77 lines
3.4 KiB
Text
77 lines
3.4 KiB
Text
|
===========================================================================
|
||
|
|
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..touch.xres)
|
||
|
|
event.tfinger.y - the y coordinate of the touch (0..touch.yres)
|
||
|
|
event.tfinger.pressure - the pressure of the touch (0..touch.pressureres)
|
||
|
|
|
||
|
|
SDL_FINGERMOTION:
|
||
|
|
Sent when a finger (or stylus) is moved on the touch device.
|
||
|
|
Fields:
|
||
|
|
Same as FINGERDOWN but with additional:
|
||
|
|
event.tfginer.dx - chagne in x coordinate during this motion event.
|
||
|
|
event.tfginer.dy - chagne in y coordinate during this motion event.
|
||
|
|
|
||
|
|
SDL_FINGERMOTION:
|
||
|
|
Sent when a finger (or stylus) is lifted from the touch device.
|
||
|
|
Fields:
|
||
|
|
Same as FINGERDOWN.
|
||
|
|
|
||
|
|
|
||
|
|
===========================================================================
|
||
|
|
Functions
|
||
|
|
===========================================================================
|
||
|
|
SDL provides the ability to access the underlying Touch and Finger structures.
|
||
|
|
These structures should _never_ be modified.
|
||
|
|
|
||
|
|
The following functions are included from SDL_Touch.h
|
||
|
|
|
||
|
|
To get a SDL_Touch device call SDL_GetTouch(touchId).
|
||
|
|
This returns an SDL_Touch*.
|
||
|
|
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!
|
||
|
|
|
||
|
|
An SDL_Touch has the following fields:
|
||
|
|
>pressure_max, pressure_min, x_max, x_min, y_max, y_min
|
||
|
|
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.
|
||
|
|
On Mac/iPhone systems _max will always be 0, and _min will always be 1.
|
||
|
|
|
||
|
|
>xres,yres,pressures:
|
||
|
|
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.
|
||
|
|
|
||
|
|
>native_xres,native_yres,native_pressureres:
|
||
|
|
The native resolution of the touch device AS REPORTED BY THE OPERATING SYSTEM.
|
||
|
|
On Mac/iPhone systems these will always be 1.
|
||
|
|
|
||
|
|
>num_fingers:
|
||
|
|
The number of fingers currently down on the device.
|
||
|
|
|
||
|
|
>fingers:
|
||
|
|
An array of pointers to the fingers which are on the device.
|
||
|
|
|
||
|
|
|
||
|
|
The most common reason to get a touch device is to normalize inputs. This would look something like:
|
||
|
|
|
||
|
|
SDL_Touch* inTouch = SDL_GetTouch(event.tfinger.touchId);
|
||
|
|
if(inTouch == NULL) continue;
|
||
|
|
|
||
|
|
float x = ((float)event.tfinger.x)/inTouch->xres;
|
||
|
|
float y = ((float)event.tfinger.y)/inTouch->yres;
|
||
|
|
|
||
|
|
|
||
|
|
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.
|
||
|
|
This returns an SDL_Finger*, or null if the finger does not exist, or has been removed.
|
||
|
|
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.
|
||
|
|
As a result, be very careful to check for null return values.
|
||
|
|
|
||
|
|
An SDL_Finger has the following fields:
|
||
|
|
>x,y,pressure:
|
||
|
|
The current coordinates of the touch.
|
||
|
|
>xdelta,ydelta:
|
||
|
|
The change in position resulting from the last finger motion.
|
||
|
|
>last_x, last_y, last_pressure:
|
||
|
|
The previous coordinates of the touch.
|