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SDL_gesture.c
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/*
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: */