Merge pull request #3153 from hbatagelo/feature/1369

Make server-side decorations scale aware

src/server/shell/decoration/basic_decoration.cpp

@@ -266,9 +266,15 @@ void msd::BasicDecoration::set_cursor(std::string const& cursor_image_name)
     shell->modify_surface(session, decoration_surface, spec);
 }
 
+void msd::BasicDecoration::set_scale(float new_scale)
+{
+    scale = new_scale;
+    window_state_updated();
+}
+
 auto msd::BasicDecoration::new_window_state() const -> std::unique_ptr<WindowState>
 {
-    return std::make_unique<WindowState>(static_geometry, window_surface);
+    return std::make_unique<WindowState>(static_geometry, window_surface, scale);
 }
 
 auto msd::BasicDecoration::create_surface() const -> std::shared_ptr<scene::Surface>
@@ -369,7 +375,8 @@ void msd::BasicDecoration::update(
             &WindowState::titlebar_rect,
             &WindowState::left_border_rect,
             &WindowState::right_border_rect,
-            &WindowState::bottom_border_rect}) ||
+            &WindowState::bottom_border_rect,
+            &WindowState::scale}) ||
         input_updated({
             &InputState::buttons}))
     {
@@ -383,7 +390,8 @@ void msd::BasicDecoration::update(
     if (window_updated({
             &WindowState::focused_state,
             &WindowState::side_border_width,
-            &WindowState::side_border_height}))
+            &WindowState::side_border_height,
+            &WindowState::scale}))
     {
         new_buffers.emplace_back(
             buffer_streams->left_border,
@@ -396,7 +404,8 @@ void msd::BasicDecoration::update(
     if (window_updated({
             &WindowState::focused_state,
             &WindowState::bottom_border_width,
-            &WindowState::bottom_border_height}))
+            &WindowState::bottom_border_height,
+            &WindowState::scale}))
     {
         new_buffers.emplace_back(
             buffer_streams->bottom_border,
@@ -406,7 +415,8 @@ void msd::BasicDecoration::update(
     if (window_updated({
             &WindowState::focused_state,
             &WindowState::window_name,
-            &WindowState::titlebar_rect}) ||
+            &WindowState::titlebar_rect,
+            &WindowState::scale}) ||
         input_updated({
             &InputState::buttons}))
     {

src/server/shell/decoration/basic_decoration.h

@@ -85,6 +85,8 @@ class BasicDecoration
     void request_close();
     void set_cursor(std::string const& cursor_image_name);
 
+    void set_scale(float scale) override;
+
 protected:
     /// Creates an up-to-date WindowState object
     auto new_window_state() const -> std::unique_ptr<WindowState>;
@@ -108,6 +110,8 @@ class BasicDecoration
     std::shared_ptr<input::CursorImages> const cursor_images;
     std::shared_ptr<scene::Session> const session;
 
+    float scale{1.0f};
+
     class BufferStreams;
     std::unique_ptr<BufferStreams> buffer_streams;
     std::unique_ptr<Renderer> renderer;

src/server/shell/decoration/basic_manager.cpp

@@ -17,6 +17,9 @@
 #include "basic_manager.h"
 #include "decoration.h"
 
+#include <mir/graphics/display_configuration.h>
+#include <mir/graphics/null_display_configuration_observer.h>
+
 #include <boost/throw_exception.hpp>
 #include <vector>
 
@@ -25,9 +28,47 @@ namespace mg = mir::graphics;
 namespace msh = mir::shell;
 namespace msd = mir::shell::decoration;
 
-msd::BasicManager::BasicManager(DecorationBuilder&& decoration_builder)
-    : decoration_builder{decoration_builder}
+class msd::DisplayConfigurationListener :  public mg::NullDisplayConfigurationObserver
 {
+public:
+    using Callback = std::function<void(mg::DisplayConfiguration const&)>;
+
+    explicit DisplayConfigurationListener(Callback callback) : callback{std::move(callback)} {}
+
+private:
+    void initial_configuration(std::shared_ptr<mg::DisplayConfiguration const> const& config) override
+    {
+        callback(*config);
+    }
+    void configuration_applied(std::shared_ptr<mg::DisplayConfiguration const> const& config) override
+    {
+        callback(*config);
+    }
+
+    Callback const callback;
+};
+
+msd::BasicManager::BasicManager(
+    ObserverRegistrar<mg::DisplayConfigurationObserver>& display_configuration_observers,
+    DecorationBuilder&& decoration_builder) :
+    decoration_builder{std::move(decoration_builder)},
+    display_config_monitor{std::make_shared<DisplayConfigurationListener>(
+        [&](mg::DisplayConfiguration const& config)
+        {
+            // Use the maximum scale to ensure sharp-looking decorations on all outputs
+            auto max_output_scale{0.0f};
+            config.for_each_output(
+                [&](mg::DisplayConfigurationOutput const& output)
+                {
+                    if (!output.used || !output.connected) return;
+                    if (!output.valid() || (output.current_mode_index >= output.modes.size())) return;
+
+                    max_output_scale = std::max(max_output_scale, output.scale);
+                });
+            set_scale(max_output_scale);
+        })}
+{
+    display_configuration_observers.register_interest(display_config_monitor);
 }
 
 msd::BasicManager::~BasicManager()
@@ -53,6 +94,7 @@ void msd::BasicManager::decorate(std::shared_ptr<ms::Surface> const& surface)
         lock.unlock();
         auto decoration = decoration_builder(locked_shell, surface);
         lock.lock();
+        decoration->set_scale(scale);
         decorations[surface.get()] = std::move(decoration);
     }
 }
@@ -85,3 +127,16 @@ void msd::BasicManager::undecorate_all()
     // Destroy the decorations outside the lock
     to_destroy.clear();
 }
+
+void msd::BasicManager::set_scale(float new_scale)
+{
+    std::lock_guard lock{mutex};
+    if (new_scale != scale)
+    {
+        scale = new_scale;
+        for (auto& it : decorations)
+        {
+            it.second->set_scale(scale);
+        }
+    }
+}

src/server/shell/decoration/basic_manager.h

@@ -18,10 +18,15 @@
 #define MIR_SHELL_DECORATION_BASIC_MANAGER_H_
 
 #include "manager.h"
+
+#include <mir/observer_registrar.h>
+
 #include <functional>
 #include <unordered_map>
 #include <mutex>
 
+namespace mir::graphics { class DisplayConfigurationObserver; }
+
 namespace mir
 {
 class Executor;
@@ -35,17 +40,20 @@ class Shell;
 namespace decoration
 {
 class Decoration;
+class DisplayConfigurationListener;
 
 /// Facilitates decorating windows with Mir's built-in server size decorations
-class BasicManager
-    : public Manager
+class BasicManager :
+    public Manager
 {
 public:
     using DecorationBuilder = std::function<std::unique_ptr<Decoration>(
         std::shared_ptr<shell::Shell> const& shell,
         std::shared_ptr<scene::Surface> const& surface)>;
 
-    BasicManager(DecorationBuilder&& decoration_builder);
+    BasicManager(
+        mir::ObserverRegistrar<mir::graphics::DisplayConfigurationObserver>& display_configuration_observers,
+        DecorationBuilder&& decoration_builder);
     ~BasicManager();
 
     void init(std::weak_ptr<shell::Shell> const& shell) override;
@@ -55,10 +63,14 @@ class BasicManager
 
 private:
     DecorationBuilder const decoration_builder;
+    std::shared_ptr<DisplayConfigurationListener> const display_config_monitor;
     std::weak_ptr<shell::Shell> shell;
 
     std::mutex mutex;
     std::unordered_map<scene::Surface*, std::unique_ptr<Decoration>> decorations;
+    float scale{1.0f};
+
+    void set_scale(float new_scale);
 };
 }
 }

src/server/shell/decoration/decoration.h

@@ -30,6 +30,8 @@ class Decoration
     Decoration() = default;
     virtual ~Decoration() = default;
 
+    virtual void set_scale(float new_scale) = 0;
+
 private:
     Decoration(Decoration const&) = delete;
     Decoration& operator=(Decoration const&) = delete;