--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/events/SDL_gesture.c	Wed Jul 07 04:13:08 2010 -0700
@@ -0,0 +1,189 @@
+/*
+    SDL - Simple DirectMedia Layer
+    Copyright (C) 1997-2010 Sam Lantinga
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+    Sam Lantinga
+    slouken@libsdl.org
+*/
+#include "SDL_config.h"
+
+/* General mouse handling code for SDL */
+
+#include "SDL_events.h"
+#include "SDL_events_c.h"
+#include "SDL_gesture_c.h"
+
+//TODO: Replace with malloc
+#define MAXFINGERS 3
+#define MAXTOUCHES 2
+
+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 {
+  int id;
+  Point res;
+  Point centroid;
+  TouchPoint gestureLast[MAXFINGERS];
+  int numDownFingers;
+} GestureTouch;
+
+GestureTouch gestureTouch[MAXTOUCHES];
+int numGestureTouches = 0;
+int SDL_GestureAddTouch(SDL_Touch* touch) { 
+  if(numGestureTouches >= MAXTOUCHES) return -1;
+  
+  gestureTouch[numGestureTouches].res.x = touch->xres;
+  gestureTouch[numGestureTouches].res.y = touch->yres;
+  gestureTouch[numGestureTouches].numDownFingers = 0;
+
+  gestureTouch[numGestureTouches].res.x = touch->xres;
+  gestureTouch[numGestureTouches].id = touch->id;
+
+  numGestureTouches++;
+  return 0;
+}
+
+GestureTouch * SDL_GetGestureTouch(int id) {
+  int i;
+  for(i = 0;i < numGestureTouches; i++) {
+    //printf("%i ?= %i\n",gestureTouch[i].id,id);
+    if(gestureTouch[i].id == id) return &gestureTouch[i];
+  }
+  return NULL;
+}
+
+int SDL_SendGestureMulti(GestureTouch* touch,float dTheta,float dDist) {
+  SDL_Event event;
+  event.mgesture.type = SDL_MULTIGESTURE;
+  event.mgesture.touchId = touch->id;
+  event.mgesture.x = touch->centroid.x;
+  event.mgesture.y = touch->centroid.y;
+  event.mgesture.dTheta = dTheta;
+  event.mgesture.dDist = dDist;  
+  return SDL_PushEvent(&event) > 0;
+}
+
+void SDL_GestureProcessEvent(SDL_Event* event)
+{
+  if(event->type == SDL_FINGERMOTION || 
+     event->type == SDL_FINGERDOWN ||
+     event->type == SDL_FINGERUP) {
+    GestureTouch* inTouch = SDL_GetGestureTouch(event->tfinger.touchId);
+
+
+    //Shouldn't be possible
+    if(inTouch == NULL) return;
+    
+    
+    float x = ((float)event->tfinger.x)/inTouch->res.x;
+    float y = ((float)event->tfinger.y)/inTouch->res.y;
+    int j,empty = -1;
+    
+    for(j = 0;j<inTouch->numDownFingers;j++) {
+      if(inTouch->gestureLast[j].f.id != event->tfinger.fingerId) continue;
+
+      if(event->type == SDL_FINGERUP) {
+	inTouch->numDownFingers--;
+	inTouch->gestureLast[j] = inTouch->gestureLast[inTouch->numDownFingers];
+	break;
+      }
+      else {
+	float dx = x - inTouch->gestureLast[j].f.p.x;
+	float dy = y - inTouch->gestureLast[j].f.p.y;
+	inTouch->centroid.x += dx/inTouch->numDownFingers;
+	inTouch->centroid.y += dy/inTouch->numDownFingers;    
+	if(inTouch->numDownFingers > 1) {
+	  Point lv; //Vector from centroid to last x,y position
+	  Point v; //Vector from centroid to current x,y position
+	  lv = inTouch->gestureLast[j].cv;
+	  float lDist = sqrt(lv.x*lv.x + lv.y*lv.y);
+	  //printf("lDist = %f\n",lDist);
+	  v.x = x - inTouch->centroid.x;
+	  v.y = y - inTouch->centroid.y;
+	  inTouch->gestureLast[j].cv = v;
+	  float Dist = sqrt(v.x*v.x+v.y*v.y);
+	  // cos(dTheta) = (v . lv)/(|v| * |lv|)
+	  
+	  //Normalize Vectors to simplify angle calculation
+	  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 = (Dist - lDist);
+	  if(lDist == 0) {dDist = 0;dtheta = 0;} //To avoid impossible values
+	  inTouch->gestureLast[j].dDist = dDist;
+	  inTouch->gestureLast[j].dtheta = dtheta;
+	  
+	  //printf("dDist = %f, dTheta = %f\n",dDist,dtheta);
+	  //gdtheta = gdtheta*.9 + dtheta*.1;
+	  //gdDist  =  gdDist*.9 +  dDist*.1
+	  //knob.r += dDist/numDownFingers;
+	  //knob.ang += dtheta;
+	  //printf("thetaSum = %f, distSum = %f\n",gdtheta,gdDist);
+	  //printf("id: %i dTheta = %f, dDist = %f\n",j,dtheta,dDist);
+	  SDL_SendGestureMulti(inTouch,dtheta,dDist);
+	}
+	else {
+	  inTouch->gestureLast[j].dDist = 0;
+	  inTouch->gestureLast[j].dtheta = 0;
+	  inTouch->gestureLast[j].cv.x = 0;
+	  inTouch->gestureLast[j].cv.y = 0;
+	}
+	inTouch->gestureLast[j].f.p.x = x;
+	inTouch->gestureLast[j].f.p.y = y;
+	break;
+	//pressure?
+      }      
+    }
+    
+    if(j == inTouch->numDownFingers) {
+      //printf("Finger Down!!!\n");
+      inTouch->numDownFingers++;
+      inTouch->centroid.x = (inTouch->centroid.x*(inTouch->numDownFingers - 1)+ 
+			     x)/inTouch->numDownFingers;
+      inTouch->centroid.y = (inTouch->centroid.y*(inTouch->numDownFingers - 1)+
+			     y)/inTouch->numDownFingers;
+      
+      inTouch->gestureLast[j].f.id = event->tfinger.fingerId;
+      inTouch->gestureLast[j].f.p.x  = x;
+      inTouch->gestureLast[j].f.p.y  = y;	
+      inTouch->gestureLast[j].cv.x = 0;
+      inTouch->gestureLast[j].cv.y = 0;
+    }
+  }
+}  
+  
+  /* vi: set ts=4 sw=4 expandtab: */
+