in progress

Author: szager-chromium

index.bs

@@ -57,9 +57,6 @@ urlPrefix: https://heycam.github.io/webidl/
 	urlPrefix: #idl-; type:interface; text: double
 	urlPrefix: #idl-; type:interface; text: undefined
 	url: #hierarchyrequesterror; type: exception; text: HierarchyRequestError
-urlPrefix: https://drafts.csswg.org/css-backgrounds/
-	url: #shadow-blur; type:dfn; text: blur
-	url: #blur-radius; type:dfn; text: blur radius
 urlPrefix: https://drafts.csswg.org/css-box/
 	url: #containing-block; type: dfn; text: containing block
 	url: #padding-area; type: dfn; text: padding area
@@ -81,6 +78,8 @@ urlPrefix: https://drafts.csswg.org/cssom-view-1/
 	url: #pinch-zoom; type:dfn; text: pinch zoom
 urlPrefix: https://drafts.csswg.org/css2/visuren.html
 	url: #viewport; type:dfn; text: viewport
+urlPrefix: https://drafts.fxtf.org/filter-effects/
+	url: #funcdef-filter-blur; type:dfn; text: blur
 </pre>
 
 <pre class="link-defaults">
@@ -580,30 +579,30 @@ which is initialized to an empty list.
 This list holds <dfn interface>IntersectionObserverRegistration</dfn> records,
 which have:
 	* an <dfn attribute for=IntersectionObserverRegistration>observer</dfn> property
-	holding an {{IntersectionObserver}}.
+		holding an {{IntersectionObserver}}.
 	* a <dfn attribute for=IntersectionObserverRegistration>previousThresholdIndex</dfn> property
-	holding a number between -1 and the length of the observer's {{IntersectionObserver/thresholds}} property (inclusive).
+		holding a number between -1 and the length of the observer's {{IntersectionObserver/thresholds}} property (inclusive).
 	* a <dfn attribute for=IntersectionObserverRegistration>previousIsIntersecting</dfn> property
-	holding a boolean.
+		holding a boolean.
 	* a <dfn attribute for=IntersectionObserverRegistration>lastUpdateTime</dfn> property
-	holding a {{DOMHighResTimeStamp}} value.
+		holding a {{DOMHighResTimeStamp}} value.
 	* a <dfn attribute for=IntersectionObserverRegistration>previousIsVisible</dfn> property
-	holding a boolean.
+		holding a boolean.
 
 <h4 id='intersection-observer-private-slots'>
 IntersectionObserver</h4>
 
 {{IntersectionObserver}} objects have the following internal slots:
 	* A <dfn attribute for=IntersectionObserver>\[[QueuedEntries]]</dfn> slot
-	initialized to an empty list.
+		initialized to an empty list.
 	* A <dfn attribute for=IntersectionObserver>\[[ObservationTargets]]</dfn> slot
-	initialized to an empty list.
+		initialized to an empty list.
 	* A <dfn attribute for=IntersectionObserver>\[[callback]]</dfn> slot
-	which is initialized by {{IntersectionObserver(callback, options)}}.
+		which is initialized by {{IntersectionObserver(callback, options)}}.
 	* A <dfn attribute for=IntersectionObserver>\[[rootMargin]]</dfn> slot
-	which is a list of four pixel lengths or percentages.
+		which is a list of four pixel lengths or percentages.
 	* A <dfn attribute for=IntersectionObserver>\[[scrollMargin]]</dfn> slot
-	which is a list of four pixel lengths or percentages.
+		which is a list of four pixel lengths or percentages.
 
 <h3 id='algorithms'>
 Algorithms</h2>
@@ -746,6 +745,32 @@ run these steps:
 6. Map |intersectionRect| to the coordinate space of the <a>viewport</a> of the {{document}} containing |target|.
 7. Return |intersectionRect|.
 
+<h4 id='calculate-visibility-algo'>
+Compute whether a Target is unoccluded, untransformed, unfiltered, and opaque.</h4>
+
+To compute the <dfn>visibility</dfn> of a <a>target</a>, run these steps:
+1. If the |observer|'s {{IntersectionObserver/trackVisibility}} attribute is false, return true.
+2. If the <a>target</a> has an <a>effective transformation matrix</a> other than a 2D translation or proportional 2D upscaling, return false.
+3. If the <a>target</a>, or any element in its <a>containing block chain</a>, has an effective opacity other than 100%, return false.
+4. If the <a>target</a>, or any element in its <a>containing block chain</a>, has any filters applied, return false.
+5. If the implementation cannot guarantee that the <a>target</a> is completely unoccluded by other page content, return false.
+
+Note: Implementations should use the <a>ink overflow rectangle</a> of page content when determining whether a <a>target</a> is occluded. For blur effects, which have theoretically infinite extent, the <a>ink overflow rectangle</a> is defined by the finite-area approximation described for the <a>blur</a> filter function.
+
+6. Return true.
+
+<h4 id='calculate-effective-transformation-matrix'>Calculate a <a>target</a>'s Effective Transformation Matrix</h4>
+To compute the <dfn>effective transformation matrix</dfn> of a <a>target</a>, run these steps:
+	1. Let |matrix| be the <a>serialization</a> of the <a>identity transform function</a>.
+	2. Let |container| be the target.
+	3. While |container| is not the <a>intersection root</a>:
+		1. Set |t| to |container|'s <a>transformation matrix</a>.
+		2. Set |matrix| to |t| <a>post-multiplied</a> by |matrix|.
+		3. If |container| is the root element of a <a>nested browsing context</a>,
+	               update |container| to be the <a>browsing context container</a> of |container|. Otherwise, update |container| to be the <a>containing block</a> of |container|.
+	4. Return |matrix|.
+
+
 <h4 id='update-intersection-observations-algo'>
 Run the Update Intersection Observations Steps</h4>
 
@@ -758,45 +783,54 @@ To <dfn export>run the update intersection observations steps</dfn> for a
 2. For each |observer| in |observer list|:
 	1. Let |rootBounds| be |observer|'s <a>root intersection rectangle</a>.
 	2. For each |target| in |observer|'s internal {{[[ObservationTargets]]}} slot, processed in the same order that {{observe()}} was called on each |target|:
-		1. Let:
+		1. Let |registration| be the {{IntersectionObserverRegistration}} record 
+				in |target|'s internal {{[[RegisteredIntersectionObservers]]}} slot
+				whose {{IntersectionObserverRegistration/observer}} property is equal to |observer|.
+		2. If <code>(|time| - |registration|.{{IntersectionObserverRegistration/lastUpdateTime}} < |observer|.{{IntersectionObserver/delay}})</code>, skip further processing for |target|.
+		3. Set |registration|.{{IntersectionObserverRegistration/lastUpdateTime}} to |time|.
+		4. Let:
 			- |thresholdIndex| be 0.
 			- |isIntersecting| be false.
 			- |targetRect| be a {{DOMRectReadOnly}} with |x|, |y|, |width|, and |height| set to 0.
 			- |intersectionRect| be a {{DOMRectReadOnly}} with |x|, |y|, |width|, and |height| set to 0.
-		2. If the <a>intersection root</a> is not the <a>implicit root</a>,
+		5. If the <a>intersection root</a> is not the <a>implicit root</a>,
 			and |target| is not in the same {{document}} as the <a>intersection root</a>,
 			skip to step 11.
-		3. If the <a>intersection root</a> is an {{Element}},
+		6. If the <a>intersection root</a> is an {{Element}},
 			and |target| is not a descendant of the <a>intersection root</a>
 			in the <a>containing block chain</a>, skip to step 11.
-		4. Set |targetRect| to the {{DOMRectReadOnly}} obtained by <a>getting the bounding box</a> for
+		7. Set |targetRect| to the {{DOMRectReadOnly}} obtained by <a>getting the bounding box</a> for
 			|target|.
-		4. Let |intersectionRect| be the result of running the <a>compute the intersection</a>
+		8. Let |intersectionRect| be the result of running the <a>compute the intersection</a>
 			algorithm on |target| and |observer|'s <a>intersection root</a>.
-		5. Let |targetArea| be |targetRect|'s area.
-		6. Let |intersectionArea| be |intersectionRect|'s area.
-		7. Let |isIntersecting| be true if |targetRect| and |rootBounds| intersect or are edge-adjacent,
+		9. Let |targetArea| be |targetRect|'s area.
+		10. Let |intersectionArea| be |intersectionRect|'s area.
+		11. Let |isIntersecting| be true if |targetRect| and |rootBounds| intersect or are edge-adjacent,
 			even if the intersection has zero area (because |rootBounds| or |targetRect| have
 			zero area).
-		9. If |targetArea| is non-zero, let |intersectionRatio| be |intersectionArea| divided by |targetArea|.<br>
+		12. If |targetArea| is non-zero, let |intersectionRatio| be |intersectionArea| divided by |targetArea|.<br>
 			Otherwise, let |intersectionRatio| be <code>1</code> if |isIntersecting| is true, or <code>0</code> if |isIntersecting| is false.
-		10. Set |thresholdIndex| to the index of the first entry in |observer|.{{thresholds}} whose value is greater than |intersectionRatio|, or the length of |observer|.{{thresholds}} if |intersectionRatio| is greater than or equal to the last entry in |observer|.{{thresholds}}.
-		11. Let |intersectionObserverRegistration| be the {{IntersectionObserverRegistration}} record
-			in |target|'s internal {{[[RegisteredIntersectionObservers]]}} slot
-			whose {{IntersectionObserverRegistration/observer}} property is equal to |observer|.
-		12. Let |previousThresholdIndex| be the |intersectionObserverRegistration|'s
+		13. Set |thresholdIndex| to the index of the first entry in |observer|.{{thresholds}} whose value is greater than |intersectionRatio|, or the length of |observer|.{{thresholds}} if |intersectionRatio| is greater than or equal to the last entry in |observer|.{{thresholds}}.
+		14. Let |isVisible| be the result of running the <a>visibility</a> algorithm on |target|.
+		15. Let |previousThresholdIndex| be the |registration|'s
 		    {{IntersectionObserverRegistration/previousThresholdIndex}} property.
-		13. Let |previousIsIntersecting| be the |intersectionObserverRegistration|'s
+		16. Let |previousIsIntersecting| be the |registration|'s
 		    {{IntersectionObserverRegistration/previousIsIntersecting}} property.
-		14. If |thresholdIndex| does not equal |previousThresholdIndex| or if
-		    |isIntersecting| does not equal |previousIsIntersecting|,
+		17. Let |previousIsVisible| be the |registration|'s
+		    {{IntersectionObserverRegistration/previousIsVisible}} property.
+		18. If |thresholdIndex| does not equal |previousThresholdIndex|,
+		    or if |isIntersecting| does not equal |previousIsIntersecting|,
+		    or if |isVisible| does not equal |previousIsVisible|,
 			<a>queue an IntersectionObserverEntry</a>,
 			passing in |observer|, |time|, |rootBounds|,
-			|targetRect|, |intersectionRect|, |isIntersecting|, and |target|.
-		15. Assign |thresholdIndex| to |intersectionObserverRegistration|'s
+			|targetRect|, |intersectionRect|, |isIntersecting|,
+			|isVisible|, and |target|.
+		19. Assign |thresholdIndex| to |registration|'s
 			{{IntersectionObserverRegistration/previousThresholdIndex}} property.
-		16. Assign |isIntersecting| to |intersectionObserverRegistration|'s
+		20. Assign |isIntersecting| to |registration|'s
 			{{IntersectionObserverRegistration/previousIsIntersecting}} property.
+		21. Assign |isVisible| to |registration|'s
+			{{IntersectionObserverRegistration/previousIsVisible}} property.
 
 <h3 id='lifetime'>
 IntersectionObserver Lifetime</h2>