自学教程：C++ viewport函数代码示例

void View::resizeEvent( QResizeEvent * event ){    if ( QGraphicsScene * scene_ = scene() )        scene_->setSceneRect( 0, 0, viewport()->width(), viewport()->height() );    QGraphicsView::resizeEvent(event);}

void HistogramView::dataChanged(const QModelIndex &topLeft,const QModelIndex &bottomRight){    QAbstractItemView::dataChanged(topLeft,bottomRight);    viewport()->update();}

// paintEvent()函数具体完成柱状统计图绘制的工作void HistogramView::paintEvent(QPaintEvent *){    QPainter painter(viewport());    painter.setPen(Qt::black);    int x0=40;    int y0=250;    //y坐标轴    painter.drawLine(x0,y0,40,30);    painter.drawLine(38,32,40,30);    painter.drawLine(40,30,42,32);    painter.drawText(20,30,tr("人数"));    for(int i=1;i<5;i++)    {        painter.drawLine(-1,-i*50,1,-i*50);        painter.drawText(-20,-i*50,tr("%1").arg(i*5));    }    //x 坐标轴    painter.drawLine(x0,y0,540,250);    painter.drawLine(538,248,540,250);    painter.drawLine(540,250,538,252);    painter.drawText(545,250,tr("部门"));    int posD=x0+20;    int row;    for(row=0;row<model()->rowCount(rootIndex());row++)    {        QModelIndex index=model()->index(row,0,rootIndex());        QString dep=model()->data(index).toString();        painter.drawText(posD,y0+20,dep);        posD+=50;    }    //男    int posM=x0+20;    for(row=0;row<model()->rowCount(rootIndex());row++)    {        QModelIndex index=model()->index(row,1,rootIndex());        int male=model()->data(index).toDouble();        int width=10;        if(selections->isSelected(index))            painter.setBrush(QBrush(Qt::blue,Qt::Dense3Pattern));        else            painter.setBrush(Qt::blue);        painter.drawRect(QRect(posM,y0-male*10,width,male*10));        QRegion regionM(posM,y0-male*10,width,male*10);        MRegionList<<regionM;        posM+=50;    }    //女    int posF=x0+30;    for(row=0;row<model()->rowCount(rootIndex());row++)    {        QModelIndex index=model()->index(row,2,rootIndex());        int female=model()->data(index).toDouble();        int width=10;        if(selections->isSelected(index))            painter.setBrush(QBrush(Qt::red,Qt::Dense3Pattern));        else            painter.setBrush(Qt::red);        painter.drawRect(QRect(posF,y0-female*10,width,female*10));        QRegion regionF(posF,y0-female*10,width,female*10);        FRegionList<<regionF;        posF+=50;    }    //退休    int posS=x0+40;    for(row=0;row<model()->rowCount(rootIndex());row++)    {        QModelIndex index=model()->index(row,3,rootIndex());        int retire=model()->data(index).toDouble();        int width=10;        if(selections->isSelected(index))            painter.setBrush(QBrush(Qt::green,Qt::Dense3Pattern));        else            painter.setBrush(Qt::green);        painter.drawRect(QRect(posS,y0-retire*10,width,retire*10));        QRegion regionS(posS,y0-retire*10,width,retire*10);        SRegionList<<regionS;        posS+=50;    }}

void GraphicsDImgView::finishPanning(){    emit contentsMoved(true);    viewport()->unsetCursor();}

bool KFollowWindow::eventFilter( QObject *obj, QEvent *e ){	Q_D(KFollowWindow);	if(d->target == NULL)		return false;	if(obj == d->target->viewport())	{		switch(e->type())		{		case QEvent::WindowActivate:			{				int i = 0;			}			break;		case QEvent::WindowDeactivate:			{				if(!isVisible())				{					return false;				}				if(d->hideFlags & TargetWindowInactive)				{					bool bAborted = false;					emit aboutToHide(TargetWindowInactive, &bAborted);					if(!bAborted)					{						QMetaObject::invokeMethod(this, "hide", Qt::QueuedConnection);					}				}			}			break;		case QEvent::MouseButtonPress:			{				if(!isVisible())				{					return false;				}				if(d->target->isUnderMouse())				{					if(d->hideFlags & ClickAtTarget)					{						bool bAborted = false;						emit aboutToHide(ClickAtTarget, &bAborted);						if(!bAborted)						{							QMetaObject::invokeMethod(this, "hide", Qt::QueuedConnection);						}					}				}				else				{					if(d->hideFlags & ClickAtOther)					{						bool bAborted = false;						emit aboutToHide(ClickAtOther, &bAborted);						if(!bAborted)						{							QMetaObject::invokeMethod(this, "hide", Qt::QueuedConnection);						}					}				}			}			break;		case QEvent::Move:			{				if(!isVisible())				{					return false;				}				if(d->hideFlags & TargetWindowMoving)				{					bool bAborted = false;					emit aboutToHide(TargetWindowMoving, &bAborted);					if(!bAborted)					{						QMetaObject::invokeMethod(this, "hide", Qt::QueuedConnection);					}				}			}			break;		case QEvent::Resize:			{				if(!isVisible())				{					return false;				}				if(d->hideFlags & TargetWindowResize)				{					bool bAborted = false;					emit aboutToHide(TargetWindowResize, &bAborted);					if(!bAborted)					{						QMetaObject::invokeMethod(this, "hide", Qt::QueuedConnection);					}				}			}			break;		case QEvent::ParentChange:			{//.........这里部分代码省略.........

// setup matrices and viewport (upto you to push and pop view before and after)// if width or height are 0, assume windows dimensions (ofGetWidth(), ofGetHeight())// if nearDist or farDist are 0 assume defaults (calculated based on width / height)void ofCairoRenderer::viewport(ofRectangle v){	viewport(v.x,v.y,v.width,v.height);}

void QHexEdit::setHighlightingColor(const QColor &color){    _brushHighlighted = QBrush(color);    _penHighlighted = QPen(viewport()->palette().color(QPalette::WindowText));    viewport()->update();}

void QHexEdit::setAsciiArea(bool asciiArea){    _asciiArea = asciiArea;    viewport()->update();}

void ByteViewText::paintEvent(QPaintEvent *){    QPainter painter(viewport());    painter.translate(-horizontalScrollBar()->value() * font_width_, 0);    // Pixel offset of this row    int row_y = 0;    // Starting byte offset    int offset = verticalScrollBar()->value() * row_width_;    // Clear the area    painter.fillRect(viewport()->rect(), palette().base());    // Offset background. We want the entire height to be filled.    if (show_offset_) {        QRect offset_rect = QRect(viewport()->rect());        offset_rect.setWidth(offsetPixels());        painter.fillRect(offset_rect, palette().window());    }    if ( data_.isEmpty() ) {        return;    }    // Data rows    int widget_height = height();    int leading = fontMetrics().leading();    painter.save();    x_pos_to_column_.clear();    while( (int) (row_y + line_height_) < widget_height && offset < (int) data_.count()) {        drawLine(&painter, offset, row_y);        offset += row_width_;        row_y += line_height_ + leading;    }    painter.restore();    // We can't do this in drawLine since the next line might draw over our rect.    if (!hover_outlines_.isEmpty()) {        qreal pen_width = 1.0;        qreal hover_alpha = 0.6;        QPen ho_pen;        QColor ho_color = palette().text().color();        if (marked_byte_offset_ < 0) {            hover_alpha = 0.3;            if (devicePixelRatio() > 1) {                pen_width = 0.5;            }        }        ho_pen.setWidthF(pen_width);        ho_color.setAlphaF(hover_alpha);        ho_pen.setColor(ho_color);        painter.save();        painter.setPen(ho_pen);        painter.setBrush(Qt::NoBrush);        foreach (QRect ho_rect, hover_outlines_) {            // These look good on retina and non-retina displays on macOS.            // We might want to use fontMetrics numbers instead.            ho_rect.adjust(-1, 0, -1, -1);            painter.drawRect(ho_rect);        }

void ByteViewText::markAppendix(int start, int length){    field_a_start_ = start;    field_a_len_ = length;    viewport()->update();}

void ByteViewText::setFieldAppendixHighlight(int start, int end){    fa_bound_ = QPair<guint, guint>(qMax(0, start), qMax(0, end));    fa_bound_save_ = f_bound_;    viewport()->update();}

// ********************************************************************** Handle eventsvoid QHexEdit::keyPressEvent(QKeyEvent *event){    // Cursor movements    if (event->matches(QKeySequence::MoveToNextChar))    {        setCursorPosition(_cursorPosition + 1);        resetSelection(_cursorPosition);    }    if (event->matches(QKeySequence::MoveToPreviousChar))    {        setCursorPosition(_cursorPosition - 1);        resetSelection(_cursorPosition);    }    if (event->matches(QKeySequence::MoveToEndOfLine))    {        setCursorPosition(_cursorPosition | (2 * BYTES_PER_LINE -1));        resetSelection(_cursorPosition);    }    if (event->matches(QKeySequence::MoveToStartOfLine))    {        setCursorPosition(_cursorPosition - (_cursorPosition % (2 * BYTES_PER_LINE)));        resetSelection(_cursorPosition);    }    if (event->matches(QKeySequence::MoveToPreviousLine))    {        setCursorPosition(_cursorPosition - (2 * BYTES_PER_LINE));        resetSelection(_cursorPosition);    }    if (event->matches(QKeySequence::MoveToNextLine))    {        setCursorPosition(_cursorPosition + (2 * BYTES_PER_LINE));        resetSelection(_cursorPosition);    }    if (event->matches(QKeySequence::MoveToNextPage))    {        setCursorPosition(_cursorPosition + (((_rowsShown - 1) * 2 * BYTES_PER_LINE)));        resetSelection(_cursorPosition);    }    if (event->matches(QKeySequence::MoveToPreviousPage))    {        setCursorPosition(_cursorPosition - (((_rowsShown - 1) * 2 * BYTES_PER_LINE)));        resetSelection(_cursorPosition);    }    if (event->matches(QKeySequence::MoveToEndOfDocument))    {        setCursorPosition(_chunks->size() * 2);        resetSelection(_cursorPosition);    }    if (event->matches(QKeySequence::MoveToStartOfDocument))    {        setCursorPosition(0);        resetSelection(_cursorPosition);    }    // Select commands    if (event->matches(QKeySequence::SelectAll))    {        resetSelection(0);        setSelection(2*_chunks->size() + 1);    }    if (event->matches(QKeySequence::SelectNextChar))    {        qint64 pos = _cursorPosition + 1;        setCursorPosition(pos);        setSelection(pos);    }    if (event->matches(QKeySequence::SelectPreviousChar))    {        qint64 pos = _cursorPosition - 1;        setSelection(pos);        setCursorPosition(pos);    }    if (event->matches(QKeySequence::SelectEndOfLine))    {        qint64 pos = _cursorPosition - (_cursorPosition % (2 * BYTES_PER_LINE)) + (2 * BYTES_PER_LINE);        setCursorPosition(pos);        setSelection(pos);    }    if (event->matches(QKeySequence::SelectStartOfLine))    {        qint64 pos = _cursorPosition - (_cursorPosition % (2 * BYTES_PER_LINE));        setCursorPosition(pos);        setSelection(pos);    }    if (event->matches(QKeySequence::SelectPreviousLine))    {        qint64 pos = _cursorPosition - (2 * BYTES_PER_LINE);        setCursorPosition(pos);        setSelection(pos);    }    if (event->matches(QKeySequence::SelectNextLine))    {        qint64 pos = _cursorPosition + (2 * BYTES_PER_LINE);        setCursorPosition(pos);        setSelection(pos);    }    if (event->matches(QKeySequence::SelectNextPage))    {        qint64 pos = _cursorPosition + (((viewport()->height() / _pxCharHeight) - 1) * 2 * BYTES_PER_LINE);//.........这里部分代码省略.........

void ByteViewText::setEncoding(packet_char_enc encoding){    encoding_ = encoding;    viewport()->update();}

void QHexEdit::paintEvent(QPaintEvent *event){    QPainter painter(viewport());    if (event->rect() != _cursorRect)    {        // process some useful calculations        int pxOfsX = horizontalScrollBar()->value();        int pxPosStartY = _pxCharHeight;        // draw some patterns if needed        painter.fillRect(event->rect(), viewport()->palette().color(QPalette::Base));        if (_addressArea)            painter.fillRect(QRect(-pxOfsX, event->rect().top(), _pxPosHexX - _pxGapAdrHex/2 - pxOfsX, height()), _addressAreaColor);        if (_asciiArea)        {            int linePos = _pxPosAsciiX - (_pxGapHexAscii / 2);            painter.setPen(Qt::gray);            painter.drawLine(linePos - pxOfsX, event->rect().top(), linePos - pxOfsX, height());        }        painter.setPen(viewport()->palette().color(QPalette::WindowText));        // paint address area        if (_addressArea)        {            QString address;            for (int row=0, pxPosY = _pxCharHeight; row <= (_dataShown.size()/BYTES_PER_LINE); row++, pxPosY +=_pxCharHeight)            {                address = QString("%1").arg(_bPosFirst + row*BYTES_PER_LINE + _addressOffset, _addrDigits, 16, QChar('0'));                painter.drawText(_pxPosAdrX - pxOfsX, pxPosY, address);            }        }        // paint hex and ascii area        QPen colStandard = QPen(viewport()->palette().color(QPalette::WindowText));        painter.setBackgroundMode(Qt::TransparentMode);        for (int row = 0, pxPosY = pxPosStartY; row <= _rowsShown; row++, pxPosY +=_pxCharHeight)        {            QByteArray hex;            int pxPosX = _pxPosHexX  - pxOfsX;            int pxPosAsciiX2 = _pxPosAsciiX  - pxOfsX;            qint64 bPosLine = row * BYTES_PER_LINE;            for (int colIdx = 0; ((bPosLine + colIdx) < _dataShown.size() && (colIdx < BYTES_PER_LINE)); colIdx++)            {                QColor c = viewport()->palette().color(QPalette::Base);                painter.setPen(colStandard);                qint64 posBa = _bPosFirst + bPosLine + colIdx;                if ((getSelectionBegin() <= posBa) && (getSelectionEnd() > posBa))                {                    c = _brushSelection.color();                    painter.setPen(_penSelection);                }                else                {                    if (_highlighting)                        if (_markedShown.at((int)(posBa - _bPosFirst)))                        {                            c = _brushHighlighted.color();                            painter.setPen(_penHighlighted);                        }                }                // render hex value                QRect r;                if (colIdx == 0)                    r.setRect(pxPosX, pxPosY - _pxCharHeight + _pxSelectionSub, 2*_pxCharWidth, _pxCharHeight);                else                    r.setRect(pxPosX - _pxCharWidth, pxPosY - _pxCharHeight + _pxSelectionSub, 3*_pxCharWidth, _pxCharHeight);                painter.fillRect(r, c);                hex = _hexDataShown.mid((bPosLine + colIdx) * 2, 2);                painter.setPen(QColor::fromRgb(0, 128, 0));                painter.drawText(pxPosX, pxPosY, hex);                pxPosX += 3*_pxCharWidth;                // render ascii value                if (_asciiArea)                {                    char ch = _dataShown.at(bPosLine + colIdx);                    if ((ch < 0x20) || (ch > 0x7e))                        ch = '.';                    r.setRect(pxPosAsciiX2, pxPosY - _pxCharHeight + _pxSelectionSub, _pxCharWidth, _pxCharHeight);                    painter.fillRect(r, c);                    painter.drawText(pxPosAsciiX2, pxPosY, QChar(ch));                    pxPosAsciiX2 += _pxCharWidth;                }            }        }        painter.setBackgroundMode(Qt::TransparentMode);        painter.setPen(viewport()->palette().color(QPalette::WindowText));    }    // paint cursor    if (_blink && !_readOnly && hasFocus())        painter.fillRect(_cursorRect, this->palette().color(QPalette::WindowText));    else        painter.drawText(_pxCursorX, _pxCursorY, _hexDataShown.mid(_cursorPosition - _bPosFirst * 2, 1));//.........这里部分代码省略.........

void GraphicsDImgView::scrollContentsBy(int dx, int dy){    QGraphicsView::scrollContentsBy(dx, dy);    emit viewportRectChanged(mapToScene(viewport()->rect()).boundingRect());}

QRectF CanvasContainer::visualRect() const{    return proxy->mapFromScene(                mapToScene(viewport()->rect()))            .boundingRect().intersected(proxy->rect());}

QRect GraphicsDImgView::visibleArea() const{    return (mapToScene(viewport()->geometry()).boundingRect().toRect());}

QWidget* CanvasContainer::scaleSlider(){    if (!scaleSliderWidget)    {        scaleSliderWidget = new QWidget(this);        QHBoxLayout *layout = new QHBoxLayout(scaleSliderWidget);        QSlider *slider = new QSlider(Qt::Horizontal, scaleSliderWidget);        QLabel *label = new QLabel("100%", scaleSliderWidget);        label->setFixedWidth(label->fontMetrics().width("100.%"));        label->setAlignment(Qt::AlignHCenter | Qt::AlignVCenter);        //label->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed); //not working?        scaleSliderWidget->setLayout(layout);        layout->addWidget(slider);        layout->addWidget(label);        layout->setContentsMargins(0, 0, 0, 0);        qreal internalFactor = -100 * qLn(MIN_SCALE_FACTOR) / MIN_SCALE_FACTOR / qLn(2);        slider->setRange(-qCeil(MIN_SCALE_FACTOR * internalFactor),                         qCeil(MAX_SCALE_FACTOR - 1) * 100);        slider->setPageStep(100);        slider->setTickPosition(QSlider::TicksBelow);        auto setScaleOrigin = [=]()        {            if (proxy)            {                QPointF position = proxy->mapFromScene(mapToScene(viewport()->rect().center()));                if (proxy->rect().contains(position))                    proxy->setTransformOriginPoint(position);            }        };        auto calculateScale = [=](int sliderValue)        {            if (sliderValue >= 0)            {                qreal newScale = 1.0 + 0.01 * sliderValue;                if (!qFuzzyCompare(newScale, currentScaleFactor()))                {                    setScaleOrigin();                    setScaleFactor(1.0 + 0.01 * sliderValue);                    label->setText(QString("%1%").arg(100 + sliderValue));                }              }            else            {                qreal newScale = qPow(MIN_SCALE_FACTOR, -sliderValue / internalFactor / MIN_SCALE_FACTOR);                if (!qFuzzyCompare(newScale, currentScaleFactor()))                {                    setScaleOrigin();                    setScaleFactor(newScale);                    label->setText(QString("%1%").arg(newScale * 100, 0, 'f', 1));                }            }        };        auto calculateValue = [=](qreal scaleFactor)        {            slider->blockSignals(true);            if (scaleFactor >= 1.0)            {                int newValue = 100 * scaleFactor - 100;                if (newValue != slider->value())                {                    slider->setValue(newValue);                    label->setText(QString("%1%").arg(qFloor(100 * scaleFactor)));                }            }            else            {                int newValue = -internalFactor * MIN_SCALE_FACTOR / qLn(MIN_SCALE_FACTOR) * qLn(scaleFactor);                if (newValue != slider->value())                {                    slider->setValue(newValue);                    label->setText(QString("%1%").arg(100 * scaleFactor, 0, 'f', 1));                }            }            slider->blockSignals(false);        };        connect(slider, &QSlider::valueChanged, calculateScale);        connect(this, &CanvasContainer::scaled, calculateValue);    }    return scaleSliderWidget;}

void UIDisasm::setSelectionColor(const QColor &color){   selectionColor = color;   viewport()->update();}

QRectF View::visibleRect(){	int h = horizontalScrollBar() ? horizontalScrollBar()->height() : 0;	int w = verticalScrollBar() ? verticalScrollBar()->width() : 0;	return mapToScene(viewport()->rect().adjusted(0,0,-w,-h)).boundingRect();}

void ProfileGraphicsView::plot(struct dive *d, bool forceRedraw){	struct divecomputer *dc;	if (d)		dc = select_dc(&d->dc);	if (!forceRedraw && dive == d && (d && dc == diveDC))		return;	clear();	dive = d;	diveDC = d ? dc : NULL;	if (!isVisible() || !dive) {		return;	}	// best place to put the focus stealer code.	setFocusProxy(mainWindow()->dive_list());	scene()->setSceneRect(0,0, viewport()->width()-50, viewport()->height()-50);	toolTip = new ToolTipItem();	installEventFilter(toolTip);	scene()->addItem(toolTip);	// Fix this for printing / screen later.	// plot_set_scale(scale_mode_t);	if (!dc->samples) {		dc = fake_dc(dc);	}	QString nick = get_dc_nickname(dc->model, dc->deviceid);	if (nick.isEmpty())		nick = QString(dc->model);	if (nick.isEmpty())		nick = tr("unknown divecomputer");	if ( tr("unknown divecomputer") == nick){		mode = PLAN;	}else{		mode = DIVE;	}	/*	 * Set up limits that are independent of	 * the dive computer	 */	calculate_max_limits(dive, dc, &gc);	QRectF profile_grid_area = scene()->sceneRect();	gc.maxx = (profile_grid_area.width() - 2 * profile_grid_area.x());	gc.maxy = (profile_grid_area.height() - 2 * profile_grid_area.y());	/* This is per-dive-computer */	gc.pi = *create_plot_info(dive, dc, &gc);	/* Bounding box */	QPen pen = defaultPen;	pen.setColor(profile_color[TIME_GRID].at(0));	QGraphicsRectItem *rect = new QGraphicsRectItem(profile_grid_area);	rect->setPen(pen);	scene()->addItem(rect);	/* Depth profile */	plot_depth_profile();	plot_events(dc);	/* Temperature profile */	plot_temperature_profile();	/* Cylinder pressure plot */	plot_cylinder_pressure(dc);	/* Text on top of all graphs.. */	plot_temperature_text();	plot_depth_text();	plot_cylinder_pressure_text();	plot_deco_text();	/* Put the dive computer name in the lower left corner */	gc.leftx = 0; gc.rightx = 1.0;	gc.topy = 0; gc.bottomy = 1.0;	text_render_options_t computer = {DC_TEXT_SIZE, TIME_TEXT, LEFT, TOP};	diveComputer = plot_text(&computer, QPointF(gc.leftx, gc.bottomy), nick);	// The Time ruler should be right after the DiveComputer:	timeMarkers->setPos(0, diveComputer->y());	if (PP_GRAPHS_ENABLED) {		plot_pp_gas_profile();		plot_pp_text();	}//.........这里部分代码省略.........