5.15.2: qsizegrip.cpp original

5.15.2/qtbase/src/widgets/widgets/qsizegrip.cpp

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+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtWidgets 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 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 Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or 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.GPL2 and 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-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qsizegrip.h"
+
+#include "qapplication.h"
+#include "qevent.h"
+#include "qpainter.h"
+#include "qwindow.h"
+#include <qpa/qplatformwindow.h>
+#include "qstyle.h"
+#include "qstyleoption.h"
+#include "qlayout.h"
+#include "qdebug.h"
+#include <QDesktopWidget>
+
+#include <private/qwidget_p.h>
+#include <private/qdesktopwidget_p.h>
+#include <QtWidgets/qabstractscrollarea.h>
+
+QT_BEGIN_NAMESPACE
+
+static QWidget *qt_sizegrip_topLevelWidget(QWidget* w)
+{
+    while (w && !w->isWindow() && w->windowType() != Qt::SubWindow)
+        w = w->parentWidget();
+    return w;
+}
+
+class QSizeGripPrivate : public QWidgetPrivate
+{
+    Q_DECLARE_PUBLIC(QSizeGrip)
+public:
+    QSizeGripPrivate();
+    void init();
+    QPoint p;
+    QRect r;
+    int d;
+    int dxMax;
+    int dyMax;
+    Qt::Corner m_corner;
+    bool gotMousePress;
+    QPointer<QWidget> tlw;
+
+    Qt::Corner corner() const;
+    inline bool atBottom() const
+    {
+        return m_corner == Qt::BottomRightCorner || m_corner == Qt::BottomLeftCorner;
+    }
+
+    inline bool atLeft() const
+    {
+        return m_corner == Qt::BottomLeftCorner || m_corner == Qt::TopLeftCorner;
+    }
+
+    void updateTopLevelWidget()
+    {
+        Q_Q(QSizeGrip);
+        QWidget *w = qt_sizegrip_topLevelWidget(q);
+        if (tlw == w)
+            return;
+        if (tlw)
+            tlw->removeEventFilter(q);
+        tlw = w;
+        if (tlw)
+            tlw->installEventFilter(q);
+    }
+
+    // This slot is invoked by QLayout when the size grip is added to
+    // a layout or reparented after the tlw is shown. This re-implementation is basically
+    // the same as QWidgetPrivate::_q_showIfNotHidden except that it checks
+    // for Qt::WindowFullScreen and Qt::WindowMaximized as well.
+    void _q_showIfNotHidden()
+    {
+        Q_Q(QSizeGrip);
+        bool showSizeGrip = !(q->isHidden() && q->testAttribute(Qt::WA_WState_ExplicitShowHide));
+        updateTopLevelWidget();
+        if (tlw && showSizeGrip) {
+            Qt::WindowStates sizeGripNotVisibleState = Qt::WindowFullScreen;
+            sizeGripNotVisibleState |= Qt::WindowMaximized;
+            // Don't show the size grip if the tlw is maximized or in full screen mode.
+            showSizeGrip = !(tlw->windowState() & sizeGripNotVisibleState);
+        }
+        if (showSizeGrip)
+            q->setVisible(true);
+    }
+
+    bool m_platformSizeGrip;
+};
+
+QSizeGripPrivate::QSizeGripPrivate()
+    : dxMax(0)
+    , dyMax(0)
+    , gotMousePress(false)
+    , tlw(nullptr)
+    , m_platformSizeGrip(false)
+{
+}
+
+Qt::Corner QSizeGripPrivate::corner() const
+{
+    Q_Q(const QSizeGrip);
+    QWidget *tlw = qt_sizegrip_topLevelWidget(const_cast<QSizeGrip *>(q));
+    const QPoint sizeGripPos = q->mapTo(tlw, QPoint(0, 0));
+    bool isAtBottom = sizeGripPos.y() >= tlw->height() / 2;
+    bool isAtLeft = sizeGripPos.x() <= tlw->width() / 2;
+    if (isAtLeft)
+        return isAtBottom ? Qt::BottomLeftCorner : Qt::TopLeftCorner;
+    else
+        return isAtBottom ? Qt::BottomRightCorner : Qt::TopRightCorner;
+}
+
+/*!
+    \class QSizeGrip
+
+    \brief The QSizeGrip class provides a resize handle for resizing top-level windows.
+
+    \ingroup mainwindow-classes
+    \ingroup basicwidgets
+    \inmodule QtWidgets
+
+    This widget works like the standard Windows resize handle. In the
+    X11 version this resize handle generally works differently from
+    the one provided by the system if the X11 window manager does not
+    support necessary modern post-ICCCM specifications.
+
+    Put this widget anywhere in a widget tree and the user can use it
+    to resize the top-level window or any widget with the Qt::SubWindow
+    flag set. Generally, this should be in the lower right-hand corner.
+
+    Note that QStatusBar already uses this widget, so if you have a
+    status bar (e.g., you are using QMainWindow), then you don't need
+    to use this widget explicitly. The same goes for QDialog, for which
+    you can just call \l {QDialog::setSizeGripEnabled()}
+    {QDialog::setSizeGripEnabled()}.
+
+    On some platforms the size grip automatically hides itself when the
+    window is shown full screen or maximised.
+
+    \table 50%
+    \row \li \inlineimage fusion-statusbar-sizegrip.png Screenshot of a Fusion style size grip
+    \li A size grip widget at the bottom-right corner of a main window, shown in the
+    \l{Qt Widget Gallery}{Fusion widget style}.
+    \endtable
+
+    The QSizeGrip class inherits QWidget and reimplements the \l
+    {QWidget::mousePressEvent()}{mousePressEvent()} and \l
+    {QWidget::mouseMoveEvent()}{mouseMoveEvent()} functions to feature
+    the resize functionality, and the \l
+    {QWidget::paintEvent()}{paintEvent()} function to render the
+    size grip widget.
+
+    \sa QStatusBar, QWidget::windowState()
+*/
+
+
+/*!
+    Constructs a resize corner as a child widget of  the given \a
+    parent.
+*/
+QSizeGrip::QSizeGrip(QWidget * parent)
+    : QWidget(*new QSizeGripPrivate, parent, { })
+{
+    Q_D(QSizeGrip);
+    d->init();
+}
+
+
+void QSizeGripPrivate::init()
+{
+    Q_Q(QSizeGrip);
+    m_corner = q->isLeftToRight() ? Qt::BottomRightCorner : Qt::BottomLeftCorner;
+
+#if !defined(QT_NO_CURSOR)
+    q->setCursor(m_corner == Qt::TopLeftCorner || m_corner == Qt::BottomRightCorner
+                 ? Qt::SizeFDiagCursor : Qt::SizeBDiagCursor);
+#endif
+    q->setSizePolicy(QSizePolicy(QSizePolicy::Minimum, QSizePolicy::Fixed));
+    updateTopLevelWidget();
+}
+
+
+/*!
+    Destroys this size grip.
+*/
+QSizeGrip::~QSizeGrip()
+{
+}
+
+/*!
+  \reimp
+*/
+QSize QSizeGrip::sizeHint() const
+{
+    QStyleOption opt(0);
+    opt.init(this);
+    return (style()->sizeFromContents(QStyle::CT_SizeGrip, &opt, QSize(13, 13), this).
+            expandedTo(QApplication::globalStrut()));
+}
+
+/*!
+    Paints the resize grip.
+
+    Resize grips are usually rendered as small diagonal textured lines
+    in the lower-right corner. The paint event is passed in the \a
+    event parameter.
+*/
+void QSizeGrip::paintEvent(QPaintEvent *event)
+{
+    Q_UNUSED(event);
+    Q_D(QSizeGrip);
+    QPainter painter(this);
+    QStyleOptionSizeGrip opt;
+    opt.init(this);
+    opt.corner = d->m_corner;
+    style()->drawControl(QStyle::CE_SizeGrip, &opt, &painter, this);
+}
+
+/*!
+    \fn void QSizeGrip::mousePressEvent(QMouseEvent * event)
+
+    Receives the mouse press events for the widget, and primes the
+    resize operation. The mouse press event is passed in the \a event
+    parameter.
+*/
+
+static Qt::Edges edgesFromCorner(Qt::Corner corner)
+{
+    switch (corner) {
+    case Qt::TopLeftCorner: return Qt::TopEdge | Qt::LeftEdge;
+    case Qt::TopRightCorner: return Qt::TopEdge | Qt::RightEdge;
+    case Qt::BottomLeftCorner: return Qt::BottomEdge | Qt::LeftEdge;
+    case Qt::BottomRightCorner: return Qt::BottomEdge | Qt::RightEdge;
+    }
+    return Qt::Edges{};
+}
+
+void QSizeGrip::mousePressEvent(QMouseEvent * e)
+{
+    if (e->button() != Qt::LeftButton) {
+        QWidget::mousePressEvent(e);
+        return;
+    }
+
+    Q_D(QSizeGrip);
+    QWidget *tlw = qt_sizegrip_topLevelWidget(this);
+    d->p = e->globalPos();
+    d->gotMousePress = true;
+    d->r = tlw->geometry();
+
+    // Does the platform provide size grip support?
+    d->m_platformSizeGrip = false;
+    if (tlw->isWindow()
+        && tlw->windowHandle()
+        && !(tlw->windowFlags() & Qt::X11BypassWindowManagerHint)
+        && !tlw->testAttribute(Qt::WA_DontShowOnScreen)
+        && !tlw->hasHeightForWidth()) {
+        QPlatformWindow *platformWindow = tlw->windowHandle()->handle();
+        const Qt::Edges edges = edgesFromCorner(d->m_corner);
+        if (!QGuiApplication::platformName().contains(QStringLiteral("xcb"))) // ### FIXME QTBUG-69716
+            d->m_platformSizeGrip = platformWindow && platformWindow->startSystemResize(edges);
+    }
+
+    if (d->m_platformSizeGrip)
+        return;
+
+    // Find available desktop/workspace geometry.
+    QRect availableGeometry;
+    bool hasVerticalSizeConstraint = true;
+    bool hasHorizontalSizeConstraint = true;
+    if (tlw->isWindow())
+        availableGeometry = QDesktopWidgetPrivate::availableGeometry(tlw);
+    else {
+        const QWidget *tlwParent = tlw->parentWidget();
+        // Check if tlw is inside QAbstractScrollArea/QScrollArea.
+        // If that's the case tlw->parentWidget() will return the viewport
+        // and tlw->parentWidget()->parentWidget() will return the scroll area.
+#if QT_CONFIG(scrollarea)
+        QAbstractScrollArea *scrollArea = qobject_cast<QAbstractScrollArea *>(tlwParent->parentWidget());
+        if (scrollArea) {
+            hasHorizontalSizeConstraint = scrollArea->horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOff;
+            hasVerticalSizeConstraint = scrollArea->verticalScrollBarPolicy() == Qt::ScrollBarAlwaysOff;
+        }
+#endif // QT_CONFIG(scrollarea)
+        availableGeometry = tlwParent->contentsRect();
+    }
+
+    // Find frame geometries, title bar height, and decoration sizes.
+    const QRect frameGeometry = tlw->frameGeometry();
+    const int titleBarHeight = qMax(tlw->geometry().y() - frameGeometry.y(), 0);
+    const int bottomDecoration = qMax(frameGeometry.height() - tlw->height() - titleBarHeight, 0);
+    const int leftRightDecoration = qMax((frameGeometry.width() - tlw->width()) / 2, 0);
+
+    // Determine dyMax depending on whether the sizegrip is at the bottom
+    // of the widget or not.
+    if (d->atBottom()) {
+        if (hasVerticalSizeConstraint)
+            d->dyMax = availableGeometry.bottom() - d->r.bottom() - bottomDecoration;
+        else
+            d->dyMax = INT_MAX;
+    } else {
+        if (hasVerticalSizeConstraint)
+            d->dyMax = availableGeometry.y() - d->r.y() + titleBarHeight;
+        else
+            d->dyMax = -INT_MAX;
+    }
+
+    // In RTL mode, the size grip is to the left; find dxMax from the desktop/workspace
+    // geometry, the size grip geometry and the width of the decoration.
+    if (d->atLeft()) {
+        if (hasHorizontalSizeConstraint)
+            d->dxMax = availableGeometry.x() - d->r.x() + leftRightDecoration;
+        else
+            d->dxMax = -INT_MAX;
+    } else {
+        if (hasHorizontalSizeConstraint)
+            d->dxMax = availableGeometry.right() - d->r.right() - leftRightDecoration;
+        else
+            d->dxMax = INT_MAX;
+    }
+}
+
+
+/*!
+    \fn void QSizeGrip::mouseMoveEvent(QMouseEvent * event)
+    Resizes the top-level widget containing this widget. The mouse
+    move event is passed in the \a event parameter.
+*/
+void QSizeGrip::mouseMoveEvent(QMouseEvent * e)
+{
+    Q_D(QSizeGrip);
+    if (e->buttons() != Qt::LeftButton || d->m_platformSizeGrip) {
+        QWidget::mouseMoveEvent(e);
+        return;
+    }
+
+    QWidget* tlw = qt_sizegrip_topLevelWidget(this);
+    if (!d->gotMousePress || tlw->testAttribute(Qt::WA_WState_ConfigPending))
+        return;
+
+    QPoint np(e->globalPos());
+
+    // Don't extend beyond the available geometry; bound to dyMax and dxMax.
+    QSize ns;
+    if (d->atBottom())
+        ns.rheight() = d->r.height() + qMin(np.y() - d->p.y(), d->dyMax);
+    else
+        ns.rheight() = d->r.height() - qMax(np.y() - d->p.y(), d->dyMax);
+
+    if (d->atLeft())
+        ns.rwidth() = d->r.width() - qMax(np.x() - d->p.x(), d->dxMax);
+    else
+        ns.rwidth() = d->r.width() + qMin(np.x() - d->p.x(), d->dxMax);
+
+    ns = QLayout::closestAcceptableSize(tlw, ns);
+
+    QPoint p;
+    QRect nr(p, ns);
+    if (d->atBottom()) {
+        if (d->atLeft())
+            nr.moveTopRight(d->r.topRight());
+        else
+            nr.moveTopLeft(d->r.topLeft());
+    } else {
+        if (d->atLeft())
+            nr.moveBottomRight(d->r.bottomRight());
+        else
+            nr.moveBottomLeft(d->r.bottomLeft());
+    }
+
+    tlw->setGeometry(nr);
+}
+
+/*!
+  \reimp
+*/
+void QSizeGrip::mouseReleaseEvent(QMouseEvent *mouseEvent)
+{
+    if (mouseEvent->button() == Qt::LeftButton) {
+        Q_D(QSizeGrip);
+        d->gotMousePress = false;
+        d->p = QPoint();
+    } else {
+        QWidget::mouseReleaseEvent(mouseEvent);
+    }
+}
+
+/*!
+  \reimp
+*/
+void QSizeGrip::moveEvent(QMoveEvent * /*moveEvent*/)
+{
+    Q_D(QSizeGrip);
+    // We're inside a resize operation; no update necessary.
+    if (!d->p.isNull())
+        return;
+
+    d->m_corner = d->corner();
+#if !defined(QT_NO_CURSOR)
+    setCursor(d->m_corner == Qt::TopLeftCorner || d->m_corner == Qt::BottomRightCorner
+              ? Qt::SizeFDiagCursor : Qt::SizeBDiagCursor);
+#endif
+}
+
+/*!
+  \reimp
+*/
+void QSizeGrip::showEvent(QShowEvent *showEvent)
+{
+    QWidget::showEvent(showEvent);
+}
+
+/*!
+  \reimp
+*/
+void QSizeGrip::hideEvent(QHideEvent *hideEvent)
+{
+    QWidget::hideEvent(hideEvent);
+}
+
+/*!
+    \reimp
+*/
+void QSizeGrip::setVisible(bool visible)
+{
+    QWidget::setVisible(visible);
+}
+
+/*! \reimp */
+bool QSizeGrip::eventFilter(QObject *o, QEvent *e)
+{
+    Q_D(QSizeGrip);
+    if ((isHidden() && testAttribute(Qt::WA_WState_ExplicitShowHide))
+        || e->type() != QEvent::WindowStateChange
+        || o != d->tlw) {
+        return QWidget::eventFilter(o, e);
+    }
+    Qt::WindowStates sizeGripNotVisibleState = Qt::WindowFullScreen;
+    sizeGripNotVisibleState |= Qt::WindowMaximized;
+    // Don't show the size grip if the tlw is maximized or in full screen mode.
+    setVisible(!(d->tlw->windowState() & sizeGripNotVisibleState));
+    setAttribute(Qt::WA_WState_ExplicitShowHide, false);
+    return QWidget::eventFilter(o, e);
+}
+
+/*!
+    \reimp
+*/
+bool QSizeGrip::event(QEvent *event)
+{
+    return QWidget::event(event);
+}
+
+QT_END_NAMESPACE
+
+#include "moc_qsizegrip.cpp"