README.touch
author Michael Sartain <mikesart@valvesoftware.com>
Thu, 11 Oct 2012 09:41:43 -0700
changeset 6570 45855398762c
parent 4693 2ede56a19f2f
child 6987 7084af936d82
permissions -rw-r--r--
Add GLX_X_VISUAL_TYPE_EXT so created window will use DirectColor if available (instead of TrueColor).
Our new X11 window was being created with the TrueColor attribute, and trying to set the gamma
on that would fail. This change checks for the visual_info extension, and uses that to ask for
DirectColor if available.
     1 ===========================================================================
     2 System Specific Notes
     3 ===========================================================================
     4 Linux:
     5 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.
     6 
     7 Mac: 
     8 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.
     9 
    10 iPhone: 
    11 Works out of box.
    12 
    13 Windows:
    14 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
    15 
    16 ===========================================================================
    17 Events
    18 ===========================================================================
    19 SDL_FINGERDOWN:
    20 Sent when a finger (or stylus) is placed on a touch device.
    21 Fields:
    22 event.tfinger.touchId  - the Id of the touch device.
    23 event.tfinger.fingerId - the Id of the finger which just went down.
    24 event.tfinger.x        - the x coordinate of the touch (0..touch.xres)
    25 event.tfinger.y        - the y coordinate of the touch (0..touch.yres)
    26 event.tfinger.pressure - the pressure of the touch (0..touch.pressureres)
    27 
    28 SDL_FINGERMOTION:
    29 Sent when a finger (or stylus) is moved on the touch device.
    30 Fields:
    31 Same as FINGERDOWN but with additional:
    32 event.tfginer.dx       - change in x coordinate during this motion event.
    33 event.tfginer.dy       - change in y coordinate during this motion event.
    34 
    35 SDL_FINGERMOTION:
    36 Sent when a finger (or stylus) is lifted from the touch device.
    37 Fields:
    38 Same as FINGERDOWN.
    39 
    40 
    41 ===========================================================================
    42 Functions
    43 ===========================================================================
    44 SDL provides the ability to access the underlying Touch and Finger structures.
    45 These structures should _never_ be modified.
    46 
    47 The following functions are included from SDL_Touch.h
    48 
    49 To get a SDL_Touch device call SDL_GetTouch(touchId). 
    50 This returns an SDL_Touch*. 
    51 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!
    52 
    53 An SDL_Touch has the following fields:
    54 >xres,yres,pressures:
    55 	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. 
    56 
    57 >pressure_max, pressure_min, x_max, x_min, y_max, y_min
    58 	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.
    59 On Mac/iPhone systems _max will always be 0, and _min will always be 1. 
    60 
    61 >native_xres,native_yres,native_pressureres:
    62 	The native resolution of the touch device AS REPORTED BY THE OPERATING SYSTEM.
    63 On Mac/iPhone systems these will always be 1.
    64 
    65 >num_fingers:
    66 	The number of fingers currently down on the device.
    67 
    68 >fingers:
    69 	An array of pointers to the fingers which are on the device.
    70 
    71 
    72 The most common reason to access a touch device is to normalize inputs. This would be accomplished by code like the following:
    73 
    74       SDL_Touch* inTouch = SDL_GetTouch(event.tfinger.touchId);
    75       if(inTouch == NULL) continue; //The touch has been removed
    76 
    77       float x = ((float)event.tfinger.x)/inTouch->xres;
    78       float y = ((float)event.tfinger.y)/inTouch->yres;
    79 
    80 
    81 
    82 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.
    83 This returns an SDL_Finger*, or null if the finger does not exist, or has been removed.
    84 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. 
    85 As a result, be very careful to check for null return values.
    86 
    87 An SDL_Finger has the following fields:
    88 >x,y,pressure:
    89 	The current coordinates of the touch.
    90 >xdelta,ydelta: 
    91 	The change in position resulting from the last finger motion.
    92 >last_x, last_y, last_pressure:
    93 	 The previous coordinates of the touch.
    94 
    95 ===========================================================================
    96 Notes
    97 ===========================================================================
    98 For a complete example see test/testgesture.c
    99 
   100 Please direct questions/comments to:
   101    jim.tla+sdl_touch@gmail.com