Add selection handles for the dedicated vkb

The handles are implemented using top level windows, which will allow them
to be used for widgets and other input editors supporting the IM framework

[ChangeLog] Added support for selection handles for the dedicated VKB.

Change-Id: I5078689310f99c4ec752a0aad47a48c5a66aface
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 323 insertions, 0 deletions

diff --git a/src/virtualkeyboard/desktopinputselectioncontrol.cpp b/src/virtualkeyboard/desktopinputselectioncontrol.cpp
new file mode 100644
index 00000000..ec7f962e
--- /dev/null
+++ b/src/virtualkeyboard/desktopinputselectioncontrol.cpp
@@ -0,0 +1,323 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt Virtual Keyboard module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL$
+** 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 The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 or (at your option) any later version
+** approved by the KDE Free Qt Foundation. The licenses are as published by
+** the Free Software Foundation and appearing in the file LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "desktopinputselectioncontrol.h"
+#include "inputcontext.h"
+#include "inputselectionhandle.h"
+#include "settings.h"
+#include "platforminputcontext.h"
+
+#include <QtCore/qpropertyanimation.h>
+#include <QtGui/qguiapplication.h>
+#include <QtGui/qstylehints.h>
+#include <QtGui/qimagereader.h>
+
+namespace QtVirtualKeyboard {
+
+DesktopInputSelectionControl::DesktopInputSelectionControl(QObject *parent, InputContext *inputContext)
+    : QObject(parent),
+      m_inputContext(inputContext),
+      m_anchorSelectionHandle(),
+      m_cursorSelectionHandle(),
+      m_handleState(HandleIsReleased),
+      m_enabled(false),
+      m_anchorHandleVisible(false),
+      m_cursorHandleVisible(false),
+      m_eventFilterEnabled(true),
+      m_handleWindowSize(40, 40*1.12)   // because a finger patch is slightly taller than its width
+{
+    QWindow *focusWindow = QGuiApplication::focusWindow();
+    Q_ASSERT(focusWindow);
+    connect(m_inputContext, &InputContext::selectionControlVisibleChanged, this, &DesktopInputSelectionControl::updateVisibility);
+}
+
+/*
+ * Includes the hit area surrounding the visual handle
+ */
+QRect DesktopInputSelectionControl::handleRectForCursorRect(const QRectF &cursorRect) const
+{
+    const int topMargin = (m_handleWindowSize.height() - m_handleImage.size().height())/2;
+    const QPoint pos(int(cursorRect.x() + (cursorRect.width() - m_handleWindowSize.width())/2),
+                     int(cursorRect.bottom()) - topMargin);
+    return QRect(pos, m_handleWindowSize);
+}
+
+/*
+ * Includes the hit area surrounding the visual handle
+ */
+QRect DesktopInputSelectionControl::anchorHandleRect() const
+{
+    return handleRectForCursorRect(m_inputContext->anchorRectangle());
+}
+
+/*
+ * Includes the hit area surrounding the visual handle
+ */
+QRect DesktopInputSelectionControl::cursorHandleRect() const
+{
+    return handleRectForCursorRect(m_inputContext->cursorRectangle());
+}
+
+void DesktopInputSelectionControl::updateAnchorHandlePosition()
+{
+    if (QWindow *focusWindow = QGuiApplication::focusWindow()) {
+        const QPoint pos = focusWindow->mapToGlobal(anchorHandleRect().topLeft());
+        m_anchorSelectionHandle->setPosition(pos);
+    }
+}
+
+void DesktopInputSelectionControl::updateCursorHandlePosition()
+{
+    if (QWindow *focusWindow = QGuiApplication::focusWindow()) {
+        const QPoint pos = focusWindow->mapToGlobal(cursorHandleRect().topLeft());
+        m_cursorSelectionHandle->setPosition(pos);
+    }
+}
+
+void DesktopInputSelectionControl::updateVisibility()
+{
+    if (!m_enabled) {
+        // if VKB is hidden, we must hide the selection handles immediately,
+        // because it might mean that the application is shutting down.
+        m_anchorSelectionHandle->hide();
+        m_cursorSelectionHandle->hide();
+        m_anchorHandleVisible = false;
+        m_cursorHandleVisible = false;
+        return;
+    }
+    const bool wasAnchorVisible = m_anchorHandleVisible;
+    const bool wasCursorVisible = m_cursorHandleVisible;
+    const bool makeVisible = (m_inputContext->selectionControlVisible() || m_handleState == HandleIsMoving) && m_enabled;
+
+    m_anchorHandleVisible = makeVisible;
+    if (QWindow *focusWindow = QGuiApplication::focusWindow()) {
+        QRectF globalAnchorRectangle = m_inputContext->anchorRectangle();
+        QPoint tl = focusWindow->mapToGlobal(globalAnchorRectangle.toRect().topLeft());
+        globalAnchorRectangle.moveTopLeft(tl);
+        m_anchorHandleVisible = m_anchorHandleVisible
+                && m_inputContext->anchorRectIntersectsClipRect()
+                && !(m_inputContext->keyboardRectangle().intersects(globalAnchorRectangle));
+    }
+
+    if (wasAnchorVisible != m_anchorHandleVisible) {
+        const qreal end = m_anchorHandleVisible ? 1 : 0;
+        if (m_anchorHandleVisible)
+            m_anchorSelectionHandle->show();
+        QPropertyAnimation *anim = new QPropertyAnimation(m_anchorSelectionHandle.data(), "opacity");
+        anim->setEndValue(end);
+        anim->start(QAbstractAnimation::DeleteWhenStopped);
+    }
+
+    m_cursorHandleVisible = makeVisible;
+    if (QWindow *focusWindow = QGuiApplication::focusWindow()) {
+        QRectF globalCursorRectangle = m_inputContext->cursorRectangle();
+        QPoint tl = focusWindow->mapToGlobal(globalCursorRectangle.toRect().topLeft());
+        globalCursorRectangle.moveTopLeft(tl);
+        m_cursorHandleVisible = m_cursorHandleVisible
+                && m_inputContext->cursorRectIntersectsClipRect()
+                && !(m_inputContext->keyboardRectangle().intersects(globalCursorRectangle));
+
+    }
+
+    if (wasCursorVisible != m_cursorHandleVisible) {
+        const qreal end = m_cursorHandleVisible ? 1 : 0;
+        if (m_cursorHandleVisible)
+            m_cursorSelectionHandle->show();
+        QPropertyAnimation *anim = new QPropertyAnimation(m_cursorSelectionHandle.data(), "opacity");
+        anim->setEndValue(end);
+        anim->start(QAbstractAnimation::DeleteWhenStopped);
+    }
+}
+
+void DesktopInputSelectionControl::reloadGraphics()
+{
+    Settings *settings = Settings::instance();
+    const QString stylePath = QString::fromLatin1(":/QtQuick/VirtualKeyboard/content/styles/%1/images/selectionhandle-bottom.svg")
+                                .arg(settings->styleName());
+    QImageReader imageReader(stylePath);
+    QSize sz = imageReader.size(); // SVG handler will return default size
+    sz.scale(20, 20, Qt::KeepAspectRatioByExpanding);
+    imageReader.setScaledSize(sz);
+    m_handleImage = imageReader.read();
+
+    m_anchorSelectionHandle->applyImage(m_handleWindowSize); // applies m_handleImage for both selection handles
+    m_cursorSelectionHandle->applyImage(m_handleWindowSize);
+}
+
+void DesktopInputSelectionControl::createHandles()
+{
+    if (QWindow *focusWindow = QGuiApplication::focusWindow()) {
+        Settings *settings = Settings::instance();
+        connect(settings, &Settings::styleChanged, this, &DesktopInputSelectionControl::reloadGraphics);
+
+        m_anchorSelectionHandle.reset(new InputSelectionHandle(this, focusWindow));
+        m_cursorSelectionHandle.reset(new InputSelectionHandle(this, focusWindow));
+
+        reloadGraphics();
+        connect(QCoreApplication::instance(), &QCoreApplication::aboutToQuit, this, &DesktopInputSelectionControl::destroyHandles);
+    }
+}
+
+void DesktopInputSelectionControl::destroyHandles()
+{
+    m_anchorSelectionHandle.reset();
+    m_cursorSelectionHandle.reset();
+}
+
+void DesktopInputSelectionControl::setEnabled(bool enable)
+{
+    // setEnabled(true) just means that the handles _can_ be made visible
+    // This will typically be set when a input field gets focus (and having selection).
+    m_enabled = enable;
+    QWindow *focusWindow = QGuiApplication::focusWindow();
+    if (enable) {
+        connect(m_inputContext, &InputContext::anchorRectangleChanged, this, &DesktopInputSelectionControl::updateAnchorHandlePosition);
+        connect(m_inputContext, &InputContext::cursorRectangleChanged, this, &DesktopInputSelectionControl::updateCursorHandlePosition);
+        connect(m_inputContext, &InputContext::anchorRectIntersectsClipRectChanged, this, &DesktopInputSelectionControl::updateVisibility);
+        connect(m_inputContext, &InputContext::cursorRectIntersectsClipRectChanged, this, &DesktopInputSelectionControl::updateVisibility);
+        if (focusWindow)
+            focusWindow->installEventFilter(this);
+    } else {
+        if (focusWindow)
+            focusWindow->removeEventFilter(this);
+        disconnect(m_inputContext, &InputContext::cursorRectIntersectsClipRectChanged, this, &DesktopInputSelectionControl::updateVisibility);
+        disconnect(m_inputContext, &InputContext::anchorRectIntersectsClipRectChanged, this, &DesktopInputSelectionControl::updateVisibility);
+        disconnect(m_inputContext, &InputContext::anchorRectangleChanged, this, &DesktopInputSelectionControl::updateAnchorHandlePosition);
+        disconnect(m_inputContext, &InputContext::cursorRectangleChanged, this, &DesktopInputSelectionControl::updateCursorHandlePosition);
+    }
+    updateVisibility();
+}
+
+QImage *DesktopInputSelectionControl::handleImage()
+{
+    return &m_handleImage;
+}
+
+bool DesktopInputSelectionControl::eventFilter(QObject *object, QEvent *event)
+{
+    QWindow *focusWindow = QGuiApplication::focusWindow();
+    if (!m_cursorSelectionHandle || !m_eventFilterEnabled || object != focusWindow)
+        return false;
+    const bool windowMoved = event->type() == QEvent::Move;
+    const bool windowResized = event->type() == QEvent::Resize;
+    if (windowMoved || windowResized) {
+        if (m_enabled) {
+            if (windowMoved) {
+                updateAnchorHandlePosition();
+                updateCursorHandlePosition();
+            }
+            updateVisibility();
+        }
+    } else if (event->type() == QEvent::MouseButtonPress) {
+        QMouseEvent *me = static_cast<QMouseEvent*>(event);
+        const QPoint mousePos = me->screenPos().toPoint();
+
+        // calculate distances from mouse pos to each handle,
+        // then choose to interact with the nearest handle
+        struct SelectionHandleInfo {
+            qreal squaredDistance;
+            QPoint delta;
+            QRect rect;
+        };
+        SelectionHandleInfo handles[2];
+        handles[AnchorHandle].rect = anchorHandleRect();
+        handles[CursorHandle].rect = cursorHandleRect();
+
+        for (int i = 0; i <= CursorHandle; ++i) {
+            SelectionHandleInfo &h = handles[i];
+            QPoint curHandleCenter = focusWindow->mapToGlobal(h.rect.center());  // ### map to desktoppanel
+            const QPoint delta = mousePos - curHandleCenter;
+            h.delta = delta;
+            h.squaredDistance = QPoint::dotProduct(delta, delta);
+        }
+
+        // (squared) distances calculated, pick the closest handle
+        HandleType closestHandle = (handles[AnchorHandle].squaredDistance < handles[CursorHandle].squaredDistance ? AnchorHandle : CursorHandle);
+
+        // Can not be replaced with me->windowPos(); because the event might be forwarded from the window of the handle
+        const QPoint windowPos = focusWindow->mapFromGlobal(mousePos);
+        if (m_anchorHandleVisible && handles[closestHandle].rect.contains(windowPos)) {
+            m_currentDragHandle = closestHandle;
+            m_distanceBetweenMouseAndCursor = handles[closestHandle].delta -  QPoint(0, m_handleWindowSize.height()/2 + 4);
+            m_handleState = HandleIsHeld;
+            m_handleDragStartedPosition = mousePos;
+            const QRect otherRect = handles[1 - closestHandle].rect;
+            m_otherSelectionPoint = QPoint(otherRect.x() + otherRect.width()/2, otherRect.top() - 4);
+
+            QMouseEvent *mouseEvent = new QMouseEvent(me->type(), me->localPos(), me->windowPos(), me->screenPos(),
+                                                      me->button(), me->buttons(), me->modifiers(), me->source());
+            m_eventQueue.append(mouseEvent);
+            return true;
+        }
+    } else if (event->type() == QEvent::MouseMove) {
+        QMouseEvent *me = static_cast<QMouseEvent*>(event);
+        QPoint mousePos = me->screenPos().toPoint();
+        if (m_handleState == HandleIsHeld) {
+            QPoint delta = m_handleDragStartedPosition - mousePos;
+            const int startDragDistance = QGuiApplication::styleHints()->startDragDistance();
+            if (QPoint::dotProduct(delta, delta) > startDragDistance * startDragDistance)
+                m_handleState = HandleIsMoving;
+        }
+        if (m_handleState == HandleIsMoving) {
+            QPoint cursorPos = mousePos - m_distanceBetweenMouseAndCursor;
+            cursorPos = focusWindow->mapFromGlobal(cursorPos);
+            if (m_currentDragHandle == CursorHandle)
+                m_inputContext->setSelectionOnFocusObject(m_otherSelectionPoint, cursorPos);
+            else
+                m_inputContext->setSelectionOnFocusObject(cursorPos, m_otherSelectionPoint);
+            qDeleteAll(m_eventQueue);
+            m_eventQueue.clear();
+            return true;
+        }
+    } else if (event->type() == QEvent::MouseButtonRelease) {
+        if (m_handleState == HandleIsMoving) {
+            m_handleState = HandleIsReleased;
+            qDeleteAll(m_eventQueue);
+            m_eventQueue.clear();
+            return true;
+        } else {
+            if (QWindow *focusWindow = QGuiApplication::focusWindow()) {
+                // playback event queue. These are events that were not designated
+                // for the handles in hindsight.
+                // This is typically MousePress and MouseRelease (not interleaved with MouseMove)
+                // that should instead go through to the underlying input editor
+                m_eventFilterEnabled = false;
+                while (!m_eventQueue.isEmpty()) {
+                    QMouseEvent *e = m_eventQueue.takeFirst();
+                    QCoreApplication::sendEvent(focusWindow, e);
+                    delete e;
+                }
+                m_eventFilterEnabled = true;
+            }
+            m_handleState = HandleIsReleased;
+        }
+    }
+    return false;
+}
+} //    namespace QtVirtualKeyboard