change the mouse cursor based on context [rebuild]

ezgui/src/backend_glium.rs

@@ -233,6 +233,10 @@ impl PrerenderInnards {
         self.display.gl_window().window().request_redraw();
     }
 
+    pub fn set_cursor_icon(&self, icon: winit::window::CursorIcon) {
+        self.display.gl_window().window().set_cursor_icon(icon);
+    }
+
     pub fn draw_new_frame<'a>(&self) -> GfxCtxInnards<'a> {
         GfxCtxInnards {
             target: self.display.draw(),

ezgui/src/backend_glow.rs

@@ -287,6 +287,10 @@ impl PrerenderInnards {
         self.windowed_context.window().request_redraw();
     }
 
+    pub fn set_cursor_icon(&self, icon: winit::window::CursorIcon) {
+        self.windowed_context.window().set_cursor_icon(icon);
+    }
+
     pub fn draw_new_frame(&self) -> GfxCtxInnards {
         GfxCtxInnards {
             gl: &self.gl,

ezgui/src/backend_wasm.rs

@@ -305,6 +305,10 @@ impl PrerenderInnards {
         self.window.request_redraw();
     }
 
+    pub fn set_cursor_icon(&self, icon: winit::window::CursorIcon) {
+        self.window.set_cursor_icon(icon);
+    }
+
     pub fn draw_new_frame(&self) -> GfxCtxInnards {
         GfxCtxInnards {
             gl: &self.gl,

ezgui/src/event_ctx.rs

@@ -100,6 +100,12 @@ impl<'a> EventCtx<'a> {
     pub fn monitor_scale_factor(&self) -> f64 {
         self.prerender.inner.monitor_scale_factor()
     }
+
+    pub(crate) fn cursor_clickable(&mut self) {
+        self.prerender
+            .inner
+            .set_cursor_icon(winit::window::CursorIcon::Hand);
+    }
 }
 
 pub struct LoadingScreen<'a> {

ezgui/src/runner.rs

@@ -44,6 +44,25 @@ impl<G: GUI> State<G> {
             }
         }
 
+        // Always reset the cursor, unless we're handling an update event. If we're hovering on a
+        // button, we'll discover that by plumbing through the event.
+        if let Event::Update(_) = ev {
+        } else {
+            prerender
+                .inner
+                .set_cursor_icon(if self.canvas.drag_canvas_from.is_some() {
+                    // We haven't run canvas_movement() yet, so we don't know if the button has been
+                    // released. Bit of a hack to check this here, but better behavior.
+                    if ev == Event::LeftMouseButtonUp {
+                        winit::window::CursorIcon::Default
+                    } else {
+                        winit::window::CursorIcon::Grabbing
+                    }
+                } else {
+                    winit::window::CursorIcon::Default
+                });
+        }
+
         // It's impossible / very unlikey we'll grab the cursor in map space before the very first
         // start_drawing call.
         let input = UserInput::new(ev, &self.canvas);

ezgui/src/widgets/button.rs

@@ -91,6 +91,10 @@ impl WidgetImpl for Button {
             }
         }
 
+        if self.hovering {
+            ctx.cursor_clickable();
+        }
+
         None
     }