refactor events

core/src/event/ctx.rs

@@ -0,0 +1,36 @@
+use std::ops::{Index, IndexMut};
+
+use crate::{Ui, Widget, WidgetRef};
+
+pub struct EventCtx<'a, Ctx, Data> {
+    pub ui: &'a mut Ui,
+    pub state: &'a mut Ctx,
+    pub data: &'a mut Data,
+}
+
+pub struct EventIdCtx<'a, Ctx, Data, W: ?Sized> {
+    pub widget: WidgetRef<W>,
+    pub ui: &'a mut Ui,
+    pub state: &'a mut Ctx,
+    pub data: &'a mut Data,
+}
+
+impl<'a, Ctx, Data, W2, W: Widget> Index<WidgetRef<W>> for EventIdCtx<'a, Ctx, Data, W2> {
+    type Output = W;
+
+    fn index(&self, index: WidgetRef<W>) -> &Self::Output {
+        &self.ui[index]
+    }
+}
+
+impl<'a, Ctx, Data, W2, W: Widget> IndexMut<WidgetRef<W>> for EventIdCtx<'a, Ctx, Data, W2> {
+    fn index_mut(&mut self, index: WidgetRef<W>) -> &mut Self::Output {
+        &mut self.ui[index]
+    }
+}
+
+impl<'a, Ctx, Data, W: Widget> EventIdCtx<'a, Ctx, Data, W> {
+    pub fn widget(&mut self) -> &mut W {
+        &mut self.ui[self.widget]
+    }
+}