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dix: improve readbility of DoGetDirection.

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Use enums for the direction bits, not hardcoded bitfield values that are
added up.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Daniel Stone <daniel@fooishbar.org>
Reviewed-by: Jamey Sharp <jamey@minilop.net>
Reviewed-by: Simon Thum <simon.thum@gmx.de>
This commit is contained in:
Peter Hutterer 2011-04-20 11:12:35 +10:00
parent 709b291972
commit e804ae85fe
1 changed files with 25 additions and 12 deletions
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37
dix/ptrveloc.c
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@ -429,14 +429,27 @@ InitTrackers(DeviceVelocityPtr vel, int ntracker)
vel->num_tracker = ntracker;
}
enum directions {
N = (1 << 0),
NE = (1 << 1),
E = (1 << 2),
SE = (1 << 3),
S = (1 << 4),
SW = (1 << 5),
W = (1 << 6),
NW = (1 << 7),
UNDEFINED = 0xFF
};
/**
* return a bit field of possible directions.
* 0 = N, 2 = E, 4 = S, 6 = W, in-between is as you guess.
* There's no reason against widening to more precise directions (<45 degrees),
* should it not perform well. All this is needed for is sort out non-linear
* motion, so precision isn't paramount. However, one should not flag direction
* too narrow, since it would then cut the linear segment to zero size way too
* often.
*
* @return A bitmask for N, NE, S, SE, etc. indicating the directions for
* this movement.
*/
static int
DoGetDirection(int dx, int dy){
@ -446,23 +459,23 @@ DoGetDirection(int dx, int dy){
if(abs(dx) < 2 && abs(dy) < 2){
/* first check diagonal cases */
if(dx > 0 && dy > 0)
return 4+8+16;
return E | SE | S;
if(dx > 0 && dy < 0)
return 1+2+4;
return N | NE | E;
if(dx < 0 && dy < 0)
return 1+128+64;
return W | NW | N;
if(dx < 0 && dy > 0)
return 16+32+64;
return W | SW | S;
/* check axis-aligned directions */
if(dx > 0)
return 2+4+8; /*E*/
return NE | E | SE;
if(dx < 0)
return 128+64+32; /*W*/
return NW | W | SW;
if(dy > 0)
return 32+16+8; /*S*/
return SE | S | SW;
if(dy < 0)
return 128+1+2; /*N*/
return 255; /* shouldn't happen */
return NE | N | NW;
return UNDEFINED; /* shouldn't happen */
}
/* else, compute angle and set appropriate flags */
#ifdef _ISOC99_SOURCE
@ -478,7 +491,7 @@ DoGetDirection(int dx, int dy){
i1 = (int)(r+0.1) % 8;
i2 = (int)(r+0.9) % 8;
if(i1 < 0 || i1 > 7 || i2 < 0 || i2 > 7)
return 255; /* shouldn't happen */
return UNDEFINED; /* shouldn't happen */
return 1 << i1 | 1 << i2;
}
@ -558,7 +571,7 @@ CalcTracker(DeviceVelocityPtr vel, int offset, int cur_t){
*/
static float
QueryTrackers(DeviceVelocityPtr vel, int cur_t){
int n, offset, dir = 255, i = -1, age_ms;
int n, offset, dir = UNDEFINED, i = -1, age_ms;
/* initial velocity: a low-offset, valid velocity */
float iveloc = 0, res = 0, tmp, vdiff;
float vfac = vel->corr_mul * vel->const_acceleration; /* premultiply */