| // 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::Ltr ? "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 |