sdl

FORK: Simple Directmedia Layer
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README-touch.md (4111B)

      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 SDL_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(int index).
     51 This returns a SDL_TouchID.
     52 IMPORTANT: If the touch has been removed, or there is no touch with the given index, SDL_GetTouchDevice() 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(SDL_TouchID touchID, int 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:
     74 	The current coordinates of the touch.
     75 * pressure:
     76 	The pressure of the touch.
     77 
     78 
     79 ===========================================================================
     80 Notes
     81 ===========================================================================
     82 For a complete example see test/testgesture.c
     83 
     84 Please direct questions/comments to:
     85    jim.tla+sdl_touch@gmail.com
     86    (original author, API was changed since)