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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "core/html/HTMLImageFallbackHelper.h"
#include "core/HTMLNames.h"
#include "core/InputTypeNames.h"
#include "core/dom/ElementRareData.h"
#include "core/dom/Text.h"
#include "core/dom/shadow/ShadowRoot.h"
#include "core/html/HTMLDivElement.h"
#include "core/html/HTMLElement.h"
#include "core/html/HTMLImageElement.h"
#include "core/html/HTMLImageLoader.h"
#include "core/html/HTMLInputElement.h"
#include "core/html/HTMLStyleElement.h"
#include "wtf/text/StringBuilder.h"
namespace blink {
using namespace HTMLNames;
static bool noImageSourceSpecified(const Element& element) {
bool noSrcSpecified = !element.hasAttribute(srcAttr) ||
element.getAttribute(srcAttr).isNull() ||
element.getAttribute(srcAttr).isEmpty();
bool noSrcsetSpecified = !element.hasAttribute(srcsetAttr) ||
element.getAttribute(srcsetAttr).isNull() ||
element.getAttribute(srcsetAttr).isEmpty();
return noSrcSpecified && noSrcsetSpecified;
}
void HTMLImageFallbackHelper::createAltTextShadowTree(Element& element) {
ShadowRoot& root = element.ensureUserAgentShadowRoot();
HTMLDivElement* container = HTMLDivElement::create(element.document());
root.appendChild(container);
container->setAttribute(idAttr, AtomicString("alttext-container"));
container->setInlineStyleProperty(CSSPropertyOverflow, CSSValueHidden);
container->setInlineStyleProperty(CSSPropertyBorderWidth, 1,
CSSPrimitiveValue::UnitType::Pixels);
container->setInlineStyleProperty(CSSPropertyBorderStyle, CSSValueSolid);
container->setInlineStyleProperty(CSSPropertyBorderColor, CSSValueSilver);
container->setInlineStyleProperty(CSSPropertyDisplay, CSSValueInlineBlock);
container->setInlineStyleProperty(CSSPropertyBoxSizing, CSSValueBorderBox);
container->setInlineStyleProperty(CSSPropertyPadding, 1,
CSSPrimitiveValue::UnitType::Pixels);
HTMLImageElement* brokenImage = HTMLImageElement::create(element.document());
container->appendChild(brokenImage);
brokenImage->setIsFallbackImage();
brokenImage->setAttribute(idAttr, AtomicString("alttext-image"));
brokenImage->setAttribute(widthAttr, AtomicString("16"));
brokenImage->setAttribute(heightAttr, AtomicString("16"));
brokenImage->setAttribute(alignAttr, AtomicString("left"));
brokenImage->setInlineStyleProperty(CSSPropertyMargin, 0,
CSSPrimitiveValue::UnitType::Pixels);
HTMLDivElement* altText = HTMLDivElement::create(element.document());
container->appendChild(altText);
altText->setAttribute(idAttr, AtomicString("alttext"));
altText->setInlineStyleProperty(CSSPropertyOverflow, CSSValueHidden);
altText->setInlineStyleProperty(CSSPropertyDisplay, CSSValueBlock);
Text* text =
Text::create(element.document(), toHTMLElement(element).altText());
altText->appendChild(text);
}
PassRefPtr<ComputedStyle> HTMLImageFallbackHelper::customStyleForAltText(
Element& element,
PassRefPtr<ComputedStyle> newStyle) {
// If we have an author shadow root or have not created the UA shadow root
// yet, bail early. We can't use ensureUserAgentShadowRoot() here because that
// would alter the DOM tree during style recalc.
if (element.authorShadowRoot() || !element.userAgentShadowRoot())
return newStyle;
Element* placeHolder =
element.userAgentShadowRoot()->getElementById("alttext-container");
Element* brokenImage =
element.userAgentShadowRoot()->getElementById("alttext-image");
// Input elements have a UA shadow root of their own. We may not have replaced
// it with fallback content yet.
if (!placeHolder || !brokenImage)
return newStyle;
if (element.document().inQuirksMode()) {
// Mimic the behaviour of the image host by setting symmetric dimensions if
// only one dimension is specified.
if (newStyle->width().isSpecifiedOrIntrinsic() &&
newStyle->height().isAuto())
newStyle->setHeight(newStyle->width());
else if (newStyle->height().isSpecifiedOrIntrinsic() &&
newStyle->width().isAuto())
newStyle->setWidth(newStyle->height());
if (newStyle->width().isSpecifiedOrIntrinsic() &&
newStyle->height().isSpecifiedOrIntrinsic()) {
placeHolder->setInlineStyleProperty(CSSPropertyVerticalAlign,
CSSValueBaseline);
}
}
// If the image has specified dimensions allow the alt-text container expand
// to fill them.
if (newStyle->width().isSpecifiedOrIntrinsic() &&
newStyle->height().isSpecifiedOrIntrinsic()) {
placeHolder->setInlineStyleProperty(
CSSPropertyWidth, 100, CSSPrimitiveValue::UnitType::Percentage);
placeHolder->setInlineStyleProperty(
CSSPropertyHeight, 100, CSSPrimitiveValue::UnitType::Percentage);
}
// Make sure the broken image icon appears on the appropriate side of the
// image for the element's writing direction.
brokenImage->setInlineStyleProperty(
CSSPropertyFloat,
AtomicString(newStyle->direction() == TextDirection::kLtr ? "left"
: "right"));
// This is an <img> with no attributes, so don't display anything.
if (noImageSourceSpecified(element) &&
!newStyle->width().isSpecifiedOrIntrinsic() &&
!newStyle->height().isSpecifiedOrIntrinsic() &&
toHTMLElement(element).altText().isEmpty())
newStyle->setDisplay(EDisplay::None);
// This preserves legacy behaviour originally defined when alt-text was
// managed by LayoutImage.
if (noImageSourceSpecified(element))
brokenImage->setInlineStyleProperty(CSSPropertyDisplay, CSSValueNone);
else
brokenImage->setInlineStyleProperty(CSSPropertyDisplay, CSSValueInline);
return newStyle;
}
} // namespace blink
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