SVG content can be interactive (i.e., responsive to user-initiated events) by utilizing the following features in the SVG language:
This chapter describes:
Related information can be found in other chapters:
SVG 2 Requirement: | Support anchor change events. |
---|---|
Resolution: | SVG 2 will consider adding HTML document wide events (including hashchange) apply to SVG documents where they make sense. |
Purpose: | To allow authors to use the same set of event listener attributes on a root SVG element that they can on an HTML body or root element. |
Owner: | Cameron (ACTION-3278) |
SVG 2 Requirement: | Have event listener attributes on an appropriate interface. |
---|---|
Resolution: | SVG 2 will move all events listener attributes to Element, in accordance with the similar move in HTML. |
Purpose: | To align with HTML. |
Owner: | Cameron (ACTION-3283) |
SVG 2 Requirement: | Introduce evt as an alias to event in event handlers. |
---|---|
Resolution: | We decide to resolve ISSUE-2176 by introducing evt as an alias to event in event handlers. |
Purpose: | To align with HTML. |
Owner: | Cameron (ACTION-3093) |
SVG 2 Requirement: | Support drag & drop functionality. |
---|---|
Resolution: | SVG 2 may require drag & drop functionality, and we'll investigate HTML5's functionality for that. |
Purpose: | To allow easier drag & drop in SVG, and to align with HTML. |
Owner: | Erik (ACTION-3328) |
The following aspects of SVG are affected by events:
The following table lists all of the events which are recognized and supported in SVG. The Event name in the first column is the name to use within SVG's animation elements to define the events which can start or end animations. The DOM3 Event name in the second column is the name to use when defining DOM 3 event listeners ([DOM3EVENTS], section 4.3). The Event attribute name in the fourth column contains the corresponding name of the event attributes that can be attached to elements in the SVG language.
Requirements in the table on whether an event of a given type
bubbles or is cancelable apply only to events that are created and
dispatched by the user agent. Events of those types created from script
using the createEvent
method on the Document interface can be made to bubble
or be cancelable with the
initEvent
method.
Event name and description | DOM3 Event name | Event category | Event attribute name |
---|---|---|---|
focus Occurs when an element receives focus. The focus must be given to the element before the dispatch of this event type. |
(same) | FocusEvent | onfocus |
focusin Occurs when an element is about to receive focus. |
(same) | FocusEvent | onfocusin |
focusout Occurs when an element is about to lose focus. The event must be dispatched to before the element loses focus. The element must be the element which is about to lose focus |
(same) | FocusEvent | onfocusout |
blur Occurs when an element loses focus. The focus must be taken from the element before the dispatch of this event type. |
(same) | FocusEvent | onblur |
keydown Occurs when a key is pressed down. The keydown event type is device dependent and relies on the capabilities of the input devices and how they are mapped in the operating system. |
(same) | KeyboardEvent | onkeydown |
keyup A user agent must dispatch this event when a key is released. The keyup event type is device dependent and relies on the capabilities of the input devices and how they are mapped in the operating system. |
(same) | KeyboardEvent | onkeyup |
click Occurs when the pointing device button is clicked over
an element or when the pointer is otherwise activated in a manner that simulates such an action. A click is defined as a mousedown and mouseup
over the same screen location. The sequence of these events
is: |
(same) | MouseEvent | onclick |
mousedown Occurs when the pointing device button is pressed over an element. |
(same) | MouseEvent | onmousedown |
mouseup Occurs when the pointing device button is released over an element. |
(same) | MouseEvent | onmouseup |
mouseover Occurs when the pointing device is moved onto an element. |
(same) | MouseEvent | onmouseover |
mousemove Occurs when the pointing device is moved while it is over an element. |
(same) | MouseEvent | onmousemove |
mouseout Occurs when the pointing device is moved away from an element. |
(same) | MouseEvent | onmouseout |
load The load event is dispatched only to structurally external elements and to the Window, when the corresponding external resources have finished loading. Note that due to it's relationship with Window the load event on ‘svg’ elements is only dispatched when all resources in the document have been completely loaded. The load event and the error event on structurally external elements are mutually exclusive, only one of these events must be dispatched when processing the element in question. load events do not bubble and are not cancelable. In previous SVG specifications the load event was called SVGLoad and could be dispatched immediately after parsing an element but before the related resource(s) were fully loaded. |
(same) | none | onload |
unload Only applicable to outermost svg elements. The unload event occurs when the DOM implementation removes a document from a window or frame. unload events do not bubble and are not cancelable. |
(same) | none | onunload |
abort The abort event occurs when page loading is stopped before an element has been allowed to load completely. abort events bubble but are not cancelable. |
(same) | none | onabort |
error The error event occurs when a structurally external element does not load properly or when an error occurs during script execution. error events bubble but are not cancelable. |
(same) | none | onerror |
resize Occurs when a document view is being resized. This event is only applicable to outermost svg elements and is dispatched after the resize operation has taken place. The target of the event is the ‘svg’ element. resize events do not bubble and are not cancelable. The term 'document view' is not defined, raised in this www-svg thread. Should probably be linked to CSSOM View, and/or be clarified that it is mostly intended for standalone svg documents. The issue applies to the 'scroll' and 'SVGZoom' events as well. |
(same) | none | onresize |
scroll Occurs when a document view is being shifted along the X or Y or both axis, either through a direct user interaction or any change on the currentTranslate property available on SVGSVGElement interface. This event is only applicable to outermost svg elements and is dispatched after the shift modification has taken place. The target of the event is the ‘svg’ element. scroll events bubble only when dispatched to the document, and are not cancelable. |
(same) | none | onscroll |
SVGZoom Occurs when the zoom level of a document view is being changed, either through a direct user interaction or any change to the currentScale property available on SVGSVGElement interface. This event is only applicable to outermost svg elements and is dispatched after the zoom level modification has taken place. The target of the event is the ‘svg’ element. SVGZoom events bubble but are not cancelable. |
none | none | onzoom |
beginEvent Occurs when an animation element begins. For details, see the description of Interface TimeEvent in the SMIL Animation specification. |
none | none | onbegin |
endEvent Occurs when an animation element ends. For details, see the description of Interface TimeEvent in the SMIL Animation specification. |
none | none | onend |
repeatEvent Occurs when an animation element repeats. It is raised each time the element repeats, after the first iteration. For details, see the description of Interface TimeEvent in the SMIL Animation specification. |
none | none | onrepeat |
Details on the parameters passed to event listeners for the event types for UI Events can be found in the ([ DOM3EVENTS]) and ([UIEVENTS]) specifications where the keybard event definition in UIEVENTS takes precedence over that in DOM3EVENTS. For other event types, the parameters passed to event listeners are described elsewhere in this specification.
Event listener attributes can be specified on some elements to listen to a given event. The script in such attributes is run only in response to "bubbling" and "at target" phase events dispatched to the element.
Likewise, event-value timing specifiers used in animation element ‘begin’ and ‘end’ attributes are resolved to concrete times only in response to "bubbling" and "at target" phase events dispatched to the relevant element.
On user agents which support interactivity, it is common for authors to define SVG documents such that they are responsive to user interface events. Among the set of possible user events are pointer events, keyboard events, and document events.
In response to user interface (UI) events, the author might start an animation, perform a hyperlink to another Web page, highlight part of the document (e.g., change the color of the graphics elements which are under the pointer), initiate a "roll-over" (e.g., cause some previously hidden graphics elements to appear near the pointer) or launch a script which communicates with a remote database.
User interface events that occur because of user actions performed on a pointer device are called pointer events.
Many systems support pointer devices such as a mouse or trackball. On systems which use a mouse, pointer events consist of actions such as mouse movements and mouse clicks. On systems with a different pointer device, the pointing device often emulates the behavior of the mouse by providing a mechanism for equivalent user actions, such as a button to press which is equivalent to a mouse click.
For each pointer event, the SVG user agent determines the
target element of a given pointer event. The target
element is the topmost graphics element whose relevant
graphical content is under the pointer at the time of the
event. (See property ‘pointer-events
’ for a description
of how to determine whether an element's relevant graphical
content is under the pointer, and thus in which circumstances
that graphic element can be the target element for a pointer
event.) When an element is not displayed (i.e., when the
‘display
’ property on that element
or one of its ancestors has a value of none), that element cannot be the
target of pointer events.
If a target element for the pointer event exists, then the event is dispatched to that element according to the normal event flow ([DOM3EVENTS], section 1.2). For shadow trees created by the ‘use’ element or via script, the event must follow the Shadow DOM event dispatching algorithm [SHADOWDOM]
If a target element for the pointer event does not exist, then the event is ignored.
pointer-events
’ property.There are two distinct aspects of pointer-device interaction with an element or area:
Determining whether a pointer event results in a positive hit-test
depends upon the position of the pointer, the size and shape of the
graphics element, and the computed value of the ‘pointer-events
’
property on the element. The definition of the ‘pointer-events
’
property below describes the exact region that is sensitive to pointer
events for a given type of graphics element.
Note that the ‘svg’ element is not a graphics element, and in a Conforming SVG Stand-Alone File a outermost svg element will never be the target of pointer events, though events can bubble to this element. If a pointer event does not result in a positive hit-test on a graphics element, then it should evoke any user-agent-specific window behavior, such as a presenting a context menu or controls to allow zooming and panning of an SVG document fragment.
This specification does not define the behavior of pointer events on the outermost svg element for SVG images which are embedded by reference or inclusion within another document, e.g., whether the outermost svg element embedded in an HTML document intercepts mouse click events; future specifications may define this behavior, but for the purpose of this specification, the behavior is implementation-specific.
An element which is the target of a user interface event may have particular interaction behaviors, depending upon the type of element and whether it has explicit associated interactions, such as scripted event listeners, CSS pseudo-classes matches, or declarative animations with event-based timing. The algorithm and order for processing user interface events for a given target element, after dispatching the DOM event, is as follows:
preventDefault()
DOM method, then no further processing for this element is performed, and the
event follows the event dispatch and DOM event flow processing
as described in DOM Level 3 Events
[DOM3EVENTS] (or its successor);:hover
,
:active
, or :focus
as described in
[CSS21], section 5.11, then the relevant class
properties are applied;In different circumstances, authors may want to control under what conditions particular graphic elements can become the target of pointer events. For example, the author might want a given element to receive pointer events only when the pointer is over the stroked perimeter of a given shape. In other cases, the author might want a given element to ignore pointer events under all circumstances so that graphical elements underneath the given element will become the target of pointer events.
The effects of masking and clipping differ with respect to pointer events. A clip path is a geometric boundary, and a given point is clearly either inside or outside that boundary; thus, pointer events must be captured normally over the rendered areas of a clipped element, but must not be captured over the clipped areas, as described in the definition of clipping paths. By contrast, a mask is not a binary transition, but a pixel operation, and different behavior for fully transparent and almost-but-not-fully-transparent may be confusingly arbitrary; as a consequence, for elements with a mask applied, pointer events must still be captured even in areas where the mask goes to zero opacity. If an author wishes to achieve an effect where the transparent parts of a mask allow pointer events to pass to an element below, a combination of masking and clipping may be used.
The ‘filter
’ property has no effect on pointer events
processing, and must in this context be treated as if the ‘filter
’
wasn't specified.
For example, suppose a circle with a ‘stroke
’ of
red (i.e., the outline is solid red) and a
‘fill
’ of none (i.e., the interior is not
painted) is rendered directly on top of a rectangle with a ‘fill
’ of
blue. The author might want the circle to be
the target of pointer events only when the pointer is over the perimeter of
the circle. When the pointer is over the interior of the circle, the author
might want the underlying rectangle to be the target element of pointer
events.
The ‘pointer-events
’ property specifies under what circumstances a
given element can be the target element for a pointer event. It affects
the circumstances under which the following are processed:
Name: | pointer-events |
---|---|
Value: | bounding-box | visiblePainted | visibleFill | visibleStroke | visible | painted | fill | stroke | all | none |
Initial: | visiblePainted |
Applies to: | container elements, graphics elements and text content child elements |
Inherited: | yes |
Percentages: | N/A |
Media: | visual |
Computed value: | as specified |
Animatable: | yes |
visibility
’ property is set to
visible and when the pointer is over a
"painted" area. The pointer is over a painted area if it is over the
interior (i.e., fill) of the element and the ‘fill
’ property has
an actual value other than none or it
is over the perimeter (i.e., stroke) of the element and the ‘stroke
’
property is set to a value other than none.visibility
’
property is set to visible and when the
pointer is over the interior (i.e., fill) of the element. The value of
the ‘fill
’ property does not affect event processing.visibility
’ property is set to visible
and when the pointer is over the perimeter (i.e., stroke) of the element.
The value of the ‘stroke
’ property does not affect event processing.visibility
’ property is set to visible
and the pointer is over either the interior (i.e., fill) or the perimeter
(i.e., stroke) of the element. The values of the ‘fill
’ and
‘stroke
’ do not affect event processing.fill
’
property has an actual value other than
none or it is over the perimeter (i.e.,
stroke) of the element and the ‘stroke
’ property has an actual
value other than none. The value of the
‘visibility
’ property does not affect event processing.fill
’ and ‘visibility
’ properties do not affect event
processing.stroke
’ and ‘visibility
’ properties do not affect
event processing.fill
’, ‘stroke
’
and ‘visibility
’ properties do not affect event processing.For text elements, hit-testing is performed on a character cell basis:
fill
’ property is set to a value other than
none or the ‘stroke
’ property is set
to a value other than none, with the
additional requirement that the ‘visibility
’ property is set to
visible.visibility
’ property is set to visible.
The values of the ‘fill
’ and ‘stroke
’ properties do not affect
event processing.fill
’ property is set to a value other than
none or the ‘stroke
’ property is set to
a value other than none. The value of the
‘visibility
’ property does not affect event processing.fill
’, ‘stroke
’
and ‘visibility
’ properties do not affect event processing.For raster images, hit-testing is either performed on a whole-image basis (i.e., the rectangular area for the image is one of the determinants for whether the image receives the event) or on a per-pixel basis (i.e., the alpha values for pixels under the pointer help determine whether the image receives the event):
visibility
’
property is set to visible.visibility
’ property is set to
visible.visibility
’ property does not affect
event processing.visibility
’
property does not affect event processing.Note that for raster images, the values of properties ‘opacity
’,
‘fill-opacity
’, ‘stroke-opacity
’, ‘fill
’ and
‘stroke
’ do not affect event processing.
SVG 2 Requirement: | Support level of detail control. |
---|---|
Resolution: | We will support Level of Detail control in SVG 2. |
Purpose: | Control visibility of elements based on zoom level (useful, for example, in mapping). |
Owner: | Doug (no action) |
Note: | See Tiling and Layering Module for SVG 1.2 Tiny. |
Magnification represents a complete, uniform transformation on an SVG document fragment, where the magnify operation scales all graphical elements by the same amount. A magnify operation has the effect of a supplemental scale and translate transformation placed at the outermost level on the SVG document fragment (i.e., outside the outermost svg element).
Panning represents a translation (i.e., a shift) transformation on an SVG document fragment in response to a user interface action.
SVG user agents that operate in interaction-capable user environments are required to support the ability to magnify and pan.
The outermost svg element in an SVG document fragment has attribute ‘zoomAndPan’, which takes the possible values of disable and magnify, with the default being magnify.
If disable, the user agent shall disable any magnification and panning controls and not allow the user to magnify or pan on the given document fragment.
If magnify, in environments that support user interactivity, the user agent shall provide controls to allow the user to perform a "magnify" operation on the document fragment.
If a ‘zoomAndPan’ attribute is assigned to an inner ‘svg’ element, the ‘zoomAndPan’ setting on the inner ‘svg’ element will have no effect on the SVG user agent.
Animatable: no.
Some interactive display environments provide the ability to modify the appearance of the pointer, which is also known as the cursor. Three types of cursors are available:
The ‘cursor
’ property is used to
specify which cursor to use. The ‘cursor
’ property can be used to
reference standard built-in cursors by specifying a keyword
such as crosshair or a custom cursor. Custom cursors
are referenced via a <url> and can point to either an
external resource such as a platform-specific cursor file or to
a ‘cursor’ element, which can be
used to define a platform-independent cursor.
See the CSS Basic User Interface Module Level 3 specification
for the definition of ‘cursor
’. [CSS3UI]
SVG uses the ‘cursor
’ property to specify the type of cursor to
be displayed for the pointing device when it is over a region of an
element that is sensitive to pointer events, according to the value of
the ‘pointer-events
’ property. SVG extends the definition of
‘cursor
’ from the CSS Basic User Interface Module Level 3
specification as follows:
The ‘cursor’ element can be used to define a platform-independent custom cursor. A recommended approach for defining a platform-independent custom cursor is to create a PNG image [PNG] and define a ‘cursor’ element that references the PNG image and identifies the exact position within the image which is the pointer position (i.e., the hot spot).
The PNG format is recommended because it supports the ability to define a transparency mask via an alpha channel. If a different image format is used, this format should support the definition of a transparency mask (two options: provide an explicit alpha channel or use a particular pixel color to indicate transparency). If the transparency mask can be determined, the mask defines the shape of the cursor; otherwise, the cursor is an opaque rectangle. Typically, the other pixel information (e.g., the R, G and B channels) defines the colors for those parts of the cursor which are not masked out. Note that cursors usually contain at least two colors so that the cursor can be visible over most backgrounds.
Attribute definitions:
Name | Value | Lacuna value | Animatable |
---|---|---|---|
x, y | <length> | 0 | yes |
Name | Value | Lacuna value | Animatable |
---|---|---|---|
xlink:href | URL [URL] | (none) | yes |
SVG user agents are required to support PNG format images as targets of the ‘xlink:href’ attribute.
This section needs to defer to HTML more rather than duplicate the wording from that spec.
When an element is focused, key events received by the
document must be targeted at that element. There may be no element
focused; when no element is focused, key events received by the
document must be targeted at the Document
's root svg
element, if
there is one. If there is no root element, key events must not be
fired.
User agents may track focus for each browsing
context or Document
individually, or may support
only one focused element per top-level browsing context
— user agents should follow platform conventions in this
regard.
Which elements within a top-level browsing context currently have focus must be independent of whether or not the top-level browsing context itself has the system focus.
When a child browsing context is focused, its browsing conrtext container must also have focus.
When an element is focused, the element matches the
CSS :focus
pseudo-class.
The ‘tabindex’ attribute allows the author to control whether and element is focusable. Each element can have a tabindex focus flag set, as defined below. This flag is a factor that contributes towards determining whether an element is focusable, as described in the next section.
The user agent should follow platform conventions to determine if the element's tabindex focus flag is set and, if so, whether the element can be reached using sequential focus navigation, and if so, what its relative order should be.
The a
element that has an xlink:href
attribute must have the tabindex focus flag set.
The user agent must set the element's tabindex focus flag, but should not allow the element to be reached using sequential focus navigation.
One valid reason to ignore the requirement that sequential focus navigation not allow the author to lead to the element would be if the user's only mechanism for moving the focus is sequential focus navigation. For instance, a keyboard-only user would be unable to click on a text field with a negative ‘tabindex’, so that user's user agent would be well justified in allowing the user to tab to the control regardless.
The user agent must set the element's tabindex focus flag, should allow the element to be reached using sequential focus navigation, and should follow platform conventions to determine the element's relative order.
The user agent must set the element's tabindex focus flag, should allow the element to be reached using sequential focus navigation, and should place the element in the sequential focus navigation order so that it is:
An element that has its tabindex focus flag set but does not otherwise have an activation behavior defined has an activation behavior that does nothing.
This means that an element that is only focusable
because of its ‘tabindex’ attribute
will fire a click
event in response
to a non-mouse activation (e.g. hitting the "enter" key while the
element is focused).
The tabIndex
IDL
attribute must reflect the value of the ‘tabindex’ content attribute.
Need to decide how will replace some of the links pertainig to "in a document", "Document", and "being rendered". This is dependent on Document work that needs to be added wrt. tabindex. Do we define our own definitions vs. what is in HTML5?
An element is focusable if the user agent's default behavior allows it to be focusable or if the element has its tabindex focus flag set, but only if the element is either being rendered and only if neither the element nor any of its ancestors are inert.
User agents should make the a element focusable as part of their default behavior, unless platform conventions dictate otherwise:
Notwithstanding the above, user agents may make any element or part of an element focusable, especially to aid with accessibility or to better match platform conventions.
The focusing steps for an element are as follows:
If the element is not in a
Document
, or if the element's
Document
has no browsing context, or if
the element's Document
's browsing context
has no top-level browsing context, or if the element
is not focusable, then abort these steps.
If focusing the element will remove the focus from another element, then run the unfocusing steps for that element.
Make the element the currently focused element in its top-level browsing context.
Fire a simple event named focus
at the element.
User agents must synchronously run the focusing steps for an element whenever the user moves the focus to a focusable element.
The unfocusing steps for an element are as follows:
Unfocus the element.
Fire a simple event named focusout
at the element.
When an element that is focused stops being a focusable element, or stops being focused without another element being explicitly focused in its stead, the user agent should synchronously run the unfocusing steps for the affected element only.
For example, this might happen because the
element is removed from its Document
.
An element is being rendered if it is in a
Document
, either its parent node is itself
being rendered or it is the Document
node,
and it is not explicitly excluded from the rendering using either:
Just being off-screen does not mean the element is not being rendered.
interface SVGCursorElement : SVGElement { readonly attribute SVGAnimatedLength x; readonly attribute SVGAnimatedLength y; }; SVGCursorElement implements SVGURIReference;