Don't spread in multitasking view unless there are stacking windows

src/Widgets/MultitaskingView/MonitorClone.vala

@@ -35,7 +35,7 @@ public class Gala.MonitorClone : ActorTarget {
 
         var windows = new WindowListModel (display, STACKING, true, monitor);
 
-        window_container = new WindowCloneContainer (wm, windows, monitor_scale);
+        window_container = new WindowCloneContainer (wm, windows, monitor, monitor_scale);
         window_container.add_constraint (new Clutter.BindConstraint (this, SIZE, 0.0f));
         window_container.window_selected.connect ((w) => { window_selected (w); });
         bind_property ("monitor-scale", window_container, "monitor-scale");

src/Widgets/MultitaskingView/WindowCloneContainer.vala

@@ -18,6 +18,7 @@ public class Gala.WindowCloneContainer : ActorTarget {
 
     public WindowManager wm { get; construct; }
     public WindowListModel windows { get; construct; }
+    public int monitor { get; construct; }
     public float monitor_scale { get; construct set; }
     public bool overview_mode { get; construct; }
 
@@ -29,8 +30,8 @@ public class Gala.WindowCloneContainer : ActorTarget {
      */
     private unowned WindowClone? current_window = null;
 
-    public WindowCloneContainer (WindowManager wm, WindowListModel windows, float monitor_scale, bool overview_mode = false) {
-        Object (wm: wm, windows: windows, monitor_scale: monitor_scale, overview_mode: overview_mode);
+    public WindowCloneContainer (WindowManager wm, WindowListModel windows, int monitor, float monitor_scale, bool overview_mode = false) {
+        Object (wm: wm, windows: windows, monitor: monitor, monitor_scale: monitor_scale, overview_mode: overview_mode);
     }
 
     construct {
@@ -140,14 +141,7 @@ public class Gala.WindowCloneContainer : ActorTarget {
             return (int) (seq_b - seq_a);
         });
 
-        Mtk.Rectangle area = {
-            padding_left,
-            padding_top,
-            (int) width - padding_left - padding_right,
-            (int) height - padding_top - padding_bottom
-        };
-
-        foreach (var tilable in calculate_grid_placement (area, windows)) {
+        foreach (var tilable in calculate_window_clones_placement (windows)) {
             tilable.clone.take_slot (tilable.rect, !view_toggle);
         }
     }
@@ -322,10 +316,95 @@ public class Gala.WindowCloneContainer : ActorTarget {
         Mtk.Rectangle rect;
     }
 
+    private bool windows_overlap (GLib.List<TilableWindow?> windows) {
+        var checked_rects = new GLib.List<Mtk.Rectangle?> ();
+        foreach (var tilable in windows) {
+            var window_rect = tilable.clone.window.get_frame_rect ();
+            foreach (var checked_rect in checked_rects) {
+                if (window_rect.overlap (checked_rect)) {
+                    return true;
+                }
+            }
+
+            checked_rects.append (window_rect);
+        }
+
+        return false;
+    }
+
+    private bool window_out_of_screen (GLib.List<TilableWindow?> windows) {
+        foreach (var tilable in windows) {
+            unowned var window = tilable.clone.window;
+            var window_rect = window.get_frame_rect ();
+            var monitor_geometry = window.display.get_monitor_geometry (window.get_monitor ());
+            if (window_rect.x < monitor_geometry.x ||
+                window_rect.y < monitor_geometry.y ||
+                window_rect.x + window_rect.width > monitor_geometry.width ||
+                window_rect.y + window_rect.height > monitor_geometry.height
+            ) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private Mtk.Rectangle get_rectangle_with_padding () {
+        return {
+            padding_left,
+            padding_top,
+            (int) width - padding_left - padding_right,
+            (int) height - padding_top - padding_bottom
+        };
+    }
+
+    private GLib.List<TilableWindow?> calculate_window_clones_placement (GLib.List<TilableWindow?> windows) {
+        if (windows_overlap (windows) || window_out_of_screen (windows)) {
+            return calculate_grid_placement (windows);
+        } else {
+            Mtk.Rectangle area;
+            if (overview_mode) {
+                area = { 0, 0, (int) width, (int) height };
+            } else {
+                area = get_rectangle_with_padding ();
+            }
+
+            var monitor_geometry = wm.get_display ().get_monitor_geometry (monitor);
+            var scale = (float) area.width / monitor_geometry.width;
+
+            var result = new GLib.List<TilableWindow?> ();
+            foreach (var tilable in windows) {
+                Mtk.Rectangle rect;
+#if HAS_MUTTER46
+                tilable.rect.scale_double (scale, Mtk.RoundingStrategy.ROUND, out rect);
+#else
+                rect = {
+                    0,
+                    0,
+                    Utils.scale_to_int (tilable.rect.width, scale),
+                    Utils.scale_to_int (tilable.rect.height, scale)
+                };
+#endif
+
+                var x_ratio = (float) tilable.rect.x / monitor_geometry.width;
+                rect.x = area.x + Utils.scale_to_int (area.width, x_ratio);
+
+                var y_ratio = (float) tilable.rect.y / monitor_geometry.height;
+                rect.y = area.y + Utils.scale_to_int (area.height, y_ratio);
+
+                result.append ({ tilable.clone, rect });
+            }
+
+            return result;
+        }
+    }
+
     /**
      * Careful: List<TilableWindow?> windows will be modified in place and shouldn't be used afterwards.
      */
-    private GLib.List<TilableWindow?> calculate_grid_placement (Mtk.Rectangle area, GLib.List<TilableWindow?> windows) {
+    private GLib.List<TilableWindow?> calculate_grid_placement (GLib.List<TilableWindow?> windows) {
+        var area = get_rectangle_with_padding ();
+
         uint window_count = windows.length ();
         int columns = (int) Math.ceil (Math.sqrt (window_count));
         int rows = (int) Math.ceil (window_count / (double) columns);

src/Widgets/MultitaskingView/WorkspaceClone.vala

@@ -137,16 +137,17 @@ public class Gala.WorkspaceClone : ActorTarget {
 
     construct {
         unowned var display = workspace.get_display ();
-        var monitor_geometry = display.get_monitor_geometry (display.get_primary_monitor ());
+        var primary_monitor = display.get_primary_monitor ();
+        var monitor_geometry = display.get_monitor_geometry (primary_monitor);
 
         var background_click_action = new Clutter.ClickAction ();
         background_click_action.clicked.connect (() => activate (true));
         background = new FramedBackground (display);
         background.add_action (background_click_action);
 
-        windows = new WindowListModel (display, STACKING, true, display.get_primary_monitor (), workspace);
+        windows = new WindowListModel (display, STACKING, true, primary_monitor, workspace);
 
-        window_container = new WindowCloneContainer (wm, windows, monitor_scale) {
+        window_container = new WindowCloneContainer (wm, windows, primary_monitor, monitor_scale) {
             width = monitor_geometry.width,
             height = monitor_geometry.height,
         };

src/Widgets/WindowOverview.vala

@@ -119,7 +119,7 @@ public class Gala.WindowOverview : ActorTarget, RootTarget, ActivatableComponent
             var model = new WindowListModel (display, STACKING, true, i, null, custom_filter);
             model.items_changed.connect (on_items_changed);
 
-            window_clone_container = new WindowCloneContainer (wm, model, scale, true) {
+            window_clone_container = new WindowCloneContainer (wm, model, i, scale, true) {
                 padding_top = TOP_GAP,
                 padding_left = BORDER,
                 padding_right = BORDER,
@@ -173,7 +173,7 @@ public class Gala.WindowOverview : ActorTarget, RootTarget, ActivatableComponent
 
     private void on_items_changed (ListModel model, uint pos, uint removed, uint added) {
         // Check removed > added to make sure we only close once when the last window is removed
-        // This avoids an inifinite loop since closing will sort the windows which also triggers this signal
+        // This avoids an infinite loop since closing will sort the windows which also triggers this signal
         if (is_opened () && removed > added && model.get_n_items () == 0) {
             close ();
         }

vapi/mutter-mtk-13.vapi

@@ -80,7 +80,7 @@ namespace Mtk {
 #endif
 		public bool overlap (Mtk.Rectangle rect2);
 #if HAS_MUTTER46
-		public void scale_double (double scale, Mtk.RoundingStrategy rounding_strategy, Mtk.Rectangle dest);
+		public void scale_double (double scale, Mtk.RoundingStrategy rounding_strategy, out Mtk.Rectangle dest);
 #endif
 		public Graphene.Rect? to_graphene_rect ();
 #if HAS_MUTTER47