add missing examples

examples/button_example.cpp

@@ -0,0 +1,19 @@
+#include <iostream>
+
+#include <basic_widgets/w/button.hpp>
+
+#include "run.hpp"
+
+using widget::Button;
+
+int main()
+{
+    run_example<Button>([](Button* w, core::Font* f, int x, int y) {
+            w->click_handler = [x, y](const SDL_MouseButtonEvent&) {
+                std::cout << "button(" << x << ',' << y << "):click!" << std::endl;
+            };
+            w->font(f);
+            w->text("¡jello!");
+            });
+    return 0;
+}

examples/caption_example.cpp

@@ -0,0 +1,15 @@
+#include <basic_widgets/w/caption.hpp>
+
+#include "run.hpp"
+
+using widget::Caption;
+
+int main()
+{
+    run_example<Caption>([](Caption* w, core::Font* f, int, int) {
+            w->alignment.h = Caption::AlignmentH::CENTER;
+            w->text("¡jello!");
+            w->font(f);
+            });
+    return 0;
+}

examples/input_example.cpp

@@ -6,10 +6,10 @@ using widget::NumericInput;
 
 int main()
 {
-    run_example<NumericInput<float> >([](NumericInput<float>* w, core::Font* f) {
+    run_example<NumericInput<float> >([](NumericInput<float>* w, core::Font* f, int, int) {
             w->font(f);
             w->button_step = 0.5;
-            w->value_range(-3.14, 8);
+            w->value_range(-3.14, 8.5);
             });
     return 0;
 }

examples/run.hpp

@@ -0,0 +1,93 @@
+#ifndef BWIDGETS_EXAMPLES_RUN_HPP_
+#define BWIDGETS_EXAMPLES_RUN_HPP_
+
+#include <concepts>
+#include <functional>
+#include <iostream>
+
+#include <SDL2/SDL.h>
+#include <SDL2/SDL_ttf.h>
+
+#include <basic_widgets/core/font.hpp>
+#include <basic_widgets/core/renderer.hpp>
+#include <basic_widgets/w/base/widget.hpp>
+#include <basic_widgets/w/horizontal_layout.hpp>
+#include <basic_widgets/w/vertical_layout.hpp>
+
+using namespace bwidgets;
+
+template<typename T>
+concept Widget = std::derived_from<T, widget::Widget>;
+
+template<Widget W>
+void run_example(std::function<void (W*, core::Font*, int, int)> setup)
+{
+    try
+    {
+        core::SDLError::success_or_throw(SDL_Init(SDL_INIT_VIDEO),
+                __FILE__, __FUNCTION__, __LINE__);
+        core::SDLError::success_or_throw(TTF_Init(),
+                __FILE__, __FUNCTION__, __LINE__);
+
+        const core::Size size_init {854, 480};
+        auto* font     {new core::Font(core::Font::find("Monospace"), 24)};
+        auto* win      {SDL_CreateWindow("basic_widgets example",
+                SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
+                size_init.w, size_init.h,
+                SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE | SDL_WINDOW_UTILITY)};
+        auto* renderer {new core::Renderer(win, -1, SDL_RENDERER_ACCELERATED)};
+
+        auto* layout   {new widget::HorizontalLayout()};
+
+        for (auto y = 0; y < 3; y++)
+        {
+            auto* col = new widget::VerticalLayout();
+            for (auto x = 0; x < 3; x++)
+            {
+                auto* widget = new W();
+                setup(widget, font, x, y);
+                col->add_widget(widget);
+            }
+            layout->add_widget(col);
+        }
+
+        layout->renderer(renderer);
+        layout->viewport({0, 0, size_init.w, size_init.h});
+
+        bool quit {false};
+        while (!quit)
+        {
+            SDL_Event ev;
+            while (SDL_PollEvent(&ev) != 0)
+            {
+                switch (ev.type)
+                {
+                    case SDL_QUIT:
+                        quit = true;
+                        break;
+                    case SDL_WINDOWEVENT:
+                        if (ev.window.event == SDL_WINDOWEVENT_SIZE_CHANGED)
+                        {
+                            auto size = renderer->output_size();
+                            layout->viewport({0, 0, size.w, size.h});
+                        }
+                        break;
+                }
+                layout->handle_event(ev);
+            }
+
+            renderer->draw_color({25, 25, 25, SDL_ALPHA_OPAQUE});
+            renderer->clear();
+
+            layout->render();
+            renderer->present();
+        }
+    }
+    catch (const core::SDLError& e)
+    {
+        std::cerr << "Error: " << e.file << ":" << e.func << ":" << e.line
+            << ": " << e.what << std::endl;
+    }
+}
+
+#endif