Input: Add smooth-scrolling support to GetPointerEvents

For scroll wheel support, we used to send buttons 4/5 and 6/7 for
horizontal/vertical positive/negative scroll events.  For touchpads, we
really want more fine-grained scroll values.  GetPointerEvents now
accepts both old-school scroll button presses, and new-style scroll axis
events, while emitting both types of events to support both old and new
clients.

This works with the new XIScrollClass to mark axes as scrolling axes.
Drivers mark any valuators that send scroll events with SetScrollValuator.
(Currently missing: the XIDeviceChangeEvent being sent when a driver changes
a scroll axis at run-time. This can be added later.)

Note: the SCROLL_TYPE enums are intentionally different values to the XI2
proto values to avoid copy/overlapping range bugs.

Co-authored-by: Daniel Stone <daniel@fooishbar.org>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Daniel Stone <daniel@fooishbar.org>

3 files changed, 122 insertions, 1 deletions

diff --git a/Xi/exevents.c b/Xi/exevents.c
index a6455e6ac..74a78ecf2 100644
--- a/Xi/exevents.c
+++ b/Xi/exevents.c
@@ -1091,6 +1091,55 @@ InitValuatorAxisStruct(DeviceIntPtr dev, int axnum, Atom label, int minval, int
     if (mode & OutOfProximity)
         dev->proximity->in_proximity = FALSE;
 
+    return SetScrollValuator(dev, axnum, SCROLL_TYPE_NONE, 0, SCROLL_FLAG_NONE);
+}
+
+/**
+ * Set the given axis number as a scrolling valuator.
+ */
+Bool
+SetScrollValuator(DeviceIntPtr dev, int axnum, enum ScrollType type, double increment, int flags)
+{
+    AxisInfoPtr ax;
+    int *current_ax;
+
+    if (!dev || !dev->valuator || axnum >= dev->valuator->numAxes)
+        return FALSE;
+
+    switch (type)
+    {
+        case SCROLL_TYPE_VERTICAL:
+            current_ax = &dev->valuator->v_scroll_axis;
+            break;
+        case SCROLL_TYPE_HORIZONTAL:
+            current_ax = &dev->valuator->h_scroll_axis;
+            break;
+        case SCROLL_TYPE_NONE:
+            ax = &dev->valuator->axes[axnum];
+            ax->scroll.type = type;
+            return TRUE;
+        default:
+            return FALSE;
+    }
+
+    if (increment == 0.0)
+        return FALSE;
+
+    if (*current_ax != -1 && axnum != *current_ax)
+    {
+        ax = &dev->valuator->axes[*current_ax];
+        if (ax->scroll.type == type &&
+            (flags & SCROLL_FLAG_PREFERRED) && (ax->scroll.flags & SCROLL_FLAG_PREFERRED))
+            return FALSE;
+    }
+    *current_ax = axnum;
+
+    ax = &dev->valuator->axes[axnum];
+    ax->scroll.type = type;
+    ax->scroll.increment = increment;
+    ax->scroll.flags = flags;
+    /* FIXME: generate DeviceChanged Events */
+
     return TRUE;
 }
 
diff --git a/Xi/xiquerydevice.c b/Xi/xiquerydevice.c
index 902eb918c..9961d1b6f 100644
--- a/Xi/xiquerydevice.c
+++ b/Xi/xiquerydevice.c
@@ -229,7 +229,16 @@ SizeDeviceClasses(DeviceIntPtr dev)
     }
 
     if (dev->valuator)
-        len += sizeof(xXIValuatorInfo) * dev->valuator->numAxes;
+    {
+        int i;
+        len += (sizeof(xXIValuatorInfo)) * dev->valuator->numAxes;
+
+        for (i = 0; i < dev->valuator->numAxes; i++) {
+            if (dev->valuator->axes[i].scroll.type != SCROLL_TYPE_NONE)
+                len += sizeof(xXIScrollInfo);
+        }
+    }
+
 
     return len;
 }
@@ -369,6 +378,56 @@ SwapValuatorInfo(DeviceIntPtr dev, xXIValuatorInfo* info)
     swaps(&info->sourceid);
 }
 
+int
+ListScrollInfo(DeviceIntPtr dev, xXIScrollInfo *info, int axisnumber)
+{
+    ValuatorClassPtr v = dev->valuator;
+    AxisInfoPtr axis = &v->axes[axisnumber];
+
+    if (axis->scroll.type == SCROLL_TYPE_NONE)
+        return 0;
+
+    info->type = XIScrollClass;
+    info->length = sizeof(xXIScrollInfo)/4;
+    info->number = axisnumber;
+    switch(axis->scroll.type)
+    {
+        case SCROLL_TYPE_VERTICAL:
+            info->scroll_type = XIScrollTypeVertical;
+            break;
+        case SCROLL_TYPE_HORIZONTAL:
+            info->scroll_type = XIScrollTypeHorizontal;
+            break;
+        default:
+            ErrorF("[Xi] Unknown scroll type %d. This is a bug.\n", axis->scroll.type);
+            break;
+    }
+    info->increment.integral = (int)axis->scroll.increment;
+    info->increment.frac = (unsigned int)(axis->scroll.increment * (1UL << 16) * (1UL << 16));
+    info->sourceid = v->sourceid;
+
+    info->flags = 0;
+
+    if (axis->scroll.flags & SCROLL_FLAG_DONT_EMULATE)
+        info->flags |= XIScrollFlagNoEmulation;
+    if (axis->scroll.flags & SCROLL_FLAG_PREFERRED)
+        info->flags |= XIScrollFlagPreferred;
+
+    return info->length * 4;
+}
+
+static void
+SwapScrollInfo(DeviceIntPtr dev, xXIScrollInfo* info)
+{
+    swaps(&info->type);
+    swaps(&info->length);
+    swaps(&info->number);
+    swaps(&info->sourceid);
+    swaps(&info->scroll_type);
+    swapl(&info->increment.integral);
+    swapl(&info->increment.frac);
+}
+
 int GetDeviceUse(DeviceIntPtr dev, uint16_t *attachment)
 {
     DeviceIntPtr master = GetMaster(dev, MASTER_ATTACHED);
@@ -458,6 +517,15 @@ ListDeviceClasses(ClientPtr client, DeviceIntPtr dev,
         total_len += len;
     }
 
+    for (i = 0; dev->valuator && i < dev->valuator->numAxes; i++)
+    {
+        len = ListScrollInfo(dev, (xXIScrollInfo*)any, i);
+        if (len)
+            (*nclasses)++;
+        any += len;
+        total_len += len;
+    }
+
     return total_len;
 }
 
@@ -484,6 +552,9 @@ SwapDeviceInfo(DeviceIntPtr dev, xXIDeviceInfo* info)
             case XIValuatorClass:
                 SwapValuatorInfo(dev, (xXIValuatorInfo*)any);
                 break;
+            case XIScrollClass:
+                SwapScrollInfo(dev, (xXIScrollInfo*)any);
+                break;
         }
 
         any += len * 4;
diff --git a/Xi/xiquerydevice.h b/Xi/xiquerydevice.h
index 02f06591e..9db6aa293 100644
--- a/Xi/xiquerydevice.h
+++ b/Xi/xiquerydevice.h
@@ -44,4 +44,5 @@ int ListButtonInfo(DeviceIntPtr dev, xXIButtonInfo* info, Bool reportState);
 int ListKeyInfo(DeviceIntPtr dev, xXIKeyInfo* info);
 int ListValuatorInfo(DeviceIntPtr dev, xXIValuatorInfo* info,
 		     int axisnumber, Bool reportState);
+int ListScrollInfo(DeviceIntPtr dev, xXIScrollInfo* info, int axisnumber);
 #endif /* QUERYDEV_H */