doc/README-touch.md
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     1 Touch
       
     2 ===========================================================================
       
     3 System Specific Notes
       
     4 ===========================================================================
       
     5 Linux:
       
     6 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.
       
     7 
       
     8 Mac:
       
     9 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.
       
    10 
       
    11 iPhone: 
       
    12 Works out of box.
       
    13 
       
    14 Windows:
       
    15 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
       
    16 
       
    17 ===========================================================================
       
    18 Events
       
    19 ===========================================================================
       
    20 SDL_FINGERDOWN:
       
    21 Sent when a finger (or stylus) is placed on a touch device.
       
    22 Fields:
       
    23 event.tfinger.touchId  - the Id of the touch device.
       
    24 event.tfinger.fingerId - the Id of the finger which just went down.
       
    25 event.tfinger.x        - the x coordinate of the touch (0..1)
       
    26 event.tfinger.y        - the y coordinate of the touch (0..1)
       
    27 event.tfinger.pressure - the pressure of the touch (0..1)
       
    28 
       
    29 SDL_FINGERMOTION:
       
    30 Sent when a finger (or stylus) is moved on the touch device.
       
    31 Fields:
       
    32 Same as SDL_FINGERDOWN but with additional:
       
    33 event.tfinger.dx       - change in x coordinate during this motion event.
       
    34 event.tfinger.dy       - change in y coordinate during this motion event.
       
    35 
       
    36 SDL_FINGERUP:
       
    37 Sent when a finger (or stylus) is lifted from the touch device.
       
    38 Fields:
       
    39 Same as SDL_FINGERDOWN.
       
    40 
       
    41 
       
    42 ===========================================================================
       
    43 Functions
       
    44 ===========================================================================
       
    45 SDL provides the ability to access the underlying Finger structures.
       
    46 These structures should _never_ be modified.
       
    47 
       
    48 The following functions are included from SDL_touch.h
       
    49 
       
    50 To get a SDL_TouchID call SDL_GetTouchDevice(index).
       
    51 This returns a SDL_TouchID.
       
    52 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!
       
    53 
       
    54 The number of touch devices can be queried with SDL_GetNumTouchDevices().
       
    55 
       
    56 A SDL_TouchID may be used to get pointers to SDL_Finger.
       
    57 
       
    58 SDL_GetNumTouchFingers(touchID) may be used to get the number of fingers currently down on the device.
       
    59 
       
    60 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:
       
    61 
       
    62       float x = event.tfinger.x;
       
    63       float y = event.tfinger.y;
       
    64 
       
    65 
       
    66 
       
    67 To get a SDL_Finger, call SDL_GetTouchFinger(touchID,index), where touchID is a SDL_TouchID, and index is the requested finger.
       
    68 This returns a SDL_Finger*, or NULL if the finger does not exist, or has been removed.
       
    69 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.
       
    70 As a result, be very careful to check for NULL return values.
       
    71 
       
    72 A SDL_Finger has the following fields:
       
    73 >x,y,pressure:
       
    74 	The current coordinates of the touch.
       
    75 >pressure:
       
    76 	The pressure of the touch.
       
    77 
       
    78 ===========================================================================
       
    79 Notes
       
    80 ===========================================================================
       
    81 For a complete example see test/testgesture.c
       
    82 
       
    83 Please direct questions/comments to:
       
    84    jim.tla+sdl_touch@gmail.com
       
    85    (original author, API was changed since)