Add touch pressure information for touch events on iOS (#1090)

* Add touch pressure information for touch events on iOS

* Add a variant for calibrated touch pressure

src/platform_impl/android/mod.rs

@@ -75,6 +75,7 @@ impl EventLoop {
                                 android_glue::MotionAction::Cancel => TouchPhase::Cancelled,
                             },
                             location,
+                            force: None, // TODO
                             id: motion.pointer_id as u64,
                             device_id: DEVICE_ID,
                         }),

src/platform_impl/emscripten/mod.rs

@@ -362,6 +362,7 @@ extern "C" fn touch_callback(
                         phase,
                         id: touch.identifier as u64,
                         location,
+                        force: None, // TODO
                     }),
                 });
             }

src/platform_impl/ios/ffi.rs

@@ -70,6 +70,24 @@ pub enum UITouchPhase {
     Cancelled,
 }
 
+#[derive(Debug, PartialEq)]
+#[allow(dead_code)]
+#[repr(isize)]
+pub enum UIForceTouchCapability {
+    Unknown = 0,
+    Unavailable,
+    Available,
+}
+
+#[derive(Debug, PartialEq)]
+#[allow(dead_code)]
+#[repr(isize)]
+pub enum UITouchType {
+    Direct = 0,
+    Indirect,
+    Pencil,
+}
+
 #[repr(C)]
 #[derive(Debug, Clone)]
 pub struct UIEdgeInsets {

src/platform_impl/ios/view.rs

@@ -6,13 +6,14 @@ use objc::{
 };
 
 use crate::{
-    event::{DeviceId as RootDeviceId, Event, Touch, TouchPhase, WindowEvent},
+    event::{DeviceId as RootDeviceId, Event, Force, Touch, TouchPhase, WindowEvent},
     platform::ios::MonitorHandleExtIOS,
     platform_impl::platform::{
         app_state::AppState,
         event_loop,
         ffi::{
-            id, nil, CGFloat, CGPoint, CGRect, UIInterfaceOrientationMask, UIRectEdge, UITouchPhase,
+            id, nil, CGFloat, CGPoint, CGRect, UIForceTouchCapability, UIInterfaceOrientationMask,
+            UIRectEdge, UITouchPhase, UITouchType,
         },
         window::PlatformSpecificWindowBuilderAttributes,
         DeviceId,
@@ -218,6 +219,27 @@ unsafe fn get_window_class() -> &'static Class {
                         break;
                     }
                     let location: CGPoint = msg_send![touch, locationInView: nil];
+                    let touch_type: UITouchType = msg_send![touch, type];
+                    let trait_collection: id = msg_send![object, traitCollection];
+                    let touch_capability: UIForceTouchCapability =
+                        msg_send![trait_collection, forceTouchCapability];
+                    let force = if touch_capability == UIForceTouchCapability::Available {
+                        let force: CGFloat = msg_send![touch, force];
+                        let max_possible_force: CGFloat = msg_send![touch, maximumPossibleForce];
+                        let altitude_angle: Option<f64> = if touch_type == UITouchType::Pencil {
+                            let angle: CGFloat = msg_send![touch, altitudeAngle];
+                            Some(angle as _)
+                        } else {
+                            None
+                        };
+                        Some(Force::Calibrated {
+                            force: force as _,
+                            max_possible_force: max_possible_force as _,
+                            altitude_angle,
+                        })
+                    } else {
+                        None
+                    };
                     let touch_id = touch as u64;
                     let phase: UITouchPhase = msg_send![touch, phase];
                     let phase = match phase {
@@ -235,6 +257,7 @@ unsafe fn get_window_class() -> &'static Class {
                             device_id: RootDeviceId(DeviceId { uiscreen }),
                             id: touch_id,
                             location: (location.x as f64, location.y as f64).into(),
+                            force,
                             phase,
                         }),
                     });

src/platform_impl/linux/wayland/touch.rs

@@ -39,6 +39,7 @@ pub(crate) fn implement_touch<T: 'static>(
                                     ),
                                     phase: TouchPhase::Started,
                                     location: (x, y).into(),
+                                    force: None, // TODO
                                     id: id as u64,
                                 }),
                                 wid,
@@ -61,6 +62,7 @@ pub(crate) fn implement_touch<T: 'static>(
                                     ),
                                     phase: TouchPhase::Ended,
                                     location: pt.location.into(),
+                                    force: None, // TODO
                                     id: id as u64,
                                 }),
                                 pt.wid,
@@ -78,6 +80,7 @@ pub(crate) fn implement_touch<T: 'static>(
                                     ),
                                     phase: TouchPhase::Moved,
                                     location: (x, y).into(),
+                                    force: None, // TODO
                                     id: id as u64,
                                 }),
                                 pt.wid,
@@ -94,6 +97,7 @@ pub(crate) fn implement_touch<T: 'static>(
                                     ),
                                     phase: TouchPhase::Cancelled,
                                     location: pt.location.into(),
+                                    force: None, // TODO
                                     id: pt.id as u64,
                                 }),
                                 pt.wid,

src/platform_impl/linux/x11/event_processor.rs

@@ -918,6 +918,7 @@ impl<T: 'static> EventProcessor<T> {
                                     device_id: mkdid(xev.deviceid),
                                     phase,
                                     location,
+                                    force: None, // TODO
                                     id: xev.detail as u64,
                                 }),
                             })

src/platform_impl/windows/event_loop.rs

@@ -1499,6 +1499,7 @@ unsafe extern "system" fn public_window_callback<T>(
                                 continue;
                             },
                             location,
+                            force: None, // TODO
                             id: input.dwID as u64,
                             device_id: DEVICE_ID,
                         }),
@@ -1603,6 +1604,7 @@ unsafe extern "system" fn public_window_callback<T>(
                                 continue;
                             },
                             location,
+                            force: None, // TODO
                             id: pointer_info.pointerId as u64,
                             device_id: DEVICE_ID,
                         }),