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Fixed bug 3871 - Touch events are not normalised on X11

Trent Gamblin

The documentation for SDL_TouchFingerEvent says that the x and y coordinates are normalised between 0-1. I've found that to be true on Windows, Android and iOS but on X11 they are in pixel coordinates. This patch fixes the issue. This was the cleanest way I could do it with what was available without changing things around a lot but you may know a better way.
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slouken committed Oct 11, 2017
1 parent b53c35d commit c0019b7f4999cbcad64b9629aefc6b874d23fa3a
Showing with 30 additions and 3 deletions.
  1. +30 −3 src/video/x11/SDL_x11xinput2.c
@@ -73,6 +73,24 @@ xinput2_version_atleast(const int version, const int wantmajor, const int wantmi
{
return ( version >= ((wantmajor * 1000) + wantminor) );
}

static void
xinput2_normalize_touch_coordinates(SDL_VideoData *videodata, Window window,
double in_x, double in_y, float *out_x, float *out_y)
{
int i;
for (i = 0; i < videodata->numwindows; i++) {
SDL_WindowData *d = videodata->windowlist[i];
if (d->xwindow == window) {
*out_x = in_x / (d->window->w-1);
*out_y = in_y / (d->window->h-1);
return;
}
}
// couldn't find the window...
*out_x = in_x;
*out_y = in_y;
}
#endif /* SDL_VIDEO_DRIVER_X11_XINPUT2 */

void
@@ -171,22 +189,31 @@ X11_HandleXinput2Event(SDL_VideoData *videodata,XGenericEventCookie *cookie)
#if SDL_VIDEO_DRIVER_X11_XINPUT2_SUPPORTS_MULTITOUCH
case XI_TouchBegin: {
const XIDeviceEvent *xev = (const XIDeviceEvent *) cookie->data;
float x, y;
xinput2_normalize_touch_coordinates(videodata, xev->event,
xev->event_x, xev->event_y, &x, &y);
SDL_SendTouch(xev->sourceid,xev->detail,
SDL_TRUE, xev->event_x, xev->event_y, 1.0);
SDL_TRUE, x, y, 1.0);
return 1;
}
break;
case XI_TouchEnd: {
const XIDeviceEvent *xev = (const XIDeviceEvent *) cookie->data;
float x, y;
xinput2_normalize_touch_coordinates(videodata, xev->event,
xev->event_x, xev->event_y, &x, &y);
SDL_SendTouch(xev->sourceid,xev->detail,
SDL_FALSE, xev->event_x, xev->event_y, 1.0);
SDL_FALSE, x, y, 1.0);
return 1;
}
break;
case XI_TouchUpdate: {
const XIDeviceEvent *xev = (const XIDeviceEvent *) cookie->data;
float x, y;
xinput2_normalize_touch_coordinates(videodata, xev->event,
xev->event_x, xev->event_y, &x, &y);
SDL_SendTouchMotion(xev->sourceid,xev->detail,
xev->event_x, xev->event_y, 1.0);
x, y, 1.0);
return 1;
}
break;

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