mkwin

A tiny window/platform layer for Linux (X11) and Windows (Win32). It owns the OS window, a shared-memory framebuffer, DPI scale, and the input/event pump - and nothing else. No widgets, no layout, no theming, no text layout. You draw 32-bit pixels into a buffer it hands you and tell it to present.

mkwin was split out of the mkgui toolkit so the same window layer can back both mkgui and bespoke programs that do their own rendering - a skinned media player, a demo, a tool - without dragging a whole widget toolkit along. mkgui consumes mkwin as a submodule; a standalone program consumes it the same way.

What it does: create/destroy top-level and transient windows, hand you a software framebuffer sized to the window, present it (XShm / GDI DIB), pump input as neutral events you pull, and cover the platform-specific plumbing around it - DPI scaling, window geometry and min-size, undecorated and arbitrarily shaped windows, cursors, class/icon hints, override-redirect popups (menus/tooltips), clipboard (including the X11 INCR protocol for large selections), file drag-and-drop, a monotonic clock, and two opt-in modules (glyph rasterization, embedded OpenGL child windows).

What it deliberately does not do: anything above the pixel. No drawing primitives, no fonts-as-text, no widgets, no layout, no event meaning. mkwin never calls back into your logic; it hands you input and a buffer and gets out of the way.

C99. Single translation unit.

mkwin is source-level and single-TU. Your program includes the header for the API and includes the platform .c exactly once into its own translation unit:

#include "mkwin.h"
#ifdef _WIN32
#include "mkwin_win32.c"
#else
#include "mkwin_linux.c"
#endif

MKWIN_API is static by default, so everything folds into your unity build with no exported symbols. Define MKWIN_LIBRARY to build mkwin as a standalone object with external linkage instead.

The two optional modules are off unless you ask:

• -DMKWIN_FONT compiles the glyph-rasterization primitive (FreeType on Linux, GDI on Windows). A program with its own bitmap font leaves it undefined.
• -DMKWIN_GLVIEW compiles the embedded-OpenGL child-window support.

git submodule add https://github.com/vtlmks/mkwin.git mkwin

then build with -Imkwin so the #includes resolve.

mkwin owns the framebuffer, dimensions and DPI scale, but a host reads them every frame. Rather than route every read through an accessor, you may hand mkwin_open the addresses of your own fields via struct mkwin_host; mkwin writes through them whenever a value changes (open, resize, DPI change). Pass a zeroed struct (or NULL) to use the accessors (mkwin_framebuffer, mkwin_size, mkwin_scale) exclusively - they are always valid.

#include "mkwin.h"
#include "mkwin_linux.c"   // once, in this TU (mkwin_win32.c on Windows)

int main(void) {
	uint32_t *fb;
	int32_t   w, h;
	float     scale;
	struct mkwin_host host = { &fb, &w, &h, &scale };

	struct mkwin_window *win = mkwin_open(NULL, "mkwin", 800, 600, 0, "mkwin-example", &host);
	if(!win) {
		return 1;
	}
	mkwin_map(win);

	uint32_t running = 1;
	while(running) {
		mkwin_wait(win, -1);            // block until there is input
		struct mkwin_event ev;
		while(mkwin_poll(win, &ev)) {
			if(ev.type == MKWIN_EV_CLOSE) {
				running = 0;
			}
			// fb / w / h are already up to date after MKWIN_EV_RESIZE
		}

		for(int32_t i = 0; i < w * h; ++i) {
			fb[i] = 0x00204060;         // one 0x00RRGGBB pixel per element
		}
		mkwin_present(win);
	}

	mkwin_destroy(win);
	return 0;
}

Build it (Linux, as a standalone object):

gcc -std=c99 -O2 -DMKWIN_LIBRARY example.c -o example -lX11 -lXext

Full API reference: documentation/doc.md.

MIT. See LICENSE. Copyright (c) 2026 Peter Fors.