# YASL (Yet Another Surface Library)

YASL is a minimal, modern, and high-performance desktop window surface library written in C.

It provides window creation, frame pacing, high-DPI scaling, and input routing without bundling audio, physics, or game engine components.

## Features

- **Lean Core**: No audio, no font rendering, and no widget toolkit overhead.
- **Wayland Protocol Coverage**:
  - `xdg-shell` toplevels and hierarchical popups (`xdg_popup` + `xdg_positioner`).
  - Fractional scaling via `wp_fractional_scale_v1` and `wp_viewporter`.
  - Presentation feedback and refresh rate timing via `wp_presentation` and `wp_fifo_v1`.
  - Cursor shapes via `wp_cursor_shape_device_v1`.
  - Graphics tablets and stylus input via `zwp_tablet_v2` (pressure, tilt, eraser).
  - Text Input Method (IME) composition via `zwp_text_input_v3`.
  - Primary selection and clipboard transfers via `wl_data_device` and `zwp_primary_selection_v1`.
  - Interactive client-side window move and resize triggers (`xdg_toplevel_move`, `xdg_toplevel_resize`).
- **macOS Cocoa & Metal**:
  - Native `NSWindow` and `CAMetalLayer` presentation.
  - Vsync pacing via `CADisplayLink`.
- **Zero Framework Leaks**:
  - Self-contained UTF-8 validation.
  - Self-contained event queue.
  - No terminal-specific telemetry or hardcoded application names.

## Building

Build with Meson and Ninja:

```sh
meson setup build
ninja -C build
ninja -C build test
```

## Quick Example

```c
#include <yasl/yasl.h>

static bool running = true;

static void on_draw(struct yasl_surface *s, struct yasl_frame *frame, void *ud)
{
    /* Present frame target */
    struct yasl_damage_list dmg = { .n = -1 };
    yasl_surface_present(s, &frame->target, &dmg);
}

static void on_close(struct yasl_surface *s, void *ud)
{
    (void)s; (void)ud;
    running = false;
}

int main(void)
{
    struct yasl_display_spec dspec = { .app_id = "org.example.app" };
    struct yasl_display *d = yasl_display_open(NULL, &dspec);

    struct yasl_surface_spec sspec = {
        .title = "YASL Application",
        .size = { .x = 800, .y = 600 },
    };
    struct yasl_surface *s = yasl_surface_create_toplevel(d, &sspec);
    struct yasl_surface_cbs cbs = {
        .draw = on_draw,
        .close = on_close,
    };
    yasl_surface_set_callbacks(s, &cbs, NULL);
    yasl_surface_schedule_redraw(s);

    while (running) {
        yasl_display_dispatch(d);
        struct yasl_input_event ev;
        while (yasl_surface_input_poll(s, &ev)) {
            if (ev.kind == YASL_INPUT_KEY && ev.key.action == YASL_KEY_PRESS) {
                if (ev.key.key == 0xff1b) /* Escape */
                    running = false;
            }
        }
        yasl_display_flush(d);
    }

    yasl_surface_destroy(s);
    yasl_display_close(d);
    return 0;
}
```

## License

MIT License.