From d9eccc940a5cad117bcae26960b12d428f8028c3 Mon Sep 17 00:00:00 2001
From: Andrea Blankenstijn <a.b@kaze.ch>
Date: Sun, 15 Aug 2021 20:04:53 +0200
Subject: [PATCH] rewrite how events are held

---
 .clang-format                                 |   6 +-
 examples/button_example.cpp                   |   4 +-
 inc/basic_widgets/w/base/input.hpp            | 102 +++++++++---------
 inc/basic_widgets/w/base/layout.hpp           |   2 +-
 inc/basic_widgets/w/base/widget.hpp           |  13 +--
 inc/basic_widgets/w/button.hpp                |  13 ++-
 inc/basic_widgets/w/feat/event_handler.hpp    |  32 ++++++
 .../w/feat/event_handler_impl.hpp             |  24 +++++
 inc/basic_widgets/w/feat/focus_handler.hpp    |  19 ++--
 .../w/feat/focus_handler_impl.hpp             |  32 ++++++
 inc/basic_widgets/w/feat/keyboard_handler.hpp |  37 ++-----
 .../w/feat/keyboard_handler_impl.hpp          |  31 ++++++
 inc/basic_widgets/w/feat/mouse_handler.hpp    |  38 +++----
 .../w/feat/mouse_handler_impl.hpp             |  54 ++++++++++
 inc/basic_widgets/w/numeric_input.hpp         |  14 ++-
 meson.build                                   |  10 +-
 src/w/base/layout.cpp                         |   4 +-
 src/w/base/widget.cpp                         |  34 ------
 src/w/button.cpp                              |  10 +-
 src/w/feat/event_handler_impl.cpp             |  32 ++++++
 src/w/feat/keyboard_handler_impl.cpp          |  23 ++++
 src/w/feat/mouse_handler.cpp                  |  60 -----------
 src/w/feat/mouse_handler_impl.cpp             |  50 +++++++++
 23 files changed, 396 insertions(+), 248 deletions(-)
 create mode 100644 inc/basic_widgets/w/feat/event_handler.hpp
 create mode 100644 inc/basic_widgets/w/feat/event_handler_impl.hpp
 create mode 100644 inc/basic_widgets/w/feat/focus_handler_impl.hpp
 create mode 100644 inc/basic_widgets/w/feat/keyboard_handler_impl.hpp
 create mode 100644 inc/basic_widgets/w/feat/mouse_handler_impl.hpp
 create mode 100644 src/w/feat/event_handler_impl.cpp
 create mode 100644 src/w/feat/keyboard_handler_impl.cpp
 delete mode 100644 src/w/feat/mouse_handler.cpp
 create mode 100644 src/w/feat/mouse_handler_impl.cpp

diff --git a/.clang-format b/.clang-format
index 6aa77c4..80b5f17 100644
--- a/.clang-format
+++ b/.clang-format
@@ -34,11 +34,11 @@ EmptyLineBeforeAccessModifier: Always
 FixNamespaceComments: false
 IncludeBlocks: Regroup
 IncludeCategories:
-    - Regex: '<[[:alnum:].]+>'
+    - Regex: '<[[:alnum:]._]+>'
       Priority: -10
-    - Regex: '^<fontconfig/'
+    - Regex: '^<fontconfig'
       Priority: -5
-    - Regex: '^<SDL2/'
+    - Regex: '^<SDL'
       Priority: -5
     - Regex: '^<basic_widgets/'
       Priority: 0
diff --git a/examples/button_example.cpp b/examples/button_example.cpp
index fb24208..1cc15a5 100644
--- a/examples/button_example.cpp
+++ b/examples/button_example.cpp
@@ -9,9 +9,9 @@ using bwidgets::Button;
 auto main() -> int
 {
     run_example<Button>([](auto w, auto f, auto x, auto y) {
-        w->click_handler = [x, y](const SDL_MouseButtonEvent&) {
+        w->click_handler([x, y](const SDL_MouseButtonEvent&) {
             std::cout << "button(" << x << ',' << y << "):click!" << std::endl;
-        };
+        });
         w->font(f);
         w->text("+");
     });
diff --git a/inc/basic_widgets/w/base/input.hpp b/inc/basic_widgets/w/base/input.hpp
index 3d47015..1aa8622 100644
--- a/inc/basic_widgets/w/base/input.hpp
+++ b/inc/basic_widgets/w/base/input.hpp
@@ -13,8 +13,8 @@
 #include <basic_widgets/core/math.hpp>
 #include <basic_widgets/core/type/concepts.hpp>
 #include <basic_widgets/w/caption.hpp>
-#include <basic_widgets/w/feat/keyboard_handler.hpp>
-#include <basic_widgets/w/feat/mouse_handler.hpp>
+#include <basic_widgets/w/feat/keyboard_handler_impl.hpp>
+#include <basic_widgets/w/feat/mouse_handler_impl.hpp>
 
 namespace bwidgets
 {
@@ -22,29 +22,57 @@ namespace bwidgets
     template<typename T>
     class Input : public Widget,
                   public FontHandler,
-                  public KeyboardHandler,
-                  public MouseHandler
+                  public KeyboardHandlerImpl,
+                  public MouseHandlerImpl
     {
     protected:
         Caption _input_caption;
 
         Input(Widget* parent = nullptr) : Widget {parent}, _input_caption {this}
         {
-            FocusHandler::_focus_area = &_widget_area;
-            MouseHandler::_click_area = &_widget_area;
-            _input_caption.text(value_to_string(value));
-        }
+            FocusHandlerImpl::focus_handler([this](bool focus) {
+                if (focus) {
+                    SDL_StartTextInput();
+                }
+                // focus loss.
+                else if (FocusHandlerImpl::focus()) {
+                    value = value_from_string(input_text());
+                    input_text(value_to_string(value));
+                    SDL_StopTextInput();
+                    _input_caption.text(value_to_string(value));
+                }
+            });
 
-        void _handle_focus_change(bool focus) override
-        {
-            if (focus) {
-                SDL_StartTextInput();
-            }
-            else {
-                value = value_from_string(input_text());
-                input_text(value_to_string(value));
-                SDL_StopTextInput();
-            }
+            KeyboardHandlerImpl::key_handler([this](const SDL_KeyboardEvent& key) {
+                if (key.type == SDL_KEYDOWN) {
+                    switch (key.keysym.sym) {
+                        case SDLK_BACKSPACE: {
+                            std::string txt = input_text();
+                            if (txt.length() > 0) {
+                                txt.pop_back();
+                                input_text(txt);
+                            }
+                            break;
+                        }
+                        case SDLK_RETURN:
+                        case SDLK_RETURN2: // what is return2 btw?
+                        case SDLK_KP_ENTER:
+                            value = value_from_string(input_text());
+                            FocusHandlerImpl::focus(false);
+                            break;
+                    }
+                }
+            });
+            KeyboardHandlerImpl::text_input_handler(
+              [this](const SDL_TextInputEvent& input) {
+                  if (is_valid_input(input.text)) {
+                      input_text(input_text() + input.text);
+                  }
+              });
+            KeyboardHandlerImpl::enable_keyboard_handler();
+
+            MouseHandlerImpl::enable_mouse_handler(&(Input::_widget_area),
+                                                   &(Input::_viewport));
         }
 
         void _handle_font_change(const std::shared_ptr<Font>& f) override
@@ -67,28 +95,6 @@ namespace bwidgets
               {rect_margin(_widget_area, {border_width, border_width})}, vp));
         }
 
-        void _handle_key(const SDL_KeyboardEvent& key) override
-        {
-            if (key.type == SDL_KEYDOWN) {
-                switch (key.keysym.sym) {
-                    case SDLK_BACKSPACE: {
-                        std::string txt = input_text();
-                        if (txt.length() > 0) {
-                            txt.pop_back();
-                            input_text(txt);
-                        }
-                        break;
-                    }
-                    case SDLK_RETURN:
-                    case SDLK_RETURN2: // what is return2 btw?
-                    case SDLK_KP_ENTER:
-                        value = value_from_string(input_text());
-                        focus(false);
-                        break;
-                }
-            }
-        }
-
         void _handle_renderer_change(const std::shared_ptr<Renderer>& r) override
         {
             _input_caption.renderer(r);
@@ -97,27 +103,21 @@ namespace bwidgets
         void _handle_rendering() override
         {
             for (int i = border_width - 1; i >= 0; i--) {
-                const auto  factor      = linear(i, 0, border_width);
-                const auto& color_end   = _has_focus ? color_bg_focused : color_bg;
-                const auto  color_start = color_end / 2;
+                const auto  factor = linear(i, 0, border_width);
+                const auto& color_end =
+                  FocusHandlerImpl::focus() ? color_bg_focused : color_bg;
+                const auto color_start = color_end / 2;
                 _renderer->draw_color(lerp(color_start, color_end, factor))
                   ->draw_rect(rect_margin(_widget_area, {i, i}));
             }
 
-            if (MouseHandler::_is_hovered || FocusHandler::_has_focus)
+            if (hovered() || FocusHandlerImpl::focus())
                 _input_caption.font_color_bg(color_bg_focused);
             else _input_caption.font_color_bg(color_bg);
 
             _input_caption.render();
         }
 
-        void _handle_text_input(const SDL_TextInputEvent& input) override
-        {
-            if (is_valid_input(input.text)) {
-                input_text(input_text() + input.text);
-            }
-        }
-
     public:
         static const int          default_border_width = 3;
         inline static const Color default_color_bg = {200, 200, 200, SDL_ALPHA_OPAQUE};
diff --git a/inc/basic_widgets/w/base/layout.hpp b/inc/basic_widgets/w/base/layout.hpp
index 845a19f..bd5859a 100644
--- a/inc/basic_widgets/w/base/layout.hpp
+++ b/inc/basic_widgets/w/base/layout.hpp
@@ -38,7 +38,7 @@ namespace bwidgets
         auto operator=(const Layout&) = delete;
         auto operator=(Layout&&) = delete;
 
-        auto               handle_event(const SDL_Event&) -> Layout* override;
+        void               handle_event(const SDL_Event&) override;
         [[nodiscard]] auto size() const noexcept -> Size override = 0;
 
         virtual auto add_widget(std::unique_ptr<Widget>) -> Layout*;
diff --git a/inc/basic_widgets/w/base/widget.hpp b/inc/basic_widgets/w/base/widget.hpp
index 09aa52d..2d5c926 100644
--- a/inc/basic_widgets/w/base/widget.hpp
+++ b/inc/basic_widgets/w/base/widget.hpp
@@ -5,6 +5,7 @@
 
 #include <basic_widgets/core/renderer.hpp>
 #include <basic_widgets/core/type/size.hpp>
+#include <basic_widgets/w/feat/event_handler_impl.hpp>
 
 union SDL_Event;
 
@@ -12,15 +13,13 @@ struct SDL_Renderer;
 
 namespace bwidgets
 {
-    class Widget
+    class Widget : public virtual EventHandlerImpl
     {
     protected:
         std::shared_ptr<Renderer> _renderer;
         SDL_Rect                  _viewport {0, 0, 0, 0};
         SDL_Rect                  _widget_area {0, 0, 0, 0};
 
-        explicit Widget(Widget* p = nullptr) noexcept : parent {p} {}
-
         virtual void _handle_geometry_change(const SDL_Rect&) = 0;
         virtual void _handle_renderer_change(const std::shared_ptr<Renderer>&) {}
         virtual void _handle_rendering() = 0;
@@ -28,14 +27,8 @@ namespace bwidgets
     public:
         Widget* parent;
 
-        Widget(const Widget&) noexcept = default;
-        Widget(Widget&&) noexcept      = default;
-        virtual ~Widget() noexcept     = default;
+        explicit Widget(Widget* p = nullptr) noexcept : parent {p} {}
 
-        auto operator=(const Widget&) = delete;
-        auto operator=(Widget&&) = delete;
-
-        virtual auto               handle_event(const SDL_Event&) -> Widget*;
         [[nodiscard]] virtual auto size() const noexcept -> Size = 0;
 
         virtual auto               render() -> Widget* final;
diff --git a/inc/basic_widgets/w/button.hpp b/inc/basic_widgets/w/button.hpp
index 56bdd44..135568a 100644
--- a/inc/basic_widgets/w/button.hpp
+++ b/inc/basic_widgets/w/button.hpp
@@ -6,20 +6,19 @@
 
 #include <basic_widgets/core/type/color.hpp>
 #include <basic_widgets/w/caption.hpp>
-#include <basic_widgets/w/feat/mouse_handler.hpp>
+#include <basic_widgets/w/feat/mouse_handler_impl.hpp>
 
 namespace bwidgets
 {
-    class Button : public Widget,
-                   public FontHandler,
-                   public MouseHandler
+    class Button : public virtual Widget,
+                   public virtual FontHandler,
+                   public virtual MouseHandlerImpl
     {
     protected:
         Caption  _caption;
         SDL_Rect _caption_area {};
         Color    _color_foreground = default_color_fg;
 
-        void _handle_focus_change(bool) override {}
         void _handle_font_change(const std::shared_ptr<Font>&) override;
         void _handle_font_color_change(Color, Color)
         override;
@@ -38,6 +37,10 @@ namespace bwidgets
         Color                                 color_bg       = default_color_bg;
         Color                                 color_bg_hover = default_color_bg_hover;
 
+        using EventHandlerImpl::handle_event;
+        using FocusHandlerImpl::focus;
+        using FocusHandlerImpl::focus_handler;
+
         Button(Widget* parent = nullptr) noexcept;
         Button(const Button&) = delete;
         Button(Button&&)      = delete;
diff --git a/inc/basic_widgets/w/feat/event_handler.hpp b/inc/basic_widgets/w/feat/event_handler.hpp
new file mode 100644
index 0000000..39a0472
--- /dev/null
+++ b/inc/basic_widgets/w/feat/event_handler.hpp
@@ -0,0 +1,32 @@
+#ifndef BWIDGETS_EVENT_HANDLER_HPP
+#define BWIDGETS_EVENT_HANDLER_HPP
+
+#include <functional>
+#include <utility>
+
+#include <SDL_events.h>
+
+namespace bwidgets
+{
+    class EventHandler
+    {
+    public:
+        using handler_t =
+          std::pair<SDL_EventType, std::function<void(const SDL_Event&)>>;
+
+    protected:
+        EventHandler() = default;
+
+    public:
+        EventHandler(const EventHandler&) = delete;
+        EventHandler(EventHandler&&)      = delete;
+        auto operator=(const EventHandler&) -> EventHandler& = delete;
+        auto operator=(EventHandler&&) -> EventHandler& = delete;
+
+        virtual ~EventHandler() = default;
+
+        virtual void handle_event(const SDL_Event&) = 0;
+    };
+}
+
+#endif
diff --git a/inc/basic_widgets/w/feat/event_handler_impl.hpp b/inc/basic_widgets/w/feat/event_handler_impl.hpp
new file mode 100644
index 0000000..eca5ab1
--- /dev/null
+++ b/inc/basic_widgets/w/feat/event_handler_impl.hpp
@@ -0,0 +1,24 @@
+#ifndef BWIDGETS_EVENT_HANDLER_IMPL_HPP
+#define BWIDGETS_EVENT_HANDLER_IMPL_HPP
+
+#include <unordered_map>
+
+#include <basic_widgets/w/feat/event_handler.hpp>
+
+namespace bwidgets
+{
+    class EventHandlerImpl : public virtual EventHandler
+    {
+        std::unordered_map<SDL_EventType, std::function<void(const SDL_Event&)>>
+          _event_handlers {};
+
+    protected:
+        auto _add_event_handler(handler_t) -> bool;
+        auto _remove_event_handler(SDL_EventType) -> std::pair<handler_t, bool>;
+
+    public:
+        void handle_event(const SDL_Event&) override;
+    };
+}
+
+#endif
diff --git a/inc/basic_widgets/w/feat/focus_handler.hpp b/inc/basic_widgets/w/feat/focus_handler.hpp
index 2d4ed10..0e6db8a 100644
--- a/inc/basic_widgets/w/feat/focus_handler.hpp
+++ b/inc/basic_widgets/w/feat/focus_handler.hpp
@@ -1,32 +1,25 @@
 #ifndef BWIDGETS_FOCUS_HANDLER_HPP
 #define BWIDGETS_FOCUS_HANDLER_HPP
 
+#include <functional>
+
 struct SDL_Rect;
 
 namespace bwidgets
 {
     class FocusHandler
     {
-    protected:
-        const SDL_Rect* _focus_area = nullptr;
-        bool            _has_focus  = false;
-
-        virtual void _handle_focus_change(bool) = 0;
-
     public:
         FocusHandler()                    = default;
         FocusHandler(const FocusHandler&) = delete;
         FocusHandler(FocusHandler&&)      = delete;
-        virtual ~FocusHandler()           = default;
-
         auto operator=(FocusHandler&&) = delete;
         auto operator=(const FocusHandler&) = delete;
 
-        virtual void focus(bool focus) final
-        {
-            _handle_focus_change(focus);
-            _has_focus = focus;
-        }
+        virtual ~FocusHandler()                               = default;
+        virtual void focus(bool focus)                        = 0;
+        virtual bool focus()                                  = 0;
+        virtual void focus_handler(std::function<void(bool)>) = 0;
     };
 }
 
diff --git a/inc/basic_widgets/w/feat/focus_handler_impl.hpp b/inc/basic_widgets/w/feat/focus_handler_impl.hpp
new file mode 100644
index 0000000..c33bbb6
--- /dev/null
+++ b/inc/basic_widgets/w/feat/focus_handler_impl.hpp
@@ -0,0 +1,32 @@
+#ifndef BWIDGETS_FOCUS_HANDLER_IMPL_HPP
+#define BWIDGETS_FOCUS_HANDLER_IMPL_HPP
+
+#include <basic_widgets/w/feat/focus_handler.hpp>
+
+namespace bwidgets
+{
+    class FocusHandlerImpl : public virtual FocusHandler
+    {
+        bool                      _has_focus {false};
+        std::function<void(bool)> _focus_handler {[](auto) {}};
+
+    public:
+        void focus(bool focus_) override
+        {
+            _focus_handler(focus_);
+            _has_focus = focus_;
+        }
+
+        bool focus() override
+        {
+            return _has_focus;
+        }
+
+        void focus_handler(decltype(_focus_handler) handler) final
+        {
+            _focus_handler = std::move(handler);
+        }
+    };
+}
+
+#endif
diff --git a/inc/basic_widgets/w/feat/keyboard_handler.hpp b/inc/basic_widgets/w/feat/keyboard_handler.hpp
index d56b0a4..cfdb6e0 100644
--- a/inc/basic_widgets/w/feat/keyboard_handler.hpp
+++ b/inc/basic_widgets/w/feat/keyboard_handler.hpp
@@ -1,6 +1,7 @@
-#ifndef BWIDGETS_KEYBOARD_HANDLER
-#define BWIDGETS_KEYBOARD_HANDLER
+#ifndef BWIDGETS_KEYBOARD_HANDLER_HPP
+#define BWIDGETS_KEYBOARD_HANDLER_HPP
 
+#include <basic_widgets/w/feat/event_handler.hpp>
 #include <basic_widgets/w/feat/focus_handler.hpp>
 
 struct SDL_KeyboardEvent;
@@ -8,34 +9,18 @@ struct SDL_TextInputEvent;
 
 namespace bwidgets
 {
-    class KeyboardHandler : public virtual FocusHandler
+    class KeyboardHandler : public virtual EventHandler,
+                            public virtual FocusHandler
     {
     protected:
-        virtual void _handle_key(const SDL_KeyboardEvent&)         = 0;
-        virtual void _handle_text_input(const SDL_TextInputEvent&) = 0;
+        using EventHandler::EventHandler;
 
     public:
-        using FocusHandler::FocusHandler;
-
-        KeyboardHandler(const KeyboardHandler&) = delete;
-        KeyboardHandler(KeyboardHandler&&)      = delete;
-        ~KeyboardHandler() override             = default;
-        auto operator=(const KeyboardHandler&) = delete;
-        auto operator=(KeyboardHandler&&) = delete;
-
-        virtual auto handle_keyboard(const SDL_KeyboardEvent& ev)
-          -> KeyboardHandler* final
-        {
-            if (_has_focus) _handle_key(ev);
-            return this;
-        }
-
-        virtual auto handle_keyboard(const SDL_TextInputEvent& ev)
-          -> KeyboardHandler* final
-        {
-            if (_has_focus) _handle_text_input(ev);
-            return this;
-        }
+        virtual void disable_keyboard_handler()                                 = 0;
+        virtual void enable_keyboard_handler()                                  = 0;
+        virtual void key_handler(std::function<void(const SDL_KeyboardEvent&)>) = 0;
+        virtual void
+        text_input_handler(std::function<void(const SDL_TextInputEvent&)>) = 0;
     };
 }
 
diff --git a/inc/basic_widgets/w/feat/keyboard_handler_impl.hpp b/inc/basic_widgets/w/feat/keyboard_handler_impl.hpp
new file mode 100644
index 0000000..a5b09cd
--- /dev/null
+++ b/inc/basic_widgets/w/feat/keyboard_handler_impl.hpp
@@ -0,0 +1,31 @@
+#ifndef BWIDGETS_KEYBOARD_HANDLER_IMPL_HPP
+#define BWIDGETS_KEYBOARD_HANDLER_IMPL_HPP
+
+#include <basic_widgets/w/feat/event_handler_impl.hpp>
+#include <basic_widgets/w/feat/focus_handler_impl.hpp>
+#include <basic_widgets/w/feat/keyboard_handler.hpp>
+
+namespace bwidgets
+{
+    class KeyboardHandlerImpl : public KeyboardHandler,
+                                virtual public EventHandlerImpl,
+                                virtual public FocusHandlerImpl
+    {
+        std::function<void(const SDL_KeyboardEvent&)>  _key_handler {[](auto) {}};
+        std::function<void(const SDL_TextInputEvent&)> _input_handler {[](auto) {}};
+
+    public:
+        void disable_keyboard_handler() override;
+        void enable_keyboard_handler() override;
+        void key_handler(decltype(_key_handler) handler) override
+        {
+            _key_handler = std::move(handler);
+        }
+        void text_input_handler(decltype(_input_handler) handler) override
+        {
+            _input_handler = std::move(handler);
+        }
+    };
+}
+
+#endif
diff --git a/inc/basic_widgets/w/feat/mouse_handler.hpp b/inc/basic_widgets/w/feat/mouse_handler.hpp
index 90b0c74..dbc25c9 100644
--- a/inc/basic_widgets/w/feat/mouse_handler.hpp
+++ b/inc/basic_widgets/w/feat/mouse_handler.hpp
@@ -1,8 +1,7 @@
 #ifndef BWIDGETS_MOUSE_HANDLER_HPP
 #define BWIDGETS_MOUSE_HANDLER_HPP
 
-#include <functional>
-
+#include <basic_widgets/w/feat/event_handler.hpp>
 #include <basic_widgets/w/feat/focus_handler.hpp>
 
 struct SDL_MouseButtonEvent;
@@ -10,35 +9,22 @@ struct SDL_MouseMotionEvent;
 
 namespace bwidgets
 {
-    class MouseHandler : public virtual FocusHandler
+    class MouseHandler : virtual public FocusHandler,
+                         virtual public EventHandler
     {
     protected:
-        const SDL_Rect* _click_area = nullptr;
-        bool            _is_hovered = false;
-        bool            _is_pushed  = false;
+        using EventHandler::EventHandler;
 
-        virtual void _handle_mouse_button(const SDL_MouseButtonEvent&,
-                                          const SDL_Rect&) {};
-        virtual void _handle_mouse_motion(const SDL_MouseMotionEvent&,
-                                          const SDL_Rect&) {};
-        virtual void _on_push(bool) {};
+        virtual void _on_push(bool) = 0;
 
     public:
-        std::function<void(const SDL_MouseButtonEvent&)> click_handler = nullptr;
-
-        using FocusHandler::FocusHandler;
-
-        MouseHandler(const MouseHandler&) = delete;
-        MouseHandler(MouseHandler&&)      = delete;
-        ~MouseHandler() override          = default;
-        auto operator=(const MouseHandler&) = delete;
-        auto operator=(MouseHandler&&) = delete;
-
-        virtual auto handle_mouse(const SDL_MouseButtonEvent&, const SDL_Rect&)
-          -> MouseHandler* final;
-        virtual auto handle_mouse(const SDL_MouseMotionEvent&, const SDL_Rect&)
-          -> MouseHandler* final;
-        virtual auto push(bool) -> MouseHandler* final;
+        virtual void click_handler(std::function<void(const SDL_MouseButtonEvent&)>) = 0;
+        virtual void disable_mouse_handler()                                         = 0;
+        virtual void enable_mouse_handler(const SDL_Rect*, const SDL_Rect*)          = 0;
+        [[nodiscard]] virtual bool hovered() const                                   = 0;
+        virtual void
+        mouse_motion_handler(std::function<void(const SDL_MouseMotionEvent&)>) = 0;
+        [[nodiscard]] virtual bool pushed() const                              = 0;
     };
 }
 
diff --git a/inc/basic_widgets/w/feat/mouse_handler_impl.hpp b/inc/basic_widgets/w/feat/mouse_handler_impl.hpp
new file mode 100644
index 0000000..90c45c1
--- /dev/null
+++ b/inc/basic_widgets/w/feat/mouse_handler_impl.hpp
@@ -0,0 +1,54 @@
+#ifndef BWIDGETS_MOUSE_HANDLER_IMPL_HPP
+#define BWIDGETS_MOUSE_HANDLER_IMPL_HPP
+
+#include <basic_widgets/w/feat/event_handler_impl.hpp>
+#include <basic_widgets/w/feat/focus_handler_impl.hpp>
+#include <basic_widgets/w/feat/mouse_handler.hpp>
+
+namespace bwidgets
+{
+    class MouseHandlerImpl : public MouseHandler,
+                             virtual public EventHandlerImpl,
+                             virtual public FocusHandlerImpl
+    {
+    private:
+        bool _hovered {false};
+        bool _pushed {false};
+
+        std::function<void(const SDL_MouseButtonEvent&)> _click_handler {[](auto) {}};
+        std::function<void(const SDL_MouseMotionEvent&)> _motion_handler {[](auto) {}};
+
+    protected:
+        using MouseHandler::MouseHandler;
+
+        void _on_push(bool) override {}
+
+    public:
+        void
+        click_handler(std::function<void(const SDL_MouseButtonEvent&)> handler) override
+        {
+            _click_handler = std::move(handler);
+        }
+
+        void disable_mouse_handler() override;
+
+        void enable_mouse_handler(const SDL_Rect*, const SDL_Rect*) override;
+        [[nodiscard]] bool hovered() const override
+        {
+            return _hovered;
+        }
+
+        void mouse_motion_handler(
+          std::function<void(const SDL_MouseMotionEvent&)> handler) override
+        {
+            _motion_handler = std::move(handler);
+        }
+
+        [[nodiscard]] bool pushed() const override
+        {
+            return _pushed;
+        }
+    };
+}
+
+#endif
diff --git a/inc/basic_widgets/w/numeric_input.hpp b/inc/basic_widgets/w/numeric_input.hpp
index a5ec8c9..3fa8a74 100644
--- a/inc/basic_widgets/w/numeric_input.hpp
+++ b/inc/basic_widgets/w/numeric_input.hpp
@@ -2,14 +2,13 @@
 #define BWIDGETS_NUMERIC_INPUT_HPP
 
 #include <limits>
+#include <type_traits>
 
 #include <basic_widgets/core/math.hpp>
 #include <basic_widgets/core/type/concepts.hpp>
 #include <basic_widgets/w/base/input.hpp>
 #include <basic_widgets/w/button.hpp>
 
-#include <type_traits>
-
 namespace bwidgets
 {
     template<Numeric T>
@@ -94,25 +93,25 @@ namespace bwidgets
 
             _increment_button.text("+");
 
-            _increment_button.click_handler = [this](const SDL_MouseButtonEvent&) {
+            _increment_button.click_handler([this](const SDL_MouseButtonEvent&) {
                 T new_value = this->value + button_step;
                 if (_value_range.second - this->value < button_step)
                     new_value = _value_range.second;
 
                 this->value = new_value;
                 this->input_text(this->value_to_string(new_value));
-            };
+            });
 
             _decrement_button.text("-");
 
-            _decrement_button.click_handler = [this](const SDL_MouseButtonEvent&) {
+            _decrement_button.click_handler([this](const SDL_MouseButtonEvent&) {
                 T new_value = this->value - button_step;
                 if (this->value - _value_range.first < button_step)
                     new_value = _value_range.first;
 
                 this->value = new_value;
                 this->input_text(this->value_to_string(new_value));
-            };
+            });
         }
 
         NumericInput(const NumericInput&) = delete;
@@ -121,12 +120,11 @@ namespace bwidgets
         auto operator=(const NumericInput&) = delete;
         auto operator=(NumericInput&&) = delete;
 
-        auto handle_event(const SDL_Event& ev) -> Widget* override
+        void handle_event(const SDL_Event& ev) override
         {
             Input<T>::handle_event(ev);
             _increment_button.handle_event(ev);
             _decrement_button.handle_event(ev);
-            return this;
         }
 
         [[nodiscard]] auto is_valid_input(const std::string& input) const noexcept
diff --git a/meson.build b/meson.build
index 543b837..ae393ae 100644
--- a/meson.build
+++ b/meson.build
@@ -9,7 +9,7 @@ project('sdl2_basic_widgets', 'cpp',
     ],
     license: 'EUPL-1.2')
 
-add_project_arguments('-pedantic', '-Winline', language: 'cpp')
+add_project_arguments('-pedantic', language: 'cpp')
 
 if (get_option('buildtype').startswith('debug'))
     add_project_arguments('-DBWIDGETS_DEBUG', language: 'cpp')
@@ -32,7 +32,9 @@ libbasic_widgets = static_library('basic_widgets',
     'src/w/base/widget.cpp',
     'src/w/button.cpp',
     'src/w/caption.cpp',
-    'src/w/feat/mouse_handler.cpp',
+    'src/w/feat/event_handler_impl.cpp',
+    'src/w/feat/keyboard_handler_impl.cpp',
+    'src/w/feat/mouse_handler_impl.cpp',
     dependencies : [sdl, fontconfig],
     include_directories : pub_api,
     install : true)
@@ -44,24 +46,28 @@ libbasic_widgets_dep = declare_dependency(
 
 executable('button_demo',
     'examples/button_example.cpp',
+    dependencies: [sdl],
     include_directories : pub_api,
     link_with : libbasic_widgets,
     install : false)
 
 executable('caption_demo',
     'examples/caption_example.cpp',
+    dependencies: [sdl],
     include_directories : pub_api,
     link_with : libbasic_widgets,
     install : false)
 
 executable('example_demo',
     'examples/example_example.cpp',
+    dependencies: [sdl],
     include_directories : pub_api,
     link_with : libbasic_widgets,
     install : false)
 
 executable('input_demo',
     'examples/input_example.cpp',
+    dependencies: [sdl],
     include_directories : pub_api,
     link_with : libbasic_widgets,
     install : false)
diff --git a/src/w/base/layout.cpp b/src/w/base/layout.cpp
index a04e631..c3e0531 100644
--- a/src/w/base/layout.cpp
+++ b/src/w/base/layout.cpp
@@ -17,10 +17,10 @@ void Layout::for_widgets(const std::function<void(Widget*)>& f)
     for (const auto& w : _widgets) f(w.get());
 }
 
-auto Layout::handle_event(const SDL_Event& ev) -> Layout*
+void Layout::handle_event(const SDL_Event& ev)
 {
+    EventHandlerImpl::handle_event(ev);
     for (const auto& w : _widgets) w->handle_event(ev);
-    return this;
 }
 
 void Layout::_handle_geometry_change(const SDL_Rect& vp)
diff --git a/src/w/base/widget.cpp b/src/w/base/widget.cpp
index d058c77..c96be7c 100644
--- a/src/w/base/widget.cpp
+++ b/src/w/base/widget.cpp
@@ -1,41 +1,7 @@
-#include <SDL2/SDL_assert.h>
-#include <SDL2/SDL_events.h>
-
 #include <basic_widgets/w/base/widget.hpp>
-#include <basic_widgets/w/feat/keyboard_handler.hpp>
-#include <basic_widgets/w/feat/mouse_handler.hpp>
 
 using namespace bwidgets;
 
-auto Widget::handle_event(const SDL_Event& ev) -> Widget*
-{
-    if (auto* handler = dynamic_cast<KeyboardHandler*>(this); handler) {
-        switch (ev.type) {
-            case SDL_KEYDOWN:
-            case SDL_KEYUP:
-                handler->handle_keyboard(ev.key);
-                break;
-            case SDL_TEXTINPUT:
-                handler->handle_keyboard(ev.text);
-                break;
-        }
-    }
-
-    if (auto* handler = dynamic_cast<MouseHandler*>(this); handler) {
-        switch (ev.type) {
-            case SDL_MOUSEBUTTONDOWN:
-            case SDL_MOUSEBUTTONUP:
-                handler->handle_mouse(ev.button, _viewport);
-                break;
-            case SDL_MOUSEMOTION:
-                handler->handle_mouse(ev.motion, _viewport);
-                break;
-        }
-    }
-
-    return this;
-}
-
 auto Widget::render() -> Widget*
 {
     if (_renderer == nullptr) return this;
diff --git a/src/w/button.cpp b/src/w/button.cpp
index fbdb8c5..1d6bc43 100644
--- a/src/w/button.cpp
+++ b/src/w/button.cpp
@@ -13,13 +13,13 @@ const Color Button::default_color_fg {0, 0, 0, SDL_ALPHA_OPAQUE};
 
 Button::Button(Widget* parent) noexcept : Widget {parent}, _caption {this}
 {
-    _focus_area = _click_area = &_widget_area;
-    _caption.alignment        = Caption::Alignment::CENTER;
+    enable_mouse_handler(&_widget_area, &_viewport);
+    _caption.alignment = Caption::Alignment::CENTER;
 
     _caption.render_mode(Font::RenderMode::BLENDED);
 
     border_gradient = [this](int len, int pos, float divider) -> Color {
-        const auto& end_color   = _is_hovered ? color_bg_hover : color_bg;
+        const auto& end_color   = hovered() ? color_bg_hover : color_bg;
         const auto  start_color = end_color / divider;
         const auto  factor      = linear(pos, 0, len);
         return lerp(start_color, end_color, factor);
@@ -74,8 +74,8 @@ void Button::_handle_renderer_change(const std::shared_ptr<Renderer>& r)
 
 void Button::_handle_rendering()
 {
-    Color      c       = _is_hovered ? color_bg_hover : color_bg;
-    const auto divider = _is_pushed ? 1.5 : 2;
+    Color      c       = hovered() ? color_bg_hover : color_bg;
+    const auto divider = pushed() ? 1.5 : 2;
     auto       x       = 0;
     auto       y       = 0;
     const auto biggest = border_size.w > border_size.h ? border_size.w : border_size.h;
diff --git a/src/w/feat/event_handler_impl.cpp b/src/w/feat/event_handler_impl.cpp
new file mode 100644
index 0000000..743070b
--- /dev/null
+++ b/src/w/feat/event_handler_impl.cpp
@@ -0,0 +1,32 @@
+#include <basic_widgets/w/feat/event_handler_impl.hpp>
+
+using namespace bwidgets;
+
+void EventHandlerImpl::handle_event(const SDL_Event& ev)
+{
+    auto type = static_cast<SDL_EventType>(ev.type);
+    if (!_event_handlers.contains(type)) return;
+
+    _event_handlers[type](ev);
+}
+
+auto EventHandlerImpl::_add_event_handler(handler_t event_handler) -> bool
+{
+    if (_event_handlers.contains(event_handler.first)) return false;
+
+    _event_handlers.emplace(event_handler);
+    return true;
+}
+
+auto EventHandlerImpl::_remove_event_handler(SDL_EventType ev_type)
+  -> std::pair<handler_t, bool>
+{
+    handler_t handler;
+    auto      pos = _event_handlers.find(ev_type);
+    if (pos == _event_handlers.end()) return {handler, false};
+
+    handler = {ev_type, _event_handlers[ev_type]};
+    _event_handlers.erase(pos);
+
+    return {handler, true};
+}
diff --git a/src/w/feat/keyboard_handler_impl.cpp b/src/w/feat/keyboard_handler_impl.cpp
new file mode 100644
index 0000000..9128ccc
--- /dev/null
+++ b/src/w/feat/keyboard_handler_impl.cpp
@@ -0,0 +1,23 @@
+#include <basic_widgets/w/feat/keyboard_handler_impl.hpp>
+
+using namespace bwidgets;
+
+void KeyboardHandlerImpl::disable_keyboard_handler()
+{
+    _remove_event_handler(SDL_KEYDOWN);
+    _remove_event_handler(SDL_KEYUP);
+    _remove_event_handler(SDL_TEXTINPUT);
+}
+
+void KeyboardHandlerImpl::enable_keyboard_handler()
+{
+    const auto keyboard_handler = [this](const SDL_Event& ev) {
+        if (FocusHandlerImpl::focus()) _key_handler(ev.key);
+    };
+
+    _add_event_handler({SDL_KEYDOWN, keyboard_handler});
+    _add_event_handler({SDL_KEYUP, keyboard_handler});
+    _add_event_handler({SDL_TEXTINPUT, [this](const SDL_Event& ev) {
+                            if (FocusHandlerImpl::focus()) _input_handler(ev.text);
+                        }});
+}
diff --git a/src/w/feat/mouse_handler.cpp b/src/w/feat/mouse_handler.cpp
deleted file mode 100644
index 437042c..0000000
--- a/src/w/feat/mouse_handler.cpp
+++ /dev/null
@@ -1,60 +0,0 @@
-#include <SDL2/SDL_events.h>
-#include <SDL2/SDL_rect.h>
-
-#include <basic_widgets/core/math.hpp>
-#include <basic_widgets/w/feat/mouse_handler.hpp>
-
-using namespace bwidgets;
-
-auto MouseHandler::handle_mouse(const SDL_MouseButtonEvent& ev, const SDL_Rect& orig)
-  -> MouseHandler*
-{
-    if (_click_area == nullptr) return this;
-
-    const SDL_Point p {ev.x, ev.y};
-    const SDL_Rect  vp {rect_offset(*_click_area, orig)};
-
-    if (ev.type == SDL_MOUSEBUTTONDOWN) {
-        if (SDL_PointInRect(&p, &vp) == SDL_TRUE) {
-            push(true);
-            _handle_mouse_button(ev, vp);
-        }
-        else focus(false);
-    }
-    else {
-        if (_is_pushed) {
-            if (SDL_PointInRect(&p, &vp) == SDL_TRUE) {
-                focus(true);
-
-                if (click_handler != nullptr) click_handler(ev);
-            }
-            push(false);
-            _handle_mouse_button(ev, vp);
-        }
-    }
-
-    return this;
-}
-
-auto MouseHandler::handle_mouse(const SDL_MouseMotionEvent& ev, const SDL_Rect& orig)
-  -> MouseHandler*
-{
-    if (_click_area == nullptr) return this;
-
-    const SDL_Point p {ev.x, ev.y};
-    const SDL_Rect  vp {rect_offset(*_click_area, orig)};
-
-    _is_hovered = SDL_PointInRect(&p, &vp) != 0;
-
-    if (_is_hovered) _handle_mouse_motion(ev, orig);
-
-    return this;
-}
-
-auto MouseHandler::push(bool state) -> MouseHandler*
-{
-    _on_push(state);
-    _is_pushed = state;
-
-    return this;
-}
diff --git a/src/w/feat/mouse_handler_impl.cpp b/src/w/feat/mouse_handler_impl.cpp
new file mode 100644
index 0000000..f61f4e5
--- /dev/null
+++ b/src/w/feat/mouse_handler_impl.cpp
@@ -0,0 +1,50 @@
+#include <basic_widgets/core/math.hpp>
+#include <basic_widgets/w/feat/mouse_handler_impl.hpp>
+
+using namespace bwidgets;
+
+void MouseHandlerImpl::disable_mouse_handler()
+{
+    EventHandlerImpl::_remove_event_handler(SDL_MOUSEBUTTONDOWN);
+    EventHandlerImpl::_remove_event_handler(SDL_MOUSEBUTTONUP);
+    _remove_event_handler(SDL_MOUSEMOTION);
+}
+
+// NOLINTNEXTLINE(readability-function-cognitive-complexity)
+void MouseHandlerImpl::enable_mouse_handler(const SDL_Rect* area, const SDL_Rect* vp)
+{
+    if (!area || !vp) throw std::logic_error("ptr parameters cannot be null.");
+
+    _add_event_handler({SDL_MOUSEBUTTONDOWN, [this, area, vp](const SDL_Event& ev) {
+                            auto      absolute_area = rect_offset(*area, *vp);
+                            SDL_Point p             = {ev.button.x, ev.button.y};
+                            if (SDL_PointInRect(&p, &absolute_area) == SDL_FALSE) {
+                                FocusHandlerImpl::focus(false);
+                                return;
+                            }
+                            _on_push(true);
+                            _pushed = true;
+                        }});
+    _add_event_handler({SDL_MOUSEBUTTONUP, [this, area, vp](const SDL_Event& ev) {
+                            auto      absolute_area = rect_offset(*area, *vp);
+                            SDL_Point p             = {ev.button.x, ev.button.y};
+                            if (_pushed) {
+                                _on_push(false);
+                                _pushed = false;
+                            }
+                            if (SDL_PointInRect(&p, &absolute_area) == SDL_FALSE) return;
+
+                            FocusHandlerImpl::focus(true);
+                            _click_handler(ev.button);
+                        }});
+    _add_event_handler({SDL_MOUSEMOTION, [this, area, vp](const SDL_Event& ev) {
+                            auto      absolute_area = rect_offset(*area, *vp);
+                            SDL_Point p             = {ev.motion.x, ev.motion.y};
+                            if (SDL_PointInRect(&p, &absolute_area) == SDL_FALSE) {
+                                _hovered = false;
+                                return;
+                            }
+                            _hovered = true;
+                            _motion_handler(ev.motion);
+                        }});
+}