iOS: add class QIOSInputContext (to handle keyboard)

This change will add an initial implementation of the
QPlatformInputContext for dealing with the keyboard.

Change-Id: I29c1cfbbebb8456977b8a1db0e966973cd2c24a5
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>

1 files changed, 134 insertions, 0 deletions

diff --git a/src/plugins/platforms/ios/qiosinputcontext.mm b/src/plugins/platforms/ios/qiosinputcontext.mm
new file mode 100644
index 0000000000..7937337e4a
--- /dev/null
+++ b/src/plugins/platforms/ios/qiosinputcontext.mm
@@ -0,0 +1,134 @@
+/****************************************************************************
+**
+** 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.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qiosinputcontext.h"
+#include "qioswindow.h"
+#include <QGuiApplication>
+
+@interface QIOSKeyboardListener : NSObject {
+@public
+    QIOSInputContext *m_context;
+    BOOL m_keyboardVisible;
+}
+@end
+
+@implementation QIOSKeyboardListener
+
+- (id)initWithQIOSInputContext:(QIOSInputContext *)context
+{
+    self = [super init];
+    if (self) {
+        m_context = context;
+        m_keyboardVisible = NO;
+        // After the keyboard became undockable (iOS5), UIKeyboardWillShow/UIKeyboardWillHide
+        // no longer works for all cases. So listen to keyboard frame changes instead:
+        [[NSNotificationCenter defaultCenter]
+            addObserver:self
+            selector:@selector(keyboardDidChangeFrame:)
+            name:@"UIKeyboardDidChangeFrameNotification" object:nil];
+    }
+    return self;
+}
+
+- (void) dealloc
+{
+    [[NSNotificationCenter defaultCenter]
+        removeObserver:self
+        name:@"UIKeyboardDidChangeFrameNotification" object:nil];
+    [super dealloc];
+}
+
+- (void) keyboardDidChangeFrame:(NSNotification *)notification
+{
+    CGRect frame;
+    [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] getValue:&frame];
+    BOOL visible = CGRectIntersectsRect(frame, [UIScreen mainScreen].bounds);
+    if (m_keyboardVisible != visible) {
+        m_keyboardVisible = visible;
+        m_context->emitInputPanelVisibleChanged();
+    }
+}
+
+@end
+
+QIOSInputContext::QIOSInputContext()
+    : QPlatformInputContext(),
+    m_keyboardListener([[QIOSKeyboardListener alloc] initWithQIOSInputContext:this])
+{
+}
+
+QIOSInputContext::~QIOSInputContext()
+{
+    [m_keyboardListener release];
+}
+
+void QIOSInputContext::showInputPanel()
+{
+    if (isInputPanelVisible())
+        return;
+
+    // Documentation tells that one should call (and recall, if necessary) becomeFirstResponder/resignFirstResponder
+    // to show/hide the keyboard. This is slightly inconvenient, since there exist no API to get the current first
+    // responder. Rather than searching for it from the top, we assume that the view backing the focus window in Qt
+    // is the best candidate as long as there exist no first responder from before (which the isInputPanelVisible
+    // test on top should catch). Note that Qt will forward keyevents to whichever QObject that needs it, regardless of
+    // which UIView the input actually came from. So in this respect, we're undermining iOS' responder chain.
+    if (QWindow *window = QGuiApplication::focusWindow()) {
+        QIOSWindow *qiosWindow = static_cast<QIOSWindow *>(window->handle());
+        [qiosWindow->nativeView() becomeFirstResponder];
+    }
+}
+
+void QIOSInputContext::hideInputPanel()
+{
+    if (!isInputPanelVisible())
+        return;
+
+    if (QWindow *window = QGuiApplication::focusWindow()) {
+        QIOSWindow *qiosWindow = static_cast<QIOSWindow *>(window->handle());
+        [qiosWindow->nativeView() resignFirstResponder];
+    }
+}
+
+bool QIOSInputContext::isInputPanelVisible() const
+{
+    return m_keyboardListener->m_keyboardVisible;
+}