1 /* 2 * Copyright (C) 1999 Lars Knoll (knoll (at) kde.org) 3 * (C) 2004-2005 Allan Sandfeld Jensen (kde (at) carewolf.com) 4 * Copyright (C) 2006, 2007 Nicholas Shanks (webkit (at) nickshanks.com) 5 * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved. 6 * Copyright (C) 2007 Alexey Proskuryakov <ap (at) webkit.org> 7 * Copyright (C) 2007, 2008 Eric Seidel <eric (at) webkit.org> 8 * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/) 9 * Copyright (c) 2011, Code Aurora Forum. All rights reserved. 10 * Copyright (C) Research In Motion Limited 2011. All rights reserved. 11 * Copyright (C) 2013 Google Inc. All rights reserved. 12 * 13 * This library is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU Library General Public 15 * License as published by the Free Software Foundation; either 16 * version 2 of the License, or (at your option) any later version. 17 * 18 * This library is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 21 * Library General Public License for more details. 22 * 23 * You should have received a copy of the GNU Library General Public License 24 * along with this library; see the file COPYING.LIB. If not, write to 25 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 26 * Boston, MA 02110-1301, USA. 27 */ 28 29 #include "config.h" 30 #include "core/css/resolver/SharedStyleFinder.h" 31 32 #include "HTMLNames.h" 33 #include "XMLNames.h" 34 #include "core/css/resolver/StyleResolver.h" 35 #include "core/css/resolver/StyleResolverState.h" 36 #include "core/dom/ContainerNode.h" 37 #include "core/dom/Document.h" 38 #include "core/dom/Element.h" 39 #include "core/dom/FullscreenElementStack.h" 40 #include "core/dom/Node.h" 41 #include "core/dom/NodeRenderStyle.h" 42 #include "core/dom/NodeTraversal.h" 43 #include "core/dom/QualifiedName.h" 44 #include "core/dom/SpaceSplitString.h" 45 #include "core/dom/shadow/ElementShadow.h" 46 #include "core/html/HTMLElement.h" 47 #include "core/html/HTMLInputElement.h" 48 #include "core/html/HTMLOptGroupElement.h" 49 #include "core/html/track/WebVTTElement.h" 50 #include "core/rendering/style/RenderStyle.h" 51 #include "core/svg/SVGElement.h" 52 #include "wtf/HashSet.h" 53 #include "wtf/text/AtomicString.h" 54 55 namespace WebCore { 56 57 using namespace HTMLNames; 58 59 static const unsigned cStyleSearchThreshold = 10; 60 static const unsigned cStyleSearchLevelThreshold = 10; 61 62 static inline bool parentElementPreventsSharing(const Element* parentElement) 63 { 64 if (!parentElement) 65 return false; 66 return parentElement->hasFlagsSetDuringStylingOfChildren(); 67 } 68 69 Node* SharedStyleFinder::locateCousinList(Element* parent, unsigned& visitedNodeCount) const 70 { 71 if (visitedNodeCount >= cStyleSearchThreshold * cStyleSearchLevelThreshold) 72 return 0; 73 if (!parent || !parent->isStyledElement()) 74 return 0; 75 if (parent->hasScopedHTMLStyleChild()) 76 return 0; 77 if (parent->inlineStyle()) 78 return 0; 79 if (parent->isSVGElement() && toSVGElement(parent)->animatedSMILStyleProperties()) 80 return 0; 81 if (parent->hasID() && m_features.idsInRules.contains(parent->idForStyleResolution().impl())) 82 return 0; 83 if (isShadowHost(parent) && parent->shadow()->containsActiveStyles()) 84 return 0; 85 86 RenderStyle* parentStyle = parent->renderStyle(); 87 unsigned subcount = 0; 88 Node* thisCousin = parent; 89 Node* currentNode = parent->previousSibling(); 90 91 // Reserve the tries for this level. This effectively makes sure that the algorithm 92 // will never go deeper than cStyleSearchLevelThreshold levels into recursion. 93 visitedNodeCount += cStyleSearchThreshold; 94 while (thisCousin) { 95 while (currentNode) { 96 ++subcount; 97 if (!currentNode->hasScopedHTMLStyleChild() && currentNode->renderStyle() == parentStyle && currentNode->lastChild() 98 && currentNode->isElementNode() && !parentElementPreventsSharing(toElement(currentNode)) 99 && !toElement(currentNode)->shadow() 100 ) { 101 // Adjust for unused reserved tries. 102 visitedNodeCount -= cStyleSearchThreshold - subcount; 103 return currentNode->lastChild(); 104 } 105 if (subcount >= cStyleSearchThreshold) 106 return 0; 107 currentNode = currentNode->previousSibling(); 108 } 109 currentNode = locateCousinList(thisCousin->parentElement(), visitedNodeCount); 110 thisCousin = currentNode; 111 } 112 113 return 0; 114 } 115 116 117 bool SharedStyleFinder::canShareStyleWithControl(const ElementResolveContext& context, Element* element) const 118 { 119 if (!element->hasTagName(inputTag) || !context.element()->hasTagName(inputTag)) 120 return false; 121 122 HTMLInputElement* thisInputElement = toHTMLInputElement(element); 123 HTMLInputElement* otherInputElement = toHTMLInputElement(context.element()); 124 if (thisInputElement->elementData() != otherInputElement->elementData()) { 125 if (thisInputElement->fastGetAttribute(typeAttr) != otherInputElement->fastGetAttribute(typeAttr)) 126 return false; 127 if (thisInputElement->fastGetAttribute(readonlyAttr) != otherInputElement->fastGetAttribute(readonlyAttr)) 128 return false; 129 } 130 131 if (thisInputElement->isAutofilled() != otherInputElement->isAutofilled()) 132 return false; 133 if (thisInputElement->shouldAppearChecked() != otherInputElement->shouldAppearChecked()) 134 return false; 135 if (thisInputElement->shouldAppearIndeterminate() != otherInputElement->shouldAppearIndeterminate()) 136 return false; 137 if (thisInputElement->isRequired() != otherInputElement->isRequired()) 138 return false; 139 140 if (element->isDisabledFormControl() != context.element()->isDisabledFormControl()) 141 return false; 142 143 if (element->isDefaultButtonForForm() != context.element()->isDefaultButtonForForm()) 144 return false; 145 146 if (context.document()->containsValidityStyleRules()) { 147 bool willValidate = element->willValidate(); 148 149 if (willValidate != context.element()->willValidate()) 150 return false; 151 152 if (willValidate && (element->isValidFormControlElement() != context.element()->isValidFormControlElement())) 153 return false; 154 155 if (element->isInRange() != context.element()->isInRange()) 156 return false; 157 158 if (element->isOutOfRange() != context.element()->isOutOfRange()) 159 return false; 160 } 161 162 return true; 163 } 164 165 bool SharedStyleFinder::classNamesAffectedByRules(const SpaceSplitString& classNames) const 166 { 167 for (unsigned i = 0; i < classNames.size(); ++i) { 168 if (m_features.classesInRules.contains(classNames[i].impl())) 169 return true; 170 } 171 return false; 172 } 173 174 static inline bool elementHasDirectionAuto(Element* element) 175 { 176 // FIXME: This line is surprisingly hot, we may wish to inline hasDirectionAuto into StyleResolver. 177 return element->isHTMLElement() && toHTMLElement(element)->hasDirectionAuto(); 178 } 179 180 bool SharedStyleFinder::sharingCandidateHasIdenticalStyleAffectingAttributes(const ElementResolveContext& context, Element* sharingCandidate) const 181 { 182 if (context.element()->elementData() == sharingCandidate->elementData()) 183 return true; 184 if (context.element()->fastGetAttribute(XMLNames::langAttr) != sharingCandidate->fastGetAttribute(XMLNames::langAttr)) 185 return false; 186 if (context.element()->fastGetAttribute(langAttr) != sharingCandidate->fastGetAttribute(langAttr)) 187 return false; 188 189 if (!m_elementAffectedByClassRules) { 190 if (sharingCandidate->hasClass() && classNamesAffectedByRules(sharingCandidate->classNames())) 191 return false; 192 } else if (sharingCandidate->hasClass()) { 193 // SVG elements require a (slow!) getAttribute comparision because "class" is an animatable attribute for SVG. 194 if (context.element()->isSVGElement()) { 195 if (context.element()->getAttribute(classAttr) != sharingCandidate->getAttribute(classAttr)) 196 return false; 197 } else if (context.element()->classNames() != sharingCandidate->classNames()) { 198 return false; 199 } 200 } else { 201 return false; 202 } 203 204 if (context.element()->presentationAttributeStyle() != sharingCandidate->presentationAttributeStyle()) 205 return false; 206 207 if (context.element()->hasTagName(progressTag)) { 208 if (context.element()->shouldAppearIndeterminate() != sharingCandidate->shouldAppearIndeterminate()) 209 return false; 210 } 211 212 return true; 213 } 214 215 bool SharedStyleFinder::canShareStyleWithElement(const ElementResolveContext& context, Element* element) const 216 { 217 RenderStyle* style = element->renderStyle(); 218 if (!style) 219 return false; 220 if (style->unique()) 221 return false; 222 if (style->hasUniquePseudoStyle()) 223 return false; 224 if (element->tagQName() != context.element()->tagQName()) 225 return false; 226 if (element->inlineStyle()) 227 return false; 228 if (element->needsStyleRecalc()) 229 return false; 230 if (element->isSVGElement() && toSVGElement(element)->animatedSMILStyleProperties()) 231 return false; 232 if (element->isLink() != context.element()->isLink()) 233 return false; 234 if (element->hovered() != context.element()->hovered()) 235 return false; 236 if (element->active() != context.element()->active()) 237 return false; 238 if (element->focused() != context.element()->focused()) 239 return false; 240 if (element->shadowPseudoId() != context.element()->shadowPseudoId()) 241 return false; 242 if (element == element->document()->cssTarget()) 243 return false; 244 if (!sharingCandidateHasIdenticalStyleAffectingAttributes(context, element)) 245 return false; 246 if (element->additionalPresentationAttributeStyle() != context.element()->additionalPresentationAttributeStyle()) 247 return false; 248 249 if (element->hasID() && m_features.idsInRules.contains(element->idForStyleResolution().impl())) 250 return false; 251 if (element->hasScopedHTMLStyleChild()) 252 return false; 253 if (isShadowHost(element) && element->shadow()->containsActiveStyles()) 254 return 0; 255 256 // FIXME: We should share style for option and optgroup whenever possible. 257 // Before doing so, we need to resolve issues in HTMLSelectElement::recalcListItems 258 // and RenderMenuList::setText. See also https://bugs.webkit.org/show_bug.cgi?id=88405 259 if (element->hasTagName(optionTag) || isHTMLOptGroupElement(element)) 260 return false; 261 262 bool isControl = element->isFormControlElement(); 263 264 if (isControl != context.element()->isFormControlElement()) 265 return false; 266 267 if (isControl && !canShareStyleWithControl(context, element)) 268 return false; 269 270 if (style->transitions() || style->animations()) 271 return false; 272 273 // Turn off style sharing for elements that can gain layers for reasons outside of the style system. 274 // See comments in RenderObject::setStyle(). 275 if (element->hasTagName(iframeTag) || element->hasTagName(frameTag) || element->hasTagName(embedTag) || element->hasTagName(objectTag) || element->hasTagName(appletTag) || element->hasTagName(canvasTag)) 276 return false; 277 278 if (elementHasDirectionAuto(element)) 279 return false; 280 281 if (element->isLink() && context.elementLinkState() != style->insideLink()) 282 return false; 283 284 if (element->isUnresolvedCustomElement() != context.element()->isUnresolvedCustomElement()) 285 return false; 286 287 // Deny sharing styles between WebVTT and non-WebVTT nodes. 288 if (element->isWebVTTElement() != context.element()->isWebVTTElement()) 289 return false; 290 291 if (element->isWebVTTElement() && context.element()->isWebVTTElement() && toWebVTTElement(element)->isPastNode() != toWebVTTElement(context.element())->isPastNode()) 292 return false; 293 294 if (FullscreenElementStack* fullscreen = FullscreenElementStack::fromIfExists(context.document())) { 295 if (element == fullscreen->webkitCurrentFullScreenElement() || context.element() == fullscreen->webkitCurrentFullScreenElement()) 296 return false; 297 } 298 299 return true; 300 } 301 302 inline Element* SharedStyleFinder::findSiblingForStyleSharing(const ElementResolveContext& context, Node* node, unsigned& count) const 303 { 304 for (; node; node = node->previousSibling()) { 305 if (!node->isStyledElement()) 306 continue; 307 if (canShareStyleWithElement(context, toElement(node))) 308 break; 309 if (count++ == cStyleSearchThreshold) 310 return 0; 311 } 312 return toElement(node); 313 } 314 315 #ifdef STYLE_STATS 316 Element* SharedStyleFinder::searchDocumentForSharedStyle(const ElementResolveContext& context) const 317 { 318 for (Element* element = context.element()->document()->documentElement(); element; element = ElementTraversal::next(element)) { 319 if (canShareStyleWithElement(context, element)) 320 return element; 321 } 322 return 0; 323 } 324 #endif 325 326 RenderStyle* SharedStyleFinder::locateSharedStyle(const ElementResolveContext& context, RenderStyle* newStyle) 327 { 328 STYLE_STATS_ADD_SEARCH(); 329 if (!context.element() || !context.element()->isStyledElement()) 330 return 0; 331 332 // If the element has inline style it is probably unique. 333 if (context.element()->inlineStyle()) 334 return 0; 335 if (context.element()->isSVGElement() && toSVGElement(context.element())->animatedSMILStyleProperties()) 336 return 0; 337 // Ids stop style sharing if they show up in the stylesheets. 338 if (context.element()->hasID() && m_features.idsInRules.contains(context.element()->idForStyleResolution().impl())) 339 return 0; 340 // Active and hovered elements always make a chain towards the document node 341 // and no siblings or cousins will have the same state. 342 if (context.element()->hovered()) 343 return 0; 344 if (context.element()->active()) 345 return 0; 346 // There is always only one focused element. 347 if (context.element()->focused()) 348 return 0; 349 if (parentElementPreventsSharing(context.element()->parentElement())) 350 return 0; 351 if (context.element()->hasScopedHTMLStyleChild()) 352 return 0; 353 if (context.element() == context.document()->cssTarget()) 354 return 0; 355 if (elementHasDirectionAuto(context.element())) 356 return 0; 357 if (context.element()->hasActiveAnimations()) 358 return 0; 359 // When a dialog is first shown, its style is mutated to center it in the 360 // viewport. So the styles can't be shared since the viewport position and 361 // size may be different each time a dialog is opened. 362 if (context.element()->hasTagName(dialogTag)) 363 return 0; 364 if (isShadowHost(context.element()) && context.element()->shadow()->containsActiveStyles()) 365 return 0; 366 367 STYLE_STATS_ADD_ELEMENT_ELIGIBLE_FOR_SHARING(); 368 369 // Cache whether context.element() is affected by any known class selectors. 370 // FIXME: This should be an explicit out parameter, instead of a member variable. 371 m_elementAffectedByClassRules = context.element() && context.element()->hasClass() && classNamesAffectedByRules(context.element()->classNames()); 372 373 // Check previous siblings and their cousins. 374 unsigned count = 0; 375 unsigned visitedNodeCount = 0; 376 Element* shareElement = 0; 377 Node* cousinList = context.element()->previousSibling(); 378 while (cousinList) { 379 shareElement = findSiblingForStyleSharing(context, cousinList, count); 380 if (shareElement) 381 break; 382 cousinList = locateCousinList(cousinList->parentElement(), visitedNodeCount); 383 } 384 385 #ifdef STYLE_STATS 386 // FIXME: these stats don't to into account whether or not sibling/attribute 387 // rules prevent these nodes from actually sharing 388 if (shareElement) { 389 STYLE_STATS_ADD_SEARCH_FOUND_SIBLING_FOR_SHARING(); 390 } else { 391 shareElement = searchDocumentForSharedStyle(context); 392 if (shareElement) 393 STYLE_STATS_ADD_SEARCH_MISSED_SHARING(); 394 shareElement = 0; 395 } 396 #endif 397 398 // If we have exhausted all our budget or our cousins. 399 if (!shareElement) 400 return 0; 401 402 // Can't share if sibling rules apply. This is checked at the end as it should rarely fail. 403 if (m_styleResolver->styleSharingCandidateMatchesRuleSet(context, newStyle, m_siblingRuleSet)) 404 return 0; 405 // Can't share if attribute rules apply. 406 if (m_styleResolver->styleSharingCandidateMatchesRuleSet(context, newStyle, m_uncommonAttributeRuleSet)) 407 return 0; 408 // Tracking child index requires unique style for each node. This may get set by the sibling rule match above. 409 if (parentElementPreventsSharing(context.element()->parentElement())) 410 return 0; 411 STYLE_STATS_ADD_STYLE_SHARED(); 412 return shareElement->renderStyle(); 413 } 414 415 } 416
