feat: add type-safe native platform headers and portable drag support

- Add include/yasl/native/{wayland,cocoa,x11}.h with type-safe handle accessors.
- Unify drag-and-drop and window carry support across Wayland, X11, and Cocoa.
- Preserve full ABI compatibility for capability flags.
- Install native headers conditionally based on enabled backend.
- Include missing tablet example and backend test suites.

1 files changed, 62 insertions, 0 deletions

diff --git a/tests/wayland/test_tablet.c b/tests/wayland/test_tablet.c
new file mode 100644
index 0000000..449c446
--- /dev/null
+++ b/tests/wayland/test_tablet.c
@@ -0,0 +1,62 @@
+#include "../../src/wayland/pointer.c"
+#include <assert.h>
+
+static struct yasl_mouse_event next(struct wayland_surface *surface)
+{
+    struct yasl_input_event event;
+    assert(yasl_surface_input_poll(&surface->base, &event));
+    assert(event.surface == &surface->base && event.kind == YASL_INPUT_MOUSE);
+    return event.mouse;
+}
+
+int main(void)
+{
+    struct wayland_display display = {.base.ops = &yasl_wayland_backend};
+    struct wayland_surface surface = {.base.display = &display.base, .conn = &display,
+                                      .scale_factor = 1.5};
+    struct seat seat = {.conn = &display, .tablet_focus = &surface};
+    struct tablet_tool tool = {.seat = &seat};
+    seat.tool = &tool;
+    tablet_tool_motion(&tool, NULL, wl_fixed_from_int(100), wl_fixed_from_int(120));
+    tool_pressure(&tool, NULL, 32768);
+    tool_tilt(&tool, NULL, wl_fixed_from_int(-35), wl_fixed_from_int(42));
+    tablet_tool_down(&tool, NULL, 1);
+    tool_frame(&tool, NULL, 0);
+    struct yasl_mouse_event ev = next(&surface);
+    assert(ev.kind == YASL_PTR_MOTION && ev.device == YASL_PTR_DEV_PEN);
+    assert(ev.pos.x == 150 && ev.pos.y == 180 && ev.pen.pressure == 32768);
+    assert(ev.pen.tilt_x == -35 && ev.pen.tilt_y == 42);
+    ev = next(&surface);
+    assert(ev.kind == YASL_PTR_PRESS && ev.button == 0 && ev.pen.pressure == 32768);
+
+    /* Stationary pressure and tilt changes are still motion samples. */
+    tool_pressure(&tool, NULL, 100000);
+    tool_tilt(&tool, NULL, wl_fixed_from_int(-120), wl_fixed_from_int(120));
+    tool_frame(&tool, NULL, 0);
+    ev = next(&surface);
+    assert(ev.kind == YASL_PTR_MOTION && ev.pen.pressure == 65535);
+    assert(ev.pos.x == 150 && ev.pos.y == 180);
+    assert(ev.pen.tilt_x == -90 && ev.pen.tilt_y == 90);
+    tablet_tool_up(&tool, NULL);
+    tool_frame(&tool, NULL, 0);
+    ev = next(&surface);
+    assert(ev.kind == YASL_PTR_RELEASE && ev.button == 0 && !ev.pen.pressure);
+
+    tool_type(&tool, NULL, ZWP_TABLET_TOOL_V2_TYPE_ERASER);
+    tool_pressure(&tool, NULL, 22000);
+    tool_frame(&tool, NULL, 0);
+    assert(next(&surface).device == YASL_PTR_DEV_ERASER);
+    tool_wheel(&tool, NULL, 0, 1);
+    tool_frame(&tool, NULL, 0);
+    ev = next(&surface);
+    assert(ev.kind == YASL_PTR_SCROLL && ev.device == YASL_PTR_DEV_ERASER);
+    tablet_tool_proximity_out(&tool, NULL);
+    ev = next(&surface);
+    assert(ev.kind == YASL_PTR_LEAVE && ev.device == YASL_PTR_DEV_ERASER && !ev.pen.pressure);
+    assert(!seat.tool && !seat.tablet_focus && !seat.tool_buttons);
+    assert(!(yasl_display_caps(&display.base) & YASL_CAP_TABLET));
+    display.tablet_mgr = (void *)&display; /* Capability depends on protocol availability. */
+    assert(yasl_display_caps(&display.base) & YASL_CAP_TABLET);
+    input_queue_clear(&surface.input);
+    return 0;
+}