&mut self, axis: Axis) -> UIRegionAxisView<'_> {
         UIRegionAxisView {
             top_left: self.top_left.axis_mut(axis),
@@ -188,12 +189,27 @@ impl UiRegion {
     }
 
     pub fn center(&self) -> UiPos {
-        UiPos::center().within(self)
+        Align::Center.pos().within(self)
     }
 
     pub fn in_size(&self, size: Vec2) -> Vec2 {
         self.bot_right.to_size(size) - self.top_left.to_size(size)
     }
+
+    pub fn select_aligned(&self, size: Vec2, align: Align) -> Self {
+        Self::from_size_align(size, align).within(self)
+    }
+
+    pub fn from_size_align(size: Vec2, align: Align) -> Self {
+        let mut top_left = UiPos::from(align);
+        top_left.offset -= size * align.anchor();
+        let mut bot_right = UiPos::from(align);
+        bot_right.offset += size * (Vec2::ONE - align.anchor());
+        Self {
+            top_left,
+            bot_right,
+        }
+    }
 }
 
 #[derive(Debug)]