move widgets on draw if region size is same

src/layout/pos.rs

@@ -1,6 +1,6 @@
 use crate::{
     layout::{Align, Axis, Vec2},
-    util::{F32Util, impl_op},
+    util::{LerpUtil, impl_op},
 };
 
 #[repr(C)]
@@ -52,23 +52,26 @@ impl UiVec2 {
     }
 
     pub const fn within(&self, region: &UiRegion) -> UiVec2 {
-        let anchor = self.rel.lerp(region.top_left.rel, region.bot_right.rel);
-        let offset = self.abs + self.rel.lerp(region.top_left.abs, region.bot_right.abs);
-        UiVec2 {
-            rel: anchor,
-            abs: offset,
-        }
+        let rel = self.rel.lerp(region.top_left.rel, region.bot_right.rel);
+        let abs = self.abs + self.rel.lerp(region.top_left.abs, region.bot_right.abs);
+        UiVec2 { rel, abs }
+    }
+
+    pub const fn outside(&self, region: &UiRegion) -> UiVec2 {
+        let rel = self.rel.lerp_inv(region.top_left.rel, region.bot_right.rel);
+        let abs = self.abs - rel.lerp(region.top_left.abs, region.bot_right.abs);
+        UiVec2 { rel, abs }
     }
 
     pub fn axis_mut(&mut self, axis: Axis) -> UiScalarView<'_> {
         match axis {
             Axis::X => UiScalarView {
-                anchor: &mut self.rel.x,
-                offset: &mut self.abs.x,
+                rel: &mut self.rel.x,
+                abs: &mut self.abs.x,
             },
             Axis::Y => UiScalarView {
-                anchor: &mut self.rel.y,
-                offset: &mut self.abs.y,
+                rel: &mut self.rel.y,
+                abs: &mut self.abs.y,
             },
         }
     }
@@ -110,6 +113,9 @@ impl UiVec2 {
     }
 }
 
+impl_op!(UiVec2 Add add; rel abs);
+impl_op!(UiVec2 Sub sub; rel abs);
+
 impl const From<Align> for UiVec2 {
     fn from(align: Align) -> Self {
         Self::anchor(align.anchor())
@@ -204,6 +210,12 @@ impl UiRegion {
             bot_right: self.bot_right.within(parent),
         }
     }
+    pub fn outside(&self, parent: &Self) -> Self {
+        Self {
+            top_left: self.top_left.outside(parent),
+            bot_right: self.bot_right.outside(parent),
+        }
+    }
     pub fn axis_mut(&mut self, axis: Axis) -> UIRegionAxisView<'_> {
         UIRegionAxisView {
             top_left: self.top_left.axis_mut(axis),
@@ -243,6 +255,10 @@ impl UiRegion {
         self.bot_right.to_size(size) - self.top_left.to_size(size)
     }
 
+    pub fn size(&self) -> UiVec2 {
+        self.bot_right - self.top_left
+    }
+
     pub fn select_aligned(&self, size: Vec2, align: Align) -> Self {
         Self::from_size_align(size, align).within(self)
     }
@@ -292,19 +308,19 @@ pub struct UIRegionAxisView<'a> {
 }
 
 pub struct UiScalarView<'a> {
-    pub anchor: &'a mut f32,
-    pub offset: &'a mut f32,
+    pub rel: &'a mut f32,
+    pub abs: &'a mut f32,
 }
 
 impl UiScalarView<'_> {
     pub fn set(&mut self, scalar: UiScalar) {
-        *self.anchor = scalar.rel;
-        *self.offset = scalar.abs;
+        *self.rel = scalar.rel;
+        *self.abs = scalar.abs;
     }
     pub fn get(self) -> UiScalar {
         UiScalar {
-            rel: *self.anchor,
-            abs: *self.offset,
+            rel: *self.rel,
+            abs: *self.abs,
         }
     }
 }