trust + fix redraw bug

core/src/primitive/layer.rs

@@ -1,6 +1,9 @@
 use std::ops::{Index, IndexMut};
 
-use crate::render::{MaskIdx, Primitive, PrimitiveHandle, PrimitiveInst, Primitives};
+use crate::{
+    render::{MaskIdx, Primitive, PrimitiveHandle, PrimitiveInst, Primitives},
+    util::to_mut,
+};
 
 pub type LayerId = usize;
 
@@ -176,8 +179,7 @@ impl<'a, T> Iterator for LayerIteratorMut<'a, T> {
     fn next(&mut self) -> Option<Self::Item> {
         let i = self.inner.next()?;
         // SAFETY: requires index iterator to work properly
-        #[allow(mutable_transmutes)]
-        let layer = unsafe { std::mem::transmute::<&T, &mut T>(&self.inner.vec[i].data) };
+        let layer = unsafe { to_mut(&self.inner.vec[i].data) };
         Some((i, layer))
     }
 }
@@ -186,8 +188,7 @@ impl<'a, T> DoubleEndedIterator for LayerIteratorMut<'a, T> {
     fn next_back(&mut self) -> Option<Self::Item> {
         let i = self.inner.next_back()?;
         // SAFETY: requires index iterator to work properly
-        #[allow(mutable_transmutes)]
-        let layer = unsafe { std::mem::transmute::<&T, &mut T>(&self.inner.vec[i].data) };
+        let layer = unsafe { to_mut(&self.inner.vec[i].data) };
         Some((i, layer))
     }
 }