Workspace back and forth (#253)

* implement workspace back and forth

* Make our own ID counter instead of SerialCounter, use a newtype

* Rename FocusWorkspaceBackAndForth to FocusWorkspacePrevious

* Add focus-workspace-previous to tests

* Don't special case in switch_workspace_previous

* Minor clean up

* Add switch_workspace_auto_back_and_forth to tests

* Skip animation on switch_workspace_previous

* Preserve previous_workspace_id on workspace movement

* Make Workspace::id private with a getter

Reduce the chance it gets overwritten.

* Add test for workspace ID uniqueness

* Update previous workspace ID upon moving workspace across monitors

---------

Co-authored-by: Ivan Molodetskikh <yalterz@gmail.com>

src/layout/workspace.rs

@@ -18,6 +18,7 @@ use crate::animation::Animation;
 use crate::niri_render_elements;
 use crate::render_helpers::renderer::NiriRenderer;
 use crate::swipe_tracker::SwipeTracker;
+use crate::utils::id::IdCounter;
 use crate::utils::output_size;
 
 /// Amount of touchpad movement to scroll the view for the width of one working area.
@@ -76,11 +77,25 @@ pub struct Workspace<W: LayoutElement> {
 
     /// Configurable properties of the layout.
     pub options: Rc<Options>,
+
+    /// Unique ID of this workspace.
+    id: WorkspaceId,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct OutputId(String);
 
+static WORKSPACE_ID_COUNTER: IdCounter = IdCounter::new();
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct WorkspaceId(u32);
+
+impl WorkspaceId {
+    fn next() -> WorkspaceId {
+        WorkspaceId(WORKSPACE_ID_COUNTER.next())
+    }
+}
+
 niri_render_elements! {
     WorkspaceRenderElement<R> => {
         Tile = TileRenderElement<R>,
@@ -225,6 +240,7 @@ impl<W: LayoutElement> Workspace<W> {
             view_offset_adj: None,
             activate_prev_column_on_removal: None,
             options,
+            id: WorkspaceId::next(),
         }
     }
 
@@ -240,9 +256,14 @@ impl<W: LayoutElement> Workspace<W> {
             view_offset_adj: None,
             activate_prev_column_on_removal: None,
             options,
+            id: WorkspaceId::next(),
         }
     }
 
+    pub fn id(&self) -> WorkspaceId {
+        self.id
+    }
+
     pub fn advance_animations(&mut self, current_time: Duration, is_active: bool) {
         if let Some(ViewOffsetAdjustment::Animation(anim)) = &mut self.view_offset_adj {
             anim.set_current_time(current_time);