kc3-lang/SDL/docs/README-touch.md

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  Date : 2014-07-29T08:04:15
  

  Moved documentation to docs, recreated a simple README.txt, fixed build

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  float x = event.tfinger.x;
  float y = event.tfinger.y;

The current coordinates of the touch.

The pressure of the touch.

Source

• docs/README-touch.md

• Touch
  ===========================================================================
  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 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)
  

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