defmin/defmax are screen coords and thus use a min-inclusive, max-exclusive range. device axes ranges are inclusive, so bump the max up by one to get the scaling right.
This fixes off-by-one coordinate errors if the coordinate matrix is used to bind the device to a fraction of the screen. It introduces an off-by-one scaling error in the device coordinate range, but since most devices have a higher resolution than the screen (e.g. a Wacom I4 has 5080 dpi) the effect of this should be limited. This error manifests when we have numScreens > 1, as the scaling from desktop size back to screen size drops one device unit. Signed-off-by: Peter Hutterer <[email protected]> --- Changes to v2: - comment added explaining where the valuators are off now afaict, we can't win here anyway, and off by one device unit is the least amount of pain. dix/devices.c | 4 ++-- dix/getevents.c | 14 ++++++++++---- 2 files changed, 12 insertions(+), 6 deletions(-) diff --git a/dix/devices.c b/dix/devices.c index fa94a94..7b423de 100644 --- a/dix/devices.c +++ b/dix/devices.c @@ -112,8 +112,8 @@ DeviceSetTransform(DeviceIntPtr dev, float *transform_data) * Transform is the user supplied (affine) transform * InvScale scales coordinates back up into their native range */ - sx = dev->valuator->axes[0].max_value - dev->valuator->axes[0].min_value; - sy = dev->valuator->axes[1].max_value - dev->valuator->axes[1].min_value; + sx = dev->valuator->axes[0].max_value - dev->valuator->axes[0].min_value + 1; + sy = dev->valuator->axes[1].max_value - dev->valuator->axes[1].min_value + 1; /* invscale */ pixman_f_transform_init_scale(&scale, sx, sy); diff --git a/dix/getevents.c b/dix/getevents.c index a4f192c..1438625 100644 --- a/dix/getevents.c +++ b/dix/getevents.c @@ -297,11 +297,11 @@ rescaleValuatorAxis(double coord, AxisInfoPtr from, AxisInfoPtr to, if (from && from->min_value < from->max_value) { fmin = from->min_value; - fmax = from->max_value; + fmax = from->max_value + 1; } if (to && to->min_value < to->max_value) { tmin = to->min_value; - tmax = to->max_value; + tmax = to->max_value + 1; } if (fmin == tmin && fmax == tmax) @@ -913,9 +913,9 @@ scale_to_desktop(DeviceIntPtr dev, ValuatorMask *mask, /* scale x&y to desktop coordinates */ *screenx = rescaleValuatorAxis(x, dev->valuator->axes + 0, NULL, - screenInfo.x, screenInfo.width - 1); + screenInfo.x, screenInfo.width); *screeny = rescaleValuatorAxis(y, dev->valuator->axes + 1, NULL, - screenInfo.y, screenInfo.height - 1); + screenInfo.y, screenInfo.height); *devx = x; *devy = y; @@ -1355,6 +1355,12 @@ QueuePointerEvents(DeviceIntPtr device, int type, * is the last coordinate on the first screen and must be rescaled for the * event to be m. XI2 clients that do their own coordinate mapping would * otherwise interpret the position of the device elsewere to the cursor. + * However, this scaling leads to losses: + * if we have two ScreenRecs we scale from e.g. [0..44704] (Wacom I4) to + * [0..2048[. that gives us 2047.954 as desktop coord, or the per-screen + * coordinate 1023.954. Scaling that back into the device coordinate range + * gives us 44703. So off by one device unit. It's a bug, but we'll have to + * live with it because with all this scaling, we just cannot win. * * @return the number of events written into events. */ -- 1.8.1.4 _______________________________________________ [email protected]: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: http://lists.x.org/mailman/listinfo/xorg-devel
