From 72d77bc50451d67be67229d0a64c7443a0c297c8 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Tue, 7 Nov 2023 15:33:04 +0100
Subject: [PATCH] Only one Memory window interaction

---
 crates/egui/src/containers/window.rs |  4 +--
 crates/egui/src/context.rs           |  2 +-
 crates/egui/src/memory.rs            | 42 ++++++++++++++++------------
 3 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/crates/egui/src/containers/window.rs b/crates/egui/src/containers/window.rs
index 4eaa3539a..f19736849 100644
--- a/crates/egui/src/containers/window.rs
+++ b/crates/egui/src/containers/window.rs
@@ -640,7 +640,7 @@ fn window_interaction(
         }
     }
 
-    let mut window_interaction = ctx.memory(|mem| mem.window_interaction);
+    let mut window_interaction = ctx.memory(|mem| mem.window_interaction());
 
     if window_interaction.is_none() {
         if let Some(hover_window_interaction) = resize_hover(ctx, possible, area_layer_id, rect) {
@@ -650,7 +650,7 @@ fn window_interaction(
                     mem.interaction.drag_id = Some(id);
                     mem.interaction.drag_is_window = true;
                     window_interaction = Some(hover_window_interaction);
-                    mem.window_interaction = window_interaction;
+                    mem.set_window_interaction(window_interaction);
                 });
             }
         }
diff --git a/crates/egui/src/context.rs b/crates/egui/src/context.rs
index 2fa144cce..65d3068ab 100644
--- a/crates/egui/src/context.rs
+++ b/crates/egui/src/context.rs
@@ -945,7 +945,7 @@ impl Context {
                                     // potential start of a drag
                                     memory.interaction.drag_id = Some(id);
                                     memory.interaction.drag_is_window = false;
-                                    memory.window_interaction = None; // HACK: stop moving windows (if any)
+                                    memory.set_window_interaction(None); // HACK: stop moving windows (if any)
                                     response.is_pointer_button_down_on = true;
                                     response.dragged = true;
                                 }
diff --git a/crates/egui/src/memory.rs b/crates/egui/src/memory.rs
index c0623d872..fcff2d5f7 100644
--- a/crates/egui/src/memory.rs
+++ b/crates/egui/src/memory.rs
@@ -3,8 +3,9 @@
 use epaint::{emath::Rangef, vec2, Vec2};
 
 use crate::{
-    area, window, EventFilter, Id, IdMap, InputState, LayerId, Pos2, Rect, Style, ViewportId,
-    ViewportIdMap,
+    area,
+    window::{self, WindowInteraction},
+    EventFilter, Id, IdMap, InputState, LayerId, Pos2, Rect, Style, ViewportId, ViewportIdMap,
 };
 
 // ----------------------------------------------------------------------------
@@ -87,18 +88,9 @@ pub struct Memory {
     #[cfg_attr(feature = "persistence", serde(skip))]
     pub(crate) viewport_id: ViewportId,
 
-    #[cfg_attr(feature = "persistence", serde(skip))]
-    pub(crate) window_interaction: Option<window::WindowInteraction>,
-
-    #[cfg_attr(feature = "persistence", serde(skip))]
-    pub(crate) window_interactions: ViewportIdMap<window::WindowInteraction>,
-
     #[cfg_attr(feature = "persistence", serde(skip))]
     pub(crate) drag_value: crate::widgets::drag_value::MonoState,
 
-    #[cfg_attr(feature = "persistence", serde(skip))]
-    areas: ViewportIdMap<Areas>,
-
     /// Which popup-window is open (if any)?
     /// Could be a combo box, color picker, menu etc.
     #[cfg_attr(feature = "persistence", serde(skip))]
@@ -106,6 +98,15 @@ pub struct Memory {
 
     #[cfg_attr(feature = "persistence", serde(skip))]
     everything_is_visible: bool,
+
+    // -------------------------------------------------
+
+    // Per-viewport:
+    #[cfg_attr(feature = "persistence", serde(skip))]
+    areas: ViewportIdMap<Areas>,
+
+    #[cfg_attr(feature = "persistence", serde(skip))]
+    window_interactions: ViewportIdMap<window::WindowInteraction>,
 }
 
 impl Default for Memory {
@@ -119,7 +120,6 @@ impl Default for Memory {
             interactions: Default::default(),
             interaction: Default::default(),
             viewport_id: Default::default(),
-            window_interaction: Default::default(),
             window_interactions: Default::default(),
             drag_value: Default::default(),
             areas: Default::default(),
@@ -560,15 +560,10 @@ impl Memory {
 
         if !prev_input.pointer.any_down() {
             self.window_interactions.remove(&viewport_id);
-            self.window_interaction = None;
         }
     }
 
     pub(crate) fn pause_frame(&mut self, viewport_id: ViewportId) {
-        if let Some(window_interaction) = self.window_interaction {
-            self.window_interactions
-                .insert(viewport_id, window_interaction);
-        }
         self.interactions
             .insert(viewport_id, std::mem::take(&mut self.interaction));
     }
@@ -594,7 +589,6 @@ impl Memory {
     pub(crate) fn resume_frame(&mut self, viewport_id: ViewportId) {
         self.interaction = self.interactions.remove(&viewport_id).unwrap_or_default();
         self.viewport_id = viewport_id;
-        self.window_interaction = self.window_interactions.remove(&viewport_id);
     }
 
     /// Access memory of the [`Area`](crate::containers::area::Area)s, such as `Window`s.
@@ -748,6 +742,18 @@ impl Memory {
     pub fn area_rect(&self, id: impl Into<Id>) -> Option<Rect> {
         self.areas().get(id.into()).map(|state| state.rect())
     }
+
+    pub(crate) fn window_interaction(&self) -> Option<WindowInteraction> {
+        self.window_interactions.get(&self.viewport_id).copied()
+    }
+
+    pub(crate) fn set_window_interaction(&mut self, wi: Option<WindowInteraction>) {
+        if let Some(wi) = wi {
+            self.window_interactions.insert(self.viewport_id, wi);
+        } else {
+            self.window_interactions.remove(&self.viewport_id);
+        }
+    }
 }
 
 /// ## Popups