QPlainTextDocumentLayout Class Reference

The QPlainTextDocumentLayout class implements a plain text layout for QTextDocument. More...

#include <qplaintextedit.h>

Inheritance diagram for QPlainTextDocumentLayout:

Public Functions
QRectF	blockBoundingRect (const QTextBlock &block) const
	Reimplemented Function More...
int	cursorWidth () const
QSizeF	documentSize () const
	Reimplemented Function More...
void	draw (QPainter *, const PaintContext &)
	Reimplemented Function More...
void	ensureBlockLayout (const QTextBlock &block) const
	Ensures that block has a valid layout. More...
QRectF	frameBoundingRect (QTextFrame *) const
	Reimplemented Function More...
int	hitTest (const QPointF &, Qt::HitTestAccuracy) const
	Reimplemented Function More...
int	pageCount () const
	Reimplemented Function More...
	QPlainTextDocumentLayout (QTextDocument *document)
	Constructs a plain text document layout for the text document. More...
void	requestUpdate ()
	Requests a complete update on all views. More...
void	setCursorWidth (int width)
	~QPlainTextDocumentLayout ()
	Destructs a plain text document layout. More...
Public Functions inherited from QAbstractTextDocumentLayout
QString	anchorAt (const QPointF &pos) const
	Returns the reference of the anchor the given position, or an empty string if no anchor exists at that point. More...
QTextDocument *	document () const
	Returns the text document that this layout is operating on. More...
QTextObjectInterface *	handlerForObject (int objectType) const
	Returns a handler for objects of the given objectType. More...
QPaintDevice *	paintDevice () const
	Returns the paint device used to render the document's layout. More...
	QAbstractTextDocumentLayout (QTextDocument *doc)
	Creates a new text document layout for the given document. More...
void	registerHandler (int objectType, QObject *component)
	Registers the given component as a handler for items of the given objectType. More...
void	setPaintDevice (QPaintDevice *device)
	Sets the paint device used for rendering the document's layout to the given device. More...
	~QAbstractTextDocumentLayout ()
Public Functions inherited from QObject
bool	blockSignals (bool b)
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it). More...
const QObjectList &	children () const
	Returns a list of child objects. More...
bool	connect (const QObject *sender, const char *signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const
bool	disconnect (const char *signal=0, const QObject *receiver=0, const char *member=0)
bool	disconnect (const QObject *receiver, const char *member=0)
void	dumpObjectInfo ()
	Dumps information about signal connections, etc. More...
void	dumpObjectTree ()
	Dumps a tree of children to the debug output. More...
QList< QByteArray >	dynamicPropertyNames () const
	Returns the names of all properties that were dynamically added to the object using setProperty(). More...
virtual bool	event (QEvent *)
	This virtual function receives events to an object and should return true if the event e was recognized and processed. More...
virtual bool	eventFilter (QObject *, QEvent *)
	Filters events if this object has been installed as an event filter for the watched object. More...
template<typename T >
T	findChild (const QString &aName=QString()) const
	Returns the child of this object that can be cast into type T and that is called name, or 0 if there is no such object. More...
template<typename T >
QList< T >	findChildren (const QString &aName=QString()) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects. More...
template<typename T >
QList< T >	findChildren (const QRegExp &re) const
bool	inherits (const char *classname) const
	Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false. More...
void	installEventFilter (QObject *)
	Installs an event filter filterObj on this object. More...
bool	isWidgetType () const
	Returns true if the object is a widget; otherwise returns false. More...
void	killTimer (int id)
	Kills the timer with timer identifier, id. More...
virtual const QMetaObject *	metaObject () const
	Returns a pointer to the meta-object of this object. More...
void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children. More...
QString	objectName () const
QObject *	parent () const
	Returns a pointer to the parent object. More...
QVariant	property (const char *name) const
	Returns the value of the object's name property. More...
Q_INVOKABLE	QObject (QObject *parent=0)
	Constructs an object with parent object parent. More...
void	removeEventFilter (QObject *)
	Removes an event filter object obj from this object. More...
void	setObjectName (const QString &name)
void	setParent (QObject *)
	Makes the object a child of parent. More...
bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value. More...
void	setUserData (uint id, QObjectUserData *data)
bool	signalsBlocked () const
	Returns true if signals are blocked; otherwise returns false. More...
int	startTimer (int interval)
	Starts a timer and returns a timer identifier, or returns zero if it could not start a timer. More...
QThread *	thread () const
	Returns the thread in which the object lives. More...
QObjectUserData *	userData (uint id) const
virtual	~QObject ()
	Destroys the object, deleting all its child objects. More...

Protected Functions
void	documentChanged (int from, int, int charsAdded)
	Reimplemented Function More...
Protected Functions inherited from QAbstractTextDocumentLayout
virtual void	drawInlineObject (QPainter *painter, const QRectF &rect, QTextInlineObject object, int posInDocument, const QTextFormat &format)
	This function is called to draw the inline object, object, with the given painter within the rectangle specified by rect using the specified text format. More...
QTextCharFormat	format (int pos)
	Returns the character format that is applicable at the given position. More...
int	formatIndex (int pos)
	Returns the index of the format at position pos. More...
virtual void	positionInlineObject (QTextInlineObject item, int posInDocument, const QTextFormat &format)
	Lays out the inline object item using the given text format. More...
	QAbstractTextDocumentLayout (QAbstractTextDocumentLayoutPrivate &, QTextDocument *)
virtual void	resizeInlineObject (QTextInlineObject item, int posInDocument, const QTextFormat &format)
	Sets the size of the inline object item corresponding to the text format. More...
Protected Functions inherited from QObject
virtual void	childEvent (QChildEvent *)
	This event handler can be reimplemented in a subclass to receive child events. More...
virtual void	connectNotify (const char *signal)
	This virtual function is called when something has been connected to signal in this object. More...
virtual void	customEvent (QEvent *)
	This event handler can be reimplemented in a subclass to receive custom events. More...
virtual void	disconnectNotify (const char *signal)
	This virtual function is called when something has been disconnected from signal in this object. More...
	QObject (QObjectPrivate &dd, QObject *parent=0)
int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal. More...
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns 0. More...
int	senderSignalIndex () const
virtual void	timerEvent (QTimerEvent *)
	This event handler can be reimplemented in a subclass to receive timer events for the object. More...

Private Functions
qreal	blockWidth (const QTextBlock &block)
void	layoutBlock (const QTextBlock &block)
QPlainTextDocumentLayoutPrivate *	priv () const
void	setTextWidth (qreal newWidth)
qreal	textWidth () const

Properties
int	cursorWidth
	This property specifies the width of the cursor in pixels. More...

Friends
class	QPlainTextEdit
class	QPlainTextEditPrivate

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	Schedules this object for deletion. More...
Signals inherited from QAbstractTextDocumentLayout
void	documentSizeChanged (const QSizeF &newSize)
	This signal is emitted when the size of the document layout changes to newSize. More...
void	pageCountChanged (int newPages)
	This signal is emitted when the number of pages in the layout changes; newPages is the updated page count. More...
void	update (const QRectF &=QRectF(0., 0., 1000000000., 1000000000.))
	This signal is emitted when the rectangle rect has been updated. More...
void	updateBlock (const QTextBlock &block)
	This signal is emitted when the specified block has been updated. More...
Signals inherited from QObject
void	destroyed (QObject *=0)
	This signal is emitted immediately before the object obj is destroyed, and can not be blocked. More...
Static Public Functions inherited from QObject
static bool	connect (const QObject *sender, const char *signal, const QObject *receiver, const char *member, Qt::ConnectionType=Qt::AutoConnection)
	Creates a connection of the given type from the signal in the sender object to the method in the receiver object. More...
static bool	connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)
static bool	disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *member)
	Disconnects signal in object sender from method in object receiver. More...
static bool	disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &member)
static uint	registerUserData ()
static QString	tr (const char *sourceText, const char *comment=0, int n=-1)
static QString	trUtf8 (const char *sourceText, const char *comment=0, int n=-1)
Static Public Variables inherited from QObject
static const QMetaObject	staticMetaObject
	This variable stores the meta-object for the class. More...
Protected Variables inherited from QObject
QScopedPointer< QObjectData >	d_ptr
Static Protected Variables inherited from QObject
static const QMetaObject	staticQtMetaObject
Related Functions inherited from QObject
T	qFindChildqFindChildren (const QObject *obj, const QString &name)()
QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()
QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QRegExp &regExp)()
T *	qobject_cast (QObject *object)
	QObjectList
void *	qt_find_obj_child (QObject *parent, const char *type, const QString &name)
	Returns a pointer to the object named name that inherits type and with a given parent. More...

Detailed Description

The QPlainTextDocumentLayout class implements a plain text layout for QTextDocument.

Since

4.4

A QPlainTextDocumentLayout is required for text documents that can be display or edited in a QPlainTextEdit. See QTextDocument::setDocumentLayout().

QPlainTextDocumentLayout uses the QAbstractTextDocumentLayout API that QTextDocument requires, but redefines it partially in order to support plain text better. For instances, it does not operate on vertical pixels, but on paragraphs (called blocks) instead. The height of a document is identical to the number of paragraphs it contains. The layout also doesn't support tables or nested frames, or any sort of advanced text layout that goes beyond a list of paragraphs with syntax highlighting.

Definition at line 280 of file qplaintextedit.h.

Constructors and Destructors

QPlainTextDocumentLayout()

QPlainTextDocumentLayout::QPlainTextDocumentLayout

(

QTextDocument *

document

)

Constructs a plain text document layout for the text document.

Definition at line 142 of file qplaintextedit.cpp.

    :QAbstractTextDocumentLayout(* new QPlainTextDocumentLayoutPrivate, document) {
}

~QPlainTextDocumentLayout()

QPlainTextDocumentLayout::~QPlainTextDocumentLayout

(

)

Destructs a plain text document layout.

Definition at line 148 of file qplaintextedit.cpp.

{}

Functions

blockBoundingRect()

QRectF QPlainTextDocumentLayout::blockBoundingRect ( const QTextBlock &  block ) const

virtual

Reimplemented Function

Implements QAbstractTextDocumentLayout.

Definition at line 198 of file qplaintextedit.cpp.

Referenced by QPlainTextEditPrivate::_q_adjustScrollbars(), QPlainTextEditControl::blockBoundingRect(), QPlainTextEdit::blockBoundingRect(), documentChanged(), QPlainTextEditControl::hitTest(), and QPlainTextEditPrivate::verticalOffset().

{
    if (!block.isValid()) { return QRectF(); }
    QTextLayout *tl = block.layout();
    if (!tl->lineCount())
        const_cast<QPlainTextDocumentLayout*>(this)->layoutBlock(block);
    QRectF br;
    if (block.isVisible()) {
        br = QRectF(QPointF(0, 0), tl->boundingRect().bottomRight());
        if (tl->lineCount() == 1)
            br.setWidth(qMax(br.width(), tl->lineAt(0).naturalTextWidth()));
        qreal margin = document()->documentMargin();
        br.adjust(0, 0, margin, 0);
        if (!block.next().isValid())
            br.adjust(0, 0, 0, margin);
    }
    return br;

}

blockWidth()

qreal QPlainTextDocumentLayout::blockWidth ( const QTextBlock &  block )

private

Definition at line 429 of file qplaintextedit.cpp.

Referenced by documentChanged(), and layoutBlock().

{
    QTextLayout *layout = block.layout();
    if (!layout->lineCount())
        return 0; // only for layouted blocks
    qreal blockWidth = 0;
    for (int i = 0; i < layout->lineCount(); ++i) {
        QTextLine line = layout->lineAt(i);
        blockWidth = qMax(line.naturalTextWidth() + 8, blockWidth);
    }
    return blockWidth;
}

cursorWidth()

int QPlainTextDocumentLayout::cursorWidth

(

)

const

Referenced by setCursorWidth().

documentChanged()

void QPlainTextDocumentLayout::documentChanged ( int  from, int  , int  charsAdded  )

protectedvirtual

Reimplemented Function

Implements QAbstractTextDocumentLayout.

Definition at line 295 of file qplaintextedit.cpp.

{
    Q_D(QPlainTextDocumentLayout);
    QTextDocument *doc = document();
    int newBlockCount = doc->blockCount();

    QTextBlock changeStartBlock = doc->findBlock(from);
    QTextBlock changeEndBlock = doc->findBlock(qMax(0, from + charsAdded - 1));

    if (changeStartBlock == changeEndBlock && newBlockCount == d->blockCount) {
        QTextBlock block = changeStartBlock;
        int blockLineCount = block.layout()->lineCount();
        if (block.isValid() && blockLineCount) {
            QRectF oldBr = blockBoundingRect(block);
            layoutBlock(block);
            QRectF newBr = blockBoundingRect(block);
            if (newBr.height() == oldBr.height()) {
                if (!d->blockUpdate)
                    emit updateBlock(block);
                return;
            }
        }
    } else {
        QTextBlock block = changeStartBlock;
        do {
            block.clearLayout();
            if (block == changeEndBlock)
                break;
            block = block.next();
        } while(block.isValid());
    }

    if (newBlockCount != d->blockCount) {

        int changeEnd = changeEndBlock.blockNumber();
        int blockDiff = newBlockCount - d->blockCount;
        int oldChangeEnd = changeEnd - blockDiff;

        if (d->maximumWidthBlockNumber > oldChangeEnd)
            d->maximumWidthBlockNumber += blockDiff;

        d->blockCount = newBlockCount;
        if (d->blockCount == 1)
            d->maximumWidth = blockWidth(doc->firstBlock());

        if (!d->blockDocumentSizeChanged)
            emit documentSizeChanged(documentSize());

        if (blockDiff == 1 && changeEnd == newBlockCount -1 ) {
            if (!d->blockUpdate) {
                QTextBlock b = changeStartBlock;
                for(;;) {
                    emit updateBlock(b);
                    if (b == changeEndBlock)
                        break;
                    b = b.next();
                }
            }
            return;
        }
    }

    if (!d->blockUpdate)
    emit update(QRectF(0., -doc->documentMargin(), 1000000000., 1000000000.)); // optimization potential
}

documentSize()

QSizeF QPlainTextDocumentLayout::documentSize ( ) const

virtual

Reimplemented Function

Implements QAbstractTextDocumentLayout.

Definition at line 180 of file qplaintextedit.cpp.

Referenced by QPlainTextEditPrivate::_q_adjustScrollbars(), documentChanged(), and layoutBlock().

{
    Q_D(const QPlainTextDocumentLayout);
    return QSizeF(d->maximumWidth, document()->lineCount());
}

draw()

void QPlainTextDocumentLayout::draw ( QPainter *  , const PaintContext &    )

virtual

Reimplemented Function

Implements QAbstractTextDocumentLayout.

Definition at line 154 of file qplaintextedit.cpp.

{
}

ensureBlockLayout()

void QPlainTextDocumentLayout::ensureBlockLayout

(

const QTextBlock &

block

)

const

Ensures that block has a valid layout.

Definition at line 221 of file qplaintextedit.cpp.

{
    if (!block.isValid())
        return;
    QTextLayout *tl = block.layout();
    if (!tl->lineCount())
        const_cast<QPlainTextDocumentLayout*>(this)->layoutBlock(block);
}

frameBoundingRect()

QRectF QPlainTextDocumentLayout::frameBoundingRect ( QTextFrame *  ) const

virtual

Reimplemented Function

Implements QAbstractTextDocumentLayout.

Definition at line 189 of file qplaintextedit.cpp.

{
    Q_D(const QPlainTextDocumentLayout);
    return QRectF(0, 0, qMax(d->width, d->maximumWidth), qreal(INT_MAX));
}

hitTest()

int QPlainTextDocumentLayout::hitTest ( const QPointF &  , Qt::HitTestAccuracy    ) const

virtual

Reimplemented Function

Implements QAbstractTextDocumentLayout.

Definition at line 161 of file qplaintextedit.cpp.

{
//     this function is used from
//     QAbstractTextDocumentLayout::anchorAt(), but is not
//     implementable in a plain text document layout, because the
//     layout depends on the top block and top line which depends on
//     the view
    return -1;
}

layoutBlock()

void QPlainTextDocumentLayout::layoutBlock ( const QTextBlock &  block )

private

Definition at line 362 of file qplaintextedit.cpp.

Referenced by documentChanged().

{
    Q_D(QPlainTextDocumentLayout);
    QTextDocument *doc = document();
    qreal margin = doc->documentMargin();
    qreal blockMaximumWidth = 0;

    qreal height = 0;
    QTextLayout *tl = block.layout();
    QTextOption option = doc->defaultTextOption();
    tl->setTextOption(option);

    int extraMargin = 0;
    if (option.flags() & QTextOption::AddSpaceForLineAndParagraphSeparators) {
        QFontMetrics fm(block.charFormat().font());
        extraMargin += fm.width(QChar(0x21B5));
    }
    tl->beginLayout();
    qreal availableWidth = d->width;
    if (availableWidth <= 0) {
        availableWidth = qreal(INT_MAX); // similar to text edit with pageSize.width == 0
    }
    availableWidth -= 2*margin + extraMargin;
    while (1) {
        QTextLine line = tl->createLine();
        if (!line.isValid())
            break;
        line.setLeadingIncluded(true);
        line.setLineWidth(availableWidth);
        line.setPosition(QPointF(margin, height));
        height += line.height();
        blockMaximumWidth = qMax(blockMaximumWidth, line.naturalTextWidth() + 2*margin);
    }
    tl->endLayout();

    int previousLineCount = doc->lineCount();
    const_cast<QTextBlock&>(block).setLineCount(block.isVisible() ? tl->lineCount() : 0);
    int lineCount = doc->lineCount();

    bool emitDocumentSizeChanged = previousLineCount != lineCount;
    if (blockMaximumWidth > d->maximumWidth) {
        // new longest line
        d->maximumWidth = blockMaximumWidth;
        d->maximumWidthBlockNumber = block.blockNumber();
        emitDocumentSizeChanged = true;
    } else if (block.blockNumber() == d->maximumWidthBlockNumber && blockMaximumWidth < d->maximumWidth) {
        // longest line shrinking
        QTextBlock b = doc->firstBlock();
        d->maximumWidth = 0;
        QTextBlock maximumBlock;
        while (b.isValid()) {
            qreal blockMaximumWidth = blockWidth(b);
            if (blockMaximumWidth > d->maximumWidth) {
                d->maximumWidth = blockMaximumWidth;
                maximumBlock = b;
            }
            b = b.next();
        }
        if (maximumBlock.isValid()) {
            d->maximumWidthBlockNumber = maximumBlock.blockNumber();
            emitDocumentSizeChanged = true;
        }
    }
    if (emitDocumentSizeChanged && !d->blockDocumentSizeChanged)
        emit documentSizeChanged(documentSize());
}

pageCount()

int QPlainTextDocumentLayout::pageCount ( ) const

virtual

Reimplemented Function

Implements QAbstractTextDocumentLayout.

Definition at line 174 of file qplaintextedit.cpp.

{ return 1; }

priv()

QPlainTextDocumentLayoutPrivate * QPlainTextDocumentLayout::priv ( ) const

private

Definition at line 250 of file qplaintextedit.cpp.

Referenced by QPlainTextEditPrivate::_q_adjustScrollbars(), QPlainTextEditPrivate::append(), QPlainTextEditPrivate::relayoutDocument(), and QPlainTextEdit::setDocument().

{
    Q_D(const QPlainTextDocumentLayout);
    return const_cast<QPlainTextDocumentLayoutPrivate*>(d);
}

requestUpdate()

void QPlainTextDocumentLayout::requestUpdate

(

)

Requests a complete update on all views.

Definition at line 261 of file qplaintextedit.cpp.

{
    emit update(QRectF(0., -document()->documentMargin(), 1000000000., 1000000000.));
}

setCursorWidth()

void QPlainTextDocumentLayout::setCursorWidth

(

int

width

)

Definition at line 238 of file qplaintextedit.cpp.

{
    Q_D(QPlainTextDocumentLayout);
    d->cursorWidth = width;
}

setTextWidth()

void QPlainTextDocumentLayout::setTextWidth ( qreal  newWidth )

private

Definition at line 267 of file qplaintextedit.cpp.

Referenced by QPlainTextEditPrivate::relayoutDocument().

{
    Q_D(QPlainTextDocumentLayout);
    d->width = d->maximumWidth = newWidth;
    d->relayout();
}

textWidth()

qreal QPlainTextDocumentLayout::textWidth ( ) const

private

Definition at line 274 of file qplaintextedit.cpp.

Referenced by QPlainTextEditPrivate::relayoutDocument().

{
    Q_D(const QPlainTextDocumentLayout);
    return d->width;
}

Friends and Related Functions

QPlainTextEdit

friend class QPlainTextEdit

friend

Definition at line 318 of file qplaintextedit.h.

QPlainTextEditPrivate

friend class QPlainTextEditPrivate

friend

Definition at line 319 of file qplaintextedit.h.

Properties

cursorWidth

int QPlainTextDocumentLayout::cursorWidth

private

This property specifies the width of the cursor in pixels.

The default value is 1.

Definition at line 284 of file qplaintextedit.h.

---

The documentation for this class was generated from the following files:

• /src/gui/widgets/qplaintextedit.h
• /src/gui/widgets/qplaintextedit.cpp