Add support for 2-dimensional scrolling with touch pads

Signed-off-by: Spaceship Operations <spaceshipoperations@gmail.com>

src/keybind.c

@@ -65,6 +65,10 @@ static const struct key_binding default_bindings[] = {
     { .key = XKB_KEY_Right, .action = kb_step_right },
     { .key = XKB_KEY_Up, .action = kb_step_up },
     { .key = XKB_KEY_Down, .action = kb_step_down },
+    { .key = XKB_KEY_KP_Left, .action = kb_step_left },
+    { .key = XKB_KEY_KP_Right, .action = kb_step_right },
+    { .key = XKB_KEY_KP_Up, .action = kb_step_up },
+    { .key = XKB_KEY_KP_Down, .action = kb_step_down },
     { .key = XKB_KEY_equal, .action = kb_zoom, .params = "+10" },
     { .key = XKB_KEY_plus, .action = kb_zoom, .params = "+10" },
     { .key = XKB_KEY_minus, .action = kb_zoom, .params = "-10" },

src/ui.c

@@ -28,6 +28,16 @@
 #define BTN_LEFT 0x110 // from <linux/input-event-codes.h>
 #endif
 
+#ifndef WL_POINTER_AXIS_ENUM
+#define WL_POINTER_AXIS_ENUM
+// from <wayland-client-protocol.h>
+enum wl_pointer_axis {
+    WL_POINTER_AXIS_VERTICAL_SCROLL = 0,
+    WL_POINTER_AXIS_HORIZONTAL_SCROLL = 1,
+};
+#endif
+
+
 /** Loop state */
 enum state {
     state_ok,
@@ -349,7 +359,11 @@ static void on_pointer_button(void* data, struct wl_pointer* wl_pointer,
 static void on_pointer_axis(void* data, struct wl_pointer* wl_pointer,
                             uint32_t time, uint32_t axis, wl_fixed_t value)
 {
-    xkb_keysym_t key = value > 0 ? XKB_KEY_SunPageDown : XKB_KEY_SunPageUp;
+    xkb_keysym_t key;
+    if (axis == WL_POINTER_AXIS_HORIZONTAL_SCROLL)
+        key = value > 0 ? XKB_KEY_KP_Right : XKB_KEY_KP_Left;
+    else
+        key = value > 0 ? XKB_KEY_KP_Down : XKB_KEY_KP_Up;
     viewer_on_keyboard(key);
 }