From f8fc12250edc216e43e6668cf48073227fea3be9 Mon Sep 17 00:00:00 2001
From: Doublonmousse <115779707+Doublonmousse@users.noreply.github.com>
Date: Tue, 12 Nov 2024 20:07:02 +0100
Subject: [PATCH] mapping between gtk timestamp and instant

---
 crates/rnote-ui/src/canvas/input.rs |  6 +--
 crates/rnote-ui/src/canvas/mod.rs   | 60 ++++++++++++++++++++++++++++-
 2 files changed, 60 insertions(+), 6 deletions(-)

diff --git a/crates/rnote-ui/src/canvas/input.rs b/crates/rnote-ui/src/canvas/input.rs
index 8775ec852b..85a90e9f0b 100644
--- a/crates/rnote-ui/src/canvas/input.rs
+++ b/crates/rnote-ui/src/canvas/input.rs
@@ -18,7 +18,7 @@ pub(crate) fn handle_pointer_controller_event(
     event: &gdk::Event,
     mut pen_state: PenState,
 ) -> (glib::Propagation, PenState) {
-    let now = Instant::now();
+    let now = canvas.get_time(event.time());
     let mut widget_flags = WidgetFlags::default();
     let touch_drawing = canvas.touch_drawing();
     let gdk_event_type = event.event_type();
@@ -370,9 +370,7 @@ fn retrieve_pointer_elements(
             }
 
             let entry_delta = Duration::from_millis(event_time.saturating_sub(entry.time()) as u64);
-            let Some(entry_time) = now.checked_sub(entry_delta) else {
-                continue;
-            };
+            let entry_time = canvas.get_time(event_time);
 
             if let BacklogPolicy::Limit(delta_limit) = backlog_policy {
                 // We go back in time, so `entry_delta` will increase
diff --git a/crates/rnote-ui/src/canvas/mod.rs b/crates/rnote-ui/src/canvas/mod.rs
index 11bee39b2b..f00243fb54 100644
--- a/crates/rnote-ui/src/canvas/mod.rs
+++ b/crates/rnote-ui/src/canvas/mod.rs
@@ -28,9 +28,9 @@ use rnote_engine::ext::GraphenePointExt;
 use rnote_engine::ext::GrapheneRectExt;
 use rnote_engine::Camera;
 use rnote_engine::{Engine, WidgetFlags};
-use std::cell::{Cell, Ref, RefCell, RefMut};
+use std::cell::{Cell, OnceCell, Ref, RefCell, RefMut};
 use std::path::Path;
-use std::time::Duration;
+use std::time::{Duration, Instant};
 use tracing::{debug, error, warn};
 
 #[derive(Debug, Default)]
@@ -53,6 +53,8 @@ struct Connections {
 }
 
 mod imp {
+    use std::time::Instant;
+
     use super::*;
 
     #[derive(Debug)]
@@ -87,6 +89,11 @@ mod imp {
         pub(crate) show_drawing_cursor: Cell<bool>,
 
         pub(crate) last_export_dir: RefCell<Option<gio::File>>,
+
+        // mapping from gtk timestamp to instant
+        pub mapping_time: OnceCell<Instant>,
+        pub last_gtk_time: RefCell<u32>,
+        pub overflow_duration: RefCell<Duration>,
     }
 
     impl Default for RnCanvas {
@@ -181,6 +188,10 @@ mod imp {
                 show_drawing_cursor: Cell::new(false),
 
                 last_export_dir: RefCell::new(None),
+
+                mapping_time: OnceCell::new(),
+                last_gtk_time: RefCell::new(0),
+                overflow_duration: RefCell::new(Duration::default()),
             }
         }
     }
@@ -1479,4 +1490,49 @@ impl RnCanvas {
             na::point![f64::from(self.width()), f64::from(self.height())],
         )
     }
+
+    pub(crate) fn get_time(&self, time_gtk: u32) -> Instant {
+        // this is built so that we get the time by the mapping_time +
+        // time_gtk*1e-3 seconds
+        // time_gtk cannot be 0, 0 is the absence of timestamp
+        if self.imp().mapping_time.get().is_none() {
+            let _ = self.imp().mapping_time.set(
+                Instant::now()
+                    .checked_sub(Duration::from_millis(time_gtk as u64))
+                    .unwrap_or(Instant::now()),
+            );
+            self.imp().last_gtk_time.replace(time_gtk);
+            return Instant::now();
+        } else {
+            let overflow = time_gtk
+                .checked_sub(*self.imp().last_gtk_time.borrow())
+                .is_none()
+                && (time_gtk != 0);
+            if overflow {
+                let _ = self.imp().overflow_duration.replace_with(|&mut old| {
+                    old.checked_add(Duration::from_millis(u32::MAX as u64))
+                        .unwrap()
+                });
+            }
+            let time_out = self
+                .imp()
+                .mapping_time
+                .get()
+                .unwrap()
+                .checked_add(
+                    self.imp()
+                        .overflow_duration
+                        .borrow()
+                        .checked_add(Duration::from_millis(if time_gtk == 0 {
+                            *self.imp().last_gtk_time.borrow()
+                        } else {
+                            time_gtk
+                        } as u64))
+                        .unwrap(),
+                )
+                .unwrap();
+            self.imp().last_gtk_time.replace(time_gtk);
+            return time_out;
+        }
+    }
 }