README.touch - third_party/sdl - Git at Google

 ===========================================================================
 System Specific Notes
 ===========================================================================
 Linux:
 The linux touch system is currently based off event streams, and proc/bus/devices. The active user must be given permissions to read /dev/input/TOUCHDEVICE, where TOUCHDEVICE is the event stream for your device. Currently only Wacom tablets are supported. If you have an unsupported tablet contact me at jim.tla+sdl_touch@gmail.com and I will help you get support for it.

 Mac:
 The Mac and Iphone API's are pretty. If your touch device supports them then you'll be fine. If it doesn't, then there isn't much we can do.

 iPhone:
 Works out of box.

 Windows:
 Unfortunately there is no windows support as of yet. Support for Windows 7 is planned, but we currently have no way to test. If you have a Windows 7 WM_TOUCH supported device, and are willing to help test please contact me at jim.tla+sdl_touch@gmail.com

 ===========================================================================
 Events
 ===========================================================================
 SDL_FINGERDOWN:
 Sent when a finger (or stylus) is placed on a touch device.
 Fields:
 event.tfinger.touchId  - the Id of the touch device.
 event.tfinger.fingerId - the Id of the finger which just went down.
 event.tfinger.x        - the x coordinate of the touch (0..touch.xres)
 event.tfinger.y        - the y coordinate of the touch (0..touch.yres)
 event.tfinger.pressure - the pressure of the touch (0..touch.pressureres)

 SDL_FINGERMOTION:
 Sent when a finger (or stylus) is moved on the touch device.
 Fields:
 Same as FINGERDOWN but with additional:
 event.tfginer.dx       - change in x coordinate during this motion event.
 event.tfginer.dy       - change in y coordinate during this motion event.

 SDL_FINGERMOTION:
 Sent when a finger (or stylus) is lifted from the touch device.
 Fields:
 Same as FINGERDOWN.


 ===========================================================================
 Functions
 ===========================================================================
 SDL provides the ability to access the underlying Touch and Finger structures.
 These structures should _never_ be modified.

 The following functions are included from SDL_Touch.h

 To get a SDL_Touch device call SDL_GetTouch(touchId).
 This returns an SDL_Touch*.
 IMPORTANT: If the touch has been removed, or there is no touch with the given ID, SDL_GetTouch will return null. Be sure to check for this!

 An SDL_Touch has the following fields:
 >xres,yres,pressures:
 	The resolution at which x,y, and pressure values are reported. Currently these will always be equal to 2^15, but this may not always be the case.

 >pressure_max, pressure_min, x_max, x_min, y_max, y_min
 	Which give, respectively, the maximum and minumum values that the touch digitizer can return for pressure, x coordiniate, and y coordinate AS REPORTED BY THE OPERATING SYSTEM.
 On Mac/iPhone systems _max will always be 0, and _min will always be 1.

 >native_xres,native_yres,native_pressureres:
 	The native resolution of the touch device AS REPORTED BY THE OPERATING SYSTEM.
 On Mac/iPhone systems these will always be 1.

 >num_fingers:
 	The number of fingers currently down on the device.

 >fingers:
 	An array of pointers to the fingers which are on the device.


 The most common reason to access a touch device is to normalize inputs. This would be accomplished by code like the following:

       SDL_Touch* inTouch = SDL_GetTouch(event.tfinger.touchId);
       if(inTouch == NULL) continue; //The touch has been removed

       float x = ((float)event.tfinger.x)/inTouch->xres;
       float y = ((float)event.tfinger.y)/inTouch->yres;


 To get an SDL_Finger, call SDL_GetFinger(touch,fingerId), where touch is a pointer to an SDL_Touch device, and fingerId is the id of the requested finger.
 This returns an SDL_Finger*, or null if the finger does not exist, or has been removed.
 An SDL_Finger is guaranteed to be persistent for the duration of a touch, but it will be de-allocated as soon as the finger is removed. This occurs when the SDL_FINGERUP event is _added_ to the event queue, and thus _before_ the FINGERUP event is polled.
 As a result, be very careful to check for null return values.

 An SDL_Finger has the following fields:
 >x,y,pressure:
 	The current coordinates of the touch.
 >xdelta,ydelta:
 	The change in position resulting from the last finger motion.
 >last_x, last_y, last_pressure:
 	 The previous coordinates of the touch.

 ===========================================================================
 Notes
 ===========================================================================
 For a complete example see test/testgesture.c

 Please direct questions/comments to:
    jim.tla+sdl_touch@gmail.com
	===========================================================================
	System Specific Notes
	===========================================================================
	Linux:
	The linux touch system is currently based off event streams, and proc/bus/devices. The active user must be given permissions to read /dev/input/TOUCHDEVICE, where TOUCHDEVICE is the event stream for your device. Currently only Wacom tablets are supported. If you have an unsupported tablet contact me at jim.tla+sdl_touch@gmail.com and I will help you get support for it.

	Mac:
	The Mac and Iphone API's are pretty. If your touch device supports them then you'll be fine. If it doesn't, then there isn't much we can do.

	iPhone:
	Works out of box.

	Windows:
	Unfortunately there is no windows support as of yet. Support for Windows 7 is planned, but we currently have no way to test. If you have a Windows 7 WM_TOUCH supported device, and are willing to help test please contact me at jim.tla+sdl_touch@gmail.com

	===========================================================================
	Events
	===========================================================================
	SDL_FINGERDOWN:
	Sent when a finger (or stylus) is placed on a touch device.
	Fields:
	event.tfinger.touchId - the Id of the touch device.
	event.tfinger.fingerId - the Id of the finger which just went down.
	event.tfinger.x - the x coordinate of the touch (0..touch.xres)
	event.tfinger.y - the y coordinate of the touch (0..touch.yres)
	event.tfinger.pressure - the pressure of the touch (0..touch.pressureres)

	SDL_FINGERMOTION:
	Sent when a finger (or stylus) is moved on the touch device.
	Fields:
	Same as FINGERDOWN but with additional:
	event.tfginer.dx - change in x coordinate during this motion event.
	event.tfginer.dy - change in y coordinate during this motion event.

	SDL_FINGERMOTION:
	Sent when a finger (or stylus) is lifted from the touch device.
	Fields:
	Same as FINGERDOWN.


	===========================================================================
	Functions
	===========================================================================
	SDL provides the ability to access the underlying Touch and Finger structures.
	These structures should _never_ be modified.

	The following functions are included from SDL_Touch.h

	To get a SDL_Touch device call SDL_GetTouch(touchId).
	This returns an SDL_Touch*.
	IMPORTANT: If the touch has been removed, or there is no touch with the given ID, SDL_GetTouch will return null. Be sure to check for this!

	An SDL_Touch has the following fields:
	>xres,yres,pressures:
	The resolution at which x,y, and pressure values are reported. Currently these will always be equal to 2^15, but this may not always be the case.

	>pressure_max, pressure_min, x_max, x_min, y_max, y_min
	Which give, respectively, the maximum and minumum values that the touch digitizer can return for pressure, x coordiniate, and y coordinate AS REPORTED BY THE OPERATING SYSTEM.
	On Mac/iPhone systems _max will always be 0, and _min will always be 1.

	>native_xres,native_yres,native_pressureres:
	The native resolution of the touch device AS REPORTED BY THE OPERATING SYSTEM.
	On Mac/iPhone systems these will always be 1.

	>num_fingers:
	The number of fingers currently down on the device.

	>fingers:
	An array of pointers to the fingers which are on the device.


	The most common reason to access a touch device is to normalize inputs. This would be accomplished by code like the following:

	SDL_Touch* inTouch = SDL_GetTouch(event.tfinger.touchId);
	if(inTouch == NULL) continue; //The touch has been removed

	float x = ((float)event.tfinger.x)/inTouch->xres;
	float y = ((float)event.tfinger.y)/inTouch->yres;



	To get an SDL_Finger, call SDL_GetFinger(touch,fingerId), where touch is a pointer to an SDL_Touch device, and fingerId is the id of the requested finger.
	This returns an SDL_Finger*, or null if the finger does not exist, or has been removed.
	An SDL_Finger is guaranteed to be persistent for the duration of a touch, but it will be de-allocated as soon as the finger is removed. This occurs when the SDL_FINGERUP event is _added_ to the event queue, and thus _before_ the FINGERUP event is polled.
	As a result, be very careful to check for null return values.

	An SDL_Finger has the following fields:
	>x,y,pressure:
	The current coordinates of the touch.
	>xdelta,ydelta:
	The change in position resulting from the last finger motion.
	>last_x, last_y, last_pressure:
	The previous coordinates of the touch.

	===========================================================================
	Notes
	===========================================================================
	For a complete example see test/testgesture.c

	Please direct questions/comments to:
	jim.tla+sdl_touch@gmail.com