- Qt 6.12
- Qt PDF
- C++ Classes
- QPdfPageNavigator
- Qt 6.12.0 Reference Documentation

# QPdfPageNavigator Class

Navigation history within a PDF document. More...

Header: | `#include <QPdfPageNavigator>`
Since: | Qt 6.4
Inherits: | QObject

- List of all members, including inherited members

## Properties

backAvailable : bool currentLocation : QPointF currentPage : int | currentZoom : qreal forwardAvailable : bool

## Public Functions

| QPdfPageNavigator(QObject *parent)
virtual | ~QPdfPageNavigator() override
bool | backAvailable() const
QPointF | currentLocation() const
int | currentPage() const
qreal | currentZoom() const
bool | forwardAvailable() const

## Public Slots

void | back()
void | clear()
void | forward()
void | jump(QPdfLink destination)
void | jump(int page, const QPointF &location, qreal zoom = 0)
void | update(int page, const QPointF &location, qreal zoom)

## Signals

void | backAvailableChanged(bool available)
void | currentLocationChanged(QPointF location)
void | currentPageChanged(int page)
void | currentZoomChanged(qreal zoom)
void | forwardAvailableChanged(bool available)
void | jumped(QPdfLink current)

## Detailed Description

The QPdfPageNavigator class remembers which destinations the user has visited in a PDF document, and provides the ability to traverse backward and forward. It is used to implement back and forward actions similar to the back and forward buttons in a web browser.

See also QPdfDocument.

## Property Documentation

### `[read-only]` backAvailable : bool

Holds `true` if a back destination is available in the history: that is, if push() or forward() has been called.

Access functions:

bool | backAvailable() const

Notifier signal:

void | backAvailableChanged(bool available)

### `[read-only]` currentLocation : QPointF

This property holds the current location on the page that is being viewed (the location that was last given to jump() or update()). The default is `0, 0`.

Access functions:

QPointF | currentLocation() const

Notifier signal:

void | currentLocationChanged(QPointF location)

### `[read-only]` currentPage : int

This property holds the current page that is being viewed. The default is `0`.

Access functions:

int | currentPage() const

Notifier signal:

void | currentPageChanged(int page)

### `[read-only]` currentZoom : qreal

This property holds the magnification scale (1 logical pixel = 1 point) on the page that is being viewed. The default is `1`.

Access functions:

qreal | currentZoom() const

Notifier signal:

void | currentZoomChanged(qreal zoom)

### `[read-only]` forwardAvailable : bool

Holds `true` if a forward destination is available in the history: that is, if back() has been previously called.

Access functions:

bool | forwardAvailable() const

Notifier signal:

void | forwardAvailableChanged(bool available)

## Member Function Documentation

### `[explicit]` QPdfPageNavigator::QPdfPageNavigator(QObject *parent)

Constructs a page navigation stack with parent object parent.

### `[override virtual noexcept]` QPdfPageNavigator::~QPdfPageNavigator()

Destroys the page navigation stack.

### `[slot]` void QPdfPageNavigator::back()

Pops the stack, updates the currentPage, currentLocation and currentZoom properties to the most-recently-viewed destination, and then emits the jumped() signal.

### `[slot]` void QPdfPageNavigator::clear()

Clear the history and restore currentPage, currentLocation and currentZoom to their default values.

### `[slot]` void QPdfPageNavigator::forward()

Goes back to the page, location and zoom level that was being viewed before back() was called, and then emits the jumped() signal.

If a new destination was pushed since the last time back() was called, the forward() function does nothing, because there is a branch in the timeline which causes the "future" to be lost.

### `[slot]` void QPdfPageNavigator::jump(QPdfLink destination)

Adds the given destination to the history of visited locations.

In this case, PDF views respond to the jumped signal by scrolling to place `destination.rectangles` in the viewport, as opposed to placing `destination.location` in the viewport. So it's appropriate to call this method to jump to a search result from QPdfSearchModel (because the rectangles cover the region of text found). To jump to a hyperlink destination, call jump(page, location, zoom) instead, because in that case the QPdfLink object's `rectangles` cover the hyperlink origin location rather than the destination.

Note: This slot is overloaded. To connect to this slot:

     // Connect using qOverload:
     connect(sender, &SenderClass::signal,
             pdfPageNavigator, qOverload(&QPdfPageNavigator::jump));

     // Or using a lambda as wrapper:
     connect(sender, &SenderClass::signal,
             pdfPageNavigator, [receiver = pdfPageNavigator](QPdfLink destination) { receiver->jump(destination); });

For more examples and approaches, see connecting to overloaded slots.

### `[slot]` void QPdfPageNavigator::jump(int page, const QPointF &location, qreal zoom = 0)

Adds the given destination, consisting of page, location, and zoom, to the history of visited locations.

The zoom argument represents magnification (where `1` is the default scale, 1 logical pixel = 1 point). If zoom is not given or is `0`, currentZoom keeps its existing value, and currentZoomChanged is not emitted.

The location should be the same as QPdfLink::location() if the user is following a link; and since that is specified as the upper-left corner of the destination, it is best for consistency to always use the location visible in the upper-left corner of the viewport, in points.

If forwardAvailable is `true`, calling this function represents a branch in the timeline which causes the "future" to be lost, and therefore forwardAvailable will change to `false`.

Note: This slot is overloaded. To connect to this slot:

     // Connect using qOverload:
     connect(sender, &SenderClass::signal,
             pdfPageNavigator, qOverload(&QPdfPageNavigator::jump));

     // Or using a lambda as wrapper:
     connect(sender, &SenderClass::signal,
             pdfPageNavigator, [receiver = pdfPageNavigator](int page, const QPointF &location, qreal zoom) { receiver->jump(page, location, zoom); });

For more examples and approaches, see connecting to overloaded slots.

### `[signal]` void QPdfPageNavigator::jumped(QPdfLink current)

This signal is emitted when an abrupt jump occurs, to the current page index, location on the page, and zoom level; but not when simply scrolling through the document one page at a time. That is, jump(), forward() and back() emit this signal, but update() does not.

If `current.rectangles.length > 0`, they are rectangles that cover a specific destination area: a search result that should be made visible; otherwise, `current.location` is the destination location on the `page` (a hyperlink destination, or during forward/back navigation).

### `[slot]` void QPdfPageNavigator::update(int page, const QPointF &location, qreal zoom)

Modifies the current destination, consisting of page, location and zoom.

This can be called periodically while the user is manually moving around the document, so that after back() is called, forward() will jump back to the most-recently-viewed destination rather than the destination that was last specified by push().

The `currentZoomChanged`, `currentPageChanged` and `currentLocationChanged` signals will be emitted if the respective properties are actually changed. The jumped signal is not emitted, because this operation represents smooth movement rather than a navigational jump.