third_party/WebKit/Source/core/dom/IntersectionObservation.cpp - Issue 1449623002: IntersectionObserver: second cut.

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Issue 1449623002: IntersectionObserver: second cut. (Closed) Base URL: https://chromium.googlesource.com/chromium/src@master

Patch Set: Implemented root margin Created 5 years ago

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	1 // Copyright 2015 The Chromium Authors. All rights reserved.

	2 // Use of this source code is governed by a BSD-style license that can be

	3 // found in the LICENSE file.

	4

	5 #include "config.h"

	6 #include "core/dom/IntersectionObservation.h"

	7

	8 #include "core/dom/IntersectionObserver.h"

	9 #include "core/frame/FrameView.h"

	10 #include "core/layout/LayoutBox.h"

	11 #include "core/layout/LayoutText.h"

	12 #include "core/layout/LayoutView.h"

	13 #include "core/paint/PaintLayer.h"

	14

	15 namespace blink {

	16

	17 IntersectionObservation::IntersectionObservation(IntersectionObserver& observer, Element* target, bool canReportRootBounds)

	18 : m_observer(observer)

	19 , m_target(target->createWeakPtr())
	esprehn 2015/12/12 00:14:13 your controller should keep the factory, not the e your controller should keep the factory, not the element szager1 2015/12/16 19:15:34 Done. Show quoted text On 2015/12/12 00:14:13, esprehn wrote: > your controller should keep the factory, not the element Done.
	20 , m_active(true)

	21 , m_canReportRootBounds(canReportRootBounds)

	22 , m_lastVisibleRatio(0)

	23 {

	24 target->addIntersectionObservation(*this);

	25 }

	26

	27 bool IntersectionObservation::computeGeometry(LayoutRect& targetRect, LayoutRect & rootRect, LayoutRect& intersectionRect)

	28 {

	29 Element* rootElement = observer()->root();

	30 bool rootIsDocumentElement = (rootElement == rootElement->document().documen tElement());
	ojan 2015/12/12 01:06:28 Not sure this documentElement check is correct. Th Not sure this documentElement check is correct. The documentElement is actually the <html> element. There's no element that corresponds to the layoutView. So, the null root value is special in that way as well. szager1 2015/12/16 19:15:34 If root is not provided in the constructor, it doe Show quoted text On 2015/12/12 01:06:28, ojan wrote: > Not sure this documentElement check is correct. The documentElement is actually > the <html> element. There's no element that corresponds to the layoutView. So, > the null root value is special in that way as well. If root is not provided in the constructor, it does this: root = toLocalFrame(mainFrame)->document()->documentElement(); This can also be set explicitly, e.g. "new IntersectionObserver(callback {root: document.documentElement()})". I don't think there's any reason to distinguish between these two cases. The reason for setting rootLayoutObject to be the layout view if rootIsDocumentElement is to make sure this code is ready for root layer scrolling.
	31 LayoutObject* rootLayoutObject = rootIsDocumentElement ? rootElement->docume nt().layoutView() : rootElement->layoutObject();

	32 if (!rootLayoutObject->isBoxModelObject())

	33 return false;

	34 LayoutObject* targetLayoutObject = m_target->layoutObject();

	35

	36 // Initialize intersectionRect to bounds of target, in target's coordinate s pace.

	37 if (targetLayoutObject->isBoxModelObject())

	38 targetRect = intersectionRect = toLayoutBoxModelObject(targetLayoutObjec t)->visualOverflowRect();

	39 else if (targetLayoutObject->isText())

	40 targetRect = intersectionRect = toLayoutText(targetLayoutObject)->visual OverflowRect();

	41 else

	42 return false;

	43

	44 // Map targetRect into document coordinates.

	45 targetRect = LayoutRect(targetLayoutObject->localToAbsoluteQuad(FloatQuad(Fl oatRect(targetRect)), UseTransforms \| ApplyContainerFlip \| TraverseDocumentBound aries).boundingBox());

	46

	47 // Map and clip intersectionRect into root element coordinates.

	48 targetLayoutObject->mapToVisibleRectInContainerSpace(toLayoutBoxModelObject( rootLayoutObject), intersectionRect, nullptr);

	49 if (rootLayoutObject->hasOverflowClip()) {

	50 LayoutBox* rootLayoutBox = toLayoutBox(rootLayoutObject);

	51 LayoutRect clipRect(LayoutPoint(), LayoutSize(rootLayoutBox->layer()->si ze()));

	52 m_observer->applyRootMargin(clipRect);

	53 rootLayoutBox->flipForWritingMode(intersectionRect);

	54 intersectionRect.intersect(clipRect);

	55 rootLayoutBox->flipForWritingMode(intersectionRect);

	56 }

	57

	58 // Map intersectionRect into document coordinates.

	59 intersectionRect = LayoutRect(rootLayoutObject->localToAbsoluteQuad(FloatQua d(FloatRect(intersectionRect))).boundingBox());

	60

	61 // Clip to FrameView visible area if necessary, and get root bounds in docum ent coordinates.

	62 if (rootIsDocumentElement) {

	63 rootRect = LayoutRect(rootElement->document().view()->visibleContentRect ());

	64 m_observer->applyRootMargin(rootRect);

	65 intersectionRect.intersect(rootRect);

	66 } else {

	67 if (rootLayoutObject->isBox())

	68 rootRect = LayoutRect(toLayoutBox(rootLayoutObject)->absoluteContent Box());
	esprehn 2015/12/12 00:14:13 this method is so big, you might want to move some this method is so big, you might want to move some code into separate static methods so it can read like a series of computations with the big blocks out of line szager1 2015/12/16 19:15:35 I added helper functions, this method is now short Show quoted text On 2015/12/12 00:14:13, esprehn wrote: > this method is so big, you might want to move some code into separate static > methods so it can read like a series of computations with the big blocks out of > line I added helper functions, this method is now short.
	69 else

	70 rootRect = LayoutRect(rootLayoutObject->absoluteBoundingBoxRect());

	71 m_observer->applyRootMargin(rootRect);

	72 }

	73

	74 // Map all rects to FrameView coordinates.

	75 LayoutPoint scrollPosition(rootElement->document().view()->scrollPosition()) ;

	76 targetRect.moveBy(-scrollPosition);

	77 intersectionRect.moveBy(-scrollPosition);

	78 rootRect.moveBy(-scrollPosition);

	79

	80 if (intersectionRect.size().isZero())

	81 intersectionRect = LayoutRect();

	82

	83 return true;

	84 }

	85

	86 void IntersectionObservation::computeIntersectionObservations(int timestamp)
	esprehn 2015/12/12 00:14:13 timestamps are doubles on the web, what is this in timestamps are doubles on the web, what is this int? szager1 2015/12/16 19:15:34 I think I switched types mid-way through :) I cha Show quoted text On 2015/12/12 00:14:13, esprehn wrote: > timestamps are doubles on the web, what is this int? I think I switched types mid-way through :) I changed this to double throughout.
	87 {

	88 // TODO: rootMargin is not yet supported.

	89 Element* targetElement = target();

	90 if (!targetElement \|\| !isActive())

	91 return;

	92 LayoutObject* targetLayoutObject = targetElement->layoutObject();

	93 // TODO: Support SVG

	94 if (!targetLayoutObject \|\| (!targetLayoutObject->isBox() && !targetLayoutObj ect->isInline()))
	esprehn 2015/12/12 00:14:13 break your early returns into multiple statements. break your early returns into multiple statements. if (!targetLayoutObject) return; if (!targetLayoutObject->isBox() && !targetLayoutObject->isInline()) return; szager1 2015/12/16 19:15:34 Done. Show quoted text On 2015/12/12 00:14:13, esprehn wrote: > break your early returns into multiple statements. > > if (!targetLayoutObject) > return; > if (!targetLayoutObject->isBox() && !targetLayoutObject->isInline()) > return; Done.
	95 return;

	96

	97 LayoutRect targetRect, rootRect, intersectionRect;

	98 if (!computeGeometry(targetRect, rootRect, intersectionRect))
	esprehn 2015/12/12 00:14:13 use a struct? having so many out params is kind of use a struct? having so many out params is kind of weird, but I guess the layout code loves to do this ojan 2015/12/12 01:06:28 We usually use structs for these in the layout cod Show quoted text On 2015/12/12 at 00:14:13, esprehn wrote: > use a struct? having so many out params is kind of weird, but I guess the layout code loves to do this We usually use structs for these in the layout code as well. szager1 2015/12/16 19:15:34 Added struct IntersectionGeometry for this. Show quoted text On 2015/12/12 01:06:28, ojan wrote: > On 2015/12/12 at 00:14:13, esprehn wrote: > > use a struct? having so many out params is kind of weird, but I guess the > layout code loves to do this > > We usually use structs for these in the layout code as well. Added struct IntersectionGeometry for this.
	99 return;

	100 if (!m_canReportRootBounds)

	101 rootRect = LayoutRect();
	esprehn 2015/12/12 00:14:13 can computeGeometry do this instead of here? can computeGeometry do this instead of here? szager1 2015/12/16 19:15:34 Done. Show quoted text On 2015/12/12 00:14:13, esprehn wrote: > can computeGeometry do this instead of here? Done.
	102

	103 float intersectionArea = intersectionRect.size().width().toFloat() * interse ctionRect.size().height().toFloat();

	104 float targetArea = targetRect.size().width().toFloat() * targetRect.size().h eight().toFloat();

	105 if (!targetArea)

	106 return;
	esprehn 2015/12/12 00:14:13 can we move this before the intersectionArea compu can we move this before the intersectionArea computation to early return sooner, also can inline the computeGeometry logic in such a way to early return before doing all of the work? szager1 2015/12/16 19:15:34 Done. Show quoted text On 2015/12/12 00:14:13, esprehn wrote: > can we move this before the intersectionArea computation to early return sooner, > also can inline the computeGeometry logic in such a way to early return before > doing all of the work? Done.
	107 float newVisibleRatio = intersectionArea / targetArea;

	108 size_t newThresholdIndex = observer()->firstThresholdGreaterThan(newVisibleR atio);

	109 size_t oldThresholdIndex = observer()->firstThresholdGreaterThan(lastVisible Ratio());

	110 setLastVisibleRatio(newVisibleRatio);
	ojan 2015/12/12 01:06:28 Can we actually just store the index? We don't nee Can we actually just store the index? We don't need the ratio for anything. That way you don't need to recompute the index for the last ratio. Also, you could get bitpack the index with the bools in the Observation. It's not an optimization that will matter, but may as well if it's free and adds no complexity. szager1 2015/12/16 19:15:34 Done. Show quoted text On 2015/12/12 01:06:28, ojan wrote: > Can we actually just store the index? We don't need the ratio for anything. That > way you don't need to recompute the index for the last ratio. Also, you could > get bitpack the index with the bools in the Observation. It's not an > optimization that will matter, but may as well if it's free and adds no > complexity. Done.
	111 if (oldThresholdIndex != newThresholdIndex)

	112 observer()->enqueueIntersectionObserverEntry(new IntersectionObserverEnt ry(timestamp / 1000., pixelSnappedIntRect(targetRect), pixelSnappedIntRect(rootR ect), pixelSnappedIntRect(intersectionRect), targetElement));
	esprehn 2015/12/12 00:14:13 .0, but timestamp should be a double too .0, but timestamp should be a double too szager1 2015/12/16 19:15:34 Done. Show quoted text On 2015/12/12 00:14:13, esprehn wrote: > .0, but timestamp should be a double too Done.
	113 }

	114

	115 void IntersectionObservation::disconnect()

	116 {

	117 observer()->disconnect(*this);

	118 if (m_target)

	119 m_target->removeIntersectionObservation(*this);

	120 }

	121

	122 DEFINE_TRACE(IntersectionObservation)

	123 {

	124 visitor->trace(m_observer);

	125 visitor->trace(m_target);

	126 }

	127

	128 } // namespace blink {

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