Listen to scroll wheel (glium only)

emigui/README.md

@@ -16,7 +16,8 @@ This is the core library crate Emigui. It is fully platform independent without
 * [ ] Scroll areas
     * [x] Vertical scrolling
     * [ ] Horizontal scrolling
-    * [ ] Scroll-wheel input
+    * [x] Scroll-wheel input
+        * [ ] Scroll-wheel input in web verions
     * [x] Drag background to scroll
     * [ ] Kinetic scrolling
 * [ ] Menu bar (File, Edit, etc)

emigui/src/context.rs

@@ -125,19 +125,21 @@ impl Context {
         }
     }
 
-    pub fn interact(&self, layer: Layer, rect: Rect, interaction_id: Option<Id>) -> InteractInfo {
-        let mut memory = self.memory.lock();
-        let input = &self.input;
-
-        let hovered = if let Some(mouse_pos) = input.mouse_pos {
-            rect.contains(mouse_pos) && layer == memory.layer_at(mouse_pos)
+    pub fn contains_mouse_pos(&self, layer: Layer, rect: &Rect) -> bool {
+        if let Some(mouse_pos) = self.input.mouse_pos {
+            rect.contains(mouse_pos) && layer == self.memory.lock().layer_at(mouse_pos)
         } else {
             false
-        };
+        }
+    }
 
+    pub fn interact(&self, layer: Layer, rect: Rect, interaction_id: Option<Id>) -> InteractInfo {
+        let hovered = self.contains_mouse_pos(layer, &rect);
+
+        let mut memory = self.memory.lock();
         let active = interaction_id.is_some() && memory.active_id == interaction_id;
 
-        if input.mouse_pressed {
+        if self.input.mouse_pressed {
             if hovered && interaction_id.is_some() {
                 if memory.active_id.is_some() {
                     // Already clicked something else this frame
@@ -164,14 +166,14 @@ impl Context {
                     active: false,
                 }
             }
-        } else if input.mouse_released {
+        } else if self.input.mouse_released {
             InteractInfo {
                 rect,
                 hovered,
                 clicked: hovered && active,
                 active,
             }
-        } else if input.mouse_down {
+        } else if self.input.mouse_down {
             InteractInfo {
                 rect,
                 hovered: hovered && active,

emigui/src/scroll_area.rs

@@ -68,6 +68,13 @@ impl ScrollArea {
             state.offset.y -= ctx.input.mouse_move.y;
         }
 
+        // TODO: check that nothing else is being inteacted with
+        if ctx.contains_mouse_pos(outer_region.layer, &outer_rect)
+            && ctx.memory.lock().active_id.is_none()
+        {
+            state.offset.y -= ctx.input.scroll_delta.y;
+        }
+
         let show_scroll = content_size.y > inner_size.y;
         if show_scroll {
             let corner_radius = scroll_bar_width / 2.0;

emigui/src/types.rs

@@ -8,7 +8,9 @@ use crate::{
 // ----------------------------------------------------------------------------
 
 /// What the integration gives to the gui.
+/// All coordinates in emigui is in point/logical coordinates.
 #[derive(Clone, Copy, Debug, Default, Deserialize)]
+#[serde(default)]
 pub struct RawInput {
     /// Is the button currently down?
     pub mouse_down: bool,
@@ -16,6 +18,9 @@ pub struct RawInput {
     /// Current position of the mouse in points.
     pub mouse_pos: Option<Pos2>,
 
+    /// How many pixels the user scrolled
+    pub scroll_delta: Vec2,
+
     /// Size of the screen in points.
     pub screen_size: Vec2,
 
@@ -46,6 +51,9 @@ pub struct GuiInput {
     /// How much the mouse moved compared to last frame, in points.
     pub mouse_move: Vec2,
 
+    /// How many pixels the user scrolled
+    pub scroll_delta: Vec2,
+
     /// Size of the screen in points.
     pub screen_size: Vec2,
 
@@ -68,6 +76,7 @@ impl GuiInput {
             mouse_released: last.mouse_down && !new.mouse_down,
             mouse_pos: new.mouse_pos,
             mouse_move,
+            scroll_delta: new.scroll_delta,
             screen_size: new.screen_size,
             pixels_per_point: new.pixels_per_point,
             time: new.time,