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Refactor QXcbKeyboard::updateModifiers() 

The current implementation is poorly documented and hides the mapping
between keysyms and modifier bits.
This changeset adds documentation about the inner workings and makes
the keysym/modifier bit mapping reusable. (The latter will be needed for
xkb keymap synthesis if the XKEYBOARD extension is unavailable.)

Change-Id: I70c6d204b2357365db4dafeda680132ab6823ca3
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>
bb10
Frank Richter 2017-12-19 13:19:07 +01:00 committed by Gatis Paeglis
parent 7fd5fe17c2
commit f8b164e1c3
2 changed files with 92 additions and 26 deletions
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116
src/plugins/platforms/xcb/qxcbkeyboard.cpp
View File

@ -1289,20 +1289,56 @@ void QXcbKeyboard::updateVModToRModMapping()
#endif
}
// Small helper: set modifier bit, if modifier position is valid
static inline void applyModifier(uint *mask, int modifierBit)
{
if (modifierBit >= 0 && modifierBit < 8)
*mask |= 1 << modifierBit;
}
void QXcbKeyboard::updateModifiers()
{
memset(&rmod_masks, 0, sizeof(rmod_masks));
// Compute X modifier bits for Qt modifiers
KeysymModifierMap keysymMods(keysymsToModifiers());
applyModifier(&rmod_masks.alt, keysymMods.value(XK_Alt_L, -1));
applyModifier(&rmod_masks.alt, keysymMods.value(XK_Alt_R, -1));
applyModifier(&rmod_masks.meta, keysymMods.value(XK_Meta_L, -1));
applyModifier(&rmod_masks.meta, keysymMods.value(XK_Meta_R, -1));
applyModifier(&rmod_masks.altgr, keysymMods.value(XK_Mode_switch, -1));
applyModifier(&rmod_masks.super, keysymMods.value(XK_Super_L, -1));
applyModifier(&rmod_masks.super, keysymMods.value(XK_Super_R, -1));
applyModifier(&rmod_masks.hyper, keysymMods.value(XK_Hyper_L, -1));
applyModifier(&rmod_masks.hyper, keysymMods.value(XK_Hyper_R, -1));
resolveMaskConflicts();
}
// Small helper: check if an array of xcb_keycode_t contains a certain code
static inline bool keycodes_contains(xcb_keycode_t *codes, xcb_keycode_t which)
{
while (*codes != XCB_NO_SYMBOL) {
if (*codes == which) return true;
codes++;
}
return false;
}
QXcbKeyboard::KeysymModifierMap QXcbKeyboard::keysymsToModifiers()
{
// The core protocol does not provide a convenient way to determine the mapping
// of modifier bits. Clients must retrieve and search the modifier map to determine
// the keycodes bound to each modifier, and then retrieve and search the keyboard
// mapping to determine the keysyms bound to the keycodes. They must repeat this
// process for all modifiers whenever any part of the modifier mapping is changed.
memset(&rmod_masks, 0, sizeof(rmod_masks));
xcb_connection_t *conn = xcb_connection();
auto modMapReply = Q_XCB_REPLY(xcb_get_modifier_mapping, conn);
KeysymModifierMap map;
auto modMapReply = Q_XCB_REPLY(xcb_get_modifier_mapping, xcb_connection());
if (!modMapReply) {
qWarning("Qt: failed to get modifier mapping");
return;
return map;
}
// for Alt and Meta L and R are the same
@ -1318,34 +1354,62 @@ void QXcbKeyboard::updateModifiers()
modKeyCodes[i] = xcb_key_symbols_get_keycode(m_key_symbols, symbols[i]);
xcb_keycode_t *modMap = xcb_get_modifier_mapping_keycodes(modMapReply.get());
const int w = modMapReply->keycodes_per_modifier;
for (size_t i = 0; i < numSymbols; ++i) {
for (int bit = 0; bit < 8; ++bit) {
uint mask = 1 << bit;
for (int x = 0; x < w; ++x) {
xcb_keycode_t keyCode = modMap[x + bit * w];
xcb_keycode_t *itk = modKeyCodes[i];
while (itk && *itk != XCB_NO_SYMBOL)
if (*itk++ == keyCode) {
uint sym = symbols[i];
if ((sym == XK_Alt_L || sym == XK_Alt_R))
rmod_masks.alt = mask;
if ((sym == XK_Meta_L || sym == XK_Meta_R))
rmod_masks.meta = mask;
if (sym == XK_Mode_switch)
rmod_masks.altgr = mask;
if ((sym == XK_Super_L) || (sym == XK_Super_R))
rmod_masks.super = mask;
if ((sym == XK_Hyper_L) || (sym == XK_Hyper_R))
rmod_masks.hyper = mask;
}
const int modMapLength = xcb_get_modifier_mapping_keycodes_length(modMapReply.get());
/* For each modifier of "Shift, Lock, Control, Mod1, Mod2, Mod3,
* Mod4, and Mod5" the modifier map contains keycodes_per_modifier
* key codes that are associated with a modifier.
*
* As an example, take this 'xmodmap' output:
* xmodmap: up to 4 keys per modifier, (keycodes in parentheses):
*
* shift Shift_L (0x32), Shift_R (0x3e)
* lock Caps_Lock (0x42)
* control Control_L (0x25), Control_R (0x69)
* mod1 Alt_L (0x40), Alt_R (0x6c), Meta_L (0xcd)
* mod2 Num_Lock (0x4d)
* mod3
* mod4 Super_L (0x85), Super_R (0x86), Super_L (0xce), Hyper_L (0xcf)
* mod5 ISO_Level3_Shift (0x5c), Mode_switch (0xcb)
*
* The corresponding raw modifier map would contain keycodes for:
* Shift_L (0x32), Shift_R (0x3e), 0, 0,
* Caps_Lock (0x42), 0, 0, 0,
* Control_L (0x25), Control_R (0x69), 0, 0,
* Alt_L (0x40), Alt_R (0x6c), Meta_L (0xcd), 0,
* Num_Lock (0x4d), 0, 0, 0,
* 0,0,0,0,
* Super_L (0x85), Super_R (0x86), Super_L (0xce), Hyper_L (0xcf),
* ISO_Level3_Shift (0x5c), Mode_switch (0xcb), 0, 0
*/
/* Create a map between a modifier keysym (as per the symbols array)
* and the modifier bit it's associated with (if any).
* As modMap contains key codes, search modKeyCodes for a match;
* if one is found we can look up the associated keysym.
* Together with the modifier index this will be used
* to compute a mapping between X modifier bits and Qt's
* modifiers (Alt, Ctrl etc). */
for (int i = 0; i < modMapLength; i++) {
if (modMap[i] == XCB_NO_SYMBOL)
continue;
// Get key symbol for key code
for (size_t k = 0; k < numSymbols; k++) {
if (modKeyCodes[k] && keycodes_contains(modKeyCodes[k], modMap[i])) {
// Key code is for modifier. Record mapping
xcb_keysym_t sym = symbols[k];
/* As per modMap layout explanation above, dividing
* by keycodes_per_modifier gives the 'row' in the
* modifier map, which in turn is the modifier bit. */
map[sym] = i / modMapReply->keycodes_per_modifier;
break;
}
}
}
for (size_t i = 0; i < numSymbols; ++i)
free(modKeyCodes[i]);
resolveMaskConflicts();
return map;
}
void QXcbKeyboard::resolveMaskConflicts()

2
src/plugins/platforms/xcb/qxcbkeyboard.h
View File

@ -96,6 +96,8 @@ protected:
void clearXKBConfig();
// when XKEYBOARD not present on the X server
void updateModifiers();
typedef QMap<xcb_keysym_t, int> KeysymModifierMap;
KeysymModifierMap keysymsToModifiers();
// when XKEYBOARD is present on the X server
void updateVModMapping();
void updateVModToRModMapping();