Merge pull request #684 from psFried/events

Switch to event-based input handling

Author: mitchmindtree

src/events/global_input.rs

@@ -0,0 +1,158 @@
+//! Handles all of the global input events and state.
+//! The core of this module is the `GlobalInput` struct. It is responsible for aggregating
+//! and interpreting raw input events into high-level semantic events.
+
+use events::{InputState, UiEvent, MouseClick, MouseDrag, Scroll, InputProvider};
+use input::MouseButton;
+use position::{Point, Scalar};
+use widget::Index;
+
+/// Global input event handler that also implements `InputProvider`. The `Ui` passes all events
+/// to it's `GlobalInput` instance, which aggregates and interprets the events to provide
+/// so-called 'high-level' events to widgets. This input gets reset after every update by the `Ui`.
+pub struct GlobalInput {
+    /// The `InputState` as it was at the end of the last update cycle.
+    pub start_state: InputState,
+    /// The most recent `InputState`, with updates from handling all the events
+    /// this update cycle
+    pub current_state: InputState,
+    events: Vec<UiEvent>,
+    drag_threshold: Scalar,
+}
+
+/// Iterator over global `UiEvent`s. Unlike the `WidgetInputEventIterator`, this will
+/// never filter out any events, and all coordinates will be reative to the (0,0) origin
+/// of the window.
+pub type GlobalInputEventIterator<'a> = ::std::slice::Iter<'a, UiEvent>;
+
+impl <'a> InputProvider<'a, GlobalInputEventIterator<'a>> for GlobalInput {
+    fn all_events(&'a self) -> GlobalInputEventIterator {
+        self.events.iter()
+    }
+
+    fn current_state(&'a self) -> &'a InputState {
+        &self.current_state
+    }
+
+    fn mouse_button_down(&self, button: MouseButton) -> Option<Point> {
+         self.current_state().mouse_buttons.get(button).map(|_| {
+             self.mouse_position()
+         })
+    }
+}
+
+impl GlobalInput {
+
+    /// Returns a fresh new `GlobalInput`
+    pub fn new(drag_threshold: Scalar) -> GlobalInput {
+        GlobalInput{
+            events: Vec::new(),
+            drag_threshold: drag_threshold,
+            start_state: InputState::new(),
+            current_state: InputState::new(),
+        }
+    }
+
+    /// Adds a new event and updates the internal state.
+    pub fn push_event(&mut self, event: UiEvent) {
+        use input::Input::{Release, Move};
+        use input::Motion::MouseRelative;
+        use input::Motion::MouseScroll;
+        use input::Button::Mouse;
+
+        let maybe_new_event = match event {
+            UiEvent::Raw(Release(Mouse(button))) => self.handle_mouse_release(button),
+            UiEvent::Raw(Move(MouseRelative(x, y))) => self.handle_mouse_move([x, y]),
+            UiEvent::Raw(Move(MouseScroll(x, y))) => self.mouse_scroll(x, y),
+            _ => None
+        };
+
+        self.current_state.update(&event);
+        self.events.push(event);
+        if let Some(new_event) = maybe_new_event {
+            self.push_event(new_event);
+        }
+    }
+
+    /// Called at the end of every update cycle in order to prepare the `GlobalInput` to
+    /// handle events for the next one.
+    pub fn reset(&mut self) {
+        self.events.clear();
+        self.start_state = self.current_state.clone();
+    }
+
+    /// Returns the most up to date position of the mouse
+    pub fn mouse_position(&self) -> Point {
+        self.current_state.mouse_position
+    }
+
+    /// Returns the input state as it was after the last update
+    pub fn starting_state(&self) -> &InputState {
+        &self.start_state
+    }
+
+    /// Returns the most up to date info on which widget is capturing the mouse
+    pub fn currently_capturing_mouse(&self) -> Option<Index> {
+        self.current_state.widget_capturing_mouse
+    }
+
+    /// Returns the most up to date info on which widget is capturing the keyboard
+    pub fn currently_capturing_keyboard(&self) -> Option<Index> {
+        self.current_state.widget_capturing_keyboard
+    }
+
+
+    fn mouse_scroll(&self, x: f64, y: f64) -> Option<UiEvent> {
+        Some(UiEvent::Scroll(Scroll{
+            x: x,
+            y: y,
+            modifiers: self.current_state.modifiers
+        }))
+    }
+
+    fn handle_mouse_move(&self, move_to: Point) -> Option<UiEvent> {
+        self.current_state.mouse_buttons.pressed_button().and_then(|btn_and_point| {
+            if self.is_drag(btn_and_point.1, move_to) {
+                Some(UiEvent::MouseDrag(MouseDrag{
+                    button: btn_and_point.0,
+                    start: btn_and_point.1,
+                    end: move_to,
+                    in_progress: true,
+                    modifier: self.current_state.modifiers
+                }))
+            } else {
+                None
+            }
+        })
+    }
+
+    fn handle_mouse_release(&self, button: MouseButton) -> Option<UiEvent> {
+        self.current_state.mouse_buttons.get(button).map(|point| {
+            if self.is_drag(point, self.current_state.mouse_position) {
+                UiEvent::MouseDrag(MouseDrag{
+                    button: button,
+                    start: point,
+                    end: self.current_state.mouse_position,
+                    modifier: self.current_state.modifiers,
+                    in_progress: false
+                })
+            } else {
+                UiEvent::MouseClick(MouseClick {
+                    button: button,
+                    location: point,
+                    modifier: self.current_state.modifiers
+                })
+            }
+        })
+    }
+
+    fn is_drag(&self, a: Point, b: Point) -> bool {
+        distance_between(a, b) > self.drag_threshold
+    }
+}
+
+fn distance_between(a: Point, b: Point) -> Scalar {
+    let dx_2 = (a[0] - b[0]).powi(2);
+    let dy_2 = (a[1] - b[1]).powi(2);
+    (dx_2 + dy_2).abs().sqrt()
+}