This avoids an inconsistency (discussed in #1044) when using D3 inside Node.js,
where D3 internally creates a JSDOM document during initialization, but then
subsequently depends on the current global document, which is not exposed. D3
now always refers to the global document at the time of initialization, and
does not depend on the current global document or window.
Rather than computing the ending value when the transition starts, the ending
value is computed when the transition is scheduled. This gives more predictable
behavior and makes it easier to debug evaluation errors since they occur
immediately (during user code) rather than inside a d3_timer callback.
The behavior of attrTween and styleTween are unchanged, since the interpolator
can only be constructed once the starting value is known. This commit also
removes d3.tween; I may add this back in a future commit, but I think there is
probably a better way to specify an interpolator for transitions.
This commit moves easing and event listeners down to the node's transition
object, allowing these fields to be modified via post-selection. This removes
the last vestige of private state for transitions.
This required a few changes to tests that depended on the order of callbacks for
tweens and events. Because timers are called back in reverse order, tweens are
now initialized in reverse order, and listeners are now invoked in order.
It is now possible to reselect elements with scheduled transitions and redefine
associated tweens; this enables "post-selection" to customize the behavior of
reusable components undergoing transitions, such as an axis. This commit also
makes it much easier to sequence transitions.
Previously, a transition's tweens were stored privately by the transition and
could only be accessed through the transition. This made it impossible to modify
transitions created by components: the transition is not accessible externally,
and cannot be reselected from the document. Consider the following snippet:
g.select(".x.axis")
.call(xAxis)
.selectAll("text")
.attr("dy", null);
If `g` is a selection, then this code alters the appearance of the axis as
expected. However, if `g` is a transition, then transition.selectAll creates a
new concurrent transition, and now multiple tweens compete to set the "dy"
attribute. Oy!
Under the new design, an element's scheduled tweens are stored semi-privately on
the node (in the existing node.__transition__). Transition parameters can thus
be reselected and modified by transitions that share the same id. If you now
reselect a transitioning element, you modify the transition rather creating a
competing transition; this should be less surprising and allow greater control.
As a side-effect of this change, it is no longer possible to schedule concurrent
transitions on the same element, even with the same id: only one transition may
be active on a given element at any time. (Note that you can still schedule
multiple future transitions on the same element, and concurrent transitions on
different elements.) For example, you could previously schedule overlapping
transitions with different easing functions, delays or durations, provided you
were careful to avoid conflict. This seems like a relatively obscure use-case
compared to modifying a transition, so I believe this is a reasonable change.
This commit also changes transition.transition, such that the returned
transition starts at the end of the originating transition, rather than
overlapping. This makes it much easier to schedule sequenced transitions without
the complexity of transition.each("end") and d3.select(this).
Also, transitions are now simply arrays of nodes, consistent with selections!
Note: the previous commit broke some tests relating to locale date
parsing, due to expecting "%m/%d/%y". On my system, the "en_US" locale
uses "%m/%d/%Y" by default. I've updated the tests to use %Y.
This avoids having to include a large number of locales in the D3
repository, and also reduces the potential for typos when transcribing
locale mappings.
You can now build a locale-specific version of d3.time.format. For example,
LANG=fr_FR make
will pull strings from the time/format-fr_FR.js file, rather than en_US.
John Firebaugh
Mike Bostock
Jason Davies