Decouple WindowState from DecorationStrategy

src/server/shell/decoration/decoration_strategy.cpp

@@ -321,7 +321,7 @@ struct RendererStrategy : public msd::RendererStrategy
     static auto alloc_pixels(geom::Size size) -> std::unique_ptr<Pixel[]>;
 };
 
-class DecorationStrategy : public msd::DecorationStrategy, public std::enable_shared_from_this<DecorationStrategy>
+class DecorationStrategy : public msd::DecorationStrategy
 {
 public:
     ~DecorationStrategy() override = default;
@@ -335,26 +335,8 @@ class DecorationStrategy : public msd::DecorationStrategy, public std::enable_sh
     auto new_window_state(const std::shared_ptr<mir::scene::Surface>& window_surface,
                           float scale) const -> std::unique_ptr<WindowState> override;
     auto resize_corner_input_size() const -> geom::Size override;
-    auto titlebar_height() const -> geom::Height override;
-    auto side_border_width() const -> geom::Width override;
-    auto bottom_border_height() const -> geom::Height override;
 };
 
-auto DecorationStrategy::titlebar_height() const -> geom::Height
-{
-    return static_geometry()->titlebar_height;
-}
-
-auto DecorationStrategy::side_border_width() const -> geom::Width
-{
-    return static_geometry()->side_border_width;
-}
-
-auto DecorationStrategy::bottom_border_height() const -> geom::Height
-{
-    return static_geometry()->bottom_border_height;
-}
-
 auto DecorationStrategy::resize_corner_input_size() const -> geom::Size
 {
     return static_geometry()->resize_corner_input_size;
@@ -369,7 +351,12 @@ auto DecorationStrategy::new_window_state(const std::shared_ptr<mir::scene::Surf
                                           float scale) const -> std::unique_ptr<WindowState>
 
 {
-    return std::make_unique<WindowState>(shared_from_this(), window_surface, scale);
+    return std::make_unique<WindowState>(
+        window_surface,
+        static_geometry()->titlebar_height,
+        static_geometry()->side_border_width,
+        static_geometry()->bottom_border_height,
+        scale);
 }
 
 auto DecorationStrategy::compute_size_with_decorations(

src/server/shell/decoration/decoration_strategy.h

@@ -82,8 +82,10 @@ class WindowState
 {
 public:
     WindowState(
-        std::shared_ptr<const DecorationStrategy>&& decoration_strategy,
         std::shared_ptr<scene::Surface> const& window_surface,
+        geometry::Height fixed_titlebar_height,
+        geometry::Width fixed_side_border_width,
+        geometry::Height fixed_bottom_border_height,
         float scale);
 
     ~WindowState();
@@ -166,11 +168,6 @@ class DecorationStrategy
     virtual ~DecorationStrategy() = default;
 
 private:
-    virtual auto titlebar_height() const -> geometry::Height = 0;
-    virtual auto side_border_width() const -> geometry::Width = 0;
-    virtual auto bottom_border_height() const -> geometry::Height = 0;
-    friend class WindowState;
-
     DecorationStrategy(DecorationStrategy const&) = delete;
     DecorationStrategy& operator=(DecorationStrategy const&) = delete;
 };

src/server/shell/decoration/window.cpp

@@ -30,64 +30,79 @@ class msd::WindowState::Self
 {
 public:
     Self(
-    std::shared_ptr<const DecorationStrategy>&& decoration_strategy,
-    std::shared_ptr<scene::Surface> const& surface,
-    float scale);
-
-    std::shared_ptr<const DecorationStrategy> const decoration_strategy;
-    geometry::Size const window_size_;
-    BorderType const border_type_;
-    MirWindowFocusState const focus_state_;
-    std::string const window_name_;
-    float const scale_;
+        std::shared_ptr<scene::Surface> const& surface,
+        geometry::Height fixed_titlebar_height,
+        geometry::Width fixed_side_border_width,
+        geometry::Height fixed_bottom_border_height,
+        float scale);
+
+    geometry::Height const fixed_titlebar_height;
+    geometry::Width const fixed_side_border_width;
+    geometry::Height const fixed_bottom_border_height;
+    geometry::Size const window_size;
+    BorderType const border_type;
+    MirWindowFocusState const focus_state;
+    std::string const window_name;
+    float const scale;
 };
 
 msd::WindowState::Self::Self(
-    std::shared_ptr<const DecorationStrategy>&& decoration_strategy,
     std::shared_ptr<scene::Surface> const& surface,
+    geometry::Height fixed_titlebar_height,
+    geometry::Width fixed_side_border_width,
+    geometry::Height fixed_bottom_border_height,
     float scale)
-    : decoration_strategy{std::move(decoration_strategy)},
-      window_size_{surface->window_size()},
-      border_type_{border_type_for(surface->type(), surface->state())},
-      focus_state_{surface->focus_state()},
-      window_name_{surface->name()},
-      scale_{scale}
+    : fixed_titlebar_height(fixed_titlebar_height),
+      fixed_side_border_width(fixed_side_border_width),
+      fixed_bottom_border_height(fixed_bottom_border_height),
+      window_size{surface->window_size()},
+      border_type{border_type_for(surface->type(), surface->state())},
+      focus_state{surface->focus_state()},
+      window_name{surface->name()},
+      scale{scale}
 {
 }
 
 msd::WindowState::WindowState(
-    std::shared_ptr<const DecorationStrategy>&& decoration_strategy,
     std::shared_ptr<scene::Surface> const& surface,
+    geometry::Height fixed_titlebar_height,
+    geometry::Width fixed_side_border_width,
+    geometry::Height fixed_bottom_border_height,
     float scale)
-    : self{std::make_unique<Self>(std::move(decoration_strategy), surface, scale)}
+    : self{std::make_unique<Self>(
+        surface,
+        fixed_titlebar_height,
+        fixed_side_border_width,
+        fixed_bottom_border_height,
+        scale)}
 {
 }
 
 mir::shell::decoration::WindowState::~WindowState() = default;
 
 auto msd::WindowState::window_size() const -> geom::Size
 {
-    return self->window_size_;
+    return self->window_size;
 }
 
 auto msd::WindowState::border_type() const -> BorderType
 {
-    return self->border_type_;
+    return self->border_type;
 }
 
 auto msd::WindowState::focused_state() const -> MirWindowFocusState
 {
-    return self->focus_state_;
+    return self->focus_state;
 }
 
 auto msd::WindowState::window_name() const -> std::string
 {
-    return self->window_name_;
+    return self->window_name;
 }
 
 auto msd::WindowState::titlebar_width() const -> geom::Width
 {
-    switch (self->border_type_)
+    switch (self->border_type)
     {
     case BorderType::Full:
     case BorderType::Titlebar:
@@ -102,11 +117,11 @@ auto msd::WindowState::titlebar_width() const -> geom::Width
 
 auto msd::WindowState::titlebar_height() const -> geom::Height
 {
-    switch (self->border_type_)
+    switch (self->border_type)
     {
     case BorderType::Full:
     case BorderType::Titlebar:
-        return self->decoration_strategy->titlebar_height();
+        return self->fixed_titlebar_height;
     case BorderType::None:
         return {};
     }
@@ -117,10 +132,10 @@ auto msd::WindowState::titlebar_height() const -> geom::Height
 
 auto msd::WindowState::side_border_width() const -> geom::Width
 {
-    switch (self->border_type_)
+    switch (self->border_type)
     {
     case BorderType::Full:
-        return self->decoration_strategy->side_border_width();
+        return self->fixed_side_border_width;
     case BorderType::Titlebar:
     case BorderType::None:
         return {};
@@ -132,7 +147,7 @@ auto msd::WindowState::side_border_width() const -> geom::Width
 
 auto msd::WindowState::side_border_height() const -> geom::Height
 {
-    switch (self->border_type_)
+    switch (self->border_type)
     {
     case BorderType::Full:
         return window_size().height - as_delta(titlebar_height()) - as_delta(bottom_border_height());
@@ -152,10 +167,10 @@ auto msd::WindowState::bottom_border_width() const -> geom::Width
 
 auto msd::WindowState::bottom_border_height() const -> geom::Height
 {
-    switch (self->border_type_)
+    switch (self->border_type)
     {
     case BorderType::Full:
-        return self->decoration_strategy->bottom_border_height();
+        return self->fixed_bottom_border_height;
     case BorderType::Titlebar:
     case BorderType::None:
         return {};
@@ -195,7 +210,7 @@ auto msd::WindowState::bottom_border_rect() const -> geom::Rectangle
 
 auto msd::WindowState::scale() const -> float
 {
-    return self->scale_;
+    return self->scale;
 }
 
 class msd::WindowSurfaceObserverManager::Observer