244 lines
7.7 KiB
C
244 lines
7.7 KiB
C
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
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/* Find the keycode for the key above the tab key */
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/*
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* Copyright 2010 Red Hat, Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*/
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/* The standard cycle-windows keybinding should be the key above the
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* tab key. This will have a different keysym on different keyboards -
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* it's the ` (grave) key on US keyboards but something else on many
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* other national layouts. So we need to figure out the keycode for
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* this key without reference to key symbol.
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*
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* The "correct" way to do this is to get the XKB geometry from the
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* X server, find the Tab key, find the key above the Tab key in the
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* same section and use the keycode for that key. This is what I
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* implemented here, but unfortunately, fetching the geometry is rather
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* slow (It could take 20ms or more.)
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*
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* If you looking for a way to optimize Mutter startup performance:
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* On all Linux systems using evdev the key above TAB will have
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* keycode 49. (KEY_GRAVE=41 + the 8 code point offset between
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* evdev keysyms and X keysyms.) So a configure option
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* --with-above-tab-keycode=49 could be added that bypassed this
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* code. It wouldn't work right for displaying Mutter remotely
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* to a non-Linux X server, but that is pretty rare.
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*/
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#include <config.h>
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#include <string.h>
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#include "display-private.h"
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#include <X11/keysym.h>
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#ifdef HAVE_XKB
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#include <X11/XKBlib.h>
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#include <X11/extensions/XKBgeom.h>
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static guint
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compute_above_tab_keycode (Display *xdisplay)
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{
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XkbDescPtr keyboard;
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XkbGeometryPtr geometry;
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int i, j, k;
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int tab_keycode;
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char *tab_name;
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XkbSectionPtr tab_section;
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XkbBoundsRec tab_bounds;
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XkbKeyPtr best_key = NULL;
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guint best_keycode = (guint)-1;
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int best_x_dist = G_MAXINT;
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int best_y_dist = G_MAXINT;
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/* We need only the Names and the Geometry, but asking for these results
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* in the Keyboard information retrieval failing for unknown reasons.
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* (Testing with xorg-1.9.1.) So we ask for a part that we don't need
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* as well.
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*/
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keyboard = XkbGetKeyboard (xdisplay,
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XkbGBN_ClientSymbolsMask | XkbGBN_KeyNamesMask | XkbGBN_GeometryMask,
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XkbUseCoreKbd);
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if (!keyboard)
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return best_keycode;
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geometry = keyboard->geom;
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/* There could potentially be multiple keys with the Tab keysym on the keyboard;
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* but XKeysymToKeycode() returns us the one that the alt-Tab binding will
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* use which is good enough
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*/
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tab_keycode = XKeysymToKeycode (xdisplay, XK_Tab);
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if (tab_keycode == 0 || tab_keycode < keyboard->min_key_code || tab_keycode > keyboard->max_key_code)
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goto out;
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/* The keyboard geometry is stored by key "name" rather than keycode.
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* (Key names are 4-character strings like like TAB or AE01.) We use the
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* 'names' part of the keyboard description to map keycode to key name.
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*
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* XKB has a "key aliases" feature where a single keyboard key can have
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* multiple names (with separate sets of aliases in the 'names' part and
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* in the 'geometry' part), but I don't really understand it or how it is used,
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* so I'm ignoring it here.
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*/
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tab_name = keyboard->names->keys[tab_keycode].name; /* Not NULL terminated! */
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/* First, iterate through the keyboard geometry to find the tab key; the keyboard
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* geometry has a three-level heirarchy of section > row > key
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*/
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for (i = 0; i < geometry->num_sections; i++)
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{
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XkbSectionPtr section = &geometry->sections[i];
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for (j = 0; j < section->num_rows; j++)
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{
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int x = 0;
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int y = 0;
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XkbRowPtr row = §ion->rows[j];
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for (k = 0; k < row->num_keys; k++)
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{
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XkbKeyPtr key = &row->keys[k];
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XkbShapePtr shape = XkbKeyShape (geometry, key);
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if (row->vertical)
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y += key->gap;
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else
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x += key->gap;
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if (strncmp (key->name.name, tab_name, XkbKeyNameLength) == 0)
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{
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tab_section = section;
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tab_bounds = shape->bounds;
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tab_bounds.x1 += row->left + x;
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tab_bounds.x2 += row->left + x;
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tab_bounds.y1 += row->top + y;
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tab_bounds.y2 += row->top + y;
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goto found_tab;
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}
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if (row->vertical)
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y += (shape->bounds.y2 - shape->bounds.y1);
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else
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x += (shape->bounds.x2 - shape->bounds.x1);
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}
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}
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}
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/* No tab key found */
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goto out;
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found_tab:
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/* Now find the key that:
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* - Is in the same section as the Tab key
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* - Has a horizontal center in the Tab key's horizonal bounds
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* - Is above the Tab key at a distance closer than any other key
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* - In case of ties, has its horizontal center as close as possible
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* to the Tab key's horizontal center
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*/
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for (j = 0; j < tab_section->num_rows; j++)
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{
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int x = 0;
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int y = 0;
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XkbRowPtr row = &tab_section->rows[j];
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for (k = 0; k < row->num_keys; k++)
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{
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XkbKeyPtr key = &row->keys[k];
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XkbShapePtr shape = XkbKeyShape(geometry, key);
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XkbBoundsRec bounds = shape->bounds;
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int x_center;
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int x_dist, y_dist;
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if (row->vertical)
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y += key->gap;
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else
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x += key->gap;
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bounds.x1 += row->left + x;
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bounds.x2 += row->left + x;
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bounds.y1 += row->top + y;
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bounds.y2 += row->top + y;
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y_dist = tab_bounds.y1 - bounds.y2;
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if (y_dist < 0)
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continue;
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x_center = (bounds.x1 + bounds.x2) / 2;
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if (x_center < tab_bounds.x1 || x_center > tab_bounds.x2)
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continue;
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x_dist = ABS (x_center - (tab_bounds.x1 + tab_bounds.x2) / 2);
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if (y_dist < best_y_dist ||
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(y_dist == best_y_dist && x_dist < best_x_dist))
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{
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best_key = key;
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best_x_dist = x_dist;
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best_y_dist = y_dist;
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}
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if (row->vertical)
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y += (shape->bounds.y2 - shape->bounds.y1);
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else
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x += (shape->bounds.x2 - shape->bounds.x1);
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}
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}
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if (best_key == NULL)
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goto out;
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/* Now we need to resolve the name of the best key back to a keycode */
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for (i = keyboard->min_key_code; i < keyboard->max_key_code; i++)
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{
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if (strncmp (best_key->name.name, keyboard->names->keys[i].name, XkbKeyNameLength) == 0)
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{
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best_keycode = i;
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break;
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}
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}
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out:
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XkbFreeKeyboard (keyboard, 0, True);
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return best_keycode;
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}
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#else /* !HAVE_XKB */
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static guint
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compute_above_tab_keycode (Display *xdisplay)
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{
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return XKeysymToKeycode (xdisplay, XK_grave);
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}
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#endif /* HAVE_XKB */
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guint
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meta_display_get_above_tab_keycode (MetaDisplay *display)
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{
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if (display->above_tab_keycode == 0) /* not yet computed */
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display->above_tab_keycode = compute_above_tab_keycode (display->xdisplay);
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if (display->above_tab_keycode == (guint)-1) /* failed to compute */
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return 0;
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else
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return display->above_tab_keycode;
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}
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