Moved Multi finger gesture recognition into the library.

touchTest/gestureSDLTest.c

@@ -0,0 +1,687 @@
+#include <stdio.h>
+#include <SDL.h>
+#include <math.h>
+#include <SDL_touch.h>
+
+#define PI 3.1415926535897
+#define PHI ((sqrt(5)-1)/2)
+#define WIDTH 640
+#define HEIGHT 480
+#define BPP 4
+#define DEPTH 32
+
+#define MAXFINGERS 3
+
+#define DOLLARNPOINTS 64
+#define DOLLARSIZE 256
+
+//MUST BE A POWER OF 2!
+#define EVENT_BUF_SIZE 256
+
+SDL_Event events[EVENT_BUF_SIZE];
+int eventWrite;
+
+int mousx,mousy;
+int keystat[512];
+int bstatus;
+
+int colors[7] = {0xFF,0xFF00,0xFF0000,0xFFFF00,0x00FFFF,0xFF00FF,0xFFFFFF};
+
+int index2fingerid[MAXFINGERS];
+int fingersDown;
+
+typedef struct {
+  float x,y;
+} Point;
+
+typedef struct {
+  Point p;
+  float pressure;
+  int id;
+} Finger;
+
+typedef struct {
+  Finger f;
+  Point cv;
+  float dtheta,dDist;
+} TouchPoint;
+
+ 
+typedef struct { //dt + s
+  Point d,s; //direction, start
+  int points;
+} Line;
+
+
+typedef struct {
+  float length;
+  
+  int numPoints;
+  Point p[EVENT_BUF_SIZE]; //To be safe
+} DollarPath;
+
+typedef struct {
+  float ang,r;
+  Point p;
+} Knob;
+
+Knob knob;
+
+Finger finger[MAXFINGERS];
+
+
+DollarPath dollarPath[MAXFINGERS];
+
+#define MAXTEMPLATES 4
+
+Point dollarTemplate[MAXTEMPLATES][DOLLARNPOINTS];
+int numDollarTemplates = 0;
+#ifdef DRAW_VECTOR_EST
+Line gestureLine[MAXFINGERS];
+#endif
+
+void handler (int sig)
+{
+  printf ("\exiting...(%d)\n", sig);
+  exit (0);
+}
+
+void perror_exit (char *error)
+{
+  perror (error);
+  handler (9);
+}
+
+
+void setpix(SDL_Surface *screen, int x, int y, unsigned int col)
+{
+  Uint32 *pixmem32;
+  Uint32 colour;
+  
+  if((unsigned)x > screen->w) return;
+  if((unsigned)y > screen->h) return;
+
+  pixmem32 = (Uint32*) screen->pixels  + y*screen->pitch/BPP + x;
+  
+  Uint8 r,g,b;
+  float a;
+  
+  memcpy(&colour,pixmem32,screen->format->BytesPerPixel);
+
+  SDL_GetRGB(colour,screen->format,&r,&g,&b); //Always returns 0xFFFFFF?
+  //r = 0;g = 0; b = 0;
+  a = (col>>24)&0xFF;
+  if(a == 0) a = 0xFF; //Hack, to make things easier.
+  a /= 0xFF;
+  r = r*(1-a) + ((col>>16)&0xFF)*(a);
+  g = g*(1-a) + ((col>> 8)&0xFF)*(a);
+  b = b*(1-a) + ((col>> 0)&0xFF)*(a);
+  colour = SDL_MapRGB( screen->format,r, g, b);
+  
+
+  *pixmem32 = colour;
+}
+
+void drawLine(SDL_Surface *screen,int x0,int y0,int x1,int y1,unsigned int col) {
+  float t;
+  for(t=0;t<1;t+=1.f/SDL_max(abs(x0-x1),abs(y0-y1)))
+    setpix(screen,x1+t*(x0-x1),y1+t*(y0-y1),col);
+}
+void drawCircle(SDL_Surface* screen,int x,int y,int r,unsigned int c)
+{
+
+  float a;
+  int tx;
+  
+  int ty;
+  float xr;
+  for(ty = -abs(r);ty <= abs(r);ty++) {
+    xr = sqrt(r*r - ty*ty);
+    if(r > 0) { //r > 0 ==> filled circle
+      for(tx=-xr+.5;tx<=xr-.5;tx++) {
+	setpix(screen,x+tx,y+ty,c);
+      }
+    }
+    else {
+      setpix(screen,x-xr+.5,y+ty,c);
+      setpix(screen,x+xr-.5,y+ty,c);
+    }
+  }
+}
+
+void drawKnob(SDL_Surface* screen,Knob k) {
+  //printf("Knob: x = %f, y = %f, r = %f, a = %f\n",k.p.x,k.p.y,k.r,k.ang);
+ 
+  drawCircle(screen,k.p.x*screen->w,k.p.y*screen->h,k.r*screen->w,0xFFFFFF);
+  
+  drawCircle(screen,(k.p.x+k.r/2*cos(k.ang))*screen->w,
+  	            (k.p.y+k.r/2*sin(k.ang))*screen->h,k.r/4*screen->w,0);
+  
+}
+
+void drawDollarPath(SDL_Surface* screen,Point* points,int numPoints,
+		    int rad,unsigned int col){
+  int i;
+  for(i=0;i<numPoints;i++) {
+    drawCircle(screen,points[i].x+screen->w/2,
+	       points[i].y+screen->h/2,
+	       rad,col);
+  }
+}
+
+float dollarDifference(Point* points,Point* templ,float ang) {
+  //  Point p[DOLLARNPOINTS];
+  float dist = 0;
+  Point p;
+  int i;
+  for(i = 0; i < DOLLARNPOINTS; i++) {
+    p.x = points[i].x * cos(ang) - points[i].y * sin(ang);
+    p.y = points[i].x * sin(ang) + points[i].y * cos(ang);
+    dist += sqrt((p.x-templ[i].x)*(p.x-templ[i].x)+
+		 (p.y-templ[i].y)*(p.y-templ[i].y));
+  }
+  return dist/DOLLARNPOINTS;
+  
+}
+
+float bestDollarDifference(Point* points,Point* templ) {
+  //------------BEGIN DOLLAR BLACKBOX----------------//
+  //-TRANSLATED DIRECTLY FROM PSUDEO-CODE AVAILABLE AT-//
+  //-"http://depts.washington.edu/aimgroup/proj/dollar/"-//
+  float ta = -PI/4;
+  float tb = PI/4;
+  float dt = PI/90;
+  float x1 = PHI*ta + (1-PHI)*tb;
+  float f1 = dollarDifference(points,templ,x1);
+  float x2 = (1-PHI)*ta + PHI*tb;
+  float f2 = dollarDifference(points,templ,x2);
+  while(abs(ta-tb) > dt) {
+    if(f1 < f2) {
+      tb = x2;
+      x2 = x1;
+      f2 = f1;
+      x1 = PHI*ta + (1-PHI)*tb;
+      f1 = dollarDifference(points,templ,x1);
+    }
+    else {
+      ta = x1;
+      x1 = x2;
+      f1 = f2;
+      x2 = (1-PHI)*ta + PHI*tb;
+      f2 = dollarDifference(points,templ,x2);
+    }
+  }
+  /*
+  if(f1 <= f2)
+    printf("Min angle (x1): %f\n",x1);
+  else if(f1 >  f2)
+    printf("Min angle (x2): %f\n",x2);
+  */
+  return SDL_min(f1,f2);  
+}
+
+float dollarRecognize(SDL_Surface* screen, DollarPath path,int *bestTempl) {
+
+  Point points[DOLLARNPOINTS];
+  int numPoints = dollarNormalize(path,points);
+  int i;
+  
+  int k;
+  /*
+  for(k = 0;k<DOLLARNPOINTS;k++) {
+    printf("(%f,%f)\n",points[k].x,
+	   points[k].y);
+  }
+  */
+  drawDollarPath(screen,points,numPoints,-15,0xFF6600);
+
+  int bestDiff = 10000;
+  *bestTempl = -1;
+  for(i = 0;i < numDollarTemplates;i++) {
+    int diff = bestDollarDifference(points,dollarTemplate[i]);
+    if(diff < bestDiff) {bestDiff = diff; *bestTempl = i;}
+  }
+  return bestDiff;
+}
+
+//DollarPath contains raw points, plus (possibly) the calculated length
+int dollarNormalize(DollarPath path,Point *points) {
+  int i;
+  //Calculate length if it hasn't already been done
+  if(path.length <= 0) {
+    for(i=1;i<path.numPoints;i++) {
+      float dx = path.p[i  ].x - 
+	         path.p[i-1].x;
+      float dy = path.p[i  ].y - 
+	         path.p[i-1].y;
+      path.length += sqrt(dx*dx+dy*dy);
+    }
+  }
+
+
+  //Resample
+  float interval = path.length/(DOLLARNPOINTS - 1);
+  float dist = 0;
+
+  int numPoints = 0;
+  Point centroid; centroid.x = 0;centroid.y = 0;
+  //printf("(%f,%f)\n",path.p[path.numPoints-1].x,path.p[path.numPoints-1].y);
+  for(i = 1;i < path.numPoints;i++) {
+    float d = sqrt((path.p[i-1].x-path.p[i].x)*(path.p[i-1].x-path.p[i].x)+
+		   (path.p[i-1].y-path.p[i].y)*(path.p[i-1].y-path.p[i].y));
+    //printf("d = %f dist = %f/%f\n",d,dist,interval);
+    while(dist + d > interval) {
+      points[numPoints].x = path.p[i-1].x + 
+	((interval-dist)/d)*(path.p[i].x-path.p[i-1].x);
+      points[numPoints].y = path.p[i-1].y + 
+	((interval-dist)/d)*(path.p[i].y-path.p[i-1].y);
+      centroid.x += points[numPoints].x;
+      centroid.y += points[numPoints].y;
+      numPoints++;
+
+      dist -= interval;
+    }
+    dist += d;
+  }
+  if(numPoints < 1) return 0;
+  centroid.x /= numPoints;
+  centroid.y /= numPoints;
+ 
+  //printf("Centroid (%f,%f)",centroid.x,centroid.y);
+  //Rotate Points so point 0 is left of centroid and solve for the bounding box
+  float xmin,xmax,ymin,ymax;
+  xmin = centroid.x;
+  xmax = centroid.x;
+  ymin = centroid.y;
+  ymax = centroid.y;
+  
+  float ang = atan2(centroid.y - points[0].y,
+		    centroid.x - points[0].x);
+
+  for(i = 0;i<numPoints;i++) {					       
+    float px = points[i].x;
+    float py = points[i].y;
+    points[i].x = (px - centroid.x)*cos(ang) - 
+                  (py - centroid.y)*sin(ang) + centroid.x;
+    points[i].y = (px - centroid.x)*sin(ang) + 
+                  (py - centroid.y)*cos(ang) + centroid.y;
+
+
+    if(points[i].x < xmin) xmin = points[i].x;
+    if(points[i].x > xmax) xmax = points[i].x; 
+    if(points[i].y < ymin) ymin = points[i].y;
+    if(points[i].y > ymax) ymax = points[i].y;
+  }
+
+  //Scale points to DOLLARSIZE, and translate to the origin
+  float w = xmax-xmin;
+  float h = ymax-ymin;
+
+  for(i=0;i<numPoints;i++) {
+    points[i].x = (points[i].x - centroid.x)*DOLLARSIZE/w;
+    points[i].y = (points[i].y - centroid.y)*DOLLARSIZE/h;
+  }  
+  return numPoints;
+}
+
+void DrawScreen(SDL_Surface* screen, int h)
+{
+  int x, y, xm,ym,c;
+  if(SDL_MUSTLOCK(screen))
+    {                                              
+      if(SDL_LockSurface(screen) < 0) return;
+    }
+  for(y = 0; y < screen->h; y++ )
+    {
+      for( x = 0; x < screen->w; x++ )
+        {
+	  //setpixel(screen, x, y, (x*x)/256+3*y+h, (y*y)/256+x+h, h);
+	  //xm = (x+h)%screen->w;
+	  //ym = (y+h)%screen->w;
+	  //c = sin(h/256*2*PI)*x*y/screen->w/screen->h;
+	  //setpix(screen,x,y,255*sin(xm/screen->w*2*PI),sin(h/255*2*PI)*255*y/screen->h,c);
+	  setpix(screen,x,y,((x%255)<<16) + ((y%255)<<8) + (x+y)%255);
+	  //setpix(screen,x,y,0); //Inefficient, but that's okay...
+        }
+    }
+  drawCircle(screen,mousx,mousy,-30,0xFFFFFF);
+  drawLine(screen,0,0,screen->w,screen->h,0xFFFFFF);
+
+  int i;
+//draw Touch History
+  TouchPoint gestureLast[MAXFINGERS];
+  //printf("------------------Start History------------------\n");
+  for(i = 0;i < MAXFINGERS;i++) {
+    gestureLast[i].f.id = -1;
+  }
+  int numDownFingers = 0;
+  Point centroid;
+  float gdtheta,gdDist;
+
+
+  for(i = SDL_max(0,eventWrite - EVENT_BUF_SIZE);i < eventWrite;i++) {
+    SDL_Event event = events[i&(EVENT_BUF_SIZE-1)];
+    int age = eventWrite - i - 1;
+    if(event.type == SDL_FINGERMOTION || 
+       event.type == SDL_FINGERDOWN ||
+       event.type == SDL_FINGERUP) {
+      SDL_Touch* inTouch = SDL_GetTouch(event.tfinger.touchId);
+      //SDL_Finger* inFinger = SDL_GetFinger(inTouch,event.tfinger.fingerId);
+	    
+      float x = ((float)event.tfinger.x)/inTouch->xres;
+      float y = ((float)event.tfinger.y)/inTouch->yres;
+      int j,empty = -1;
+      
+      for(j = 0;j<MAXFINGERS;j++) {
+	if(gestureLast[j].f.id == event.tfinger.fingerId) {
+	  if(event.type == SDL_FINGERUP) {
+	    numDownFingers--;
+	    if(numDownFingers <= 1) {
+	      gdtheta = 0;
+	      gdDist = 0;
+	    }
+	    if(!keystat[32]){ //spacebar
+	      int bestTempl;
+	      float error = dollarRecognize(screen,dollarPath[j],&bestTempl);
+	      if(bestTempl >= 0){
+		drawDollarPath(screen,dollarTemplate[bestTempl]
+			       ,DOLLARNPOINTS,-15,0x0066FF);		
+		printf("Dollar error: %f\n",error);
+	      }
+	      
+	    }
+	    else if(numDollarTemplates < MAXTEMPLATES) {
+	      
+	      dollarNormalize(dollarPath[j],
+			      dollarTemplate[numDollarTemplates]);
+	      /*
+	      int k;	      
+	      for(k = 0;k<DOLLARNPOINTS;k++) {
+		printf("(%f,%f)\n",dollarTemplate[numDollarTemplates][i].x,
+		       dollarTemplate[numDollarTemplates][i].y);
+		       }*/
+	      numDollarTemplates++;	      
+	    }
+
+	    gestureLast[j].f.id = -1;
+	    break;
+	  }
+	  else {
+	    dollarPath[j].p[dollarPath[j].numPoints].x = x;
+	    dollarPath[j].p[dollarPath[j].numPoints].y = y;
+	    float dx = (dollarPath[j].p[dollarPath[j].numPoints  ].x-
+			dollarPath[j].p[dollarPath[j].numPoints-1].x);
+	    float dy = (dollarPath[j].p[dollarPath[j].numPoints  ].y-
+			dollarPath[j].p[dollarPath[j].numPoints-1].y);
+	    dollarPath[j].length += sqrt(dx*dx + dy*dy);
+
+	    dollarPath[j].numPoints++;
+
+	    centroid.x = centroid.x + dx/numDownFingers;
+	    centroid.y = centroid.y + dy/numDownFingers;    
+	    if(numDownFingers > 1) {
+	      Point lv; //Vector from centroid to last x,y position
+	      Point v; //Vector from centroid to current x,y position
+	      lv.x = gestureLast[j].cv.x;
+	      lv.y = gestureLast[j].cv.y;
+	      float lDist = sqrt(lv.x*lv.x + lv.y*lv.y);
+	      
+	      v.x = x - centroid.x;
+	      v.y = y - centroid.y;
+	      gestureLast[j].cv = v;
+	      float Dist = sqrt(v.x*v.x+v.y*v.y);
+	      // cos(dTheta) = (v . lv)/(|v| * |lv|)
+	      
+	      lv.x/=lDist;
+	      lv.y/=lDist;
+	      v.x/=Dist;
+	      v.y/=Dist;
+	      float dtheta = atan2(lv.x*v.y - lv.y*v.x,lv.x*v.x + lv.y*v.y);
+	      
+	      float dDist = (lDist - Dist);	      
+	      
+	      gestureLast[j].dDist = dDist;
+	      gestureLast[j].dtheta = dtheta;
+
+	      //gdtheta = gdtheta*.9 + dtheta*.1;
+	      //gdDist  =  gdDist*.9 +  dDist*.1
+	      gdtheta += dtheta;
+	      gdDist += dDist;
+
+	      //printf("thetaSum = %f, distSum = %f\n",gdtheta,gdDist);
+	      //printf("id: %i dTheta = %f, dDist = %f\n",j,dtheta,dDist);
+	    }
+	    else {
+	      gestureLast[j].dDist = 0;
+	      gestureLast[j].dtheta = 0;
+	      gestureLast[j].cv.x = 0;
+	      gestureLast[j].cv.y = 0;
+	    }
+	    gestureLast[j].f.p.x = x;
+	    gestureLast[j].f.p.y = y;
+	    break;
+	    //pressure?
+	  }	  
+	}
+	else if(gestureLast[j].f.id == -1 && empty == -1) {
+	  empty = j;
+	}
+      }
+      
+      if(j >= MAXFINGERS && empty >= 0) {
+	//	printf("Finger Down!!!\n");
+	numDownFingers++;
+	centroid.x = (centroid.x*(numDownFingers - 1) + x)/numDownFingers;
+	centroid.y = (centroid.y*(numDownFingers - 1) + y)/numDownFingers;
+	
+	j = empty;
+	gestureLast[j].f.id = event.tfinger.fingerId;
+	gestureLast[j].f.p.x  = x;
+	gestureLast[j].f.p.y  = y;
+	
+	
+	dollarPath[j].length = 0;
+	dollarPath[j].p[0].x = x;
+	dollarPath[j].p[0].y = y;
+	dollarPath[j].numPoints = 1;
+      }
+      
+      //draw the touch:
+      
+      if(gestureLast[j].f.id < 0) continue; //Finger up. Or some error...
+      
+      unsigned int c = colors[gestureLast[j].f.id%7]; 
+      unsigned int col = 
+	((unsigned int)(c*(.1+.85))) |
+	((unsigned int)((0xFF*(1-((float)age)/EVENT_BUF_SIZE))) & 0xFF)<<24;
+      x = gestureLast[j].f.p.x;
+      y = gestureLast[j].f.p.y;
+      if(event.type == SDL_FINGERMOTION)
+	drawCircle(screen,x*screen->w,y*screen->h,5,col);
+      else if(event.type == SDL_FINGERDOWN)
+	drawCircle(screen,x*screen->w,y*screen->h,-10,col);     
+      
+      //if there is a centroid, draw it
+      if(numDownFingers > 1) {
+	unsigned int col = 
+	  ((unsigned int)(0xFFFFFF)) |
+	  ((unsigned int)((0xFF*(1-((float)age)/EVENT_BUF_SIZE))) & 0xFF)<<24;
+	drawCircle(screen,centroid.x*screen->w,centroid.y*screen->h,5,col);
+      }
+    }
+  }
+  
+
+  for(i=0;i<MAXFINGERS;i++)
+    if(finger[i].p.x >= 0 && finger[i].p.y >= 0)
+      if(finger[i].pressure > 0)
+	drawCircle(screen,finger[i].p.x*screen->w,finger[i].p.y*screen->h
+		   ,20,0xFF*finger[i].pressure);
+      else
+	drawCircle(screen,finger[i].p.x*screen->w,finger[i].p.y*screen->h
+		   ,20,0xFF);
+
+
+  
+  keystat[32] = 0;
+  
+  if(knob.p.x > 0)
+    drawKnob(screen,knob);
+  
+  if(SDL_MUSTLOCK(screen)) SDL_UnlockSurface(screen);
+  
+  SDL_Flip(screen);
+}
+
+SDL_Surface* initScreen(int width,int height)
+{
+  return SDL_SetVideoMode(width, height, DEPTH,
+			  SDL_HWSURFACE | SDL_RESIZABLE);
+}
+
+int main(int argc, char* argv[])
+{  
+  SDL_Surface *screen;
+  SDL_Event event;
+  
+  int keypress = 0;
+  int h=0,s=1,i,j;
+
+  //gesture variables
+  int numDownFingers = 0;
+  float gdtheta = 0,gdDist = 0;
+  Point centroid;
+  knob.r = .1;
+  knob.ang = 0;
+  TouchPoint gestureLast[MAXFINGERS];
+  
+
+
+  memset(keystat,0,512*sizeof(keystat[0]));
+  if (SDL_Init(SDL_INIT_VIDEO) < 0 ) return 1;
+  
+  if (!(screen = initScreen(WIDTH,HEIGHT)))
+    {
+      SDL_Quit();
+      return 1;
+    }
+
+  while(!keystat[27]) {
+    //Poll SDL
+    while(SDL_PollEvent(&event)) 
+      {
+	//Record _all_ events
+	events[eventWrite & (EVENT_BUF_SIZE-1)] = event;
+	eventWrite++;
+	
+	switch (event.type) 
+	  {
+	  case SDL_QUIT:
+	    keystat[27] = 1;
+	    break;
+	  case SDL_KEYDOWN:
+	    //printf("%i\n",event.key.keysym.sym);
+	    keystat[event.key.keysym.sym] = 1;
+	    //keypress = 1;
+	    break;
+	  case SDL_KEYUP:
+	      //printf("%i\n",event.key.keysym.sym);
+	    keystat[event.key.keysym.sym] = 0;
+	    //keypress = 1;
+	    break;
+	  case SDL_VIDEORESIZE:
+	    if (!(screen = initScreen(event.resize.w,
+				      event.resize.h)))
+	      {
+		SDL_Quit();
+		return 1;
+	      }
+	    break;
+	  case SDL_MOUSEMOTION:
+	    mousx = event.motion.x;
+	    mousy = event.motion.y; 
+	    break;
+	  case SDL_MOUSEBUTTONDOWN:
+	    bstatus |=  (1<<(event.button.button-1));
+	    break;
+	  case SDL_MOUSEBUTTONUP:
+	    bstatus &= ~(1<<(event.button.button-1));
+	    break;
+	  case SDL_FINGERMOTION:    
+	    ;
+	    //printf("Finger: %i,x: %i, y: %i\n",event.tfinger.fingerId,
+	    //	   event.tfinger.x,event.tfinger.y);
+	    SDL_Touch* inTouch = SDL_GetTouch(event.tfinger.touchId);
+	    SDL_Finger* inFinger = SDL_GetFinger(inTouch,event.tfinger.fingerId);
+
+	    for(i = 0;i<MAXFINGERS;i++) 
+	      if(index2fingerid[i] == event.tfinger.fingerId) 	      
+		break;
+	    if(i == MAXFINGERS) break;  
+	    if(inTouch > 0) {
+	      finger[i].p.x = ((float)event.tfinger.x)/
+		inTouch->xres;
+	      finger[i].p.y = ((float)event.tfinger.y)/
+		inTouch->yres;
+	      
+	      finger[i].pressure = 
+		((float)event.tfinger.pressure)/inTouch->pressureres;
+	      /*
+	      printf("Finger: %i, Pressure: %f Pressureres: %i\n",
+		     event.tfinger.fingerId,
+		     finger[i].pressure,
+		     inTouch->pressureres);
+	      */
+	      //printf("Finger: %i, pressure: %f\n",event.tfinger.fingerId,
+	      //   finger[event.tfinger.fingerId].pressure);
+	    }
+	    
+	    break;	    
+	  case SDL_FINGERDOWN:
+	    printf("Finger: %i down - x: %i, y: %i\n",event.tfinger.fingerId,
+		   event.tfinger.x,event.tfinger.y);
+
+	    for(i = 0;i<MAXFINGERS;i++) 
+	      if(index2fingerid[i] == -1) {
+		index2fingerid[i] = event.tfinger.fingerId;
+		break;
+	      }
+	    finger[i].p.x = event.tfinger.x;
+	    finger[i].p.y = event.tfinger.y;
+	    break;
+	  case SDL_FINGERUP:
+	    printf("Figner: %i up - x: %i, y: %i\n",event.tfinger.fingerId,
+	           event.tfinger.x,event.tfinger.y);
+	    for(i = 0;i<MAXFINGERS;i++) 
+	      if(index2fingerid[i] == event.tfinger.fingerId) {
+		index2fingerid[i] = -1;
+		break;
+	      }
+	    finger[i].p.x = -1;
+	    finger[i].p.y = -1;
+	    break;
+	  case SDL_MULTIGESTURE:
+	    knob.p.x = event.mgesture.x;
+	    knob.p.y = event.mgesture.y;
+	    knob.ang += event.mgesture.dTheta;
+	    knob.r += event.mgesture.dDist;
+	  }
+      
+    
+	
+	//And draw
+	
+      }
+    DrawScreen(screen,h);
+    //printf("c: (%f,%f)\n",centroid.x,centroid.y);
+    //printf("numDownFingers: %i\n",numDownFingers);
+    //for(i=0;i<512;i++) 
+    // if(keystat[i]) printf("%i\n",i);
+      
+    
+  }  
+  SDL_Quit();
+  
+  return 0;
+}
+

touchTest/makefile

@@ -1,4 +1,5 @@
 SDLTest : touchSimp.c touchPong.c
+	gcc gestureSDLTest.c -o gestureSDLTest `sdl-config --cflags --libs` -g
 	gcc gestureTest.c -o gestureTest `sdl-config --cflags --libs` -g
 	gcc touchTest.c -o touchTest `sdl-config --cflags --libs` -g		
 	gcc touchSimp.c -o touchSimp `sdl-config --cflags --libs` -g