Make orientation computation more robust

The MT protocol defines the angle to be between -Pi/2 and Pi/2,
and expects the defined range to be symmetric around zero.
Make the angle computation more robust against varying definitions
in the kernel drivers.

Signed-off-by: Henrik Rydberg <rydberg@bitmath.org>

1 files changed, 4 insertions, 5 deletions

diff --git a/src/touch-caps.c b/src/touch-caps.c
index 50306e0..7f243c5 100644
--- a/src/touch-caps.c
+++ b/src/touch-caps.c
@@ -49,10 +49,10 @@ void touch_caps_init(struct touch_dev *dev)
                 caps->min_y = 0;
                 caps->max_y = 768;
         }
-        if (caps->min_orient == caps->max_orient) {
-                caps->min_orient = 0;
+        if (caps->min_orient == caps->max_orient)
                 caps->max_orient = 1;
-        }
+        if (caps->min_orient + caps->max_orient != 0)
+                caps->min_orient = -caps->max_orient;
         if (caps->min_press == caps->max_press) {
                 caps->min_press = 0;
                 caps->max_press = 256;
@@ -62,8 +62,7 @@ void touch_caps_init(struct touch_dev *dev)
 float touch_angle(const struct touch_dev *dev, int orient)
 {
         const struct touch_caps *caps = &dev->caps;
-        double div = caps->max_orient - caps->min_orient;
-        return ((orient - caps->min_orient) / div - 0.5) * M_PI;
+        return orient / caps->max_orient * M_PI_2;
 }
 
 float touch_pressure(const struct touch_dev *dev, int press)