span direction (sign) now works

src/base/span.rs

@@ -1,4 +1,4 @@
-use crate::{Dir, Painter, UINum, UIRegion, UIScalar, Widget, WidgetId};
+use crate::{Dir, Painter, Sign, UINum, UIRegion, UIScalar, Widget, WidgetId};
 
 pub struct Span {
     pub children: Vec<(WidgetId, SpanLen)>,
@@ -30,6 +30,9 @@ impl Widget for Span {
                     axis.bot_right.set(start);
                 }
             }
+            if self.dir.sign == Sign::Neg {
+                child_region.flip();
+            }
             painter.draw_within(child, child_region);
         }
     }

src/layout/region.rs

@@ -40,10 +40,10 @@ impl UIPos {
         let anchor = self
             .anchor
             .lerp(region.top_left.anchor, region.bot_right.anchor);
-        let offset = self.offset;
-        // + self
-        //     .anchor
-        //     .lerp(region.top_left.offset, region.bot_right.offset);
+        let offset = self.offset
+            + self
+                .anchor
+                .lerp(region.top_left.offset, region.bot_right.offset);
         UIPos { anchor, offset }
     }
 
@@ -59,6 +59,16 @@ impl UIPos {
             },
         }
     }
+
+    pub fn flip(&mut self) {
+        self.anchor = 1.0 - self.anchor;
+        self.offset = -self.offset;
+    }
+
+    pub fn flipped(mut self) -> Self {
+        self.flip();
+        self
+    }
 }
 
 #[derive(Clone, Copy, Debug)]
@@ -133,6 +143,12 @@ impl UIRegion {
             bot_right: self.bot_right.axis_mut(axis),
         }
     }
+
+    pub fn flip(&mut self) {
+        self.top_left.flip();
+        self.bot_right.flip();
+        std::mem::swap(&mut self.top_left, &mut self.bot_right);
+    }
 }
 
 pub struct UIRegionAxisView<'a> {

src/testing/mod.rs

@@ -54,7 +54,7 @@ impl Client {
                     rect.color(UIColor::RED),
                 )
                     .span(
-                        Dir::RIGHT,
+                        Dir::LEFT,
                         [
                             fixed(100),
                             ratio(1),

src/util/math.rs

@@ -40,6 +40,15 @@ macro_rules! impl_op {
                 }
             }
         }
+        impl const $op<$T> for f32 {
+            type Output = $T;
+
+            fn $fn(self, rhs: $T) -> Self::Output {
+                $T {
+                    $($field: self.$fn(rhs.$field),)*
+                }
+            }
+        }
         impl $opa<f32> for $T {
             fn $fna(&mut self, rhs: f32) {
                 $(self.$field.$fna(rhs);)*