Add dynamic acceleration to moused(8). This introduces a '-A' flag to control

the acceleration algorithm.  It can be used together with the '-a' flag for
regular acceleration.

PR:		bin/110003
Submitted by:	Oliver Fromme <olli -at- lurza.secnetix.de>
MFC after:	1 week

3 files changed, 116 insertions, 8 deletions

diff --git a/usr.sbin/moused/Makefile b/usr.sbin/moused/Makefile
index 014bf6f..a313a21 100644
--- a/usr.sbin/moused/Makefile
+++ b/usr.sbin/moused/Makefile
@@ -3,8 +3,8 @@
 PROG=	moused
 MAN=	moused.8
 
-DPADD=	${LIBUTIL}
-LDADD=	-lutil
+DPADD=	${LIBUTIL}  ${LIBM}
+LDADD=	-lutil -lm
 
 #BINMODE=4555
 #PRECIOUSPROG=
diff --git a/usr.sbin/moused/moused.8 b/usr.sbin/moused/moused.8
index 4b2138d..c78086e 100644
--- a/usr.sbin/moused/moused.8
+++ b/usr.sbin/moused/moused.8
@@ -44,6 +44,7 @@
 .Op Fl r Ar resolution
 .Op Fl S Ar baudrate
 .Op Fl VH Op Fl U Ar distance
+.Op Fl A Ar exp Ns Op , Ns Ar offset
 .Op Fl a Ar X Ns Op , Ns Ar Y
 .Op Fl C Ar threshold
 .Op Fl m Ar N=M
@@ -213,12 +214,55 @@ mode is activated.
 The default
 .Ar distance
 is 3 pixels.
+.It Fl A Ar exp Ns Op , Ns Ar offset
+Apply exponential (dynamic) acceleration to mouse movements:
+the faster you move the mouse, the more it will be accelerated.
+That means that small mouse movements are not accelerated,
+so they are still very accurate, while a faster movement will
+drive the pointer quickly across the screen.
+.Pp
+The
+.Ar exp
+value specifies the exponent, which is basically
+the amount of acceleration.  Useful values are in the
+range 1.1 to 2.0, but it depends on your mouse hardware
+and your personal preference.  A value of 1.0 means no
+exponential acceleration.  A value of 2.0 means squared
+acceleration (i.e. if you move the mouse twice as fast,
+the pointer will move four times as fast on the screen).
+Values beyond 2.0 are possible but not recommended.
+A good value to start is probably 1.5.
+.Pp
+The optional
+.Ar offset
+value specifies the distance at which the acceleration
+begins.  The default is 1.0, which means that the
+acceleration is applied to movements larger than one unit.
+If you specify a larger value, it takes more speed for
+the acceleration to kick in, i.e. the speed range for
+small and accurate movements is wider.
+Usually the default should be sufficient, but if you're
+not satisfied with the behaviour, try a value of 2.0.
+.Pp
+Note that the
+.Fl A
+option interacts badly with the X server's own acceleration,
+which doesn't work very well anyway.  Therefore it is
+recommended to switch it off if necessary:
+.Dq xset m 1 .
 .It Fl a Ar X Ns Op , Ns Ar Y
 Accelerate or decelerate the mouse input.
 This is a linear acceleration only.
 Values less than 1.0 slow down movement, values greater than 1.0 speed it
 up.
 Specifying only one value sets the acceleration for both axes.
+.Pp
+You can use the
+.Fl a
+and
+.Fl A
+options at the same time to have the combined effect
+of linear and exponential acceleration.
 .It Fl c
 Some mice report middle button down events
 as if the left and right buttons are being pressed.
@@ -758,6 +802,7 @@ option to assign the physical right button to the logical middle button:
 .Sh SEE ALSO
 .Xr kill 1 ,
 .Xr vidcontrol 1 ,
+.Xr xset 1 ,
 .Xr keyboard 4 ,
 .Xr mse 4 ,
 .Xr psm 4 ,
diff --git a/usr.sbin/moused/moused.c b/usr.sbin/moused/moused.c
index 49f0ee7..a751774 100644
--- a/usr.sbin/moused/moused.c
+++ b/usr.sbin/moused/moused.c
@@ -70,6 +70,7 @@ __FBSDID("$FreeBSD$");
 #include <syslog.h>
 #include <termios.h>
 #include <unistd.h>
+#include <math.h>
 
 #define MAX_CLICKTHRESHOLD	2000	/* 2 seconds */
 #define MAX_BUTTON2TIMEOUT	2000	/* 2 seconds */
@@ -99,6 +100,7 @@ __FBSDID("$FreeBSD$");
 #define NoPnP		0x0010
 #define VirtualScroll	0x0020
 #define HVirtualScroll	0x0040
+#define ExponentialAcc	0x0080
 
 #define ID_NONE		0
 #define ID_PORT		1
@@ -394,6 +396,8 @@ static struct rodentparam {
     mousemode_t mode;		/* protocol information */
     float accelx;		/* Acceleration in the X axis */
     float accely;		/* Acceleration in the Y axis */
+    float expoaccel;		/* Exponential acceleration */
+    float expoffset;		/* Movement offset for exponential accel. */
     int scrollthreshold;	/* Movement distance before virtual scrolling */
 } rodent = {
     .flags = 0,
@@ -413,6 +417,8 @@ static struct rodentparam {
     .button2timeout = DFLT_BUTTON2TIMEOUT,
     .accelx = 1.0,
     .accely = 1.0,
+    .expoaccel = 1.0,
+    .expoffset = 1.0,
     .scrollthreshold = DFLT_SCROLLTHRESHOLD,
 };
 
@@ -492,6 +498,7 @@ static struct drift_xy  drift_previous={0,0}; /* steps in previous drift_time */
 
 /* function prototypes */
 
+static void	expoacc(int, int, int*, int*);
 static void	moused(void);
 static void	hup(int sig);
 static void	cleanup(int sig);
@@ -542,7 +549,7 @@ main(int argc, char *argv[])
     for (i = 0; i < MOUSE_MAXBUTTON; ++i)
 	mstate[i] = &bstate[i];
 
-    while ((c = getopt(argc, argv, "3C:DE:F:HI:PRS:T:VU:a:cdfhi:l:m:p:r:st:w:z:")) != -1)
+    while ((c = getopt(argc, argv, "3A:C:DE:F:HI:PRS:T:VU:a:cdfhi:l:m:p:r:st:w:z:")) != -1)
 	switch(c) {
 
 	case '3':
@@ -561,7 +568,7 @@ main(int argc, char *argv[])
 	case 'a':
 	    i = sscanf(optarg, "%f,%f", &rodent.accelx, &rodent.accely);
 	    if (i == 0) {
-		warnx("invalid acceleration argument '%s'", optarg);
+		warnx("invalid linear acceleration argument '%s'", optarg);
 		usage();
 	    }
 
@@ -570,6 +577,19 @@ main(int argc, char *argv[])
 
 	    break;
 
+	case 'A':
+	    rodent.flags |= ExponentialAcc;
+	    i = sscanf(optarg, "%f,%f", &rodent.expoaccel, &rodent.expoffset);
+	    if (i == 0) {
+		warnx("invalid exponential acceleration argument '%s'", optarg);
+		usage();
+	    }
+
+	    if (i == 1)
+		rodent.expoffset = 1.0;
+
+	    break;
+
 	case 'c':
 	    rodent.flags |= ChordMiddle;
 	    break;
@@ -902,6 +922,37 @@ usbmodule(void)
     return (kld_isloaded("uhub/ums") || kld_load("ums") != -1);
 }
 
+/*
+ * Function to calculate exponential acceleration.
+ *
+ * In order to give a smoother behaviour, we record the four
+ * most recent non-zero movements and use their average value
+ * to calculate the acceleration.
+ */
+
+static void
+expoacc(int dx, int dy, int *movex, int *movey)
+{
+    static float lastlength[3] = {0.0, 0.0, 0.0};
+    float fdx, fdy, length, lbase, accel;
+
+    if (dx == 0 && dy == 0) {
+	*movex = *movey = 0;
+	return;
+    }
+    fdx = dx * rodent.accelx;
+    fdy = dy * rodent.accely;
+    length = sqrtf((fdx * fdx) + (fdy * fdy));		/* Pythagoras */
+    length = (length + lastlength[0] + lastlength[1] + lastlength[2]) / 4;
+    lbase = length / rodent.expoffset;
+    accel = powf(lbase, rodent.expoaccel) / lbase;
+    *movex = lroundf(fdx * accel);
+    *movey = lroundf(fdy * accel);
+    lastlength[2] = lastlength[1];
+    lastlength[1] = lastlength[0];
+    lastlength[0] = length;	/* Insert new average, not original length! */
+}
+
 static void
 moused(void)
 {
@@ -1161,8 +1212,14 @@ moused(void)
 		if (action2.flags & MOUSE_POSCHANGED) {
 		    mouse.operation = MOUSE_MOTION_EVENT;
 		    mouse.u.data.buttons = action2.button;
-		    mouse.u.data.x = action2.dx * rodent.accelx;
-		    mouse.u.data.y = action2.dy * rodent.accely;
+		    if (rodent.flags & ExponentialAcc) {
+			expoacc(action2.dx, action2.dy,
+			    &mouse.u.data.x, &mouse.u.data.y);
+		    }
+		    else {
+			mouse.u.data.x = action2.dx * rodent.accelx;
+			mouse.u.data.y = action2.dy * rodent.accely;
+		    }
 		    mouse.u.data.z = action2.dz;
 		    if (debug < 2)
 			if (!paused)
@@ -1171,8 +1228,14 @@ moused(void)
 	    } else {
 		mouse.operation = MOUSE_ACTION;
 		mouse.u.data.buttons = action2.button;
-		mouse.u.data.x = action2.dx * rodent.accelx;
-		mouse.u.data.y = action2.dy * rodent.accely;
+		if (rodent.flags & ExponentialAcc) {
+		    expoacc(action2.dx, action2.dy,
+			&mouse.u.data.x, &mouse.u.data.y);
+		}
+		else {
+		    mouse.u.data.x = action2.dx * rodent.accelx;
+		    mouse.u.data.y = action2.dy * rodent.accely;
+		}
 		mouse.u.data.z = action2.dz;
 		if (debug < 2)
 		    if (!paused)