Function preprocess_finger_motion

SourceX/controls/touch.cpp:233–359

}

static void preprocess_finger_motion(SDL_Event *event)
{
	// front (0) or back (1) panel
	SDL_TouchID port = event->tfinger.touchId;
	// id (for multitouch)
	SDL_FingerID id = event->tfinger.fingerId;

	// find out how many fingers were down before this event
	int num_fingers_down = 0;
	for (int i = 0; i < MAX_NUM_FINGERS; i++) {
		if (finger[port][i].id >= 0) {
			num_fingers_down++;
		}
	}

	if (num_fingers_down == 0) {
		return;
	}

	if (num_fingers_down >= 1) {
		int x    = mouse_x;
		int y    = mouse_y;
		int xrel = 0;
		int yrel = 0;

		if (direct_touch) {
			x = event->tfinger.x * visible_width + x_borderwidth;
			y = event->tfinger.y * visible_height + y_borderwidth;
			dvl::OutputToLogical(&x, &y);
		} else {
			// for relative mode, use the pointer speed setting
			float speedFactor = 1.0;

			// convert touch events to relative mouse pointer events
			// Whenever an SDL_event involving the mouse is processed,
			x = (mouse_x + (event->tfinger.dx * 1.25 * speedFactor * dvl::GetOutputSurface()->w));
			y = (mouse_y + (event->tfinger.dy * 1.25 * speedFactor * dvl::GetOutputSurface()->h));
		}

		x    = clip(x, 0, dvl::GetOutputSurface()->w);
		y    = clip(y, 0, dvl::GetOutputSurface()->h);
		xrel = x - mouse_x;
		yrel = y - mouse_y;

		// update the current finger's coordinates so we can track it later
		for (int i = 0; i < MAX_NUM_FINGERS; i++) {
			if (finger[port][i].id != id)
				continue;
			finger[port][i].last_x = x;
			finger[port][i].last_y = y;
		}

		// If we are starting a multi-finger drag, start holding down the mouse button
		if (num_fingers_down >= 2 && !multi_finger_dragging[port]) {
			// only start a multi-finger drag if at least two fingers have been down long enough
			int num_fingers_downlong = 0;
			for (int i = 0; i < MAX_NUM_FINGERS; i++) {
				if (finger[port][i].id == NO_TOUCH) {