donner::svg::SVGElement Class Reference

Represents an SVG entity belonging to an SVGDocument. More...

#include "donner/svg/SVGElement.h"

Inheritance diagram for donner::svg::SVGElement:

Public Member Functions
	SVGElement (const SVGElement &other)
	Create another reference to the same SVGElement.
	SVGElement (SVGElement &&other) noexcept
	Move constructor.
	~SVGElement () noexcept=default
	Destructor.
SVGElement &	operator= (const SVGElement &other)
	Create another reference to the same SVGElement.
SVGElement &	operator= (SVGElement &&other) noexcept
	Move assignment operator.
ElementType	type () const
	Get the ElementType for known XML element types.
xml::XMLQualifiedNameRef	tagName () const
	Get the XML tag name string for this element.
bool	isKnownType () const
	Returns true if this is a known element type, returns false if this is an SVGUnknownElement.
EntityHandle	entityHandle () const
	Get the underlying EntityHandle, for advanced use-cases that require direct access to the ECS.
RcString	id () const
	Get the element id, the value of the "id" attribute.
void	setId (std::string_view id)
	Set the element id, the value of the "id" attribute.
RcString	className () const
	Get the element class name, the value of the "class" attribute.
void	setClassName (std::string_view name)
	Set the element class name, the value of the "class" attribute.
void	setStyle (std::string_view style)
	Set the element style, the value of the "style" attribute.
base::parser::ParseResult< bool >	trySetPresentationAttribute (std::string_view name, std::string_view value)
	Set the value of a presentation attribute, such as "fill" or "stroke".
bool	hasAttribute (const xml::XMLQualifiedNameRef &name) const
	Returns true if the element has an attribute with the given name.
std::optional< RcString >	getAttribute (const xml::XMLQualifiedNameRef &name) const
	Get the value of an attribute, if it exists.
SmallVector< xml::XMLQualifiedNameRef, 1 >	findMatchingAttributes (const xml::XMLQualifiedNameRef &matcher) const
	Find attributes matching the given name matcher.
void	setAttribute (const xml::XMLQualifiedNameRef &name, std::string_view value)
	Set the value of a generic XML attribute, which may be either a presentation attribute or custom user-provided attribute.
void	removeAttribute (const xml::XMLQualifiedNameRef &name)
	Remove an attribute, which may be either a presentation attribute or custom user-provided attribute.
SVGDocument	ownerDocument ()
	Get an owning reference to the SVGDocument containing this element.
std::optional< SVGElement >	parentElement () const
	Get this element's parent, if it exists.
std::optional< SVGElement >	firstChild () const
	Get the first child of this element, if it exists.
std::optional< SVGElement >	lastChild () const
	Get the last child of this element, if it exists.
std::optional< SVGElement >	previousSibling () const
	Get the previous sibling of this element, if it exists.
std::optional< SVGElement >	nextSibling () const
	Get the next sibling of this element, if it exists.
void	insertBefore (const SVGElement &newNode, std::optional< SVGElement > referenceNode)
	Insert newNode as a child, before referenceNode.
void	appendChild (const SVGElement &child)
	Append child as a child of the current node.
void	replaceChild (const SVGElement &newChild, const SVGElement &oldChild)
	Replace oldChild with newChild in the tree, removing oldChild and inserting newChild in its place.
void	removeChild (const SVGElement &child)
	Remove child from this node.
void	remove ()
	Remove this node from its parent, if it has one.
bool	operator== (const SVGElement &other) const
	Returns true if the two SVGElement handles reference the same underlying document.
bool	operator!= (const SVGElement &other) const
	Returns true if the two SVGElement handles reference the same underlying document.
template<typename Derived >
bool	isa () const
	Return true if this element "is a" instance of type, if it be cast to a specific type with cast.
template<typename Derived >
Derived	cast ()
	Cast this element to its derived type.
template<typename Derived >
Derived	cast () const
	Cast this element to its derived type (const version).
template<typename Derived >
std::optional< Derived >	tryCast ()
	Cast this element to its derived type, if possible.
template<typename Derived >
std::optional< const Derived >	tryCast () const
	Cast this element to its derived type, if possible.
std::optional< SVGElement >	querySelector (std::string_view selector)
	Find the first element in the tree that matches the given CSS selector.
const PropertyRegistry &	getComputedStyle () const
	Get the computed CSS style of this element, after the CSS cascade.

Protected Member Functions
	SVGElement (EntityHandle handle)
	Internal constructor to create an SVGElement from an EntityHandle.
Registry &	registry () const
	Get the underlying ECS Registry, which holds all data for the document, for advanced use.
EntityHandle	toHandle (Entity entity) const
	Convert an Entity to an EntityHandle, for advanced use.

Static Protected Member Functions
static EntityHandle	CreateEntity (SVGDocument &document)
	Create a new Entity within the document ECS, and return a handle to it.
static void	CreateEntityOn (EntityHandle handle, const xml::XMLQualifiedNameRef &tagName, ElementType Type)
	Create a new SVG element instance on a given Entity.

Protected Attributes
EntityHandle	handle_
	The underlying ECS Entity for this element, which holds all data.

Friends
class	DonnerController

Detailed Description

Represents an SVG entity belonging to an SVGDocument.

Each SVGElement may only belong to a single document, and each document can have only one root. SVGDocument is responsible for managing the lifetime of all elements in the document, by storing a shared pointer to the internal Registry data-store.

Data is stored using the Entity Component System (Entity Component System (ECS)) pattern, which is a data-oriented design optimized for fast data access and cache locality, particularly during rendering.

SVGDocument and SVGElement provide a facade over the ECS, and surface a familiar Document Object Model (DOM) API to traverse and manipulate the document tree, which is internally stored within Components in the ECS. This makes SVGElement a thin wrapper around an Entity, making the object lightweight and usable on the stack.

See also

SVGDocument

Entity Component System (ECS)

Constructor & Destructor Documentation

SVGElement()

donner::svg::SVGElement::SVGElement ( EntityHandle handle )

explicitprotected

Internal constructor to create an SVGElement from an EntityHandle.

To create an SVGElement, use the static Create methods on the derived class, such as SVGCircleElement::Create.

Parameters

handle

EntityHandle to wrap.

Member Function Documentation

appendChild()

void donner::svg::SVGElement::appendChild

(

const SVGElement &

child

)

Append child as a child of the current node.

If child is already in the tree, it is first removed from its parent. However, if inserting the child will create a cycle, the behavior is undefined.

Parameters

child

Node to append.

cast() [1/2]

template<typename Derived >

Derived donner::svg::SVGElement::cast ( )

inline

Cast this element to its derived type.

Precondition

Requires this element to be of type Derived::Type.

Returns

A reference to this element, cast to the derived type.

Examples

svg_tree_interaction.cc.

cast() [2/2]

template<typename Derived >

Derived donner::svg::SVGElement::cast ( ) const

inline

Cast this element to its derived type (const version).

Precondition

Requires this element to be of type Derived::Type.

Returns

A reference to this element, cast to the derived type.

CreateEntity()

EntityHandle donner::svg::SVGElement::CreateEntity ( SVGDocument & document )

staticprotected

Create a new Entity within the document ECS, and return a handle to it.

Parameters

document

Containing document.

CreateEntityOn()

void donner::svg::SVGElement::CreateEntityOn ( EntityHandle handle, const xml::XMLQualifiedNameRef & tagName, ElementType Type )

staticprotected

Create a new SVG element instance on a given Entity.

Parameters

handle	Entity to create the element on.
tagName	XML element type, e.g. "svg" or "rect", which an optional namespace.
Type	Type of the entity.

findMatchingAttributes()

SmallVector< xml::XMLQualifiedNameRef, 1 > donner::svg::SVGElement::findMatchingAttributes

(

const xml::XMLQualifiedNameRef &

matcher

)

const

Find attributes matching the given name matcher.

Parameters

matcher

Matcher to use to find attributes. If XMLQualifiedNameRef::namespacePrefix is "*", the matcher will match any namespace with the given attribute name.

Returns

A vector of attributes matching the given name matcher.

firstChild()

std::optional< SVGElement > donner::svg::SVGElement::firstChild

(

)

const

Get the first child of this element, if it exists.

Returns

The first child element, or std::nullopt if the element has no children.

getAttribute()

std::optional< RcString > donner::svg::SVGElement::getAttribute

(

const xml::XMLQualifiedNameRef &

name

)

const

Get the value of an attribute, if it exists.

Parameters

name	Name of the attribute to get.

Returns

The value of the attribute, or std::nullopt if the attribute does not exist.

hasAttribute()

bool donner::svg::SVGElement::hasAttribute

(

const xml::XMLQualifiedNameRef &

name

)

const

Returns true if the element has an attribute with the given name.

Parameters

name	Name of the attribute to check.

Returns

true if the attribute exists, false otherwise.

insertBefore()

void donner::svg::SVGElement::insertBefore	(	const SVGElement &	newNode,
		std::optional< SVGElement >	referenceNode )

Insert newNode as a child, before referenceNode.

If referenceNode is std::nullopt, append the child.

If newNode is already in the tree, it is first removed from its parent. However, if inserting the child will create a cycle, the behavior is undefined.

Parameters

newNode	New node to insert.
referenceNode	A child of this node to insert newNode before, or std::nullopt. Must be a child of the current node.

Examples

svg_tree_interaction.cc.

isa()

template<typename Derived >

bool donner::svg::SVGElement::isa ( ) const

inline

Return true if this element "is a" instance of type, if it be cast to a specific type with cast.

Template Parameters

Derived

Type to check.

lastChild()

std::optional< SVGElement > donner::svg::SVGElement::lastChild

(

)

const

Get the last child of this element, if it exists.

Returns

The last child element, or std::nullopt if the element has no children.

nextSibling()

std::optional< SVGElement > donner::svg::SVGElement::nextSibling

(

)

const

Get the next sibling of this element, if it exists.

Returns

The next sibling element, or std::nullopt if the element has no next sibling.

parentElement()

std::optional< SVGElement > donner::svg::SVGElement::parentElement

(

)

const

Get this element's parent, if it exists.

If the parent is not set, this document is either the root element or has not been inserted into the document tree.

Returns

The parent element, or std::nullopt if the parent is not set.

previousSibling()

std::optional< SVGElement > donner::svg::SVGElement::previousSibling

(

)

const

Get the previous sibling of this element, if it exists.

Returns

The previous sibling element, or std::nullopt if the element has no previous sibling.

querySelector()

std::optional< SVGElement > donner::svg::SVGElement::querySelector

(

std::string_view

selector

)

Find the first element in the tree that matches the given CSS selector.

auto element = document.svgElement().querySelector("#elementId");

To find things relative to the current element, use :scope:

auto rectInElement = element.querySelector(":scope > rect");

Parameters

selector

CSS selector to match.

Returns

The first matching element, or std::nullopt if no element matches.

remove()

void donner::svg::SVGElement::remove

(

)

Remove this node from its parent, if it has one.

Has no effect if this has no parent.

removeAttribute()

void donner::svg::SVGElement::removeAttribute

(

const xml::XMLQualifiedNameRef &

name

)

Remove an attribute, which may be either a presentation attribute or custom user-provided attribute.

If this is a presentation attribute, the presentation attributes value will be removed (internally by setting the value to 'inherit').

Parameters

name	Name of the attribute to remove.

removeChild()

void donner::svg::SVGElement::removeChild

(

const SVGElement &

child

)

Remove child from this node.

Parameters

child

Child to remove, must be a child of the current node.

replaceChild()

void donner::svg::SVGElement::replaceChild	(	const SVGElement &	newChild,
		const SVGElement &	oldChild )

Replace oldChild with newChild in the tree, removing oldChild and inserting newChild in its place.

If newChild is already in the tree, it is first removed from its parent. However, if inserting the child will create a cycle, the behavior is undefined.

Parameters

newChild	New child to insert.
oldChild	Old child to remove, must be a child of the current node.

setAttribute()

void donner::svg::SVGElement::setAttribute	(	const xml::XMLQualifiedNameRef &	name,
		std::string_view	value )

Set the value of a generic XML attribute, which may be either a presentation attribute or custom user-provided attribute.

This API supports a superset of trySetPresentationAttribute, however its parse errors are ignored. If the attribute is not a presentation attribute, or there are parse errors the attribute will be stored as a custom attribute instead.

Parameters

name	Name of the attribute to set.
value	New value to set.

setClassName()

void donner::svg::SVGElement::setClassName

(

std::string_view

name

)

Set the element class name, the value of the "class" attribute.

Parameters

name	New class name to set.

setId()

void donner::svg::SVGElement::setId

(

std::string_view

id

)

Set the element id, the value of the "id" attribute.

Parameters

id	New id to set.

setStyle()

void donner::svg::SVGElement::setStyle

(

std::string_view

style

)

Set the element style, the value of the "style" attribute.

Parameters

style

New style to set.

Examples

svg_tree_interaction.cc.

toHandle()

EntityHandle donner::svg::SVGElement::toHandle ( Entity entity ) const

inlineprotected

Convert an Entity to an EntityHandle, for advanced use.

Parameters

entity

Entity to convert.

tryCast() [1/2]

template<typename Derived >

std::optional< Derived > donner::svg::SVGElement::tryCast ( )

inline

Cast this element to its derived type, if possible.

Return std::nullopt otherwise.

Returns

A reference to this element, cast to the derived type, or std::nullopt if the element is not of the correct type.

tryCast() [2/2]

template<typename Derived >

std::optional< const Derived > donner::svg::SVGElement::tryCast ( ) const

inline

Cast this element to its derived type, if possible.

Return std::nullopt otherwise (const version).

Returns

A reference to this element, cast to the derived type, or std::nullopt if the element is not of the correct type.

trySetPresentationAttribute()

parser::ParseResult< bool > donner::svg::SVGElement::trySetPresentationAttribute	(	std::string_view	name,
		std::string_view	value )

Set the value of a presentation attribute, such as "fill" or "stroke".

Note that this accepts the CSS value, not the XML attribute value.

For example, for the following XML attributes they need to be mapped as follows before calling:

• gradientTransform -> transform
• patternTransform -> transform

Parameters

name	Name of the attribute to set.
value	New value to set.

Returns

true if the attribute was set, false if the attribute is not a valid presentation attribute for this element, or a donner::base::parser::ParseError if the value is invalid.

---

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

• donner/svg/SVGElement.h
• donner/svg/SVGElement.cc