Wt::WLength Class Reference

A value class that describes a CSS length. More...

#include <Wt/WLength.h>

Public Types
typedef LengthUnit	Unit
	Typedef for enum Wt::LengthUnit.

Public Member Functions
	WLength ()
	Creates an 'auto' length.
template<std::size_t N>
	WLength (const char(&str)[N])
	Creates a length by parsing the argument as a css length string.
	WLength (const std::string &str)
	Creates a length by parsing the argument as a css length string.
	WLength (double value, LengthUnit unit=LengthUnit::Pixel)
	Creates a length with value and unit.
	WLength (LengthUnit unit)
	Creates a length with a keyword unit.
bool	isAuto () const
	Returns whether the length is 'auto'.
double	value () const
	Returns the value.
LengthUnit	unit () const
	Returns the unit.
const std::string	cssText () const
	Returns the CSS text.
bool	operator== (const WLength &other) const
	Comparison operator.
bool	operator!= (const WLength &other) const
	Comparison operator.
double	toPixels (double fontSize=16.0) const
	Returns the (approximate) length in pixels.

Static Public Attributes
static WLength	Auto
	An 'auto' length.

Detailed Description

A value class that describes a CSS length.

The class combines a value with a unit. There is a special value auto which has a different meaning depending on the context.

The keyword units LengthUnit::FitContent, LengthUnit::MaxContent and LengthUnit::MinContent have, like auto, no numeric component: the value of a length with such a unit is ignored.

Constructor & Destructor Documentation

WLength() [1/5]

Wt::WLength::WLength

(

)

Creates an 'auto' length.

Specifies an 'auto' length.

See also

Auto

WLength() [2/5]

template<std::size_t N>

Wt::WLength::WLength

(

const char(&)

str[N]

)

Creates a length by parsing the argument as a css length string.

This supports all CSS length formats that have an API counterpart.

This is an overload for the std::string version that accepts a string literal.

WLength() [3/5]

Wt::WLength::WLength

(

const std::string &

str

)

Creates a length by parsing the argument as a css length string.

This supports all CSS length formats that have an API counterpart.

WLength() [4/5]

Wt::WLength::WLength	(	double	value,
		LengthUnit	unit = LengthUnit::Pixel )

Creates a length with value and unit.

This constructor is also used for the implicit conversion of a double to a WLength, assuming a pixel unit.

For the keyword units (LengthUnit::FitContent, LengthUnit::MaxContent and LengthUnit::MinContent) the value is ignored and normalized to -1.

WLength() [5/5]

Wt::WLength::WLength

(

LengthUnit

unit

)

Creates a length with a keyword unit.

The length has no numeric component: value() is -1, as if constructed by parsing the bare keyword.

This constructor is also used for the implicit conversion of a LengthUnit to a WLength.

Exceptions

WException

if the unit is not one of the keyword units (LengthUnit::FitContent, LengthUnit::MaxContent or LengthUnit::MinContent), since all other units require a numeric value.

Member Function Documentation

isAuto()

bool Wt::WLength::isAuto

(

)

const

Returns whether the length is 'auto'.

See also

WLength(), Auto

toPixels()

double Wt::WLength::toPixels

(

double

fontSize = 16.0

)

const

Returns the (approximate) length in pixels.

When the length isAuto(), 0 is returned, otherwise the approximate length in pixels.

Note

For percentages (LengthUnit::Percentage), and units relative to viewport size (LengthUnit::ViewportWidth, LengthUnit::ViewportHeight, LengthUnit::ViewportMin, LengthUnit::ViewportMax), a percentage of the font size is used. For the keyword units (LengthUnit::FitContent, LengthUnit::MaxContent and LengthUnit::MinContent), 0 is returned since the length depends on the content.

unit()

LengthUnit Wt::WLength::unit

(

)

const

Returns the unit.

See also

value()

value()

double Wt::WLength::value

(

)

const

Returns the value.

This is -1 for the keyword units (LengthUnit::FitContent, LengthUnit::MaxContent and LengthUnit::MinContent).

See also

unit()

Member Data Documentation

Auto

WLength Wt::WLength::Auto

static

An 'auto' length.

See also

WLength()