Add hot glow option to multiwin example. (#845)

Author: xStrom

druid/examples/multiwin.rs

@@ -14,23 +14,25 @@
 
 //! Opening and closing windows and using window and context menus.
 
-use druid::widget::{Align, Button, Flex, Label, Padding};
+use druid::widget::prelude::*;
+use druid::widget::{Align, BackgroundBrush, Button, Flex, Label, Padding};
 use druid::{
-    commands as sys_cmds, AppDelegate, AppLauncher, Command, ContextMenu, Data, DelegateCtx, Env,
-    Event, EventCtx, LocalizedString, MenuDesc, MenuItem, Selector, Target, Widget, WindowDesc,
-    WindowId,
+    commands as sys_cmds, AppDelegate, AppLauncher, Color, Command, ContextMenu, Data, DelegateCtx,
+    LocalizedString, MenuDesc, MenuItem, Selector, Target, WidgetPod, WindowDesc, WindowId,
 };
 
 use log::info;
 
 const MENU_COUNT_ACTION: Selector = Selector::new("menu-count-action");
 const MENU_INCREMENT_ACTION: Selector = Selector::new("menu-increment-action");
 const MENU_DECREMENT_ACTION: Selector = Selector::new("menu-decrement-action");
+const MENU_SWITCH_GLOW_ACTION: Selector = Selector::new("menu-switch-glow");
 
 #[derive(Debug, Clone, Default, Data)]
 struct State {
     menu_count: usize,
     selected: usize,
+    glow_hot: bool,
 }
 
 pub fn main() {
@@ -79,7 +81,58 @@ fn ui_builder() -> impl Widget<State> {
     row.add_child(Padding::new(5.0, inc_button));
     row.add_child(Padding::new(5.0, dec_button));
     col.add_flex_child(Align::centered(row), 1.0);
-    col
+    Glow::new(col)
+}
+
+struct Glow<W> {
+    inner: WidgetPod<State, W>,
+}
+
+impl<W: Widget<State>> Glow<W> {
+    pub fn new(inner: W) -> Glow<W> {
+        Glow {
+            inner: WidgetPod::new(inner),
+        }
+    }
+}
+
+impl<W: Widget<State>> Widget<State> for Glow<W> {
+    fn event(&mut self, ctx: &mut EventCtx, event: &Event, data: &mut State, env: &Env) {
+        self.inner.event(ctx, event, data, env);
+    }
+
+    fn lifecycle(&mut self, ctx: &mut LifeCycleCtx, event: &LifeCycle, data: &State, env: &Env) {
+        if let LifeCycle::HotChanged(_) = event {
+            ctx.request_paint();
+        }
+        self.inner.lifecycle(ctx, event, data, env);
+    }
+
+    fn update(&mut self, ctx: &mut UpdateCtx, old_data: &State, data: &State, env: &Env) {
+        if old_data.glow_hot != data.glow_hot {
+            ctx.request_paint();
+        }
+        self.inner.update(ctx, data, env);
+    }
+
+    fn layout(
+        &mut self,
+        ctx: &mut LayoutCtx,
+        bc: &BoxConstraints,
+        data: &State,
+        env: &Env,
+    ) -> Size {
+        let size = self.inner.layout(ctx, bc, data, env);
+        self.inner.set_layout_rect(ctx, data, env, size.to_rect());
+        size
+    }
+
+    fn paint(&mut self, ctx: &mut PaintCtx, data: &State, env: &Env) {
+        if data.glow_hot && ctx.is_hot() {
+            BackgroundBrush::Color(Color::rgb8(200, 55, 55)).paint(ctx, data, env);
+        }
+        self.inner.paint(ctx, data, env);
+    }
 }
 
 struct Delegate;
@@ -144,6 +197,10 @@ impl AppDelegate<State> for Delegate {
                 ctx.submit_command(cmd, *id);
                 false
             }
+            (_, &MENU_SWITCH_GLOW_ACTION) => {
+                data.glow_hot = !data.glow_hot;
+                false
+            }
             _ => true,
         }
     }
@@ -207,4 +264,8 @@ fn make_context_menu<T: Data>() -> MenuDesc<T> {
             LocalizedString::new("Decrement"),
             MENU_DECREMENT_ACTION,
         ))
+        .append(MenuItem::new(
+            LocalizedString::new("Glow when hot"),
+            MENU_SWITCH_GLOW_ACTION,
+        ))
 }