自学教程：C++ toCSSImageValue函数代码示例

StyleImage* CSSCursorImageValue::cachedImage(ResourceFetcher* loader, float deviceScaleFactor){    if (m_imageValue->isImageSetValue())        return toCSSImageSetValue(m_imageValue.get())->cachedImageSet(loader, deviceScaleFactor);    if (!m_accessedImage) {        m_accessedImage = true;        // For SVG images we need to lazily substitute in the correct URL. Rather than attempt        // to change the URL of the CSSImageValue (which would then change behavior like cssText),        // we create an alternate CSSImageValue to use.        if (isSVGCursor() && loader && loader->document()) {            RefPtrWillBeRawPtr<CSSImageValue> imageValue = toCSSImageValue(m_imageValue.get());            // FIXME: This will fail if the <cursor> element is in a shadow DOM (bug 59827)            if (SVGCursorElement* cursorElement = resourceReferencedByCursorElement(imageValue->url(), *loader->document())) {                RefPtrWillBeRawPtr<CSSImageValue> svgImageValue = CSSImageValue::create(loader->document()->completeURL(cursorElement->href()->currentValue()->value()));                svgImageValue->setReferrer(imageValue->referrer());                StyleFetchedImage* cachedImage = svgImageValue->cachedImage(loader);                m_image = cachedImage;                return cachedImage;            }        }        if (m_imageValue->isImageValue())            m_image = toCSSImageValue(m_imageValue.get())->cachedImage(loader);    }    if (m_image && m_image->isImageResource())        return toStyleFetchedImage(m_image);    return 0;}

CachedImage* CSSImageGeneratorValue::cachedImageForCSSValue(CSSValue* value, CachedResourceLoader* cachedResourceLoader){    if (!value)        return nullptr;    if (value->isImageValue()) {        StyleCachedImage* styleCachedImage = toCSSImageValue(value)->cachedImage(cachedResourceLoader);        if (!styleCachedImage)            return nullptr;        return styleCachedImage->cachedImage();    }        if (value->isImageGeneratorValue()) {        toCSSImageGeneratorValue(value)->loadSubimages(cachedResourceLoader);        // FIXME: Handle CSSImageGeneratorValue (and thus cross-fades with gradients and canvas).        return nullptr;    }    if (value->isPrimitiveValue() && toCSSPrimitiveValue(value)->getValueID() == CSSValueNone)        return nullptr;    ASSERT_NOT_REACHED();        return nullptr;}

bool CSSCursorImageValue::updateIfSVGCursorIsUsed(Element* element){    if (!element || !element->isSVGElement())        return false;    if (!isSVGCursor())        return false;    String url = toCSSImageValue(m_imageValue.get())->url();    if (SVGCursorElement* cursorElement = resourceReferencedByCursorElement(url, element->treeScope())) {        // FIXME: This will override hot spot specified in CSS, which is probably incorrect.        SVGLengthContext lengthContext(0);        m_hasHotSpot = true;        float x = roundf(cursorElement->x()->currentValue()->value(lengthContext));        m_hotSpot.setX(static_cast<int>(x));        float y = roundf(cursorElement->y()->currentValue()->value(lengthContext));        m_hotSpot.setY(static_cast<int>(y));        if (cachedImageURL() != element->document().completeURL(cursorElement->href()->currentValue()->value()))            clearImageResource();        SVGElement* svgElement = toSVGElement(element);#if !ENABLE(OILPAN)        m_referencedElements.add(svgElement);#endif        svgElement->setCursorImageValue(this);        cursorElement->addClient(svgElement);        return true;    }    return false;}

bool DeferredLegacyStyleInterpolation::interpolationRequiresStyleResolve(const CSSValue& value){    // FIXME: should not require resolving styles for inherit/initial/unset.    if (value.isCSSWideKeyword())        return true;    if (value.isBasicShapeCircleValue())        return interpolationRequiresStyleResolve(toCSSBasicShapeCircleValue(value));    if (value.isBasicShapeEllipseValue())        return interpolationRequiresStyleResolve(toCSSBasicShapeEllipseValue(value));    if (value.isBasicShapePolygonValue())        return interpolationRequiresStyleResolve(toCSSBasicShapePolygonValue(value));    if (value.isBasicShapeInsetValue())        return interpolationRequiresStyleResolve(toCSSBasicShapeInsetValue(value));    if (value.isPrimitiveValue())        return interpolationRequiresStyleResolve(toCSSPrimitiveValue(value));    if (value.isQuadValue())        return interpolationRequiresStyleResolve(toCSSQuadValue(value));    if (value.isValueList())        return interpolationRequiresStyleResolve(toCSSValueList(value));    if (value.isValuePair())        return interpolationRequiresStyleResolve(toCSSValuePair(value));    if (value.isImageValue())        return interpolationRequiresStyleResolve(toCSSImageValue(value));    if (value.isShadowValue())        return interpolationRequiresStyleResolve(toCSSShadowValue(value));    if (value.isSVGDocumentValue())        return interpolationRequiresStyleResolve(toCSSSVGDocumentValue(value));    // FIXME: consider other custom types.    return true;}

PassRefPtr<CSSValue> CSSValue::cloneForCSSOM() const{    switch (classType()) {    case PrimitiveClass:        return toCSSPrimitiveValue(this)->cloneForCSSOM();    case ValueListClass:        return toCSSValueList(this)->cloneForCSSOM();    case ImageClass:    case CursorImageClass:        return toCSSImageValue(this)->cloneForCSSOM();#if ENABLE(CSS_FILTERS)    case WebKitCSSFilterClass:        return toWebKitCSSFilterValue(this)->cloneForCSSOM();#endif    case WebKitCSSTransformClass:        return toWebKitCSSTransformValue(this)->cloneForCSSOM();#if ENABLE(CSS_IMAGE_SET)    case ImageSetClass:        return toCSSImageSetValue(this)->cloneForCSSOM();#endif#if ENABLE(SVG)    case SVGColorClass:        return toSVGColor(this)->cloneForCSSOM();    case SVGPaintClass:        return toSVGPaint(this)->cloneForCSSOM();#endif    default:        ASSERT(!isSubtypeExposedToCSSOM());        return TextCloneCSSValue::create(classType(), cssText());    }}

bool DeferredLegacyStyleInterpolation::interpolationRequiresStyleResolve(const CSSValue& value){    switch (value.cssValueType()) {    case CSSValue::CSS_INHERIT:        return true;    case CSSValue::CSS_PRIMITIVE_VALUE:        return interpolationRequiresStyleResolve(toCSSPrimitiveValue(value));    case CSSValue::CSS_VALUE_LIST:        return interpolationRequiresStyleResolve(toCSSValueList(value));    case CSSValue::CSS_CUSTOM:        if (value.isImageValue())            return interpolationRequiresStyleResolve(toCSSImageValue(value));        if (value.isShadowValue())            return interpolationRequiresStyleResolve(toCSSShadowValue(value));        if (value.isSVGDocumentValue())            return interpolationRequiresStyleResolve(toCSSSVGDocumentValue(value));        // FIXME: consider other custom types.        return true;    case CSSValue::CSS_INITIAL:        // FIXME: should not require resolving styles for initial.        return true;    default:        ASSERT_NOT_REACHED();        return true;    }}

bool CSSCursorImageValue::updateIfSVGCursorIsUsed(Element* element){    if (!element || !element->isSVGElement())        return false;    if (!isSVGCursor())        return false;    if (SVGCursorElement* cursorElement = resourceReferencedByCursorElement(toCSSImageValue(m_imageValue.get()).url(), element->document())) {        // FIXME: This will override hot spot specified in CSS, which is probably incorrect.        SVGLengthContext lengthContext(0);        m_hasHotSpot = true;        float x = roundf(cursorElement->x().value(lengthContext));        m_hotSpot.setX(static_cast<int>(x));        float y = roundf(cursorElement->y().value(lengthContext));        m_hotSpot.setY(static_cast<int>(y));        if (cachedImageURL() != element->document().completeURL(cursorElement->href()))            clearCachedImage();        SVGElement& svgElement = downcast<SVGElement>(*element);        m_referencedElements.add(&svgElement);        svgElement.setCursorImageValue(this);        cursorElement->addClient(&svgElement);        return true;    }    return false;}

String CSSValue::cssText() const{    if (m_isTextClone) {         ASSERT(isCSSOMSafe());        return toTextCloneCSSValue(this)->cssText();    }    ASSERT(!isCSSOMSafe() || isSubtypeExposedToCSSOM());    switch (classType()) {    case AspectRatioClass:        return toCSSAspectRatioValue(this)->customCSSText();    case BorderImageSliceClass:        return toCSSBorderImageSliceValue(this)->customCSSText();    case FontClass:        return toCSSFontValue(this)->customCSSText();    case FontFaceSrcClass:        return toCSSFontFaceSrcValue(this)->customCSSText();    case FontFeatureClass:        return toCSSFontFeatureValue(this)->customCSSText();    case FunctionClass:        return toCSSFunctionValue(this)->customCSSText();    case LinearGradientClass:        return toCSSLinearGradientValue(this)->customCSSText();    case RadialGradientClass:        return toCSSRadialGradientValue(this)->customCSSText();    case CrossfadeClass:        return toCSSCrossfadeValue(this)->customCSSText();    case ImageClass:        return toCSSImageValue(this)->customCSSText();    case InheritedClass:        return toCSSInheritedValue(this)->customCSSText();    case InitialClass:        return toCSSInitialValue(this)->customCSSText();    case PrimitiveClass:        return toCSSPrimitiveValue(this)->customCSSText();    case ShadowClass:        return toCSSShadowValue(this)->customCSSText();    case CubicBezierTimingFunctionClass:        return toCSSCubicBezierTimingFunctionValue(this)->customCSSText();    case StepsTimingFunctionClass:        return toCSSStepsTimingFunctionValue(this)->customCSSText();    case UnicodeRangeClass:        return toCSSUnicodeRangeValue(this)->customCSSText();    case ValueListClass:        return toCSSValueList(this)->customCSSText();    case CSSTransformClass:        return toCSSTransformValue(this)->customCSSText();    case LineBoxContainClass:        return toCSSLineBoxContainValue(this)->customCSSText();    case CalculationClass:        return toCSSCalcValue(this)->customCSSText();    case ImageSetClass:        return toCSSImageSetValue(this)->customCSSText();    case CSSFilterClass:        return toCSSFilterValue(this)->customCSSText();    }    ASSERT_NOT_REACHED();    return String();}

static bool subimageKnownToBeOpaque(CSSValue& value, const RenderElement* renderer){    if (value.isImageValue())        return toCSSImageValue(value).knownToBeOpaque(renderer);    if (value.isImageGeneratorValue())        return toCSSImageGeneratorValue(value).knownToBeOpaque(renderer);    ASSERT_NOT_REACHED();    return false;}

bool CSSValue::hasFailedOrCanceledSubresources() const {  if (isValueList())    return toCSSValueList(this)->hasFailedOrCanceledSubresources();  if (getClassType() == FontFaceSrcClass)    return toCSSFontFaceSrcValue(this)->hasFailedOrCanceledSubresources();  if (getClassType() == ImageClass)    return toCSSImageValue(this)->hasFailedOrCanceledSubresources();  if (getClassType() == CrossfadeClass)    return toCSSCrossfadeValue(this)->hasFailedOrCanceledSubresources();  if (getClassType() == ImageSetClass)    return toCSSImageSetValue(this)->hasFailedOrCanceledSubresources();  return false;}

PassRefPtrWillBeRawPtr<StyleImage> ElementStyleResources::styleImage(CSSPropertyID property, const CSSValue& value){    if (value.isImageValue())        return cachedOrPendingFromValue(property, toCSSImageValue(value));    if (value.isImageGeneratorValue())        return generatedOrPendingFromValue(property, toCSSImageGeneratorValue(value));    if (value.isImageSetValue())        return setOrPendingFromValue(property, toCSSImageSetValue(value));    if (value.isCursorImageValue())        return cursorOrPendingFromValue(property, toCSSCursorImageValue(value));    return nullptr;}

StyleImage* CSSCursorImageValue::cachedImage(ResourceFetcher* loader, float deviceScaleFactor){    if (m_imageValue->isImageSetValue())        return toCSSImageSetValue(m_imageValue.get())->cachedImageSet(loader, deviceScaleFactor);    if (!m_accessedImage) {        m_accessedImage = true;        if (m_imageValue->isImageValue())            m_image = toCSSImageValue(m_imageValue.get())->cachedImage(loader);    }    if (m_image && m_image->isImageResource())        return toStyleFetchedImage(m_image);    return 0;}

CSSCursorImageValue::~CSSCursorImageValue(){    if (!isSVGCursor())        return;    HashSet<SVGElement*>::const_iterator it = m_referencedElements.begin();    HashSet<SVGElement*>::const_iterator end = m_referencedElements.end();    String url = toCSSImageValue(m_imageValue.get())->url();    for (; it != end; ++it) {        SVGElement* referencedElement = *it;        referencedElement->cursorImageValueRemoved();        if (SVGCursorElement* cursorElement = resourceReferencedByCursorElement(url, referencedElement->document()))            cursorElement->removeClient(referencedElement);    }}

PassRefPtr<StyleImage> ElementStyleResources::styleImage(Document& document, const TextLinkColors& textLinkColors, Color currentColor, CSSPropertyID property, CSSValue* value){    if (value->isImageValue())        return cachedOrPendingFromValue(document, property, toCSSImageValue(value));    if (value->isImageGeneratorValue()) {        if (value->isGradientValue())            return generatedOrPendingFromValue(property, toCSSGradientValue(value)->gradientWithStylesResolved(textLinkColors, currentColor).get());        return generatedOrPendingFromValue(property, toCSSImageGeneratorValue(value));    }    if (value->isImageSetValue())        return setOrPendingFromValue(property, toCSSImageSetValue(value));    return nullptr;}

CSSCursorImageValue::~CSSCursorImageValue(){    // The below teardown is all handled by weak pointer processing in oilpan.#if !ENABLE(OILPAN)    if (!isSVGCursor())        return;    String url = toCSSImageValue(m_imageValue.get())->url();    for (SVGElement* referencedElement : m_referencedElements) {        referencedElement->cursorImageValueRemoved();        if (SVGCursorElement* cursorElement = resourceReferencedByCursorElement(url, referencedElement->treeScope()))            cursorElement->removeClient(referencedElement);    }#endif}

PassRefPtrWillBeRawPtr<StyleImage> ElementStyleResources::styleImage(Document& document, const TextLinkColors& textLinkColors, Color currentColor, CSSPropertyID property, CSSValue* value){    if (value->isImageValue())        return cachedOrPendingFromValue(document, property, toCSSImageValue(value));    if (value->isImageGeneratorValue())        return generatedOrPendingFromValue(property, toCSSImageGeneratorValue(value));    if (value->isImageSetValue())        return setOrPendingFromValue(property, toCSSImageSetValue(value));    if (value->isCursorImageValue())        return cursorOrPendingFromValue(property, toCSSCursorImageValue(value));    return nullptr;}