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Added README.touch and README.gesture. Moved touchtest/gestureSDLTest to test/testgesture
author Jim Grandpre <jim.tla@gmail.com>
date Sun, 15 Aug 2010 00:36:28 -0400
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children baf8195aeb92
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4688:494f71f57a80 4689:f9ab8df6d45a
1 ===========================================================================
2 Events
3 ===========================================================================
4 SDL_FINGERDOWN:
5 Sent when a finger (or stylus) is placed on a touch device.
6 Fields:
7 event.tfinger.touchId - the Id of the touch device.
8 event.tfinger.fingerId - the Id of the finger which just went down.
9 event.tfinger.x - the x coordinate of the touch (0..touch.xres)
10 event.tfinger.y - the y coordinate of the touch (0..touch.yres)
11 event.tfinger.pressure - the pressure of the touch (0..touch.pressureres)
12
13 SDL_FINGERMOTION:
14 Sent when a finger (or stylus) is moved on the touch device.
15 Fields:
16 Same as FINGERDOWN but with additional:
17 event.tfginer.dx - chagne in x coordinate during this motion event.
18 event.tfginer.dy - chagne in y coordinate during this motion event.
19
20 SDL_FINGERMOTION:
21 Sent when a finger (or stylus) is lifted from the touch device.
22 Fields:
23 Same as FINGERDOWN.
24
25
26 ===========================================================================
27 Functions
28 ===========================================================================
29 SDL provides the ability to access the underlying Touch and Finger structures.
30 These structures should _never_ be modified.
31
32 The following functions are included from SDL_Touch.h
33
34 To get a SDL_Touch device call SDL_GetTouch(touchId).
35 This returns an SDL_Touch*.
36 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!
37
38 An SDL_Touch has the following fields:
39 >pressure_max, pressure_min, x_max, x_min, y_max, y_min
40 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.
41 On Mac/iPhone systems _max will always be 0, and _min will always be 1.
42
43 >xres,yres,pressures:
44 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.
45
46 >native_xres,native_yres,native_pressureres:
47 The native resolution of the touch device AS REPORTED BY THE OPERATING SYSTEM.
48 On Mac/iPhone systems these will always be 1.
49
50 >num_fingers:
51 The number of fingers currently down on the device.
52
53 >fingers:
54 An array of pointers to the fingers which are on the device.
55
56
57 The most common reason to get a touch device is to normalize inputs. This would look something like:
58
59 SDL_Touch* inTouch = SDL_GetTouch(event.tfinger.touchId);
60 if(inTouch == NULL) continue;
61
62 float x = ((float)event.tfinger.x)/inTouch->xres;
63 float y = ((float)event.tfinger.y)/inTouch->yres;
64
65
66 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.
67 This returns an SDL_Finger*, or null if the finger does not exist, or has been removed.
68 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 seen.
69 As a result, be very careful to check for null return values.
70
71 An SDL_Finger has the following fields:
72 >x,y,pressure:
73 The current coordinates of the touch.
74 >xdelta,ydelta:
75 The change in position resulting from the last finger motion.
76 >last_x, last_y, last_pressure:
77 The previous coordinates of the touch.