feat: cross-platform pen pressure, tilt, and stylus handling

- Hook up Cocoa tablet, stylus, and Force Touch pressure/tilt to push_pointer
- Ensure Wayland tablet tool pressure resets cleanly on tool up
- Visualize pressure-sensitive brush scaling and telemetry in simple_window

2 files changed, 25 insertions, 2 deletions

diff --git a/src/cocoa/window.m b/src/cocoa/window.m
index 6c28f3f..451f448 100644
--- a/src/cocoa/window.m
+++ b/src/cocoa/window.m
@@ -317,14 +317,36 @@ static void push_pointer(struct yasl_surface *w, NSEvent *ev, enum yasl_pointer_
     w->mods = cocoa_mods(ev.modifierFlags);
     if (kind != YASL_PTR_LEAVE)
         w->pointer = event_pos(w, ev);
+
+    enum yasl_pointer_device device = YASL_PTR_DEV_MOUSE;
+    struct yasl_pointer_pen pen = {0};
+
+    float press = (float)ev.pressure;
+    if (ev.subtype == NSEventSubtypeTabletPoint || press > 0.0f) {
+        if (ev.pointingDeviceType == NSPointingDeviceTypeEraser)
+            device = YASL_PTR_DEV_ERASER;
+        else if (ev.pointingDeviceType == NSPointingDeviceTypePen)
+            device = YASL_PTR_DEV_PEN;
+
+        if (press > 1.0f) press = 1.0f;
+        if (press > 0.0f)
+            pen.pressure = (uint16_t)(press * 65535.0f);
+
+        NSPoint tilt = ev.tilt;
+        pen.tilt_x = (int8_t)(tilt.x * 90.0);
+        pen.tilt_y = (int8_t)(tilt.y * 90.0);
+    }
+
     struct yasl_input_event input_ev = {
-        .kind = YASL_INPUT_MOUSE,
         .surface = w,
+        .kind = YASL_INPUT_MOUSE,
         .mouse = {
             .pos = w->pointer,
-            .button = button,
+            .button = (int16_t)button,
             .kind = kind,
+            .device = device,
             .mods = w->mods,
+            .pen = pen,
         },
     };
     input_queue_push(&w->input, &input_ev);
diff --git a/src/wayland/pointer.c b/src/wayland/pointer.c
index 006eadd..5f97370 100644
--- a/src/wayland/pointer.c
+++ b/src/wayland/pointer.c
@@ -785,6 +785,7 @@ static void tablet_tool_up(void *data, struct zwp_tablet_tool_v2 *tool)
     struct seat *s = ((struct tablet_tool *)data)->seat;
     struct yasl_surface *w = s->tablet_focus;
     if (!w) return;
+    s->pen.pressure = 0;
     press_queue_push(&s->tool_presses, w, s->tool_pos, 0, true);
 }