Accessibility: Add actions for value interfaces

To support increment / decrement of sliders, dials and spin boxes.
(anything with an {in,de}crementAction or a valueInterface.

Other platforms will follow the same pattern in follow-up patches.

Task-number: QTBUG-38832
Change-Id: Ie570acc39b3d9494a8bb9f624b61a398b1d8de89
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>

3 files changed, 187 insertions, 0 deletions

diff --git a/src/platformsupport/accessibility/accessibility.pri b/src/platformsupport/accessibility/accessibility.pri
new file mode 100644
index 0000000000..d63cd9656b
--- /dev/null
+++ b/src/platformsupport/accessibility/accessibility.pri
@@ -0,0 +1,7 @@
+INCLUDEPATH += $$PWD
+
+HEADERS += \
+    $$PWD/qaccessiblebridgeutils_p.h
+
+SOURCES += \
+    $$PWD/qaccessiblebridgeutils.cpp
diff --git a/src/platformsupport/accessibility/qaccessiblebridgeutils.cpp b/src/platformsupport/accessibility/qaccessiblebridgeutils.cpp
new file mode 100644
index 0000000000..7140bb6e2d
--- /dev/null
+++ b/src/platformsupport/accessibility/qaccessiblebridgeutils.cpp
@@ -0,0 +1,119 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtGui module 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 "qaccessiblebridgeutils_p.h"
+#include <QtCore/qmath.h>
+
+#ifndef QT_NO_ACCESSIBILITY
+
+QT_BEGIN_NAMESPACE
+
+namespace QAccessibleBridgeUtils {
+
+static bool performAction(QAccessibleInterface *iface, const QString &actionName)
+{
+    if (QAccessibleActionInterface *actionIface = iface->actionInterface()) {
+        if (actionIface->actionNames().contains(actionName)) {
+            actionIface->doAction(actionName);
+            return true;
+        }
+    }
+    return false;
+}
+
+QStringList effectiveActionNames(QAccessibleInterface *iface)
+{
+    QStringList actions;
+    if (QAccessibleActionInterface *actionIface = iface->actionInterface())
+        actions = actionIface->actionNames();
+
+    if (iface->valueInterface()) {
+        if (!actions.contains(QAccessibleActionInterface::increaseAction()))
+            actions << QAccessibleActionInterface::increaseAction();
+        if (!actions.contains(QAccessibleActionInterface::decreaseAction()))
+            actions << QAccessibleActionInterface::decreaseAction();
+    }
+    return actions;
+}
+
+bool performEffectiveAction(QAccessibleInterface *iface, const QString &actionName)
+{
+    if (!iface)
+        return false;
+    if (performAction(iface, actionName))
+        return true;
+    if (actionName != QAccessibleActionInterface::increaseAction()
+        && actionName != QAccessibleActionInterface::decreaseAction())
+        return false;
+
+    QAccessibleValueInterface *valueIface = iface->valueInterface();
+    if (!valueIface)
+        return false;
+    bool success;
+    const QVariant currentVariant = valueIface->currentValue();
+    double stepSize = valueIface->minimumStepSize().toDouble(&success);
+    if (!success || qFuzzyIsNull(stepSize)) {
+        const double min = valueIface->minimumValue().toDouble(&success);
+        if (!success)
+            return false;
+        const double max = valueIface->maximumValue().toDouble(&success);
+        if (!success)
+            return false;
+        stepSize = (max - min) / 10;  // this is pretty arbitrary, we just need to provide something
+        const int typ = currentVariant.type();
+        if (typ != QMetaType::Float && typ != QMetaType::Double) {
+            // currentValue is an integer. Round it up to ensure stepping in case it was below 1
+            stepSize = qCeil(stepSize);
+        }
+    }
+    const double current = currentVariant.toDouble(&success);
+    if (!success)
+        return false;
+    if (actionName == QAccessibleActionInterface::decreaseAction())
+        stepSize = -stepSize;
+    valueIface->setCurrentValue(current + stepSize);
+    return true;
+}
+
+}   //namespace
+
+QT_END_NAMESPACE
+
+#endif
diff --git a/src/platformsupport/accessibility/qaccessiblebridgeutils_p.h b/src/platformsupport/accessibility/qaccessiblebridgeutils_p.h
new file mode 100644
index 0000000000..d05934b844
--- /dev/null
+++ b/src/platformsupport/accessibility/qaccessiblebridgeutils_p.h
@@ -0,0 +1,61 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtGui module 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 QACCESSIBLEBRIDGEUTILS_H
+#define QACCESSIBLEBRIDGEUTILS_H
+
+#ifndef QT_NO_ACCESSIBILITY
+
+#include <QtCore/qstringlist.h>
+#include <QtGui/qaccessible.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace QAccessibleBridgeUtils {
+    QStringList effectiveActionNames(QAccessibleInterface *iface);
+    bool performEffectiveAction(QAccessibleInterface *iface, const QString &actionName);
+}
+
+QT_END_NAMESPACE
+
+#endif
+
+#endif //QACCESSIBLEBRIDGEUTILS_H