From 42e8902395cb27af5c28306abd577a92c467a62d Mon Sep 17 00:00:00 2001
From: Krzysztof Sobiecki <sobkas@gmail.com>
Date: Tue, 13 Sep 2016 22:23:49 +0800
Subject: [PATCH] xwayland: Add a new input device used for pointer
 warping/locking
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Generating relative and absolute movement events from the same input
device is problematic, because an absolute pointer device doesn't
expect to see any relative motion events. To be able to generate
relative pointer motion events including unaccelerated deltas, create a
secondary pointer device 'xwayland-relative-pointer', and use that for
emitting relative motion events.

Signed-off-by: Krzysztof Sobiecki <sobkas@gmail.com>
Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
---
 hw/xwayland/xwayland-input.c | 71 ++++++++++++++++++++++++++++++++++++
 hw/xwayland/xwayland.h       |  1 +
 2 files changed, 72 insertions(+)

diff --git a/hw/xwayland/xwayland-input.c b/hw/xwayland/xwayland-input.c
index 525142965..2782225a7 100644
--- a/hw/xwayland/xwayland-input.c
+++ b/hw/xwayland/xwayland-input.c
@@ -134,6 +134,56 @@ xwl_pointer_proc(DeviceIntPtr device, int what)
 #undef NAXES
 }
 
+static int
+xwl_pointer_proc_relative(DeviceIntPtr device, int what)
+{
+#define NAXES 2
+    Atom axes_labels[NAXES] = { 0 };
+
+    switch (what) {
+    case DEVICE_INIT:
+        device->public.on = FALSE;
+
+        axes_labels[0] = XIGetKnownProperty(AXIS_LABEL_PROP_REL_X);
+        axes_labels[1] = XIGetKnownProperty(AXIS_LABEL_PROP_REL_Y);
+
+        /*
+         * We'll never send buttons, but XGetPointerMapping might in certain
+         * situations make the client think we have no buttons.
+         */
+        if (!init_pointer_buttons(device))
+            return BadValue;
+
+        if (!InitValuatorClassDeviceStruct(device, NAXES, axes_labels,
+                                           GetMotionHistorySize(), Relative))
+            return BadValue;
+
+        /* Valuators */
+        InitValuatorAxisStruct(device, 0, axes_labels[0],
+                               NO_AXIS_LIMITS, NO_AXIS_LIMITS, 1, 0, 1, Relative);
+        InitValuatorAxisStruct(device, 1, axes_labels[1],
+                               NO_AXIS_LIMITS, NO_AXIS_LIMITS, 1, 0, 1, Relative);
+
+        if (!InitPtrFeedbackClassDeviceStruct(device, xwl_pointer_control))
+            return BadValue;
+
+        return Success;
+
+    case DEVICE_ON:
+        device->public.on = TRUE;
+        return Success;
+
+    case DEVICE_OFF:
+    case DEVICE_CLOSE:
+        device->public.on = FALSE;
+        return Success;
+    }
+
+    return BadMatch;
+
+#undef NAXES
+}
+
 static void
 xwl_keyboard_control(DeviceIntPtr device, KeybdCtrl *ctrl)
 {
@@ -803,6 +853,25 @@ release_pointer(struct xwl_seat *xwl_seat)
         DisableDevice(xwl_seat->pointer, TRUE);
 }
 
+static void
+init_relative_pointer(struct xwl_seat *xwl_seat)
+{
+    if (xwl_seat->relative_pointer == NULL) {
+        xwl_seat->relative_pointer =
+            add_device(xwl_seat, "xwayland-relative-pointer",
+                       xwl_pointer_proc_relative);
+        ActivateDevice(xwl_seat->relative_pointer, TRUE);
+    }
+    EnableDevice(xwl_seat->relative_pointer, TRUE);
+}
+
+static void
+release_relative_pointer(struct xwl_seat *xwl_seat)
+{
+    if (xwl_seat->relative_pointer)
+        DisableDevice(xwl_seat->relative_pointer, TRUE);
+}
+
 static void
 init_keyboard(struct xwl_seat *xwl_seat)
 {
@@ -869,8 +938,10 @@ seat_handle_capabilities(void *data, struct wl_seat *seat,
 
     if (caps & WL_SEAT_CAPABILITY_POINTER && xwl_seat->wl_pointer == NULL) {
         init_pointer(xwl_seat);
+        init_relative_pointer(xwl_seat);
     } else if (!(caps & WL_SEAT_CAPABILITY_POINTER) && xwl_seat->wl_pointer) {
         release_pointer(xwl_seat);
+        release_relative_pointer(xwl_seat);
     }
 
     if (caps & WL_SEAT_CAPABILITY_KEYBOARD && xwl_seat->wl_keyboard == NULL) {
diff --git a/hw/xwayland/xwayland.h b/hw/xwayland/xwayland.h
index 49284359b..9f8d984fc 100644
--- a/hw/xwayland/xwayland.h
+++ b/hw/xwayland/xwayland.h
@@ -120,6 +120,7 @@ struct xwl_touch {
 
 struct xwl_seat {
     DeviceIntPtr pointer;
+    DeviceIntPtr relative_pointer;
     DeviceIntPtr keyboard;
     DeviceIntPtr touch;
     struct xwl_screen *xwl_screen;