Qt 4.0: QSizeF Class Reference

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# QSizeF Class Reference
[QtCore module]

The QSizeF class defines the size of a two-dimensional object using floating point values for accuracy. More...

    #include <QSizeF>

- List of all members, including inherited members

### Public Functions

- QSizeF ()
- QSizeF ( const QSize & size )
- QSizeF ( qreal width, qreal height )
- QSizeF boundedTo ( const QSizeF & otherSize ) const
- QSizeF expandedTo ( const QSizeF & otherSize ) const
- qreal height () const
- bool isEmpty () const
- bool isNull () const
- bool isValid () const
- qreal & rheight ()
- qreal & rwidth ()
- void scale ( qreal w, qreal h, Qt::AspectRatioMode mode )
- void scale ( const QSizeF & s, Qt::AspectRatioMode mode )
- void setHeight ( qreal height )
- void setWidth ( qreal width )
- QSize toSize () const
- void transpose ()
- qreal width () const
- QSizeF & operator*= ( qreal coeff )
- QSizeF & operator+= ( const QSizeF & s )
- QSizeF & operator-= ( const QSizeF & s )
- QSizeF & operator/= ( qreal divisor )

### Related Non-Members

- bool operator!= ( const QSizeF & s1, const QSizeF & s2 )
- const QSizeF operator* ( const QSizeF & size, qreal coeff )
- const QSizeF operator* ( qreal c, const QSizeF & s )
- const QSizeF operator+ ( const QSizeF & s1, const QSizeF & s2 )
- const QSizeF operator- ( const QSizeF & s1, const QSizeF & s2 )
- const QSizeF operator/ ( const QSizeF & size, qreal divisor )
- QDataStream & operator<< ( QDataStream & s, const QSizeF & sz )
- bool operator== ( const QSizeF & s1, const QSizeF & s2 )
- QDataStream & operator>> ( QDataStream & s, QSizeF & sz )

## Detailed Description

The QSizeF class defines the size of a two-dimensional object using floating point values for accuracy.

A size is specified by a width and a height.

The coordinate type is qreal.

The size can be set in the constructor and changed with setWidth(), setHeight(), or scale(), or using arithmetic operators. You can swap the width and height with transpose(). You can get a size which holds the maximum height and width of two sizes using expandedTo(), and the minimum height and width of two sizes using boundedTo().

See also QSize, QPointF, and QRectF.

## Member Function Documentation

### QSizeF::QSizeF ()

Constructs an invalid size.

See also isValid(), setWidth(), and setHeight().

### QSizeF::QSizeF ( const QSize & size )

Constructs a size with floating point accuracy from the given size.

### QSizeF::QSizeF ( qreal width, qreal height )

Constructs a size with width width and height height.

### QSizeF QSizeF::boundedTo ( const QSizeF & otherSize ) const

Returns a size with the minimum width and height of this size and otherSize.

See also expandedTo(), scale(), setWidth(), and setHeight().

### QSizeF QSizeF::expandedTo ( const QSizeF & otherSize ) const

Returns a size with the maximum width and height of this size and otherSize.

See also boundedTo(), scale(), setWidth(), and setHeight().

### qreal QSizeF::height () const

Returns the height.

See also width() and setHeight().

### bool QSizeF::isEmpty () const

Returns true if the width is less than or equal to 0, or the height is less than or equal to 0; otherwise returns false.

See also isNull(), isValid(), width(), and height().

### bool QSizeF::isNull () const

Returns true if the width is 0 and the height is 0; otherwise returns false.

See also isValid(), isEmpty(), width(), and height().

### bool QSizeF::isValid () const

Returns true if the width is equal to or greater than 0 and the height is equal to or greater than 0; otherwise returns false.

See also isNull(), isEmpty(), width(), and height().

### qreal & QSizeF::rheight ()

Returns a reference to the height.

Using a reference makes it possible to directly manipulate the height.

Example:

        QSizeF s(100, 10.2);
        s.rheight() += 5.5;                // s becomes (100,15.7)

See also rwidth() and setHeight().

### qreal & QSizeF::rwidth ()

Returns a reference to the width.

Using a reference makes it possible to directly manipulate the width.

Example:

        QSizeF s(100.3, 10);
        s.rwidth() += 20.5;                // s becomes (120.8,10)

See also rheight() and setWidth().

### void QSizeF::scale ( qreal w, qreal h, Qt::AspectRatioMode mode )

Scales the size to a rectangle of width w and height h according to the Qt::AspectRatioMode mode.

- If mode is Qt::IgnoreAspectRatio, the size is set to (w, h).
- If mode is Qt::KeepAspectRatio, the current size is scaled to a rectangle as large as possible inside (w, h), preserving the aspect ratio.
- If mode is Qt::KeepAspectRatioByExpanding, the current size is scaled to a rectangle as small as possible outside (w, h), preserving the aspect ratio.

Example:

        QSizeF t1(10, 12);
        t1.scale(60, 60, Qt::IgnoreAspectRatio);
        // t1 is (60, 60)

        QSizeF t2(10, 12);
        t2.scale(60, 60, Qt::KeepAspectRatio);
        // t2 is (50, 60)

        QSizeF t3(10, 12);
        t3.scale(60, 60, Qt::KeepAspectRatioByExpanding);
        // t3 is (60, 72)

See also boundedTo(), expandedTo(), setWidth(), and setHeight().

### void QSizeF::scale ( const QSizeF & s, Qt::AspectRatioMode mode )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Equivalent to scale(s.width(), s.height(), mode).

### void QSizeF::setHeight ( qreal height )

Sets the height to height.

See also height(), setWidth(), expandedTo(), boundedTo(), scale(), and transpose().

### void QSizeF::setWidth ( qreal width )

Sets the width to width.

See also width(), rwidth(), setHeight(), expandedTo(), boundedTo(), scale(), and transpose().

### QSize QSizeF::toSize () const

Returns a size with integer precision. Note that the coordinates in the returned size will be rounded to the nearest integer.

### void QSizeF::transpose ()

Swaps the width and height values.

See also expandedTo(), boundedTo(), setWidth(), and setHeight().

### qreal QSizeF::width () const

Returns the width.

See also height() and setWidth().

### QSizeF & QSizeF::operator*= ( qreal coeff )

Multiplies both the width and height by coeff and returns a reference to the size.

### QSizeF & QSizeF::operator+= ( const QSizeF & s )

Adds s to the size and returns a reference to this size.

Example:

        QSizeF s( 3, 7);
        QSizeF r(-1, 4);
        s += r;                        // s becomes (2,11)

### QSizeF & QSizeF::operator-= ( const QSizeF & s )

Subtracts s from the size and returns a reference to this size.

Example:

        QSizeF s( 3, 7);
        QSizeF r(-1, 4);
        s -= r;                        // s becomes (4,3)

### QSizeF & QSizeF::operator/= ( qreal divisor )

Divides both the width and height by divisor and returns a reference to the size.

See also QSize::scale().

## Related Non-Members

### bool operator!= ( const QSizeF & s1, const QSizeF & s2 )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns true if s1 and s2 are different; otherwise returns false.

### const QSizeF operator* ( const QSizeF & size, qreal coeff )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Multiplies size by coeff and returns the result.

See also QSize::scale().

### const QSizeF operator* ( qreal c, const QSizeF & s )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Multiplies s by c and returns the result.

See also QSize::scale().

### const QSizeF operator+ ( const QSizeF & s1, const QSizeF & s2 )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns the sum of s1 and s2; each component is added separately.

### const QSizeF operator- ( const QSizeF & s1, const QSizeF & s2 )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns s2 subtracted from s1; each component is subtracted separately.

### const QSizeF operator/ ( const QSizeF & size, qreal divisor )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Divides size by divisor and returns the result.

See also QSize::scale().

### QDataStream & operator<< ( QDataStream & s, const QSizeF & sz )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Writes the size sz to the stream s and returns a reference to the stream.

See also Format of the QDataStream operators.

### bool operator== ( const QSizeF & s1, const QSizeF & s2 )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns true if s1 and s2 are equal; otherwise returns false.

### QDataStream & operator>> ( QDataStream & s, QSizeF & sz )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Reads the size from the stream s into size sz and returns a reference to the stream.

See also Format of the QDataStream operators.