mirror of
https://github.com/libsdl-org/SDL.git
synced 2024-11-26 21:33:26 +08:00
daa38dc793
Now it returns an array and optional count, to match other SDL3 APIs. SDL_GetTouchName() was replaced with a function that takes an instance ID instead of an index, too.
83 lines
3.8 KiB
Markdown
83 lines
3.8 KiB
Markdown
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_EVENT_FINGER_DOWN:
|
|
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_EVENT_FINGER_MOTION:
|
|
Sent when a finger (or stylus) is moved on the touch device.
|
|
Fields:
|
|
Same as SDL_EVENT_FINGER_DOWN 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_EVENT_FINGER_UP:
|
|
Sent when a finger (or stylus) is lifted from the touch device.
|
|
Fields:
|
|
Same as SDL_EVENT_FINGER_DOWN.
|
|
|
|
|
|
===========================================================================
|
|
Functions
|
|
===========================================================================
|
|
SDL provides the ability to access the underlying SDL_Finger structures.
|
|
These structures should _never_ be modified.
|
|
|
|
The following functions are included from SDL_touch.h
|
|
|
|
Devices are tracked by instance ID, of type SDL_TouchID.
|
|
|
|
To get a list of available device SDL_TouchID values, call SDL_GetTouchDevices().
|
|
This returns an array of device IDs, terminated by a zero ID. Optionally, you can
|
|
get a count of IDs by passing a non-NULL int* to SDL_GetTouchDevices() if you'd
|
|
rather not iterate the whole array to get this number.
|
|
|
|
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(SDL_TouchID touchID, int 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_EVENT_FINGER_UP event is _added_ to the event queue, and thus _before_ the SDL_EVENT_FINGER_UP event is polled.
|
|
As a result, be very careful to check for NULL return values.
|
|
|
|
A SDL_Finger has the following fields:
|
|
* x, y:
|
|
The current coordinates of the touch.
|
|
* pressure:
|
|
The pressure of the touch.
|
|
|
|
|
|
Please direct questions/comments to:
|
|
jim.tla+sdl_touch@gmail.com
|
|
(original author, API was changed since)
|