SVG 2 new features

I'd like to move this into a proper matrix where we can list implementer feedback and support, but for now here's a basic list of what is new in SVG 2.

Note: this list is now mostly complete, but is still being tidied up

This list:

• Tries to describe new features and new behaviours
• Does not list features moved from one SVG spec to another (e.g. SVG Tiny 1.2 to SVG 2)

New graphics features

• Mesh gradient shape element ('mesh') and paint server ('meshgradient')
• 'hatch' element - a new paint server for generating hatches with SVG paths
• 'context-fill' and 'context-stroke' values for 'fill' and 'stroke' These allow, for example, 'marker' elements to inherit the stroke color.
• New value 'auto-start-reverse' for the 'orient' attribute of the 'marker' element. Has implementations in Firefox, WebKit, Blink, and Inkscape.
• Path features:
  • Allow closepath commands 'Z' and 'z' to fill in missing 'path data' from previous commands
  • Added bearing path commands 'B' and 'b' to 'path data'
  • New 'line join shape' definitions - 'miter-clip' and 'arcs'
• Support z-index on all SVG elements and define how SVG creates 'stacking contexts'
• non-scaling-size, non-rotation, and fixed-position as options for the 'vector-effect' attribute
• 'paint-order' property to control stroke and fill drawing order
• Allow 'markers' on all shapes
• Allow scroll bars when the 'overflow' property is set to scroll on 'svg' elements
• Allow control of the radius of focal 'circle' on the 'radialGradient' element
• extend getBBox() method of 'SVGGraphicsElement' with an argument that controls inclusion of the fill or the stroke

Text changes

• CSS based multi-line text for 'text content elements':
  1. text area is contrained using 'inline-size'
  2. SVG creates a 'content area' and defers to CSS to perform layout within that area
• Support text in a shape using the 'shape-inside' and 'shape-subtract' properties
• Text on a path changes:
  • allow 'textPath' element to directly specify path data through the path attribute
  • Allow referencing basic shapes from 'textPath' element
  • Add 'side' attribute to 'textPath' to enable control of which side of the path text is placed on
• Font features (alternative glyphs, 'font-variant', etc.)
• Support @font-face rules on 'text' element
• masks, filters and other graphics effects may now be applied to 'tspan' and 'textPath' elements
• support ::first-letter & ::first-line pseudo selectors on 'text' element
• WOFF font support now required

Use element changes

• 'use' element now defined in terms of Web Components
  • 'use' elements may now reference an entire document
  • 'use' element 'shadow tree' now consist of actual 'SVGElement' objects in a proper shadow DOM node tree, not 'SVGElementInstance' pseudo-nodes.
  • Events bubbling out of a 'use' element shadow tree must follow the shadow DOM re-targetting rules.
  • Styles rules are resolved independently for clones versus the referenced graphics
  • Some interactive animations are now triggered independently on the shadow content vs the referenced graphics.
  • Never-rendered elements will now have a computed style of display: none
  • The shadow tree must now have a 'ShadowRoot' object, and implement extra functionality from shadow DOM specs.
  • All elements in a subtree must now be cloned, not only graphics elements.
  • The shadow tree has scoped stylesheets.
  • Symbol elements can have 'x'/'y'/'width'/'height' properties.

Accessibility

• Include WAI-ARIA attributes and define semantics
• Change role mapping for the ‘a’ element to depend on whether it is actually a valid link.

Internationalisation

• ordering of 'systemLanguage' preferences follows SMIL allowReorder definition
• Add 'lang' attribute to replace xml:lang'

Interactivity

• Require user agents that support 'interaction' to include :focus and ::selection styles.
• 'clip' and 'overflow' no longer ignored when SVG document referenced via 'image'
• Allow 'bounding box' area to be used for 'pointer-events' via the 'bounding-box' value
• Replace SVG specific events with common equivalents

Document structure changes

• 'unknown' elements are treated as a 'g' or 'tspan' element
• Allow the 'script' element anywhere
• Allow 'animation elements' to be descended from the 'view' element
• Allow the 'pathLength' attribute on all 'basic shapes'
• Add 'text-decoration-fill' and 'text-decoration-stroke' properties
• Add left|middle|center keywords for 'refX' and 'refY' attributes
• Allow 'paint server elements' and 'marker' elements to descend from 'shapes' and be referenced through child(n)

Synchronise with other tech (e.g. HTML)

• Add additional attributes to the 'a' element to synchronise with HTML
• Added 'tabindex' attribute
• Update requirements for ‘id’ values to harmonize with HTML
• 'white space character' set now includes form feed (U+000C) to align with HTML and CSS
• Support 'white-space' property in favour of xml:space' attribute
• Support custom data attributes on all SVG elements
• Support percentages and CSS lengths in many places
• HTML 'link' element supported and must load external style sheets
• Add 'crossorigin' attribute to the 'image' and 'script' elements
• Inclusion of HTML 'audio', 'video', 'iframe', 'canvas', 'source', and 'track' elements

Promote attributes to presentation attributes

• Made many attributes 'presentation attributes':
  • 'd'
  • what else?
• Convert some geometry attributes to 'geometry properties' Geometry properties support lengths and percentages and auto:
  • 'ellipse' & 'circle': cx, cy
  • 'circle': 'r'
  • 'ellipse': 'rx', 'ry'
  • 'svg', 'rect', image, 'foreignObject': 'x', 'y', 'width', 'height'
• Support many properties defined by other specifications (list?)

Other Visual changes from SVG 1.1

• inner 'svg' elements and 'foreignObject' elements are no longer have 'overflow' hidden by default
• 'svg' root elements and 'foreignObject' no longer have 'overflow' hidden by default
• Allow scroll bars to be shown for 'overflow' auto in special cases

Removed

• Remove DTD
• Removed SVG Fonts
• Removed externalResourcesRequired attribute
• Removed baseProfile and version attributes from the 'svg' element
• Removed requiredFeatures attribute
• Removed the ‘contentStyleType’ attribute.
• Removed xml:base
• Removed defer keyword from preservedAspectRatio
• Removed the tref element
• removed the Alternate Glyph elements (altGlyph, altGlyphItem, glyphRef)
• Removed xlink:type, xlink:role, xlink:arcrole, xlink:show, and xlink:actuate attributes
• Removed the viewTarget attribute from the view element
• Remove contentScriptType attribute

Deprecated

• methods suspendRedraw, unsuspendRedraw, and unsuspendRedrawAll on 'SVGSVGElement'
• rootElement attribute
• forceRedraw method on 'SVGSVGElement'
• deselectAll method on 'SVGSVGElement'
• xml:space
• xlink:href
• xlink:title
• selectSubString() method on 'SVGTextContentElement' interface
• 'cursor' element

API Changes

To do: Draw up UML diagrams to show this info graphically

• Added "length" attribute and indexed property access to all list interfaces.
• Replace 'SVGMatrix' with DOMMatrix or DOMMatrixReadOnly
• Replace 'SVGRect' with DOMRect or DOMRectReadOnly
• Replace 'SVGPoint' with DOMPoint or DOMPointReadOnly
• Moved members from 'SVGStylable' and 'SVGLangSpace' to 'SVGElement' and removed those interfaces
• Added 'SVGGraphicsElement'
• Moved members from 'SVGLocatable' and 'SVGTransformable' to 'SVGGraphicsElement' and removed those interfaces
• Added 'SVGGeometryElement' with isPointInFill and isPointInStroke methods
• Removed 'SVGExternalResourcesRequired' interface
• Removed 'SVGColor' and 'SVGICCCOlor' interfaces
• Removed getPresentationAttribute method from 'SVGElement'
• Add tabindex attribute, and focus and blur methods, to 'SVGElement'
• Add activeElement attribute to Document
• 'SVGElement' now inherits GlobalEventHandlers from HTML
• extend getBBox with an argument that controls inclusion of fill or stroke
• Remove xmlbase, xmllang, and xmlspace attributes from 'SVGElement' interface
• Remove 'SVGViewSpec' interface
• Remove getTransformToElement from 'SVGGraphicsElement'
• Allow getCTM on outermost 'svg' element
• Make animVal an alias for baseVal and no longer reflect animated value
• Added dataset attribute to 'SVGElement'
• Moved methods pathLength, getTotalLength, and getPointAtLength to 'SVGGeometryElement'
• Removed 'SVGElementInstance' and 'SVGElementInstanceList' interfaces
• Removed currentView and useCurrentView properties on 'SVGSVGElement'
• Added 'SVGUnknownElement'
• Removed the viewport attribute from 'SVGSVGElement'
• 'SVGElement' has been extended to replace the core functionality from 'SVGElementInstance'.
• 'SVGSymbolElement' now inherits from 'SVGGraphicsElement'
• ShadowAnimation interface defined
• 'SVGStyleElement' now implements LinkStyle
• Remove SVGPathSeg* interfaces
• Remove 'SVGAnimatedPathData' interface
• Remove methods on 'SVGPatElement' related to SVGPathSeg* and 'SVGAnimatedPathData'
• Moved pathLength, getTotalLength() and getPointAtLength() on to 'SVGGeometryElement' interface
• animatedPoints attribute of 'SVGAnimatedPoints' now aliases the points attribute
• Remove 'SVGPaint' interface
• Replace 'SVG' specific events with common equivalents
• Define the 'SVGUseElementShadowRoot' interface as an extension of the ShadowRoot interface, and require it to be used for use-element shadow trees