eek-gtk-keyboard: Trigger event feedback on button press

Use libfeedback to trigger feedback for the button press event.

Closes: #166

eek/eek-gtk-keyboard.c

@@ -37,6 +37,10 @@
 #include "src/layout.h"
 #include "src/submission.h"
 
+#define LIBFEEDBACK_USE_UNSTABLE_API
+#include <libfeedback.h>
+
+#define SQUEEKBOARD_APP_ID "sm.puri.squeekboard"
 
 typedef struct _EekGtkKeyboardPrivate
 {
@@ -48,6 +52,7 @@ typedef struct _EekGtkKeyboardPrivate
     LevelKeyboard *keyboard; // unowned reference; it's kept in server-context
 
     GdkEventSequence *sequence; // unowned reference
+    LfbEvent *event;
 } EekGtkKeyboardPrivate;
 
 G_DEFINE_TYPE_WITH_PRIVATE (EekGtkKeyboard, eek_gtk_keyboard, GTK_TYPE_DRAWING_AREA)
@@ -135,6 +140,19 @@ eek_gtk_keyboard_real_size_allocate (GtkWidget     *self,
         size_allocate (self, allocation);
 }
 
+static void
+on_event_triggered (LfbEvent      *event,
+                    GAsyncResult  *res,
+                    gpointer      unused)
+{
+    g_autoptr (GError) err = NULL;
+
+    if (!lfb_event_trigger_feedback_finish (event, res, &err)) {
+        g_warning ("Failed to trigger feedback for '%s': %s",
+                   lfb_event_get_event (event), err->message);
+    }
+}
+
 static void depress(EekGtkKeyboard *self,
                     gdouble x, gdouble y, guint32 time)
 {
@@ -299,6 +317,11 @@ eek_gtk_keyboard_dispose (GObject *object)
         priv->keyboard = NULL;
     }
 
+    if (priv->event) {
+        g_clear_object (&priv->event);
+        lfb_uninit ();
+    }
+
     G_OBJECT_CLASS (eek_gtk_keyboard_parent_class)->dispose (object);
 }
 
@@ -330,7 +353,13 @@ eek_gtk_keyboard_class_init (EekGtkKeyboardClass *klass)
 static void
 eek_gtk_keyboard_init (EekGtkKeyboard *self)
 {
-    (void)self;
+    EekGtkKeyboardPrivate *priv = eek_gtk_keyboard_get_instance_private (EEK_GTK_KEYBOARD (self));
+    g_autoptr(GError) err = NULL;
+
+    if (lfb_init(SQUEEKBOARD_APP_ID, &err))
+        priv->event = lfb_event_new ("button-pressed");
+    else
+        g_warning ("Failed to init libfeedback: %s", err->message);
 }
 
 static void
@@ -376,3 +405,24 @@ eek_gtk_keyboard_new (EekboardContextService *eekservice,
     return GTK_WIDGET(box);*/
     return GTK_WIDGET(ret);
 }
+
+/**
+ * eek_gtk_keyboard_emit_feedback:
+ *
+ * Emit button press haptic feedback via libfeedack.
+ */
+void
+eek_gtk_keyboard_emit_feedback (EekGtkKeyboard *self)
+{
+    EekGtkKeyboardPrivate *priv;
+
+    g_return_if_fail (EEK_IS_GTK_KEYBOARD (self));
+
+    priv = eek_gtk_keyboard_get_instance_private (EEK_GTK_KEYBOARD (self));
+    if (priv->event) {
+        lfb_event_trigger_feedback_async (priv->event,
+                                          NULL,
+                                          (GAsyncReadyCallback)on_event_triggered,
+                                          NULL);
+    }
+}

eek/eek-gtk-keyboard.h

@@ -49,6 +49,7 @@ struct _EekGtkKeyboardClass
 
 GType      eek_gtk_keyboard_get_type  (void) G_GNUC_CONST;
 GtkWidget *eek_gtk_keyboard_new       (EekboardContextService *eekservice, struct submission *submission, struct squeek_layout_state *layout);
+void       eek_gtk_keyboard_emit_feedback (EekGtkKeyboard *self);
 
 G_END_DECLS
 #endif  /* EEK_GTK_KEYBOARD_H */

src/layout.rs

@@ -52,6 +52,14 @@ pub mod c {
     #[derive(Copy, Clone)]
     pub struct EekGtkKeyboard(pub *const gtk_sys::GtkWidget);
 
+    #[no_mangle]
+    extern "C" {
+        #[allow(improper_ctypes)]
+        pub fn eek_gtk_keyboard_emit_feedback(
+            keyboard: EekGtkKeyboard,
+        );
+    }
+
     /// Defined in eek-types.h
     #[repr(C)]
     #[derive(Clone, Debug, PartialEq)]
@@ -341,6 +349,9 @@ pub mod c {
                 );
                 // maybe TODO: draw on the display buffer here
                 drawing::queue_redraw(ui_keyboard);
+                unsafe {
+                    eek_gtk_keyboard_emit_feedback(ui_keyboard);
+                }
             };
         }
 
@@ -404,6 +415,9 @@ pub mod c {
                         &state,
                     );
                     // maybe TODO: draw on the display buffer here
+                    unsafe {
+                        eek_gtk_keyboard_emit_feedback(ui_keyboard);
+                    }
                 }
             } else {
                 for wrapped_key in pressed {

src/meson.build

@@ -38,6 +38,7 @@ deps = [
   dependency('gio-2.0', version: '>=2.26.0'),
   dependency('gnome-desktop-3.0', version: '>=3.0'),
   dependency('gtk+-3.0', version: '>=3.0'),
+  dependency('libfeedback-0.0'),
   dependency('wayland-client', version: '>=1.14'),
   dependency('xkbcommon'),
   cc.find_library('m'),