masonry: add pressure sensitivity to the pen's touch on the screen (#453

)

device test
* huion kamvas 13 tablet windows 10 platform

masonry/src/event.rs

@@ -10,7 +10,7 @@ use crate::WidgetId;
 
 use std::{collections::HashSet, path::PathBuf};
 
-use winit::event::{Ime, KeyEvent, Modifiers};
+use winit::event::{Force, Ime, KeyEvent, Modifiers};
 use winit::keyboard::ModifiersState;
 
 // TODO - Occluded(bool) event
@@ -95,6 +95,7 @@ pub struct PointerState {
     pub mods: Modifiers,
     pub count: u8,
     pub focus: bool,
+    pub force: Option<Force>,
 }
 
 #[derive(Debug, Clone)]
@@ -351,6 +352,7 @@ impl PointerState {
             mods: Default::default(),
             count: 0,
             focus: false,
+            force: None,
         }
     }
 }

masonry/src/event_loop_runner.rs

@@ -497,12 +497,16 @@ impl MasonryState<'_> {
                     ));
             }
             WinitWindowEvent::Touch(winit::event::Touch {
-                location, phase, ..
+                location,
+                phase,
+                force,
+                ..
             }) => {
                 // FIXME: This is naïve and should be refined for actual use.
                 //        It will also interact with gesture discrimination.
                 self.pointer_state.physical_position = location;
                 self.pointer_state.position = location.to_logical(window.scale_factor());
+                self.pointer_state.force = force;
                 match phase {
                     winit::event::TouchPhase::Started => {
                         self.render_root