README-touch.txt
changeset 7222 2435b221d77d
parent 7127 5011ddf43295
child 7241 28602f5ca96d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/README-touch.txt	Sun May 26 11:06:17 2013 -0700
@@ -0,0 +1,84 @@
+===========================================================================
+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.
+
+ac: 
+The Mac and iPhone APIs 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..1)
+event.tfinger.y        - the y coordinate of the touch (0..1)
+event.tfinger.pressure - the pressure of the touch (0..1)
+
+SDL_FINGERMOTION:
+Sent when a finger (or stylus) is moved on the touch device.
+Fields:
+Same as SDL_FINGERDOWN but with additional:
+event.tfinger.dx       - change in x coordinate during this motion event.
+event.tfinger.dy       - change in y coordinate during this motion event.
+
+SDL_FINGERUP:
+Sent when a finger (or stylus) is lifted from the touch device.
+Fields:
+Same as SDL_FINGERDOWN.
+
+
+===========================================================================
+Functions
+===========================================================================
+SDL provides the ability to access the underlying Finger structures.
+These structures should _never_ be modified.
+
+The following functions are included from SDL_touch.h
+
+To get a SDL_TouchID call SDL_GetTouchDevice(index).
+This returns a SDL_TouchID.
+IMPORTANT: If the touch has been removed, or there is no touch with the given ID, SDL_GetTouchID will return 0. Be sure to check for this!
+
+The number of touch devices can be queried with SDL_GetNumTouchDevices().
+
+A SDL_TouchID may be used to get pointers to SDL_Finger.
+
+SDL_GetNumTouchFingers(touchID) may be used to get the number of fingers currently down on the device.
+
+The most common reason to access SDL_Finger is to query the fingers outside the event. In most cases accessing the fingers is using the event. This would be accomplished by code like the following:
+
+      float x = event.tfinger.x;
+      float y = event.tfinger.y;
+
+
+
+To get a SDL_Finger, call SDL_GetTouchFinger(touchID,index), where touchID is a SDL_TouchID, and index is the requested finger.
+This returns a SDL_Finger*, or NULL if the finger does not exist, or has been removed.
+A 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 SDL_FINGERUP event is polled.
+As a result, be very careful to check for NULL return values.
+
+A SDL_Finger has the following fields:
+>x,y,pressure:
+	The current coordinates of the touch.
+>pressure:
+	The pressure of the touch.
+
+===========================================================================
+Notes
+===========================================================================
+For a complete example see test/testgesture.c
+
+Please direct questions/comments to:
+   jim.tla+sdl_touch@gmail.com
+   (original author, API was changed since)