third_party/WebKit/Source/core/css/CSSImageSetValue.cpp

/*
 * Copyright (C) 2012 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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#include "core/css/CSSImageSetValue.h"

#include "core/css/CSSImageValue.h"
#include "core/css/CSSPrimitiveValue.h"
#include "core/dom/Document.h"
#include "core/fetch/FetchInitiatorTypeNames.h"
#include "core/fetch/FetchRequest.h"
#include "core/fetch/ImageResource.h"
#include "core/fetch/ResourceFetcher.h"
#include "core/fetch/ResourceLoaderOptions.h"
#include "core/frame/Settings.h"
#include "core/style/StyleFetchedImageSet.h"
#include "core/style/StyleInvalidImage.h"
#include "platform/weborigin/KURL.h"
#include "platform/weborigin/SecurityPolicy.h"
#include "wtf/text/StringBuilder.h"
#include <algorithm>

namespace blink {

CSSImageSetValue::CSSImageSetValue()
    : CSSValueList(ImageSetClass, CommaSeparator), m_cachedScaleFactor(1) {}

CSSImageSetValue::~CSSImageSetValue() {}

void CSSImageSetValue::fillImageSet() {
  size_t length = this->length();
  size_t i = 0;
  while (i < length) {
    const CSSImageValue& imageValue = toCSSImageValue(item(i));
    String imageURL = imageValue.url();

    ++i;
    SECURITY_DCHECK(i < length);
    const CSSValue& scaleFactorValue = item(i);
    float scaleFactor = toCSSPrimitiveValue(scaleFactorValue).getFloatValue();

    ImageWithScale image;
    image.imageURL = imageURL;
    image.referrer = SecurityPolicy::generateReferrer(
        imageValue.referrer().referrerPolicy, KURL(ParsedURLString, imageURL),
        imageValue.referrer().referrer);
    image.scaleFactor = scaleFactor;
    m_imagesInSet.append(image);
    ++i;
  }

  // Sort the images so that they are stored in order from lowest resolution to
  // highest.
  std::sort(m_imagesInSet.begin(), m_imagesInSet.end(),
            CSSImageSetValue::compareByScaleFactor);
}

CSSImageSetValue::ImageWithScale CSSImageSetValue::bestImageForScaleFactor(
    float scaleFactor) {
  ImageWithScale image;
  size_t numberOfImages = m_imagesInSet.size();
  for (size_t i = 0; i < numberOfImages; ++i) {
    image = m_imagesInSet.at(i);
    if (image.scaleFactor >= scaleFactor)
      return image;
  }
  return image;
}

bool CSSImageSetValue::isCachePending(float deviceScaleFactor) const {
  return !m_cachedImage || deviceScaleFactor != m_cachedScaleFactor;
}

StyleImage* CSSImageSetValue::cachedImage(float deviceScaleFactor) const {
  ASSERT(!isCachePending(deviceScaleFactor));
  return m_cachedImage.get();
}

StyleImage* CSSImageSetValue::cacheImage(
    const Document& document,
    float deviceScaleFactor,
    CrossOriginAttributeValue crossOrigin) {
  if (!m_imagesInSet.size())
    fillImageSet();

  if (isCachePending(deviceScaleFactor)) {
    // FIXME: In the future, we want to take much more than deviceScaleFactor
    // into acount here. All forms of scale should be included:
    // Page::pageScaleFactor(), LocalFrame::pageZoomFactor(), and any CSS
    // transforms. https://bugs.webkit.org/show_bug.cgi?id=81698
    ImageWithScale image = bestImageForScaleFactor(deviceScaleFactor);
    FetchRequest request(ResourceRequest(document.completeURL(image.imageURL)),
                         FetchInitiatorTypeNames::css);
    request.mutableResourceRequest().setHTTPReferrer(image.referrer);

    if (crossOrigin != CrossOriginAttributeNotSet)
      request.setCrossOriginAccessControl(document.getSecurityOrigin(),
                                          crossOrigin);
    if (document.settings() && document.settings()->fetchImagePlaceholders())
      request.setAllowImagePlaceholder();

    if (ImageResource* cachedImage =
            ImageResource::fetch(request, document.fetcher()))
      m_cachedImage = StyleFetchedImageSet::create(
          cachedImage, image.scaleFactor, this, request.url());
    else
      m_cachedImage = StyleInvalidImage::create(image.imageURL);
    m_cachedScaleFactor = deviceScaleFactor;
  }

  return m_cachedImage.get();
}

String CSSImageSetValue::customCSSText() const {
  StringBuilder result;
  result.append("-webkit-image-set(");

  size_t length = this->length();
  size_t i = 0;
  while (i < length) {
    if (i > 0)
      result.append(", ");

    const CSSValue& imageValue = item(i);
    result.append(imageValue.cssText());
    result.append(' ');

    ++i;
    SECURITY_DCHECK(i < length);
    const CSSValue& scaleFactorValue = item(i);
    result.append(scaleFactorValue.cssText());
    // FIXME: Eventually the scale factor should contain it's own unit
    // http://wkb.ug/100120.
    // For now 'x' is hard-coded in the parser, so we hard-code it here too.
    result.append('x');

    ++i;
  }

  result.append(')');
  return result.toString();
}

bool CSSImageSetValue::hasFailedOrCanceledSubresources() const {
  if (!m_cachedImage)
    return false;
  if (Resource* cachedResource = m_cachedImage->cachedImage())
    return cachedResource->loadFailedOrCanceled();
  return true;
}

DEFINE_TRACE_AFTER_DISPATCH(CSSImageSetValue) {
  visitor->trace(m_cachedImage);
  CSSValueList::traceAfterDispatch(visitor);
}

CSSImageSetValue* CSSImageSetValue::valueWithURLsMadeAbsolute() {
  CSSImageSetValue* value = CSSImageSetValue::create();
  for (auto& item : *this)
    item->isImageValue()
        ? value->append(*toCSSImageValue(*item).valueWithURLMadeAbsolute())
        : value->append(*item);
  return value;
}

}  // namespace blink