Add UIGestureRecognizerDelegate and PanGestureRecogniser (#3597)

- Allow all gestures simultaneously recognized.
- Add PanGestureRecogniser with min/max number of touches.
- Fix sending delta values relative to Update instead to match macOS.
- Fix rotation gesture units from iOS to be in degrees instead of radians.

Co-authored-by: Mads Marquart <mads@marquart.dk>

examples/window.rs

@@ -159,6 +159,7 @@ impl Application {
             window.recognize_doubletap_gesture(true);
             window.recognize_pinch_gesture(true);
             window.recognize_rotation_gesture(true);
+            window.recognize_pan_gesture(true, 2, 2);
         }
 
         let window_state = WindowState::new(self, window)?;
@@ -428,6 +429,11 @@ impl ApplicationHandler<UserEvent> for Application {
                     info!("Rotated clockwise {delta:.5} (now: {rotated:.5})");
                 }
             },
+            WindowEvent::PanGesture { delta, phase, .. } => {
+                window.panned.x += delta.x;
+                window.panned.y += delta.y;
+                info!("Panned ({delta:?})) (now: {:?}), {phase:?}", window.panned);
+            },
             WindowEvent::DoubleTapGesture { .. } => {
                 info!("Smart zoom");
             },
@@ -502,6 +508,8 @@ struct WindowState {
     zoom: f64,
     /// The amount of rotation of the window.
     rotated: f32,
+    /// The amount of pan of the window.
+    panned: PhysicalPosition<f32>,
 
     #[cfg(macos_platform)]
     option_as_alt: OptionAsAlt,
@@ -547,6 +555,7 @@ impl WindowState {
             modifiers: Default::default(),
             occluded: Default::default(),
             rotated: Default::default(),
+            panned: Default::default(),
             zoom: Default::default(),
         };
 

src/changelog/unreleased.md

@@ -59,7 +59,8 @@ changelog entry.
 - Add `CustomCursor` which could be set via `Window::set_cursor`, implemented on
   Windows, macOS, X11, Wayland, and Web.
 - On Web, add to toggle calling `Event.preventDefault()` on `Window`.
-- On iOS, add `PinchGesture`, `DoubleTapGesture`, and `RotationGesture`
+- On iOS, add `PinchGesture`, `DoubleTapGesture`, `PanGesture` and `RotationGesture`.
+- on iOS, use `UIGestureRecognizerDelegate` for fine grained control of gesture recognizers.
 - On macOS, add services menu.
 - On Windows, add `with_title_text_color`, and `with_corner_preference` on
   `WindowAttributesExtWindows`.

src/event.rs

@@ -293,6 +293,19 @@ pub enum WindowEvent {
         phase: TouchPhase,
     },
 
+    /// N-finger pan gesture
+    ///
+    /// ## Platform-specific
+    ///
+    /// - Only available on **iOS**.
+    /// - On iOS, not recognized by default. It must be enabled when needed.
+    PanGesture {
+        device_id: DeviceId,
+        /// Change in pixels of pan gesture from last update.
+        delta: PhysicalPosition<f32>,
+        phase: TouchPhase,
+    },
+
     /// Double tap gesture.
     ///
     /// On a Mac, smart magnification is triggered by a double tap with two fingers
@@ -322,7 +335,12 @@ pub enum WindowEvent {
     ///
     /// - Only available on **macOS** and **iOS**.
     /// - On iOS, not recognized by default. It must be enabled when needed.
-    RotationGesture { device_id: DeviceId, delta: f32, phase: TouchPhase },
+    RotationGesture {
+        device_id: DeviceId,
+        /// change in rotation in degrees
+        delta: f32,
+        phase: TouchPhase,
+    },
 
     /// Touchpad pressure event.
     ///
@@ -993,6 +1011,7 @@ impl PartialEq for InnerSizeWriter {
 
 #[cfg(test)]
 mod tests {
+    use crate::dpi::PhysicalPosition;
     use crate::event;
     use std::collections::{BTreeSet, HashSet};
 
@@ -1055,6 +1074,11 @@ mod tests {
                     delta: 0.0,
                     phase: event::TouchPhase::Started,
                 });
+                with_window_event(PanGesture {
+                    device_id: did,
+                    delta: PhysicalPosition::<f32>::new(0.0, 0.0),
+                    phase: event::TouchPhase::Started,
+                });
                 with_window_event(TouchpadPressure { device_id: did, pressure: 0.0, stage: 0 });
                 with_window_event(AxisMotion { device_id: did, axis: 0, value: 0.0 });
                 with_window_event(Touch(event::Touch {

src/platform/ios.rs

@@ -155,6 +155,21 @@ pub trait WindowExtIOS {
     /// The default is to not recognize gestures.
     fn recognize_pinch_gesture(&self, should_recognize: bool);
 
+    /// Sets whether the [`Window`] should recognize pan gestures.
+    ///
+    /// The default is to not recognize gestures.
+    /// Installs [`UIPanGestureRecognizer`](https://developer.apple.com/documentation/uikit/uipangesturerecognizer) onto view
+    ///
+    /// Set the minimum number of touches required: [`minimumNumberOfTouches`](https://developer.apple.com/documentation/uikit/uipangesturerecognizer/1621208-minimumnumberoftouches)
+    ///
+    /// Set the maximum number of touches recognized: [`maximumNumberOfTouches`](https://developer.apple.com/documentation/uikit/uipangesturerecognizer/1621208-maximumnumberoftouches)
+    fn recognize_pan_gesture(
+        &self,
+        should_recognize: bool,
+        minimum_number_of_touches: u8,
+        maximum_number_of_touches: u8,
+    );
+
     /// Sets whether the [`Window`] should recognize double tap gestures.
     ///
     /// The default is to not recognize gestures.
@@ -204,6 +219,22 @@ impl WindowExtIOS for Window {
         self.window.maybe_queue_on_main(move |w| w.recognize_pinch_gesture(should_recognize));
     }
 
+    #[inline]
+    fn recognize_pan_gesture(
+        &self,
+        should_recognize: bool,
+        minimum_number_of_touches: u8,
+        maximum_number_of_touches: u8,
+    ) {
+        self.window.maybe_queue_on_main(move |w| {
+            w.recognize_pan_gesture(
+                should_recognize,
+                minimum_number_of_touches,
+                maximum_number_of_touches,
+            )
+        });
+    }
+
     #[inline]
     fn recognize_doubletap_gesture(&self, should_recognize: bool) {
         self.window.maybe_queue_on_main(move |w| w.recognize_doubletap_gesture(should_recognize));

src/platform_impl/ios/uikit/gesture_recognizer.rs

@@ -1,9 +1,13 @@
 use objc2::encode::{Encode, Encoding};
-use objc2::{extern_class, extern_methods, mutability, ClassType};
-use objc2_foundation::{CGFloat, NSInteger, NSObject, NSUInteger};
+use objc2::rc::Id;
+use objc2::runtime::ProtocolObject;
+use objc2::{extern_class, extern_methods, extern_protocol, mutability, ClassType, ProtocolType};
+use objc2_foundation::{CGFloat, CGPoint, NSInteger, NSObject, NSObjectProtocol, NSUInteger};
+
+use super::UIView;
 
-// https://developer.apple.com/documentation/uikit/uigesturerecognizer
 extern_class!(
+    /// [`UIGestureRecognizer`](https://developer.apple.com/documentation/uikit/uigesturerecognizer)
     #[derive(Debug, PartialEq, Eq, Hash)]
     pub(crate) struct UIGestureRecognizer;
 
@@ -17,14 +21,22 @@ extern_methods!(
     unsafe impl UIGestureRecognizer {
         #[method(state)]
         pub fn state(&self) -> UIGestureRecognizerState;
+
+        /// [`delegate`](https://developer.apple.com/documentation/uikit/uigesturerecognizer/1624207-delegate?language=objc)
+        /// @property(nullable, nonatomic, weak) id<UIGestureRecognizerDelegate> delegate;
+        #[method(setDelegate:)]
+        pub fn setDelegate(&self, delegate: &ProtocolObject<dyn UIGestureRecognizerDelegate>);
+
+        #[method_id(delegate)]
+        pub fn delegate(&self) -> Id<ProtocolObject<dyn UIGestureRecognizerDelegate>>;
     }
 );
 
 unsafe impl Encode for UIGestureRecognizer {
     const ENCODING: Encoding = Encoding::Object;
 }
 
-// https://developer.apple.com/documentation/uikit/uigesturerecognizer/state
+// [`UIGestureRecognizerState`](https://developer.apple.com/documentation/uikit/uigesturerecognizer/state)
 #[repr(transparent)]
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub struct UIGestureRecognizerState(NSInteger);
@@ -43,7 +55,7 @@ impl UIGestureRecognizerState {
     pub const Failed: Self = Self(5);
 }
 
-// https://developer.apple.com/documentation/uikit/uipinchgesturerecognizer
+// [`UIPinchGestureRecognizer`](https://developer.apple.com/documentation/uikit/uipinchgesturerecognizer)
 extern_class!(
     #[derive(Debug, PartialEq, Eq, Hash)]
     pub(crate) struct UIPinchGestureRecognizer;
@@ -68,8 +80,8 @@ unsafe impl Encode for UIPinchGestureRecognizer {
     const ENCODING: Encoding = Encoding::Object;
 }
 
-// https://developer.apple.com/documentation/uikit/uirotationgesturerecognizer
 extern_class!(
+    /// [`UIRotationGestureRecognizer`](https://developer.apple.com/documentation/uikit/uirotationgesturerecognizer)
     #[derive(Debug, PartialEq, Eq, Hash)]
     pub(crate) struct UIRotationGestureRecognizer;
 
@@ -93,8 +105,8 @@ unsafe impl Encode for UIRotationGestureRecognizer {
     const ENCODING: Encoding = Encoding::Object;
 }
 
-// https://developer.apple.com/documentation/uikit/uitapgesturerecognizer
 extern_class!(
+    /// [`UITapGestureRecognizer`](https://developer.apple.com/documentation/uikit/uitapgesturerecognizer)
     #[derive(Debug, PartialEq, Eq, Hash)]
     pub(crate) struct UITapGestureRecognizer;
 
@@ -117,3 +129,48 @@ extern_methods!(
 unsafe impl Encode for UITapGestureRecognizer {
     const ENCODING: Encoding = Encoding::Object;
 }
+
+extern_class!(
+    /// [`UIPanGestureRecognizer`](https://developer.apple.com/documentation/uikit/uipangesturerecognizer)
+    #[derive(Debug, PartialEq, Eq, Hash)]
+    pub(crate) struct UIPanGestureRecognizer;
+
+    unsafe impl ClassType for UIPanGestureRecognizer {
+        type Super = UIGestureRecognizer;
+        type Mutability = mutability::InteriorMutable;
+    }
+);
+
+extern_methods!(
+    unsafe impl UIPanGestureRecognizer {
+        #[method(translationInView:)]
+        pub fn translationInView(&self, view: &UIView) -> CGPoint;
+
+        #[method(setTranslation:inView:)]
+        pub fn setTranslationInView(&self, translation: CGPoint, view: &UIView);
+
+        #[method(velocityInView:)]
+        pub fn velocityInView(&self, view: &UIView) -> CGPoint;
+
+        #[method(setMinimumNumberOfTouches:)]
+        pub fn setMinimumNumberOfTouches(&self, minimum_number_of_touches: NSUInteger);
+
+        #[method(minimumNumberOfTouches)]
+        pub fn minimumNumberOfTouches(&self) -> NSUInteger;
+
+        #[method(setMaximumNumberOfTouches:)]
+        pub fn setMaximumNumberOfTouches(&self, maximum_number_of_touches: NSUInteger);
+
+        #[method(maximumNumberOfTouches)]
+        pub fn maximumNumberOfTouches(&self) -> NSUInteger;
+    }
+);
+
+extern_protocol!(
+    /// (@protocol UIGestureRecognizerDelegate)[https://developer.apple.com/documentation/uikit/uigesturerecognizerdelegate?language=objc]
+    pub(crate) unsafe trait UIGestureRecognizerDelegate: NSObjectProtocol {}
+
+    unsafe impl ProtocolType for dyn UIGestureRecognizerDelegate {
+        const NAME: &'static str = "UIGestureRecognizerDelegate";
+    }
+);

src/platform_impl/ios/uikit/mod.rs

@@ -27,8 +27,9 @@ pub(crate) use self::device::{UIDevice, UIUserInterfaceIdiom};
 pub(crate) use self::event::UIEvent;
 pub(crate) use self::geometry::UIRectEdge;
 pub(crate) use self::gesture_recognizer::{
-    UIGestureRecognizer, UIGestureRecognizerState, UIPinchGestureRecognizer,
-    UIRotationGestureRecognizer, UITapGestureRecognizer,
+    UIGestureRecognizer, UIGestureRecognizerDelegate, UIGestureRecognizerState,
+    UIPanGestureRecognizer, UIPinchGestureRecognizer, UIRotationGestureRecognizer,
+    UITapGestureRecognizer,
 };
 pub(crate) use self::responder::UIResponder;
 pub(crate) use self::screen::{UIScreen, UIScreenOverscanCompensation};