Add support for no button in a mouse event.

druid-shell/src/lib.rs

@@ -46,7 +46,7 @@ pub use hotkey::{HotKey, KeyCompare, RawMods, SysMods};
 pub use keyboard::{KeyEvent, KeyModifiers};
 pub use keycodes::KeyCode;
 pub use menu::Menu;
-pub use mouse::{Cursor, MouseButton, MouseEvent};
+pub use mouse::{Cursor, MouseButton, MouseButtonExt, MouseEvent};
 pub use window::{
     IdleHandle, IdleToken, Text, TimerToken, WinHandler, WindowBuilder, WindowHandle,
 };

druid-shell/src/mouse.rs

@@ -32,7 +32,7 @@ pub struct MouseEvent {
     pub count: u32,
     /// The currently pressed button in the case of a move or click event,
     /// or the released button in the case of a mouse-up event.
-    pub button: MouseButton,
+    pub button: Option<MouseButton>,
 }
 
 /// An indicator of which mouse button was pressed.
@@ -52,20 +52,45 @@ pub enum MouseButton {
     Unknown,
 }
 
-impl MouseButton {
+/// Adds convenience methods to `MouseButton` and `Option<MouseButton>`.
+pub trait MouseButtonExt {
     /// Returns `true` if this is the left mouse button.
+    fn is_left(self) -> bool;
+
+    /// Returns `true` if this is the right mouse button.
+    fn is_right(self) -> bool;
+}
+
+impl MouseButtonExt for MouseButton {
     #[inline(always)]
-    pub fn is_left(self) -> bool {
+    fn is_left(self) -> bool {
         self == MouseButton::Left
     }
 
-    /// Returns `true` if this is the right mouse button.
     #[inline(always)]
-    pub fn is_right(self) -> bool {
+    fn is_right(self) -> bool {
         self == MouseButton::Right
     }
 }
 
+impl MouseButtonExt for Option<MouseButton> {
+    #[inline(always)]
+    fn is_left(self) -> bool {
+        match self {
+            Some(MouseButton::Left) => true,
+            _ => false,
+        }
+    }
+
+    #[inline(always)]
+    fn is_right(self) -> bool {
+        match self {
+            Some(MouseButton::Right) => true,
+            _ => false,
+        }
+    }
+}
+
 //NOTE: this currently only contains cursors that are included by default on
 //both Windows and macOS. We may want to provide polyfills for various additional cursors,
 //and we will also want to add some mechanism for adding custom cursors.

druid-shell/src/platform/gtk/window.rs

@@ -713,28 +713,26 @@ fn make_gdk_cursor(cursor: &Cursor, gdk_window: &gdk::Window) -> Option<gdk::Cur
     )
 }
 
-fn get_mouse_button(button: u32) -> MouseButton {
+fn get_mouse_button(button: u32) -> Option<MouseButton> {
     match button {
-        1 => MouseButton::Left,
-        2 => MouseButton::Middle,
-        3 => MouseButton::Right,
-        4 => MouseButton::X1,
-        5 => MouseButton::X2,
-        _ => MouseButton::Unknown,
+        0 => None,
+        1 => Some(MouseButton::Left),
+        2 => Some(MouseButton::Middle),
+        3 => Some(MouseButton::Right),
+        4 => Some(MouseButton::X1),
+        5 => Some(MouseButton::X2),
+        _ => Some(MouseButton::Unknown),
     }
 }
 
-fn get_mouse_button_from_modifiers(modifiers: gdk::ModifierType) -> MouseButton {
+fn get_mouse_button_from_modifiers(modifiers: gdk::ModifierType) -> Option<MouseButton> {
     match modifiers {
-        modifiers if modifiers.contains(ModifierType::BUTTON1_MASK) => MouseButton::Left,
-        modifiers if modifiers.contains(ModifierType::BUTTON2_MASK) => MouseButton::Middle,
-        modifiers if modifiers.contains(ModifierType::BUTTON3_MASK) => MouseButton::Right,
-        modifiers if modifiers.contains(ModifierType::BUTTON4_MASK) => MouseButton::X1,
-        modifiers if modifiers.contains(ModifierType::BUTTON5_MASK) => MouseButton::X2,
-        _ => {
-            //FIXME: what about when no modifiers match?
-            MouseButton::Unknown
-        }
+        modifiers if modifiers.contains(ModifierType::BUTTON1_MASK) => Some(MouseButton::Left),
+        modifiers if modifiers.contains(ModifierType::BUTTON2_MASK) => Some(MouseButton::Middle),
+        modifiers if modifiers.contains(ModifierType::BUTTON3_MASK) => Some(MouseButton::Right),
+        modifiers if modifiers.contains(ModifierType::BUTTON4_MASK) => Some(MouseButton::X1),
+        modifiers if modifiers.contains(ModifierType::BUTTON5_MASK) => Some(MouseButton::X2),
+        _ => None,
     }
 }
 

druid-shell/src/platform/mac/window.rs

@@ -361,7 +361,7 @@ extern "C" fn set_frame_size(this: &mut Object, _: Sel, size: NSSize) {
 // otherwise we get it from the event itself.
 fn mouse_event(nsevent: id, view: id, button: Option<MouseButton>) -> MouseEvent {
     unsafe {
-        let button = button.unwrap_or_else(|| {
+        let button = button.or_else(|| {
             let button = NSEvent::pressedMouseButtons(nsevent);
             get_mouse_button(button as usize)
         });
@@ -380,19 +380,16 @@ fn mouse_event(nsevent: id, view: id, button: Option<MouseButton>) -> MouseEvent
     }
 }
 
-fn get_mouse_button(mask: usize) -> MouseButton {
+fn get_mouse_button(mask: usize) -> Option<MouseButton> {
     //TODO: this doesn't correctly handle multiple buttons being pressed.
     match mask {
-        mask if mask & 1 > 0 => MouseButton::Left,
-        mask if mask & 1 << 1 > 0 => MouseButton::Right,
-        mask if mask & 1 << 2 > 0 => MouseButton::Middle,
-        mask if mask & 1 << 3 > 0 => MouseButton::X1,
-        mask if mask & 1 << 4 > 0 => MouseButton::X2,
-        _ => {
-            //FIXME: this gets called when the mouse moves, where there
-            //may be no buttons down. This is mostly a problem with our API?
-            MouseButton::Unknown
-        }
+        mask if mask == 0 => None,
+        mask if mask & 1 > 0 => Some(MouseButton::Left),
+        mask if mask & 1 << 1 > 0 => Some(MouseButton::Right),
+        mask if mask & 1 << 2 > 0 => Some(MouseButton::Middle),
+        mask if mask & 1 << 3 > 0 => Some(MouseButton::X1),
+        mask if mask & 1 << 4 > 0 => Some(MouseButton::X2),
+        _ => Some(MouseButton::Unknown),
     }
 }
 

druid-shell/src/platform/windows/window.rs

@@ -633,14 +633,13 @@ impl WndProc for MyWndProc {
                     let pos = Point::new(px as f64, py as f64);
                     let mods = get_mod_state();
                     let button = match wparam {
-                        w if (w & 1) > 0 => MouseButton::Left,
-                        w if (w & 1 << 1) > 0 => MouseButton::Right,
-                        w if (w & 1 << 5) > 0 => MouseButton::Middle,
-                        w if (w & 1 << 6) > 0 => MouseButton::X1,
-                        w if (w & 1 << 7) > 0 => MouseButton::X2,
-                        //FIXME: I guess we probably do want `MouseButton::None`?
-                        //this feels bad, but also this gets discarded in druid anyway.
-                        _ => MouseButton::Unknown,
+                        w if w == 0 => None,
+                        w if (w & 1) > 0 => Some(MouseButton::Left),
+                        w if (w & 1 << 1) > 0 => Some(MouseButton::Right),
+                        w if (w & 1 << 5) > 0 => Some(MouseButton::Middle),
+                        w if (w & 1 << 6) > 0 => Some(MouseButton::X1),
+                        w if (w & 1 << 7) > 0 => Some(MouseButton::X2),
+                        _ => Some(MouseButton::Unknown),
                     };
                     let event = MouseEvent {
                         pos,
@@ -680,10 +679,7 @@ impl WndProc for MyWndProc {
                             match HIWORD(wparam as u32) {
                                 1 => MouseButton::X1,
                                 2 => MouseButton::X2,
-                                _ => {
-                                    warn!("unexpected X button event");
-                                    return None;
-                                }
+                                _ => MouseButton::Unknown,
                             }
                         }
                         _ => unreachable!(),
@@ -703,8 +699,8 @@ impl WndProc for MyWndProc {
                     let event = MouseEvent {
                         pos,
                         mods,
-                        button,
                         count,
+                        button: Some(button),
                     };
                     if count > 0 {
                         s.enter_mouse_capture(hwnd, button);

druid-shell/src/platform/x11/application.rs

@@ -112,7 +112,7 @@ impl Application {
                                 meta: false,
                             },
                             count: 0,
-                            button: MouseButton::Left,
+                            button: Some(MouseButton::Left),
                         };
                         WINDOW_MAP.with(|map| {
                             let mut windows = map.borrow_mut();
@@ -137,7 +137,7 @@ impl Application {
                                 meta: false,
                             },
                             count: 0,
-                            button: MouseButton::Left,
+                            button: Some(MouseButton::Left),
                         };
                         WINDOW_MAP.with(|map| {
                             let mut windows = map.borrow_mut();
@@ -161,7 +161,7 @@ impl Application {
                                 meta: false,
                             },
                             count: 0,
-                            button: MouseButton::Left,
+                            button: Some(MouseButton::Left),
                         };
                         WINDOW_MAP.with(|map| {
                             let mut windows = map.borrow_mut();

druid/examples/game_of_life.rs

@@ -249,7 +249,7 @@ impl Widget<AppData> for GameOfLifeWidget {
                 }
             }
             Event::MouseDown(e) => {
-                if e.button == MouseButton::Left {
+                if e.button == Some(MouseButton::Left) {
                     data.drawing = true;
                     let grid_pos_opt = self.grid_pos(e.pos);
                     grid_pos_opt
@@ -258,7 +258,7 @@ impl Widget<AppData> for GameOfLifeWidget {
                 }
             }
             Event::MouseUp(e) => {
-                if e.button == MouseButton::Left {
+                if e.button == Some(MouseButton::Left) {
                     data.drawing = false;
                 }
             }

druid/examples/multiwin.rs

@@ -17,8 +17,8 @@
 use druid::widget::{Align, 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,
+    Event, EventCtx, LocalizedString, MenuDesc, MenuItem, MouseButtonExt, Selector, Target, Widget,
+    WindowDesc, WindowId,
 };
 
 use log::info;

druid/src/lib.rs

@@ -139,8 +139,8 @@ pub use piet::{Color, LinearGradient, RadialGradient, RenderContext, UnitPoint};
 // these are the types from shell that we expose; others we only use internally.
 pub use shell::{
     Application, Clipboard, ClipboardFormat, Cursor, Error as PlatformError, FileDialogOptions,
-    FileInfo, FileSpec, FormatId, HotKey, KeyCode, KeyEvent, KeyModifiers, MouseButton, RawMods,
-    SysMods, Text, TimerToken, WindowHandle,
+    FileInfo, FileSpec, FormatId, HotKey, KeyCode, KeyEvent, KeyModifiers, MouseButton,
+    MouseButtonExt, RawMods, SysMods, Text, TimerToken, WindowHandle,
 };
 
 pub use crate::core::WidgetPod;

druid/src/mouse.rs

@@ -34,7 +34,7 @@ pub struct MouseEvent {
     pub count: u32,
     /// The currently pressed button in the case of a move or click event,
     /// or the released button in the case of a mouse-up event.
-    pub button: MouseButton,
+    pub button: Option<MouseButton>,
 }
 
 impl From<druid_shell::MouseEvent> for MouseEvent {

druid/src/tests/mod.rs

@@ -54,7 +54,7 @@ fn propogate_hot() {
             window_pos: pos,
             mods: KeyModifiers::default(),
             count: 0,
-            button: MouseButton::Left,
+            button: Some(MouseButton::Left),
         }
     }
     Harness::create((), widget, |harness| {

druid/src/widget/split.rs

@@ -18,7 +18,7 @@ use crate::kurbo::{Line, Point, Rect, Size};
 use crate::widget::flex::Axis;
 use crate::{
     theme, BoxConstraints, Color, Cursor, Data, Env, Event, EventCtx, LayoutCtx, LifeCycle,
-    LifeCycleCtx, PaintCtx, RenderContext, UpdateCtx, Widget, WidgetPod,
+    LifeCycleCtx, MouseButtonExt, PaintCtx, RenderContext, UpdateCtx, Widget, WidgetPod,
 };
 
 /// A container containing two other widgets, splitting the area either horizontally or vertically.