From 32ac8b4e0f403951d0280ebb9de0f13aa3a0eb23 Mon Sep 17 00:00:00 2001
From: Bob Polis <rpb.polis@avans.nl>
Date: Fri, 13 Nov 2020 16:54:49 +0100
Subject: [PATCH] refactored event handling; added _dirty flag to only update
 when dirty

---
 src/Window.cpp | 45 ++++++++++++++++++++++++++++++---------------
 src/Window.hpp |  9 ++++++++-
 2 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/src/Window.cpp b/src/Window.cpp
index f539cfe..9447945 100644
--- a/src/Window.cpp
+++ b/src/Window.cpp
@@ -53,18 +53,12 @@ bool Window::handle_global_event(const SDL_Event& event) {
         }
     }
     switch (event.window.event) {
-        case SDL_WINDOWEVENT_CLOSE: {
-            // remove window from window list
-            SDL_Window* w {SDL_GetWindowFromID(event.window.windowID)};
-            auto it = std::remove_if(_windows.begin(), _windows.end(), [w](Window& win) {
-                return win.window() == w;
-            });
-            _windows.erase(it, _windows.end());
-            if (_windows.size() == 0) {
-                quit = true;
-            }
+        case SDL_WINDOWEVENT_CLOSE:
+            quit = close(event);
+            break;
+        case SDL_WINDOWEVENT_EXPOSED:
+            quit = expose(event);
             break;
-        }
         default:
             break;
     }
@@ -81,6 +75,24 @@ void Window::add_global_event_handler(WindowEventHandler handler, SDL_WindowEven
     }
 }
 
+bool Window::expose(const SDL_Event& event) {
+    Window* w {from_sdl(event.window.windowID)};
+    if (w) w->dirty(true);
+    return false;
+}
+
+bool Window::close(const SDL_Event& event) {
+    // remove window from window list
+    SDL_Window* w {SDL_GetWindowFromID(event.window.windowID)};
+    auto it = std::remove_if(_windows.begin(), _windows.end(), [w](Window& win) {
+        return win.window() == w;
+    });
+    _windows.erase(it, _windows.end());
+
+    // quit if it was the last window
+    return _windows.size() == 0;
+}
+
 Window::Window(const std::string& title) : _title {title} {
     SDL_Window* win = SDL_CreateWindow(title.c_str(),
                                        SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
@@ -94,10 +106,13 @@ void Window::set_size(int w, int h) {
     SDL_SetWindowSize(_w.get(), w, h);
 }
 
-void Window::update() const {
-    SDL_RenderClear(_r.get());
-    SDL_RenderCopy(_r.get(), _t.get(), nullptr, nullptr);
-    SDL_RenderPresent(_r.get());
+void Window::update() {
+    if (_dirty) {
+        _dirty = false;
+        SDL_RenderClear(_r.get());
+        SDL_RenderCopy(_r.get(), _t.get(), nullptr, nullptr);
+        SDL_RenderPresent(_r.get());
+    }
 }
 
 void Window::show_image(const Image& image) {
diff --git a/src/Window.hpp b/src/Window.hpp
index 312041a..a2dec84 100644
--- a/src/Window.hpp
+++ b/src/Window.hpp
@@ -43,18 +43,25 @@ namespace sc {
                 int width() const;
                 int height() const;
 
-                void update() const;
+                void update();
                 void show_image(const Image& image);
 
+                void dirty(bool flag) { _dirty = flag; }
+                bool dirty() const { return _dirty; }
+
             private:
                 static std::vector<Window> _windows;
                 static std::map<SDL_WindowEventID, std::vector<WindowEventHandler>> _global_event_handlers;
 
+                bool _dirty {true};
                 std::string _title;
                 std::unique_ptr<SDL_Window,   void(*)(SDL_Window*)>   _w {nullptr, SDL_DestroyWindow};
                 std::unique_ptr<SDL_Renderer, void(*)(SDL_Renderer*)> _r {nullptr, SDL_DestroyRenderer};
                 std::unique_ptr<SDL_Texture,  void(*)(SDL_Texture*)>  _t {nullptr, SDL_DestroyTexture};
                 std::map<SDL_WindowEventID, std::vector<WindowEventHandler>> _event_handlers;
+
+                static bool close(const SDL_Event& event);
+                static bool expose(const SDL_Event& event);
         };
     }
 }