From bc67b043990dfe5515ab7c9157d39377221ac782 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Mon, 28 Dec 2020 10:56:22 +0100
Subject: [PATCH] WindowServer: Don't lookup configuration values in compose()

The compose() function is supposed to be fast since it can execute
60 times per second. Let's not do obviously avoidable things like
configuration value lookups in there. :^)
---
 Services/WindowServer/Compositor.cpp    | 25 +++++++++++++++++++------
 Services/WindowServer/Compositor.h      |  7 ++++++-
 Services/WindowServer/WindowManager.cpp |  4 +---
 3 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/Services/WindowServer/Compositor.cpp b/Services/WindowServer/Compositor.cpp
index 698d12bece..ab072be8d1 100644
--- a/Services/WindowServer/Compositor.cpp
+++ b/Services/WindowServer/Compositor.cpp
@@ -112,11 +112,20 @@ void Compositor::init_bitmaps()
     invalidate_screen();
 }
 
+void Compositor::did_construct_window_manager(Badge<WindowManager>)
+{
+    auto& wm = WindowManager::the();
+    m_wallpaper_mode = mode_to_enum(wm.config()->read_entry("Background", "Mode", "simple"));
+    m_custom_background_color = Color::from_string(wm.config()->read_entry("Background", "Color", ""));
+
+    invalidate_screen();
+    invalidate_occlusions();
+    compose();
+}
+
 void Compositor::compose()
 {
     auto& wm = WindowManager::the();
-    if (m_wallpaper_mode == WallpaperMode::Unchecked)
-        m_wallpaper_mode = mode_to_enum(wm.config()->read_entry("Background", "Mode", "simple"));
     auto& ws = Screen::the();
 
     {
@@ -185,10 +194,8 @@ void Compositor::compose()
     });
 
     Color background_color = wm.palette().desktop_background();
-    String background_color_entry = wm.config()->read_entry("Background", "Color", "");
-    if (!background_color_entry.is_empty()) {
-        background_color = Color::from_string(background_color_entry).value_or(background_color);
-    }
+    if (m_custom_background_color.has_value())
+        background_color = m_custom_background_color.value();
 
 #ifdef COMPOSE_DEBUG
     dbg() << "COMPOSE: invalidated: window:" << m_invalidated_window << " cursor:" << m_invalidated_cursor << " any: " << m_invalidated_any;
@@ -600,6 +607,12 @@ void Compositor::start_compose_async_timer()
 
 bool Compositor::set_background_color(const String& background_color)
 {
+    auto color = Color::from_string(background_color);
+    if (!color.has_value())
+        return false;
+
+    m_custom_background_color = color;
+
     auto& wm = WindowManager::the();
     wm.config()->write_entry("Background", "Color", background_color);
     bool ret_val = wm.config()->sync();
diff --git a/Services/WindowServer/Compositor.h b/Services/WindowServer/Compositor.h
index d33f5258c7..1e6a3e2014 100644
--- a/Services/WindowServer/Compositor.h
+++ b/Services/WindowServer/Compositor.h
@@ -29,14 +29,15 @@
 #include <AK/OwnPtr.h>
 #include <AK/RefPtr.h>
 #include <LibCore/Object.h>
+#include <LibGfx/Color.h>
 #include <LibGfx/DisjointRectSet.h>
-#include <LibGfx/Forward.h>
 
 namespace WindowServer {
 
 class ClientConnection;
 class Cursor;
 class Window;
+class WindowManager;
 
 enum class WallpaperMode {
     Simple,
@@ -73,6 +74,8 @@ public:
 
     void invalidate_occlusions() { m_occlusions_dirty = true; }
 
+    void did_construct_window_manager(Badge<WindowManager>);
+
 private:
     Compositor();
     void init_bitmaps();
@@ -125,6 +128,8 @@ private:
 
     RefPtr<Core::Timer> m_display_link_notify_timer;
     size_t m_display_link_count { 0 };
+
+    Optional<Gfx::Color> m_custom_background_color;
 };
 
 }
diff --git a/Services/WindowServer/WindowManager.cpp b/Services/WindowServer/WindowManager.cpp
index c2f3cc0acf..568fde9190 100644
--- a/Services/WindowServer/WindowManager.cpp
+++ b/Services/WindowServer/WindowManager.cpp
@@ -74,9 +74,7 @@ WindowManager::WindowManager(const Gfx::PaletteImpl& palette)
 
     reload_config(false);
 
-    Compositor::the().invalidate_screen();
-    Compositor::the().invalidate_occlusions();
-    Compositor::the().compose();
+    Compositor::the().did_construct_window_manager({});
 }
 
 WindowManager::~WindowManager()