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))
     }
 }

core/src/ui/draw_state.rs

@@ -1,6 +1,7 @@
 use crate::{
-    ActiveData, Axis, Painter, SizeCtx, Ui, UiRegion, UiVec2, WidgetId, render::MaskIdx,
-    util::HashSet,
+    ActiveData, Axis, Painter, SizeCtx, Ui, UiRegion, UiVec2, WidgetId,
+    render::MaskIdx,
+    util::{HashSet, forget_ref},
 };
 use std::ops::{Deref, DerefMut};
 
@@ -30,9 +31,7 @@ impl<'a, State: 'static> DrawState<'a, State> {
     /// will just return if so
     pub fn redraw(&mut self, id: WidgetId) {
         self.widgets.needs_redraw.remove(&id);
-        if self.draw_started.contains(&id) {
-            return;
-        }
+        self.draw_started.remove(&id);
         // check if parent depends on the desired size of this, if so then redraw it first
         for axis in [Axis::X, Axis::Y] {
             if let Some(&(outer, old)) = self.cache.size.axis_dyn(axis).get(&id)
@@ -202,11 +201,10 @@ impl<'a, State: 'static> DrawState<'a, State> {
             *region = region.outside(&from).within(&to);
         }
         active.region = active.region.outside(&from).within(&to);
-        // children will not be changed, so this technically should not be needed
-        // probably need unsafe
-        let children = active.children.clone();
+        // SAFETY: children cannot be recursive
+        let children = unsafe { forget_ref(&active.children) };
         for child in children {
-            self.mov(child, from, to);
+            self.mov(*child, from, to);
         }
     }
 

core/src/util/mod.rs

@@ -1,4 +1,3 @@
-mod typemap;
 mod arena;
 mod borrow;
 mod change;
@@ -6,9 +5,10 @@ mod id;
 mod math;
 mod refcount;
 mod slot;
+mod trust;
+mod typemap;
 mod vec2;
 
-pub use typemap::*;
 pub use arena::*;
 pub use borrow::*;
 pub use change::*;
@@ -16,6 +16,8 @@ pub use id::*;
 pub use math::*;
 pub use refcount::*;
 pub use slot::*;
+pub use trust::*;
+pub use typemap::*;
 pub use vec2::*;
 
 pub type HashMap<K, V> = fxhash::FxHashMap<K, V>;

core/src/util/trust.rs

@@ -0,0 +1,17 @@
+#[allow(clippy::missing_safety_doc)]
+pub unsafe fn forget_ref<'a, T>(x: &T) -> &'a T {
+    unsafe { std::mem::transmute::<&T, &T>(x) }
+}
+
+#[allow(clippy::missing_safety_doc)]
+pub unsafe fn forget_mut<'a, T>(x: &mut T) -> &'a mut T {
+    unsafe { std::mem::transmute::<&mut T, &mut T>(x) }
+}
+
+#[allow(clippy::mut_from_ref, clippy::missing_safety_doc)]
+pub unsafe fn to_mut<T>(x: &T) -> &mut T {
+    #[allow(mutable_transmutes)]
+    unsafe {
+        std::mem::transmute::<&T, &mut T>(x)
+    }
+}

core/src/widget/handle.rs

@@ -56,11 +56,6 @@ impl<State, W: ?Sized> WidgetHandle<State, W> {
         }
     }
 
-    pub fn as_any(&self) -> &WidgetHandle<State, dyn Widget<State>> {
-        // SAFETY: self is repr(C) and generic only used for phantom data
-        unsafe { std::mem::transmute(self) }
-    }
-
     pub fn id(&self) -> WidgetId {
         self.id
     }

core/src/widget/widgets.rs

@@ -1,6 +1,6 @@
 use crate::{
     IdLike, Widget, WidgetData, WidgetId,
-    util::{DynBorrower, HashSet, SlotVec},
+    util::{DynBorrower, HashSet, SlotVec, forget_mut, to_mut},
 };
 
 pub struct Widgets<State> {
@@ -36,12 +36,7 @@ impl<State: 'static> Widgets<State> {
     pub(crate) fn get_dyn_dynamic<'a>(&self, id: WidgetId) -> WidgetWrapper<'a, State> {
         // SAFETY: must guarantee no other mutable references to this widget exist
         // done through the borrow variable
-        #[allow(mutable_transmutes)]
-        let data = unsafe {
-            std::mem::transmute::<&WidgetData<State>, &mut WidgetData<State>>(
-                self.vec.get(id).unwrap(),
-            )
-        };
+        let data = unsafe { forget_mut(to_mut(self.vec.get(id).unwrap())) };
         if data.borrowed {
             panic!("tried to mutably borrow the same widget twice");
         }