[input] add has_stylus property to Input class

this allows harmony to query for stylus presence

src/harmony/app/canvas.cpy

@@ -160,14 +160,13 @@ namespace app_ui:
         eraser->set_framebuffer(self.layers[cur_layer].fb.get())
 
     bool ignore_event(input::SynMotionEvent &ev):
-      #ifdef KOBO
-      ev.pressure = 0.5
-      ev.tilt_x = 0.5
-      ev.tilt_y = 0.5
-      return false
-      #else
+      if not ui::MainLoop::in.has_stylus:
+        ev.pressure = 0.5
+        ev.tilt_x = 0.5
+        ev.tilt_y = 0.5
+        return false
+
       return input::is_touch_event(ev) != NULL
-      #endif
 
 
     void on_mouse_move(input::SynMotionEvent &ev):

src/rmkit/input/device_id.cpy

@@ -57,6 +57,19 @@ namespace input:
 
     return UNKNOWN
 
+  static bool supports_stylus(int fd):
+    if fd <= 0:
+      return false
+
+    unsigned long bit[EV_MAX]
+    ioctl(fd, EVIOCGBIT(0, EV_MAX), bit)
+    if check_bit_set(fd, EV_KEY, BTN_TOOL_PEN):
+      return true
+    if check_bit_set(fd, EV_KEY, BTN_STYLUS) && test_bit(EV_ABS, bit):
+      return true
+
+    return false
+
   static EV_TYPE id_by_name(int fd):
     char name[256];
     ioctl(fd, EVIOCGNAME(sizeof(name)), name);

src/rmkit/input/input.cpy

@@ -50,6 +50,11 @@ namespace input:
       fd = _fd
       T::set_fd(fd)
 
+    bool supports_stylus():
+      return input::supports_stylus(fd)
+
+
+
     void handle_event_fd():
       int bytes = read(fd, ev_data, sizeof(input_event) * 64);
       if bytes < sizeof(input_event) || bytes == -1:
@@ -89,6 +94,7 @@ namespace input:
     public:
     int max_fd
     fd_set rdfs
+    bool has_stylus
 
     InputClass<WacomEvent, SynMotionEvent> wacom
     InputClass<TouchEvent, SynMotionEvent> touch
@@ -132,6 +138,7 @@ namespace input:
 
       self.monitor(input::ipc_fd[0])
       self.set_scaling(framebuffer::fb_info::display_width, framebuffer::fb_info::display_height)
+      self.has_stylus = supports_stylus()
       return
 
 
@@ -286,6 +293,8 @@ namespace input:
       #endif
       return
 
+    bool supports_stylus():
+      return wacom.supports_stylus() || touch.supports_stylus()
 
   // TODO: should we just put this in the SynMotionEvent?
   static WacomEvent* is_wacom_event(SynMotionEvent &syn_ev):
@@ -295,3 +304,4 @@ namespace input:
     if evt != nullptr && evt->is_touch():
       return evt
     return nullptr
+