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Set restyle subtree restyle hint if the element animates display style from 'none' to other.

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When display style is changed from 'none' to other in animation-only restyle
we need to resolve descendant elements' style that were in the display:none
subtree.

Three possible ways to resolve the descendant elements' style;

1) Traversing unstyled elements in animation-only restyle
   We can't simply traverse unstyled elements in the animation-only restyle
   since when we decided to traverse the unstyled elements we don't know yet
   the elements will be initially styled or are in display:none subtree. It
   will result that the new elements are styled in animation-only restyle,
   it's undesirable.

2) Creating a SequentialTask and resolve the descendants' style with
   ServoStyleSet::StyleNewSubtree()
   We can't resolve the descendants' styles with ServoStyleSet::StyleNewSubtree()
   in SequentialTask since at the moment we are still in servo traversal (i.e.
   sInServoTraversal is true). That means AutoSetInServoTraversal fails
   in PrepareAndTraverseSubtree().

3) Creating a SequentialTask and set restyle subtree hint and defer descendants'
   restyle in a subsequent normal traversal
   Note that, when we process throttled animations flush, we don't process
   normal traversal so the descendants will not be traversed until normal
   restyle happens but it will not be a big problem since it's really rare
   that user clicks display animation element just at the right moment when
   display property changes from none to other.  Also, if it will be really
   a problem, we should process *only* transform animations on the compositor,
   it's ideally right thing to do. Display property never runs on the
   compositor.

This patch takes the third approach.
This commit is contained in:
Hiroyuki Ikezoe 2017-08-02 18:16:10 +09:00
parent ffc01687e4
commit 0841db70ee
4 changed files with 119 additions and 10 deletions
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27
components/style/gecko/wrapper.rs
View file

@ -18,7 +18,7 @@ use CaseSensitivityExt;
use app_units::Au;
use applicable_declarations::ApplicableDeclarationBlock;
use atomic_refcell::{AtomicRefCell, AtomicRefMut};
use context::{QuirksMode, SharedStyleContext, UpdateAnimationsTasks};
use context::{QuirksMode, SharedStyleContext, PostAnimationTasks, UpdateAnimationsTasks};
use data::{ElementData, RestyleData};
use dom::{self, DescendantsBit, LayoutIterator, NodeInfo, TElement, TNode, UnsafeNode};
use dom::{OpaqueNode, PresentationalHintsSynthesizer};
@ -1167,6 +1167,31 @@ impl<'le> TElement for GeckoElement<'le> {
self.as_node().get_bool_flag(nsINode_BooleanFlag::ElementHasAnimations)
}
/// Process various tasks that are a result of animation-only restyle.
fn process_post_animation(&self,
tasks: PostAnimationTasks) {
use context::DISPLAY_CHANGED_FROM_NONE_FOR_SMIL;
use gecko_bindings::structs::nsChangeHint_nsChangeHint_Empty;
use gecko_bindings::structs::nsRestyleHint_eRestyle_Subtree;
debug_assert!(!tasks.is_empty(), "Should be involved a task");
// If display style was changed from none to other, we need to resolve
// the descendants in the display:none subtree. Instead of resolving
// those styles in animation-only restyle, we defer it to a subsequent
// normal restyle.
if tasks.intersects(DISPLAY_CHANGED_FROM_NONE_FOR_SMIL) {
debug_assert!(self.implemented_pseudo_element()
.map_or(true, |p| !p.is_before_or_after()),
"display property animation shouldn't run on pseudo elements \
since it's only for SMIL");
self.note_explicit_hints(nsRestyleHint_eRestyle_Subtree,
nsChangeHint_nsChangeHint_Empty);
}
}
/// Update various animation-related state on a given (pseudo-)element as
/// results of normal restyle.
fn update_animations(&self,
before_change_style: Option<Arc<ComputedValues>>,
tasks: UpdateAnimationsTasks) {