Ph_EV_KEY

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1

Hello.

I’m trying to write some code for handling raw key event. Is there some
sample code for the basic skeleton as far as this is concerned?

I’m finding it very difficult to figure out how to handle the events for the
different keys.

The only documentation for this seems to be the PkKeyDef.h file.

For example I would like to check when the following keys are hit (delete,
Ctrl-a, Alt-c, a, left arrow, right arrow, up arrow, down arrow).
What is the order for checking the members of the PkKeyEvent_t structure?
Is there any particular order for the key events? Can you explain?

Where is my sample code, which needs to be completed.

switch (key->key_sym) {
case Pk_Delete :
break;
case Pk_Left :
break;
case Pk_Right :
break;
case Pk_Up:
break;
case Pk_Down :
break;

// use this for ALT-A, not in PkKeyDef.h
case 0x041 :
break;
}


Thanks

Augie

2

Augie Henriques <augiehenriques@hotmail.com> wrote:
: Hello.

: I’m trying to write some code for handling raw key event. Is there some
: sample code for the basic skeleton as far as this is concerned?

: I’m finding it very difficult to figure out how to handle the events for the
: different keys.

: The only documentation for this seems to be the PkKeyDef.h file.

Here are some docs for PhKeyEvent_t:

Data structure describing a key event

Synopsis:

typedef struct Ph_ev_key_data {
unsigned long key_mods;
unsigned long key_flags;
unsigned long key_cap;
unsigned long key_sym;
unsigned char key_scan;
unsigned char key_zero1;
unsigned short key_zero2;
PhPoint_t pos;
unsigned short button_state;
} PhKeyEvent_t;

Description:

This structure describes a key event. It includes at least:

key_mods
Some keys (e.g. Shift or Num Lock) modify other keys. When a
modifier key is pressed or released, it’s evaluated through a
table and the key_mods field is updated accordingly. This
evaluation is done before the key event is sent.

The key_mod is a combination of the following bits:

  • Pk_KM_Shift
  • Pk_KM_Ctrl
  • Pk_KM_Alt
  • Pk_KM_AltGr
  • Pk_KM_Shl3 - not used.
  • Pk_KM_Mod6 - not used.
  • Pk_KM_Mod7 - not used.
  • Pk_KM_Mod8 - not used.
  • Pk_KM_Shift_Lock
  • Pk_KM_Ctrl_Lock
  • Pk_KM_Alt_Lock
  • Pk_KM_AltGr_Lock
  • Pk_KM_Shl3_Lock - not used.
  • Pk_KM_Mod6_Lock - not used.
  • Pk_KM_Mod7_Lock - not used.
  • Pk_KM_Mod8_Lock - not used.
  • Pk_KM_Caps_Lock
  • Pk_KM_Num_Lock
  • Pk_KM_Scroll_Lock

If the Shift key is pressed, the Shift modifier is on; if it’s
released, the Shift modifier is off. Because some keys occur
twice on the keyboard, a key release doesn’t guarantee that the
corresponding modifier is off - the matching key may still be
pressed.

key_flags
Flags that indicate the status of the key:

  • Pk_KF_Key_Down - the key has been pressed.
  • Pk_KF_Key_Repeat - the key is repeating.
  • Pk_KF_Scan_Valid - the key_scan member is valid.
  • Pk_KF_Sym_Valid - the key_sym member is valid; this bit is
    set only on a key press, not a release.
  • Pk_KF_Cap_Valid - the key_cap member is valid.
  • Pk_KF_Compose - a compose sequence is in progress.

key_cap
The unique scan code produced by the key, without any
modifiers. This member is valid only if Pk_KF_Cap_Valid is set
in the key_flags.

key_sym
The value of the key with modifiers applied to it. This member
is valid only if Pk_KF_Sym_Valid is set in the key_flags.

This field holds the value that’s used for text entry; it can
also be used in a switch statement to determine a key’s
function.

key_scan
The hardware-dependent scan code for the key. This member is
valid only if Pk_KF_Scan_Valid is set in the key_flags.

pos
The current mouse-pointer position.

button_state
The current state of the pointing-device buttons (i.e. which
buttons are currently pressed):

  • Ph_BUTTON_SELECT
  • Ph_BUTTON_MENU
  • Ph_BUTTON_ADJUST

All flags and key symbols are defined in <photon/PkKeyDef.h>.

Before using the key_cap, key_scan, or key_sym members, check the
key_flags to make sure they’re valid. The key_cap identifies the key
that caused the event, while key_sym defines the character (or
function key code) that the event carries, if any.

The keyboard is divided into groups, as dictated by ISO 9995. When a
key in the text group is pressed and the Ctrl or Alt modifier is on,
the keyboard driver doesn’t generate a key_sym. If the key is in any
other key group, the driver generates a key_sym.

For any key press event, there’s a corresponding release event. For
example, if you press the A key, key_cap is set to a in both the press
and release (and any repeats), but only the press and repeats have a
valid key_sym. Its value may be a, A, or perhaps an accented character
or some symbol, depending on whether or not this keystroke completed a
compose sequence.

Classification:

Photon

See also:

PhEvent_t

Events chapter of the Photon Programmer’s Guide

Steve Reid stever@qnx.com
TechPubs (Technical Publications)
QNX Software Systems