bugfix: translating other outputs when we resize an output

src/miracle_window_management_policy.cpp

@@ -188,7 +188,7 @@ void MiracleWindowManagementPolicy::advise_output_update(miral::Output const& up
     {
         if (pair->output.is_same_output(original))
         {
-            pair->tree.resize_display(updated.extents().size);
+            pair->tree.set_output_area(updated.extents());
             break;
         }
     }

src/node.cpp

@@ -372,5 +372,16 @@ void Node::scale_area(double x_scale, double y_scale)
         node->scale_area(x_scale, y_scale);
     }
 
+    redistribute_size();
+}
+
+void Node::translate_by(int x, int y)
+{
+    area.top_left.x = geom::X{area.top_left.x.as_int() + x};
+    area.top_left.y = geom::Y{area.top_left.y.as_int() + y};
+    for (auto node : sub_nodes)
+    {
+        node->translate_by(x, y);
+    }
     redistribute_size();
 }

src/node.h

@@ -91,6 +91,7 @@ public:
     std::shared_ptr<Node> find_nth_window_child(int i);
 
     void scale_area(double x_scale, double y_scale);
+    void translate_by(int x, int y);
 
 private:
     miral::Window window;

src/window_tree.cpp

@@ -83,14 +83,19 @@ bool WindowTree::try_select_next(miracle::Direction direction)
     return true;
 }
 
-void WindowTree::resize_display(geom::Size new_size)
+void WindowTree::set_output_area(geom::Rectangle new_area)
 {
-    double x_scale = static_cast<double>(new_size.width.as_int()) / static_cast<double>(area.size.width.as_int());
-    double y_scale = static_cast<double>(new_size.height.as_int()) / static_cast<double>(area.size.height.as_int());
+    double x_scale = static_cast<double>(new_area.size.width.as_int()) / static_cast<double>(area.size.width.as_int());
+    double y_scale = static_cast<double>(new_area.size.height.as_int()) / static_cast<double>(area.size.height.as_int());
     root_lane->scale_area(x_scale, y_scale);
     area.size = geom::Size{
         geom::Width{ceil(area.size.width.as_int() * x_scale)},
         geom::Height {ceil(area.size.height.as_int() * y_scale)}};
+
+    int position_diff_x = new_area.top_left.x.as_int() - area.top_left.x.as_int();
+    int position_diff_y = new_area.top_left.y.as_int() - area.top_left.y.as_int();
+    root_lane->translate_by(position_diff_x, position_diff_y);
+    area.top_left = new_area.top_left;
 }
 
 bool WindowTree::point_is_in_output(int x, int y)

src/window_tree.h

@@ -81,7 +81,7 @@ public:
     void advise_delete_window(miral::Window&);
 
     /// Called when the physical display is resized.
-    void resize_display(geom::Size new_size);
+    void set_output_area(geom::Rectangle new_area);
 
     bool point_is_in_output(int x, int y);