donner::svg::CssTransform Class Reference

Compared to an SVG transform, CSS transforms have additional features, such as the ability to add units to the translate() function, such as translate(1em 30px). More...

#include "donner/svg/core/CssTransform.h"

Classes
struct	Simple
	Stores a precomputed transform. More...
struct	Translate
	Stores a deferred translate() operation, which can have two <length-percentage> arguments, such as translate(1em 30px). More...

Public Types
using	Element = std::variant<Simple, Translate>
	A transform or a deferred operation.

Public Member Functions
	CssTransform ()=default
	Construct an empty transform set to identity.
	CssTransform (const Transformd &transform)
	Construct a transform initialized with the given transform.
Transformd	compute (const Boxd &viewbox, FontMetrics fontMetrics) const
	Compute the final transform from the list of transforms and deferred operations.
void	addTransform (const Transformd &transform)
	Append a transform to the transform chain.
void	addTranslate (Lengthd x, Lengthd y)
	Append a translate() operation to the transform chain.

Detailed Description

Compared to an SVG transform, CSS transforms have additional features, such as the ability to add units to the translate() function, such as translate(1em 30px).

translate() = translate( <length-percentage> [, <length-percentage> ]? )

To resolve translate(), we need to know the font size and the viewbox size, which is context-dependent, so we cannot precompute the transform from the transform function list. Instead, store a chain of of transforms and deferred operations, and compute the final transform when needed, inside the CssTransform::compute() function.

See https://www.w3.org/TR/css-transforms-1/#two-d-transform-functions for more details about CSS transforms.

CssTransform is parsed by donner::svg::parser::CssTransformParser.

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Class Documentation

donner::svg::CssTransform::Simple

struct donner::svg::CssTransform::Simple

Stores a precomputed transform.

Collaboration diagram for donner::svg::CssTransform::Simple:

Class Members
Transformd	transform	Transform to apply.

donner::svg::CssTransform::Translate

struct donner::svg::CssTransform::Translate

Stores a deferred translate() operation, which can have two <length-percentage> arguments, such as translate(1em 30px).

Collaboration diagram for donner::svg::CssTransform::Translate:

Class Members
Lengthd	x	X offset.
Lengthd	y	Y offset.

Constructor & Destructor Documentation

CssTransform()

donner::svg::CssTransform::CssTransform ( const Transformd & transform )

inlineexplicit

Construct a transform initialized with the given transform.

Parameters

transform

Initial transform.

Member Function Documentation

addTransform()

void donner::svg::CssTransform::addTransform ( const Transformd & transform )

inline

Append a transform to the transform chain.

Parameters

transform

Transform to add.

addTranslate()

void donner::svg::CssTransform::addTranslate ( Lengthd x, Lengthd y )

inline

Append a translate() operation to the transform chain.

Parameters

x	X offset.
y	Y offset.

compute()

Transformd donner::svg::CssTransform::compute ( const Boxd & viewbox, FontMetrics fontMetrics ) const

inline

Compute the final transform from the list of transforms and deferred operations.

Parameters

viewbox	Viewbox size, used to resolve percentage units.
fontMetrics	Font metrics, used to resolve 'em' and other font-relative units.

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

• donner/svg/core/CssTransform.h