Revert "dix: fix up coordinate scaling when external monitors are present"

This reverts commit d90b5f83010248be65b2039b0b2d0b9e6a4e93cf.

Reverting for two reasons:
* the scaling does not work on devices that don't advertise resolution, and
  the default resolution used (100 units/mm) is higher than most devices,
  resulting in a significant slowdown of the touchpads.
* the scaling is still affected by resolution changing. The patch worked
  before acceleration but since it maps into resolution-dependent dx/dy
  coordinates the acceleration may distort the movement after the fact. So the
  same input data generates different movements depending on the resolution.
  This can't easily be fixed for all affected devices as synaptics has its own
  velocity calculation method whereas wacom doesn't. So anything in the server
  won't work for both at the same time.

Revert this for now, until a more integrated solution can be implemented.

1 files changed, 20 insertions, 60 deletions

diff --git a/dix/getevents.c b/dix/getevents.c
index d68fa96d7..ffa89fad2 100644
--- a/dix/getevents.c
+++ b/dix/getevents.c
@@ -770,65 +770,27 @@ add_to_scroll_valuator(DeviceIntPtr dev, ValuatorMask *mask, int valuator, doubl
 }
 
 
-/* FIXME: relative events from devices with absolute axis ranges is
-   fundamentally broken. We map the device coordinate range into the screen
-   range, but don't really account for device resolution in that.
-
-   what we do here is a hack to make touchpads usable. for a given relative
-   motion vector in device coordinates:
-   1. calculate physical movement on the device in metres
-   2. calculate pixel vector that is the same physical movement on the
-      screen (times some magic number to provide sensible base speed)
-   3. calculate what percentage this vector is of the current screen
-      width/height
-   4. calculate equivalent vector in % on the device's min/max axis range
-   5. Use that device vector as the actual motion vector
-
-   e.g. 10/50mm on the device, 10/50mm on the screen are 30/100 pixels,
-   30/100 pixels are 1/3% of the width, 1/3% of the device is a vector of
-   20/80 -> use 20/80 as dx/dy.
-
-   dx/dy is then applied to the current position in device coordinates,
-   mapped to screen coordinates and thus the movement on the screen reflects
-   the motion direction on the device.
- */
 static void
 scale_for_device_resolution(DeviceIntPtr dev, ValuatorMask *mask)
 {
-    double x, y;
+    double y;
     ValuatorClassPtr v = dev->valuator;
     int xrange = v->axes[0].max_value - v->axes[0].min_value + 1;
     int yrange = v->axes[1].max_value - v->axes[1].min_value + 1;
 
-    /* Assume 100 units/m for devices without resolution */
-    int xres = 100000, yres = 100000;
-
-    /* If we have multiple screens with different dpi, it gets complicated:
-       we have to map which screen we're on and then take the dpi of that
-       screen to be somewhat accurate.  */
-    const ScreenPtr s = screenInfo.screens[0];
-    const double screen_res = 1000.0 * s->width/s->mmWidth; /* units/m */
+    double screen_ratio = 1.0 * screenInfo.width/screenInfo.height;
+    double device_ratio = 1.0 * xrange/yrange;
+    double resolution_ratio = 1.0;
+    double ratio;
 
-    /* some magic multiplier, so unaccelerated movement of x mm on the
-       device reflects x * magic mm on the screen */
-    const double magic = 4;
+    if (!valuator_mask_fetch_double(mask, 1, &y))
+        return;
 
-    if (v->axes[0].resolution != 0 && v->axes[1].resolution != 0) {
-        xres = v->axes[0].resolution;
-        yres = v->axes[1].resolution;
-    }
+    if (v->axes[0].resolution != 0 && v->axes[1].resolution != 0)
+        resolution_ratio = 1.0 * v->axes[0].resolution/v->axes[1].resolution;
 
-    if (valuator_mask_isset(mask, 0)) {
-        x = valuator_mask_get_double(mask, 0);
-        x = magic * x/xres * screen_res/screenInfo.width * xrange;
-        valuator_mask_set_double(mask, 0, x);
-    }
-
-    if (valuator_mask_isset(mask, 1)) {
-        y = valuator_mask_get_double(mask, 1);
-        y = magic * y/yres * screen_res/screenInfo.height * yrange;
-        valuator_mask_set_double(mask, 1, y);
-    }
+    ratio = device_ratio/resolution_ratio/screen_ratio;
+    valuator_mask_set_double(mask, 1, y / ratio);
 }
 
 /**
@@ -842,6 +804,15 @@ moveRelative(DeviceIntPtr dev, int flags, ValuatorMask *mask)
 {
     int i;
     Bool clip_xy = IsMaster(dev) || !IsFloating(dev);
+    ValuatorClassPtr v = dev->valuator;
+
+    /* for abs devices in relative mode, we've just scaled wrong, since we
+       mapped the device's shape into the screen shape. Undo this. */
+    if ((flags & POINTER_ABSOLUTE) == 0 && v && v->numAxes > 1 &&
+        v->axes[0].min_value < v->axes[0].max_value &&
+        v->axes[1].min_value < v->axes[1].max_value) {
+        scale_for_device_resolution(dev, mask);
+    }
 
     /* calc other axes, clip, drop back into valuators */
     for (i = 0; i < valuator_mask_size(mask); i++) {
@@ -1470,21 +1441,10 @@ fill_pointer_events(InternalEvent *events, DeviceIntPtr pDev, int type,
             set_raw_valuators(raw, &mask, raw->valuators.data);
     }
     else {
-        ValuatorClassPtr v = pDev->valuator;
-
         transformRelative(pDev, &mask);
 
-        /* for abs devices in relative mode, we've just scaled wrong, since we
-           mapped the device's shape into the screen shape. Undo this. */
-        if (v && v->numAxes > 1 &&
-            v->axes[0].min_value < v->axes[0].max_value &&
-            v->axes[1].min_value < v->axes[1].max_value) {
-            scale_for_device_resolution(pDev, &mask);
-        }
-
         if (flags & POINTER_ACCELERATE)
             accelPointer(pDev, &mask, ms);
-
         if ((flags & POINTER_NORAW) == 0 && raw)
             set_raw_valuators(raw, &mask, raw->valuators.data);