839443 - API for helping get all CSS property names

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect)

Description

[Mike Ratcliffe [:miker] [:mratcliffe] [:mikeratcliffe]]

At the moment in our computed style view (DevTools) we currently iterate the computed styled of document.body in order to get the list of possible property names.

An API to get this list would be much tidier than using this hack, an array would be fine.

I would suggest domUtils.getCSSPropertyNames()

Comment 1

[Boris Zbarsky [:bzbarsky]]

So the API I'm thinking of looks something like this:

  const unsigned long EXCLUDE_SHORTHANDS = (1<<0);
  const unsigned long INCLUDE_ALIASES = (1<<1);
  void getCSSPropertyNames([optional] in unsigned long aFlags,
			   [optional] out unsigned long aCount,
			   [retval, array, size_is(aCount)] out wstring aProps);

One question: For properties that are controlled by a pref, should the API return them always, or only when enabled?  Or should it be possible to use another flag to control that behavior (and if so, what should the default be)?

Comment 2

[Mike Ratcliffe [:miker] [:mratcliffe] [:mikeratcliffe]]

(In reply to Boris Zbarsky (:bz) from comment #1)
> One question: For properties that are controlled by a pref, should the API
> return them always, or only when enabled?

I think that only when enabled makes the most sense.

Comment 3

[Boris Zbarsky [:bzbarsky]]

Attachment: Add an API for getting our supported CSS property names in inspector code.

Comment 4

[Boris Zbarsky [:bzbarsky]]

Attachment: Add an API for getting our supported CSS property names in inspector code.

Comment 5

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 724762 [details] [diff] [review]
Add an API for getting our supported CSS property names in inspector code.

>+#define DO_PROP(_prop)                                                  \
>+  PR_BEGIN_MACRO                                                        \
>+    nsCSSProperty cssProp = nsCSSProperty(_prop);                       \
>+    if (nsCSSProps::IsEnabled(cssProp)) {                               \
>+      props[propCount] =                                                \
>+        ToNewUnicode(nsDependentCString(kCSSRawProperties[_prop]));     \
>+      if (!props[propCount]) {                                          \
>+        NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(propCount, props);        \
>+        return NS_ERROR_OUT_OF_MEMORY;                                  \
>+      }                                                                 \

You don't need to handle OOM here; it's ToNewUnicode (which has a null check that's no longer needed) -> AllocateStringCopy -> nsMemory::Alloc -> NS_Alloc

>+      ++propCount;                                                      \
>+    }                                                                   \
>+  PR_END_MACRO
>+
>+  // prop is the property id we're considering; propCount is how many properties
>+  // we've put into props so far.
>+  uint32_t prop = 0, propCount = 0;
>+  for ( ; prop < eCSSProperty_COUNT_no_shorthands; ++prop) {
>+    if (!nsCSSProps::PropHasFlags(nsCSSProperty(prop),
>+                                  CSS_PROPERTY_PARSE_INACCESSIBLE)) {

I tend to think inspector might want these, in some cases at least.  (Though perhaps not; it would be nice if not.)

r=dbaron

Comment 6

[Boris Zbarsky [:bzbarsky]]

> You don't need to handle OOM here

Ah, excellent.

Comment 7

[Boris Zbarsky [:bzbarsky]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/a3fcc4ba944c

Comment 8

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/a3fcc4ba944c

Comment 9

[Sebastian Zartner [:sebo]]

This should be documented at https://developer.mozilla.org/en-US/docs/XPCOM_Interface_Reference/inIDOMUtils.

Sebastian

Comment 10

[Florian Scholz (Open Web Docs)]

https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/22
https://developer.mozilla.org/en-US/docs/XPCOM_Interface_Reference/inIDOMUtils#getCSSPropertyNames()