qwhatsthis.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qwhatsthis.h"
#include "qpointer.h"
#include "qapplication.h"
#include <private/qguiapplication_p.h>
#include "qwidget.h"
#include "qevent.h"
#include "qpixmap.h"
#include "qscreen.h"
#include "qpainter.h"
#include "qtimer.h"
#if QT_CONFIG(action)
#include "qaction.h"
#endif // QT_CONFIG(action)
#include "qcursor.h"
#include "qbitmap.h"
#include "qtextdocument.h"
#include <qpa/qplatformtheme.h>
#include "private/qtextdocumentlayout_p.h"
#include "qdebug.h"
#if QT_CONFIG(accessibility)
#include "qaccessible.h"
#endif
 
QT_BEGIN_NAMESPACE
 
Q_CORE_EXPORT void qDeleteInEventHandler(QObject *o);
 
class QWhatsThat : public QWidget
{
    Q_OBJECT
 
public:
    QWhatsThat(const QString& txt, QWidget* parent, QWidget *showTextFor);
    ~QWhatsThat() ;
 
    static QWhatsThat *instance;
 
protected:
    void mousePressEvent(QMouseEvent*) override;
    void mouseReleaseEvent(QMouseEvent*) override;
    void mouseMoveEvent(QMouseEvent*) override;
    void keyPressEvent(QKeyEvent*) override;
    void paintEvent(QPaintEvent*) override;
 
private:
    QPointer<QWidget>widget;
    bool pressed;
    QString text;
    QTextDocument* doc;
    QString anchor;
};
 
QWhatsThat *QWhatsThat::instance = nullptr;
 
// shadowWidth not const, for XP drop-shadow-fu turns it to 0
static int shadowWidth = 6;   // also used as '5' and '6' and even '8' below
static const int vMargin = 8;
static const int hMargin = 12;
 
static inline bool dropShadow()
{
    if (const QPlatformTheme *theme = QGuiApplicationPrivate::platformTheme())
        return theme->themeHint(QPlatformTheme::DropShadow).toBool();
    return false;
}
 
QWhatsThat::QWhatsThat(const QString& txt, QWidget* parent, QWidget *showTextFor)
    : QWidget(parent, Qt::Popup),
      widget(showTextFor), pressed(false), text(txt)
{
    delete instance;
    instance = this;
    setAttribute(Qt::WA_DeleteOnClose, true);
    setAttribute(Qt::WA_NoSystemBackground, true);
    if (parent)
        setPalette(parent->palette());
    setMouseTracking(true);
    setFocusPolicy(Qt::StrongFocus);
#ifndef QT_NO_CURSOR
    setCursor(Qt::ArrowCursor);
#endif
    QRect r;
    doc = nullptr;
    ensurePolished(); // Ensures style sheet font before size calc
    if (Qt::mightBeRichText(text)) {
        doc = new QTextDocument();
        doc->setUndoRedoEnabled(false);
        doc->setDefaultFont(QApplication::font(this));
#ifdef QT_NO_TEXTHTMLPARSER
        doc->setPlainText(text);
#else
        doc->setHtml(text);
#endif
        doc->setUndoRedoEnabled(false);
        doc->adjustSize();
        r.setTop(0);
        r.setLeft(0);
        r.setSize(doc->size().toSize());
    }
    else
    {
        int sw = QGuiApplication::primaryScreen()->virtualGeometry().width() / 3;
        if (sw < 200)
            sw = 200;
        else if (sw > 300)
            sw = 300;
 
        r = fontMetrics().boundingRect(0, 0, sw, 1000,
                                        Qt::AlignLeft | Qt::AlignTop
                                        | Qt::TextWordWrap | Qt::TextExpandTabs,
                                        text);
    }
    shadowWidth = dropShadow() ? 0 : 6;
    resize(r.width() + 2*hMargin + shadowWidth, r.height() + 2*vMargin + shadowWidth);
}
 
QWhatsThat::~QWhatsThat()
{
    instance = nullptr;
    if (doc)
        delete doc;
}
 
void QWhatsThat::mousePressEvent(QMouseEvent* e)
{
    pressed = true;
    if (e->button() == Qt::LeftButton && rect().contains(e->position().toPoint())) {
        if (doc)
            anchor = doc->documentLayout()->anchorAt(e->position().toPoint() -  QPoint(hMargin, vMargin));
        return;
    }
    close();
}
 
void QWhatsThat::mouseReleaseEvent(QMouseEvent* e)
{
    if (!pressed)
        return;
    if (widget && e->button() == Qt::LeftButton && doc && rect().contains(e->position().toPoint())) {
        QString a = doc->documentLayout()->anchorAt(e->position().toPoint() -  QPoint(hMargin, vMargin));
        QString href;
        if (anchor == a)
            href = a;
        anchor.clear();
        if (!href.isEmpty()) {
            QWhatsThisClickedEvent e(href);
            if (QCoreApplication::sendEvent(widget, &e))
                return;
        }
    }
    close();
}
 
void QWhatsThat::mouseMoveEvent(QMouseEvent* e)
{
#ifdef QT_NO_CURSOR
    Q_UNUSED(e);
#else
    if (!doc)
        return;
    QString a = doc->documentLayout()->anchorAt(e->position().toPoint() -  QPoint(hMargin, vMargin));
    if (!a.isEmpty())
        setCursor(Qt::PointingHandCursor);
    else
        setCursor(Qt::ArrowCursor);
#endif
}
 
void QWhatsThat::keyPressEvent(QKeyEvent*)
{
    close();
}
 
void QWhatsThat::paintEvent(QPaintEvent*)
{
    const bool drawShadow = dropShadow();
 
    QRect r = rect();
    r.adjust(0, 0, -1, -1);
    if (drawShadow)
        r.adjust(0, 0, -shadowWidth, -shadowWidth);
    QPainter p(this);
    p.setPen(QPen(palette().toolTipText(), 0));
    p.setBrush(palette().toolTipBase());
    p.drawRect(r);
    int w = r.width();
    int h = r.height();
    p.setPen(palette().brush(QPalette::Dark).color());
    p.drawRect(1, 1, w-2, h-2);
    if (drawShadow) {
        p.setPen(palette().shadow().color());
        p.drawPoint(w + 5, 6);
        p.drawLine(w + 3, 6, w + 5, 8);
        p.drawLine(w + 1, 6, w + 5, 10);
        int i;
        for(i=7; i < h; i += 2)
            p.drawLine(w, i, w + 5, i + 5);
        for(i = w - i + h; i > 6; i -= 2)
            p.drawLine(i, h, i + 5, h + 5);
        for(; i > 0 ; i -= 2)
            p.drawLine(6, h + 6 - i, i + 5, h + 5);
    }
    r.adjust(0, 0, 1, 1);
    p.setPen(palette().toolTipText().color());
    r.adjust(hMargin, vMargin, -hMargin, -vMargin);
 
    if (doc) {
        p.translate(r.x(), r.y());
        QRect rect = r;
        rect.translate(-r.x(), -r.y());
        p.setClipRect(rect);
        QAbstractTextDocumentLayout::PaintContext context;
        context.palette.setBrush(QPalette::Text, context.palette.toolTipText());
        doc->documentLayout()->draw(&p, context);
    }
    else
    {
        p.drawText(r, Qt::AlignLeft | Qt::AlignTop | Qt::TextWordWrap | Qt::TextExpandTabs, text);
    }
}
 
static const char * const button_image[] = {
"16 16 3 1",
"         c None",
"o        c #000000",
"a        c #000080",
"o        aaaaa  ",
"oo      aaa aaa ",
"ooo    aaa   aaa",
"oooo   aa     aa",
"ooooo  aa     aa",
"oooooo  a    aaa",
"ooooooo     aaa ",
"oooooooo   aaa  ",
"ooooooooo aaa   ",
"ooooo     aaa   ",
"oo ooo          ",
"o  ooo    aaa   ",
"    ooo   aaa   ",
"    ooo         ",
"     ooo        ",
"     ooo        "};
 
class QWhatsThisPrivate : public QObject
{
 public:
    QWhatsThisPrivate();
    ~QWhatsThisPrivate();
    static QWhatsThisPrivate *instance;
    bool eventFilter(QObject *, QEvent *) override;
#if QT_CONFIG(action)
    QPointer<QAction> action;
#endif // QT_CONFIG(action)
    static void say(QWidget *, const QString &, int x = 0, int y = 0);
    static void notifyToplevels(QEvent *e);
    bool leaveOnMouseRelease;
};
 
void QWhatsThisPrivate::notifyToplevels(QEvent *e)
{
    const QWidgetList toplevels = QApplication::topLevelWidgets();
    for (auto *w : toplevels)
        QCoreApplication::sendEvent(w, e);
}
 
QWhatsThisPrivate *QWhatsThisPrivate::instance = nullptr;
 
QWhatsThisPrivate::QWhatsThisPrivate()
    : leaveOnMouseRelease(false)
{
    instance = this;
    qApp->installEventFilter(this);
 
    QPoint pos = QCursor::pos();
    if (QWidget *w = QApplication::widgetAt(pos)) {
        QHelpEvent e(QEvent::QueryWhatsThis, w->mapFromGlobal(pos), pos);
        const bool sentEvent = QCoreApplication::sendEvent(w, &e);
#ifdef QT_NO_CURSOR
        Q_UNUSED(sentEvent);
#else
        QGuiApplication::setOverrideCursor((!sentEvent || !e.isAccepted())?
                                        Qt::ForbiddenCursor:Qt::WhatsThisCursor);
    } else {
        QGuiApplication::setOverrideCursor(Qt::WhatsThisCursor);
#endif
    }
#if QT_CONFIG(accessibility)
    QAccessibleEvent event(this, QAccessible::ContextHelpStart);
    QAccessible::updateAccessibility(&event);
#endif
}
 
QWhatsThisPrivate::~QWhatsThisPrivate()
{
#if QT_CONFIG(action)
    if (action)
        action->setChecked(false);
#endif // QT_CONFIG(action)
#ifndef QT_NO_CURSOR
    QGuiApplication::restoreOverrideCursor();
#endif
#if QT_CONFIG(accessibility)
    QAccessibleEvent event(this, QAccessible::ContextHelpEnd);
    QAccessible::updateAccessibility(&event);
#endif
    instance = nullptr;
}
 
bool QWhatsThisPrivate::eventFilter(QObject *o, QEvent *e)
{
    if (!o->isWidgetType())
        return false;
    QWidget * w = static_cast<QWidget *>(o);
    bool customWhatsThis = w->testAttribute(Qt::WA_CustomWhatsThis);
    switch (e->type()) {
    case QEvent::MouseButtonPress:
    {
        QMouseEvent *me = static_cast<QMouseEvent*>(e);
        if (me->button() == Qt::RightButton || customWhatsThis)
            return false;
        QHelpEvent e(QEvent::WhatsThis, me->position().toPoint(), me->globalPosition().toPoint());
        if (!QCoreApplication::sendEvent(w, &e) || !e.isAccepted())
            leaveOnMouseRelease = true;
 
    } break;
 
    case QEvent::MouseMove:
    {
        QMouseEvent *me = static_cast<QMouseEvent*>(e);
        QHelpEvent e(QEvent::QueryWhatsThis, me->position().toPoint(), me->globalPosition().toPoint());
        const bool sentEvent = QCoreApplication::sendEvent(w, &e);
#ifdef QT_NO_CURSOR
        Q_UNUSED(sentEvent);
#else
        QGuiApplication::changeOverrideCursor((!sentEvent || !e.isAccepted())?
                                              Qt::ForbiddenCursor:Qt::WhatsThisCursor);
#endif
        Q_FALLTHROUGH();
    }
    case QEvent::MouseButtonRelease:
    case QEvent::MouseButtonDblClick:
        if (leaveOnMouseRelease && e->type() == QEvent::MouseButtonRelease)
            QWhatsThis::leaveWhatsThisMode();
        if (static_cast<QMouseEvent*>(e)->button() == Qt::RightButton || customWhatsThis)
            return false; // ignore RMB release
        break;
    case QEvent::KeyPress:
    {
        QKeyEvent *kev = static_cast<QKeyEvent *>(e);
#if QT_CONFIG(shortcut)
        if (kev->matches(QKeySequence::Cancel)) {
            QWhatsThis::leaveWhatsThisMode();
            return true;
        } else
#endif
          if (customWhatsThis) {
            return false;
        } else if (kev->key() == Qt::Key_Menu ||
                    (kev->key() == Qt::Key_F10 &&
                      kev->modifiers() == Qt::ShiftModifier)) {
            // we don't react to these keys, they are used for context menus
            return false;
        } else if (kev->key() != Qt::Key_Shift && kev->key() != Qt::Key_Alt // not a modifier key
                   && kev->key() != Qt::Key_Control && kev->key() != Qt::Key_Meta) {
            QWhatsThis::leaveWhatsThisMode();
        }
    } break;
    default:
        return false;
    }
    return true;
}
 
#if QT_CONFIG(action)
class QWhatsThisAction: public QAction
{
    Q_OBJECT
 
public:
    explicit QWhatsThisAction(QObject* parent = nullptr);
 
private slots:
    void actionTriggered();
};
 
QWhatsThisAction::QWhatsThisAction(QObject *parent) : QAction(tr("What's This?"), parent)
{
#ifndef QT_NO_IMAGEFORMAT_XPM
    QPixmap p(button_image);
    setIcon(p);
#endif
    setCheckable(true);
    connect(this, SIGNAL(triggered()), this, SLOT(actionTriggered()));
#ifndef QT_NO_SHORTCUT
    setShortcut(Qt::ShiftModifier | Qt::Key_F1);
#endif
}
 
void QWhatsThisAction::actionTriggered()
{
    if (isChecked()) {
        QWhatsThis::enterWhatsThisMode();
        QWhatsThisPrivate::instance->action = this;
    }
}
#endif // QT_CONFIG(action)
 
void QWhatsThis::enterWhatsThisMode()
{
    if (QWhatsThisPrivate::instance)
        return;
    (void) new QWhatsThisPrivate;
    QEvent e(QEvent::EnterWhatsThisMode);
    QWhatsThisPrivate::notifyToplevels(&e);
 }
 
bool QWhatsThis::inWhatsThisMode()
{
    return (QWhatsThisPrivate::instance != nullptr);
}
 
void QWhatsThis::leaveWhatsThisMode()
{
    delete QWhatsThisPrivate::instance;
    QEvent e(QEvent::LeaveWhatsThisMode);
    QWhatsThisPrivate::notifyToplevels(&e);
}
 
void QWhatsThisPrivate::say(QWidget * widget, const QString &text, int x, int y)
{
    if (text.size() == 0)
        return;
    // make a fresh widget, and set it up
    QWhatsThat *whatsThat = new QWhatsThat(text, nullptr, widget);
 
    // okay, now to find a suitable location
    QScreen *screen = widget ? widget->screen()
                             : QGuiApplication::screenAt(QPoint(x, y));
    if (!screen)
        screen = QGuiApplication::primaryScreen();
    QRect screenRect = screen->geometry();
 
    int w = whatsThat->width();
    int h = whatsThat->height();
    int sx = screenRect.x();
    int sy = screenRect.y();
 
    // first try locating the widget immediately above/below,
    // with nice alignment if possible.
    QPoint pos;
    if (widget)
        pos = widget->mapToGlobal(QPoint(0,0));
 
    if (widget && w > widget->width() + 16)
        x = pos.x() + widget->width()/2 - w/2;
    else
        x = x - w/2;
 
    // squeeze it in if that would result in part of what's this
    // being only partially visible
    if (x + w  + shadowWidth > sx+screenRect.width()) {
        x = (widget ? qMin(screenRect.width(), pos.x() + widget->width())
                    : screenRect.width())
            - w;
    }
 
    if (x < sx)
        x = sx;
 
    if (widget && h > widget->height() + 16) {
        y = pos.y() + widget->height() + 2; // below, two pixels spacing
        // what's this is above or below, wherever there's most space
        if (y + h + 10 > sy + screenRect.height())
            y = pos.y() + 2 - shadowWidth - h; // above, overlap
    }
    y = y + 2;
 
    // squeeze it in if that would result in part of what's this
    // being only partially visible
    if (y + h + shadowWidth > sy + screenRect.height()) {
        y = (widget ? qMin(screenRect.height(), pos.y() + widget->height())
                    : screenRect.height())
            - h;
    }
    if (y < sy)
        y = sy;
 
    whatsThat->move(x, y);
    whatsThat->show();
    whatsThat->grabKeyboard();
}
 
void QWhatsThis::showText(const QPoint &pos, const QString &text, QWidget *w)
{
    leaveWhatsThisMode();
    QWhatsThisPrivate::say(w, text, pos.x(), pos.y());
}
 
void QWhatsThis::hideText()
{
    qDeleteInEventHandler(QWhatsThat::instance);
}
 
#if QT_CONFIG(action)
QAction *QWhatsThis::createAction(QObject *parent)
{
    return new QWhatsThisAction(parent);
}
#endif // QT_CONFIG(action)
 
QT_END_NAMESPACE
 
#include "qwhatsthis.moc"