initial work

button.cpp

@@ -0,0 +1,35 @@
+#include "button.hpp"
+#include "widget.hpp"
+#include <SDL2/SDL_render.h>
+
+Button::Button(SDL_Renderer* r, SDL_Rect& vp)
+    : Widget(r, vp)
+{
+}
+
+void Button::handle_event(const SDL_Event& ev)
+{
+}
+
+void Button::render()
+{
+    SDL_Rect old_vp;
+
+    SDL_RenderGetViewport(_renderer, &old_vp);
+    SDL_RenderSetViewport(_renderer, &viewport);
+
+    for (int i = 0; i < 5; i++)
+    {
+        SDL_SetRenderDrawColor(
+                _renderer,
+                background_color.r * 10 / (i + 11),
+                background_color.g * 10 / (i + 11),
+                background_color.b * 10 / (i + 11),
+                background_color.a
+                );
+        SDL_Rect rect = {i, i, viewport.w - i * 2, viewport.h - 2 * i};
+        SDL_RenderFillRect(_renderer, &rect);
+    }
+
+    SDL_RenderSetViewport(_renderer, &old_vp);
+}

button.hpp

@@ -0,0 +1,16 @@
+#ifndef BUTTON_HPP
+#define BUTTON_HPP
+
+#include "widget.hpp"
+
+class Button : Widget
+{
+public:
+    SDL_Color background_color = {100, 100, 100, SDL_ALPHA_OPAQUE};
+
+    Button(SDL_Renderer*, SDL_Rect&);
+    virtual void handle_event(const SDL_Event&);
+    virtual void render();
+};
+
+#endif

meson.build

@@ -0,0 +1,10 @@
+project('sdl2_basic_widgets', 'cpp',
+  version : '0.1',
+  default_options : ['warning_level=3', 'cpp_std=c++14'])
+
+executable('sdl2_basic_widgets',
+           'widget_test.cpp',
+           'button.cpp',
+           dependencies : [
+              dependency('sdl2')],
+           install : true)

widget.hpp

@@ -0,0 +1,20 @@
+#ifndef WIDGET_HPP
+#define WIDGET_HPP
+
+#include <SDL2/SDL.h>
+
+class Widget
+{
+protected:
+    SDL_Renderer* _renderer;
+
+public:
+    SDL_Rect& viewport;
+
+    Widget(SDL_Renderer* r, SDL_Rect& vp) : _renderer(r), viewport(vp) {};
+    virtual ~Widget() {}
+    virtual void handle_event(const SDL_Event&) = 0;
+    virtual void render() = 0;
+};
+
+#endif

widget_test.cpp

@@ -0,0 +1,60 @@
+#include "button.hpp"
+#include <SDL2/SDL_pixels.h>
+#include <SDL2/SDL_render.h>
+
+int main()
+{
+    int width = 320;
+    int height = 240;
+
+    SDL_Init(SDL_INIT_VIDEO);
+    SDL_Window* win = SDL_CreateWindow(
+            "Widget test",
+            SDL_WINDOWPOS_UNDEFINED,
+            SDL_WINDOWPOS_UNDEFINED,
+            width,
+            height,
+            SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE
+            );
+    SDL_Renderer* rend = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED);
+    SDL_SetRenderDrawBlendMode(rend, SDL_BLENDMODE_BLEND);
+
+    SDL_Rect widget_vp = {10, 10, width - 20, height - 20};
+    Button widget = Button(rend, widget_vp);
+    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)
+                    {
+                        SDL_GetRendererOutputSize(rend, &width, &height);
+                        widget_vp.w = width - 20;
+                        widget_vp.h = height - 20;
+                    }
+                    break;
+                case SDL_MOUSEBUTTONUP:
+                    //_handle_click({ev.button.x, ev.button.y});
+                    break;
+            }
+        }
+
+        SDL_SetRenderDrawColor(rend, 0, 0, 0, SDL_ALPHA_OPAQUE);
+        SDL_RenderClear(rend);
+
+        widget.render();
+        SDL_RenderPresent(rend);
+    }
+
+    SDL_DestroyRenderer(rend);
+    SDL_DestroyWindow(win);
+    SDL_Quit();
+    return 0;
+}