Sensitivity: Handle sensitivities < 1.0 without rounding errors

.gitignore

@@ -1,3 +1,4 @@
+*~
 *.la
 *.lo
 *.o

driver/mprops.c

@@ -91,7 +91,7 @@ void mprops_init(struct MConfig* cfg, InputInfoPtr local) {
 	ivals[0] = cfg->trackpad_disable;
 	mprops.trackpad_disable = atom_init_integer(local->dev, MTRACK_PROP_TRACKPAD_DISABLE, 1, ivals, 8);
 
-	fvals[0] = (float)cfg->sensitivity;
+	fvals[0] = (float)mconfig_get_sensitivity(cfg);
 	mprops.sensitivity = atom_init_float(local->dev, MTRACK_PROP_SENSITIVITY, 1, fvals, mprops.float_type);
 
 	ivals[0] = cfg->touch_down;
@@ -230,9 +230,9 @@ int mprops_set_property(DeviceIntPtr dev, Atom property, XIPropertyValuePtr prop
 			return BadMatch;
 
 		if (!checkonly) {
-			cfg->sensitivity = fvals[0];
+			mconfig_set_sensitivity(cfg, fvals[0]);
 #ifdef DEBUG_PROPS
-			xf86Msg(X_INFO, "mtrack: set sensitivity to %f\n", cfg->sensitivity);
+			xf86Msg(X_INFO, "mtrack: set sensitivity to %f\n", mconfig_get_sensitivity(cfg));
 #endif
 		}
 	}

driver/mtrack.c

@@ -133,8 +133,8 @@ static int device_init(DeviceIntPtr dev, LocalDevicePtr local)
 #if GET_ABI_MAJOR(ABI_XINPUT_VERSION) >= 7
 				   axes_labels[0],
 #endif
-				   mt->caps.abs[MTDEV_POSITION_X].minimum,
-				   mt->caps.abs[MTDEV_POSITION_X].maximum,
+				   mt->caps.abs[MTDEV_POSITION_X].minimum * mt->cfg.sensitivity_smalldiv,
+				   mt->caps.abs[MTDEV_POSITION_X].maximum * mt->cfg.sensitivity_smalldiv,
 #if GET_ABI_MAJOR(ABI_XINPUT_VERSION) >= 12
 				   1, 0, 1, Absolute);
 #else
@@ -145,8 +145,8 @@ static int device_init(DeviceIntPtr dev, LocalDevicePtr local)
 #if GET_ABI_MAJOR(ABI_XINPUT_VERSION) >= 7
 				   axes_labels[1],
 #endif
-				   mt->caps.abs[MTDEV_POSITION_Y].minimum,
-				   mt->caps.abs[MTDEV_POSITION_Y].maximum,
+				   mt->caps.abs[MTDEV_POSITION_Y].minimum * mt->cfg.sensitivity_smalldiv,
+				   mt->caps.abs[MTDEV_POSITION_Y].maximum * mt->cfg.sensitivity_smalldiv,
 #if GET_ABI_MAJOR(ABI_XINPUT_VERSION) >= 12
 				   1, 0, 1, Absolute);
 #else

include/mconfig.h

@@ -161,13 +161,24 @@ struct MConfig {
 	int drag_timeout;		// How long to wait for a move after tapping? > 0
 	int drag_wait;			// How long to wait before triggering button down? >= 0
 	int drag_dist;			// How far is the finger allowed to move during wait time? >= 0
-	double sensitivity;		// Mouse movement multiplier. >= 0
+	double sensitivity_big;		// Mouse movement multiplier. >= 1.0        } real sensitivity is
+	double sensitivity_smalldiv;	// Mouse movement divisor.    >= 1.0        }   big * smalldiv
 };
 
 /* Load the MConfig struct with its defaults.
  */
 void mconfig_defaults(struct MConfig* cfg);
 
+/* Set and read ->sensitivity_big and _small.
+ *
+ * Configuration code must always use these get/set functions.
+ *
+ * Runtime code which uses the sensitivity to process events is
+ * expected to access the value in cfg directly.
+ */
+void mconfig_set_sensitivity(struct MConfig *cfg, double sensitivity);
+double mconfig_get_sensitivity(const struct MConfig *cfg);
+
 /* Initialize the MConfig struct.
  */
 void mconfig_init(struct MConfig* cfg,

src/gestures.c

@@ -388,8 +388,8 @@ static void trigger_move(struct Gestures* gs,
 {
 	if ((gs->move_type == GS_MOVE || !timercmp(&gs->time, &gs->move_wait, <)) && (dx != 0 || dy != 0)) {
 		if (trigger_drag_start(gs, cfg, dx, dy)) {
-			gs->move_dx = (int)(dx*cfg->sensitivity);
-			gs->move_dy = (int)(dy*cfg->sensitivity);
+			gs->move_dx = (int)(dx*cfg->sensitivity_big);
+			gs->move_dy = (int)(dy*cfg->sensitivity_big);
 			gs->move_type = GS_MOVE;
 			gs->move_dist = 0;
 			gs->move_dir = TR_NONE;

src/mconfig.c

@@ -21,6 +21,22 @@
 
 #include "mconfig.h"
 
+void mconfig_set_sensitivity(struct MConfig *cfg, double sensitivity)
+{
+	if (sensitivity >= 1.0) {
+		cfg->sensitivity_big = sensitivity;
+		cfg->sensitivity_smalldiv = 1.0;
+	} else {
+		cfg->sensitivity_big = 1.0;
+		cfg->sensitivity_smalldiv = 1.0 / sensitivity;
+	}
+}
+
+double mconfig_get_sensitivity(const struct MConfig * cfg)
+{
+	return cfg->sensitivity_big / cfg->sensitivity_smalldiv;
+}
+
 void mconfig_defaults(struct MConfig* cfg)
 {
 	// Configure MTState
@@ -76,7 +92,7 @@ void mconfig_defaults(struct MConfig* cfg)
 	cfg->rotate_rt_btn = DEFAULT_ROTATE_RT_BTN;
 	cfg->drag_enable = DEFAULT_DRAG_ENABLE;
 	cfg->drag_timeout = DEFAULT_DRAG_TIMEOUT;
-	cfg->sensitivity = DEFAULT_SENSITIVITY;
+	mconfig_set_sensitivity(cfg, DEFAULT_SENSITIVITY);
 }
 
 void mconfig_init(struct MConfig* cfg,
@@ -177,6 +193,6 @@ void mconfig_configure(struct MConfig* cfg,
 	cfg->drag_dist = MAXVAL(xf86SetIntOption(opts, "TapDragDist", DEFAULT_DRAG_DIST), 0);
 	cfg->axis_x_invert = xf86SetBoolOption(opts, "AxisXInvert", DEFAULT_AXIS_X_INVERT);
 	cfg->axis_y_invert = xf86SetBoolOption(opts, "AxisYInvert", DEFAULT_AXIS_Y_INVERT);
-	cfg->sensitivity = MAXVAL(xf86SetRealOption(opts, "Sensitivity", DEFAULT_SENSITIVITY), 0);
+	mconfig_set_sensitivity(cfg, MAXVAL(xf86SetRealOption(opts, "Sensitivity", DEFAULT_SENSITIVITY), 0));
 }