From a089056a95104576ab9832b01c67009f4e040243 Mon Sep 17 00:00:00 2001
From: Tom Smeding <tom.smeding@gmail.com>
Date: Sun, 12 Apr 2020 17:19:11 +0200
Subject: Initial commit

---
 .gitignore |   1 +
 window.h   | 126 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 127 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 window.h

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..9bf3746
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+compile_commands.json
diff --git a/window.h b/window.h
new file mode 100644
index 0000000..3ecfe57
--- /dev/null
+++ b/window.h
@@ -0,0 +1,126 @@
+#pragma once
+
+// Easy window creation in C++.
+//
+// This header-only library uses SDL; therefore, on a Linux system, you need to
+// add something to the effect of the following to your build system:
+//   CFLAGS += $(shell pkg-config --cflags sdl2)
+//   LDFLAGS += $(shell pkg-config --libs sdl2)
+
+#include <string>
+#include <vector>
+#include <functional>
+#include <stdexcept>
+#include <SDL.h>
+
+
+class Window {
+public:
+	class Opts {
+	public:
+		inline Opts() = default;
+
+		inline Opts& fullscreen(bool f) { _fullscreen = f; return *this; }
+		inline Opts& resizeable(bool r) { _resizable = r; return *this; }
+
+		inline bool fullscreen() const { return _fullscreen; }
+		inline bool resizable() const { return _resizable; }
+
+	private:
+		bool _fullscreen = false;
+		bool _resizable = false;
+	};
+
+	/// The width and height passed to this function are _suggestions_.
+	/// The window manager may decide to use some other size instead, and this
+	/// size may also change during execution (especially if resizable, but
+	/// perhaps also otherwise).
+	inline Window(const std::string &title, int wid_sugg, int hei_sugg);
+	inline Window(const std::string &title, int wid_sugg, int hei_sugg, Opts opts);
+
+	inline ~Window();
+
+	/// The draw buffer will be of size 3 * width * height; row-major order, RGB pixels.
+	using DrawHandler = std::function<void(std::vector<uint8_t> &drawbuf, int width, int height)>;
+	/// Return true to stop the event loop.
+	using EventHandler = std::function<bool(const SDL_Event&)>;
+
+	/// The draw function will be called after each invocation of the event
+	/// function, and might also be invoked more often as the user re-focuses the
+	/// window.
+	inline void event_loop(EventHandler eventfunc, DrawHandler drawfunc);
+
+private:
+	SDL_Window *win = nullptr;
+	std::vector<uint8_t> drawbuf;
+	SDL_Surface *surface = nullptr;
+	int surf_wid = -1, surf_hei = -1;
+};
+
+inline Window::Window(const std::string &title, int wid_sugg, int hei_sugg)
+	: Window(title, wid_sugg, hei_sugg, Opts{})
+{}
+
+inline Window::Window(const std::string &title, int wid_sugg, int hei_sugg, Opts opts) {
+	if (SDL_Init(SDL_INIT_VIDEO) < 0) {
+		throw std::runtime_error(std::string{"SDL init error: "} + SDL_GetError());
+	}
+
+	Uint32 flags = 0;
+	if (opts.fullscreen()) flags |= SDL_WINDOW_FULLSCREEN;
+	if (opts.resizable()) flags |= SDL_WINDOW_RESIZABLE;
+
+	win = SDL_CreateWindow(
+		title.data(), SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
+		wid_sugg, hei_sugg, flags
+	);
+	if (!win) {
+		throw std::runtime_error(std::string{"SDL window creation error: "} + SDL_GetError());
+	}
+
+	SDL_GetWindowSize(win, &surf_wid, &surf_hei);
+	drawbuf.resize(3 * surf_wid * surf_hei);
+	surface = SDL_CreateRGBSurfaceFrom(
+		drawbuf.data(), surf_wid, surf_hei, 24, 3 * surf_wid,
+		255, 255 << 8, 255 << 16, 0
+	);
+
+	SDL_BlitSurface(surface, nullptr, SDL_GetWindowSurface(win), nullptr);
+	SDL_UpdateWindowSurface(win);
+}
+
+inline Window::~Window() {
+	if (surface) SDL_FreeSurface(surface);
+	SDL_DestroyWindow(win);
+	SDL_Quit();
+}
+
+inline void Window::event_loop(EventHandler eventfunc, DrawHandler drawfunc) {
+	SDL_Event e;
+	while (true) {
+		if (SDL_WaitEvent(&e) == 0) {
+			throw std::runtime_error(std::string{"SDL event wait error: "} + SDL_GetError());
+		}
+
+		if (e.type == SDL_QUIT) break;
+
+		if (eventfunc(e)) break;
+
+		int width, height;
+		SDL_GetWindowSize(win, &width, &height);
+
+		if (width != surf_wid || height != surf_hei) {
+			SDL_FreeSurface(surface);
+
+			surf_wid = width;
+			surf_hei = height;
+			drawbuf.resize(3 * surf_wid * surf_hei);
+			surface = SDL_CreateRGBSurfaceFrom(
+				drawbuf.data(), surf_wid, surf_hei, 24, 3 * surf_wid,
+				255, 255 << 8, 255 << 16, 0
+			);
+		}
+
+		drawfunc(drawbuf, width, height);
+	}
+}
-- 
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