Introducing QComposeInputContext

When switching from Xlib to xcb platform plugin it was agreed that
XIM is deprecated. Users should be using QT_IM_MODULE to load input context
plugin for a more advance input method framework support.

The proposed solution is to parse the compose file directly from Qt. This
approach removes the overhead of communication protocols used in Xlib and/or IBUS.

TableGenerator class follows [1].

The compose file is searched for in the following order:

1) If the environment variable $XCOMPOSEFILE is set,
its value is used as the name of the Compose file.

2) If the user’s home directory has a file named
.XCompose, it is used as the Compose file.

3) The system provided compose file is used by mapping the
locale to a compose file from the list in
/usr/share/X11/locale/compose.dir.

Regarding step 3 - TableGenerator searches in hard-coded locations for
system-provided compose files. Here I have introcuded a new environment
variable QTCOMPOSE which can be used to prepend an extra location
to be searched.

[1] http://www.x.org/archive/X11R7.7/doc/man/man5/Compose.5.xhtml

Task-number: QTBUG-28183
Change-Id: I76dcfd454f3acc23db98192a3673c1ab2af4425f
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>

1 files changed, 105 insertions, 0 deletions

diff --git a/src/plugins/platforminputcontexts/compose/xkbcommon_workaround.h b/src/plugins/platforminputcontexts/compose/xkbcommon_workaround.h
new file mode 100644
index 0000000000..58ce143978
--- /dev/null
+++ b/src/plugins/platforminputcontexts/compose/xkbcommon_workaround.h
@@ -0,0 +1,105 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef XKBCOMMON_WORKAROUND_H
+#define XKBCOMMON_WORKAROUND_H
+
+// Function utf32_to_utf8() is borrowed from the libxkbcommon library,
+// file keysym-utf.c. The workaround should be removed once the fix from
+// https://bugs.freedesktop.org/show_bug.cgi?id=56780 gets released.
+static int utf32_to_utf8(uint32_t unichar, char *buffer)
+{
+    int count, shift, length;
+    uint8_t head;
+
+    if (unichar <= 0x007f) {
+        buffer[0] = unichar;
+        buffer[1] = '\0';
+        return 2;
+    }
+    else if (unichar <= 0x07FF) {
+        length = 2;
+        head = 0xc0;
+    }
+    else if (unichar <= 0xffff) {
+        length = 3;
+        head = 0xe0;
+    }
+    else if (unichar <= 0x1fffff) {
+        length = 4;
+        head = 0xf0;
+    }
+    else if (unichar <= 0x3ffffff) {
+        length = 5;
+        head = 0xf8;
+    }
+    else {
+        length = 6;
+        head = 0xfc;
+    }
+
+    for (count = length - 1, shift = 0; count > 0; count--, shift += 6)
+        buffer[count] = 0x80 | ((unichar >> shift) & 0x3f);
+
+    buffer[0] = head | ((unichar >> shift) & 0x3f);
+    buffer[length] = '\0';
+
+    return length + 1;
+}
+
+static bool needWorkaround(uint32_t sym)
+{
+    /* patch encoding botch */
+    if (sym == XKB_KEY_KP_Space)
+        return true;
+
+    /* special keysyms */
+    if ((sym >= XKB_KEY_BackSpace && sym <= XKB_KEY_Clear) ||
+        (sym >= XKB_KEY_KP_Multiply && sym <= XKB_KEY_KP_9) ||
+        sym == XKB_KEY_Return || sym == XKB_KEY_Escape ||
+        sym == XKB_KEY_Delete || sym == XKB_KEY_KP_Tab ||
+        sym == XKB_KEY_KP_Enter || sym == XKB_KEY_KP_Equal)
+        return true;
+
+    return false;
+}
+
+#endif // XKBCOMMON_WORKAROUND_H