Translate viewport related meta tags into @viewport descriptors as suggested by the CSS Device Adap…

Source/core/html/HTMLMetaElement-in.cpp

+/*
+ * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
+ *           (C) 1999 Antti Koivisto (koivisto@kde.org)
+ *           (C) 2001 Dirk Mueller (mueller@kde.org)
+ * Copyright (C) 2003, 2010 Apple Inc. All rights reserved.
+ * Copyright (C) 2013 Intel Corporation. All rights reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public License
+ * along with this library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "config.h"
+#include "core/html/HTMLMetaElement.h"
+
+#include "HTMLNames.h"
+#include "RuntimeEnabledFeatures.h"
+#include "core/css/CSSStyleSheet.h"
+#include "core/css/CSSValuePool.h"
+#include "core/css/MediaList.h"
+#include "core/css/StylePropertySet.h"
+#include "core/css/StyleSheetContents.h"
+#include "core/dom/Document.h"
+#include "core/dom/DocumentStyleSheetCollection.h"
+#include "wtf/text/TextPosition.h"
+
+namespace WebCore {
+
+using namespace HTMLNames;
+using namespace std;
+
+inline HTMLMetaElement::HTMLMetaElement(const QualifiedName& tagName, Document* document)
+    : HTMLElement(tagName, document)
+{
+    ASSERT(hasTagName(metaTag));
+    ScriptWrappable::init(this);
+}
+
+HTMLMetaElement::~HTMLMetaElement()
+{
+    removeStyleSheet();
+}
+
+PassRefPtr<HTMLMetaElement> HTMLMetaElement::create(Document* document)
+{
+    return adoptRef(new HTMLMetaElement(metaTag, document));
+}
+
+PassRefPtr<HTMLMetaElement> HTMLMetaElement::create(const QualifiedName& tagName, Document* document)
+{
+    return adoptRef(new HTMLMetaElement(tagName, document));
+}
+
+void HTMLMetaElement::removedFrom(ContainerNode* insertionPoint)
+{
+    HTMLElement::removedFrom(insertionPoint);
+    removeStyleSheet();
+}
+
+Node::InsertionNotificationRequest HTMLMetaElement::insertedInto(ContainerNode* insertionPoint)
+{
+    HTMLElement::insertedInto(insertionPoint);
+    if (insertionPoint->inDocument())
+        process();
+    return InsertionDone;
+}
+
+
+static inline bool isValueSeparator(UChar c, bool* ok)
+{
+    if (ok && c == ';')
+        *ok = false;
+    // Though isspace() considers \t and \v to be whitespace, Win IE doesn't.
+    return c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '=' || c == ',' || c == '\0';
+}
+
+static inline bool isPropertySeparator(UChar c, bool* ok)
+{
+    if (ok && c == ';')
+        *ok = false;
+    return c == ',';
+}
+
+float HTMLMetaElement::parsePositiveNumber(const String& property, const String& value, float minValue, float maxValue)
+{
+    size_t parsedLength;
+    float rawValue;
+    float fValue;
+    if (value.is8Bit())
+        rawValue = charactersToFloat(value.characters8(), value.length(), parsedLength);
+    else
+        rawValue = charactersToFloat(value.characters16(), value.length(), parsedLength);
+
+    if (!parsedLength || rawValue < 0) {
+        reportError(InvalidValueError, property, value);
+        return -1;
+    }
+
+    if (parsedLength < value.length())
+        reportError(TruncatedValueError, property, value);
+
+    fValue = min(maxValue, max(rawValue, minValue));
+    if (fValue != rawValue)
+        reportError(OutOfBoundsValueError, property, value);
+
+    return fValue;
+}
+
+void HTMLMetaElement::reportError(ErrorType error, const String& property, const String& value)
+{
+    StringBuilder builder;
+
+    switch (error) {
+    case NoError:
+        return;
+
+    case InvalidPropertySeparatorError:
+        builder.appendLiteral("Note that ';' is not a property separator. The list should be comma-separated.");
+        break;
+
+    case InvalidPropertyError:
+        builder.appendLiteral("Property \"");
+        builder.append(property);
+        builder.appendLiteral("\" not recognized and ignored.");
+        break;
+
+    case InvalidValueError:
+    case OutOfBoundsValueError:
+    case TruncatedValueError:
+        if (!value.isEmpty()) {
+            builder.appendLiteral("The value \"");
+            builder.append(value);
+            builder.append('\"');
+        } else {
+            builder.appendLiteral("The empty value");
+        }
+
+        if (!property.isNull()) {
+            builder.appendLiteral(" for property \"");
+            builder.append(property);
+            builder.append('\"');
+        }
+
+        if (error == InvalidValueError)
+            builder.appendLiteral(" is invalid and the property has been ignored.");
+        else if (error == OutOfBoundsValueError)
+            builder.appendLiteral(" is out of bounds and the value has been clamped.");
+        else
+            builder.appendLiteral(" was truncated to its numeric prefix.");
+        break;
+
+    default:
+        ASSERT_NOT_REACHED();
+    }
+
+    document()->addConsoleMessage(MetaContentMessageSource, WarningMessageLevel, builder.toString());
+}
+
+void HTMLMetaElement::parseContentAttribute(MutableStylePropertySet* properties, const String& content, PropertyCollector callback)
+{
+    bool ok = true;
+
+    // Tread lightly in this code -- it was specifically designed to mimic Win IE's parsing behavior.
+    int keyBegin, keyEnd;
+    int valueBegin, valueEnd;
+
+    int i = 0;
+    int length = content.length();
+    String buffer = content.lower();
+    while (i < length) {
+        // Skip to first non-separator, but don't skip past the end of the string.
+        while (isValueSeparator(buffer[i], &ok)) {
+            if (i >= length)
+                break;
+            i++;
+        }
+        keyBegin = i;
+
+        // skip to first separator
+        while (!isValueSeparator(buffer[i], &ok))
+            i++;
+        keyEnd = i;
+
+        // Skip to first '=', but don't skip past a ',' or the end of the string.
+        while (buffer[i] != '=') {
+            if (isPropertySeparator(buffer[i], &ok) || i >= length)
+                break;
+            i++;
+        }
+
+        // Skip to first non-separator, but don't skip past a ',' or the end of the string.
+        while (isValueSeparator(buffer[i], &ok)) {
+            if (isPropertySeparator(buffer[i], &ok) || i >= length)
+                break;
+            i++;
+        }
+        valueBegin = i;
+
+        // Skip to first separator.
+        while (!isValueSeparator(buffer[i], &ok))
+            i++;
+        valueEnd = i;
+
+        ASSERT_WITH_SECURITY_IMPLICATION(i <= length);
+
+        String propertyString = buffer.substring(keyBegin, keyEnd - keyBegin);
+        String valueString = buffer.substring(valueBegin, valueEnd - valueBegin);
+
+        callback(this, properties, propertyString, valueString);
+    }
+    if (!ok)
+        reportError(InvalidPropertySeparatorError, String(), String());
+}
+
+PassRefPtr<CSSValue> HTMLMetaElement::parseViewportValueAsLength(const String& propertyString, const String& valueString)
+{
+    const UChar* characters;
+    unsigned valueLength = valueString.length();
+
+    const unsigned longestValueLength = 13;
+    UChar characterBuffer[longestValueLength];
+    if (valueString.is8Bit()) {
+        unsigned length = std::min(longestValueLength, valueLength);
+        const LChar* characters8 = valueString.characters8();
+        for (unsigned i = 0; i < length; ++i)
+            characterBuffer[i] = characters8[i];
+        characters = characterBuffer;
+    } else {
+        characters = valueString.characters16();
+    }
+
+    SWITCH(characters, valueLength) {
+        CASE("device-width") {
+            return cssValuePool().createValue(100, CSSPrimitiveValue::CSS_PERCENTAGE);
+        }
+        CASE("device-height") {
+            return cssValuePool().createValue(100, CSSPrimitiveValue::CSS_PERCENTAGE);
+        }
+    }
+
+    // Other keywords and unknown values translate to 1px.
+    float value = parsePositiveNumber(propertyString, valueString, float(1), float(10000));
+    if (value >= 0)
+        return cssValuePool().createValue(value, CSSPrimitiveValue::CSS_PX);
+
+    return 0;
+}
+
+PassRefPtr<CSSValue> HTMLMetaElement::parseViewportValueAsZoom(const String& propertyString, const String& valueString)
+{
+    const UChar* characters;
+    unsigned valueLength = valueString.length();
+
+    const unsigned longestValueLength = 13;
+    UChar characterBuffer[longestValueLength];
+    if (valueString.is8Bit()) {
+        unsigned length = std::min(longestValueLength, valueLength);
+        const LChar* characters8 = valueString.characters8();
+        for (unsigned i = 0; i < length; ++i)
+            characterBuffer[i] = characters8[i];
+        characters = characterBuffer;
+    } else {
+        characters = valueString.characters16();
+    }
+
+    float value = -1;
+    SWITCH(characters, valueLength) {
+        CASE("yes") {
+            value = 1;
+        }
+        CASE("no") {
+            value = 0.1;
+        }
+        CASE("device-width") {
+            value = 10;
+        }
+        CASE("device-height") {
+            value = 10;
+        }
+    }
+
+    if (value < 0)
+        value = parsePositiveNumber(propertyString, valueString, float(0.1), float(10));
+    if (value >= 0)
+        return cssValuePool().createValue(value, CSSPrimitiveValue::CSS_NUMBER);
+
+    return 0;
+}
+
+CSSValueID HTMLMetaElement::parseViewportValueAsUserZoom(const String& propertyString, const String& valueString)
+{
+    const UChar* characters;
+    unsigned valueLength = valueString.length();
+
+    const unsigned longestValueLength = 13;
+    UChar characterBuffer[longestValueLength];
+    if (valueString.is8Bit()) {
+        unsigned length = std::min(longestValueLength, valueLength);
+        const LChar* characters8 = valueString.characters8();
+        for (unsigned i = 0; i < length; ++i)
+            characterBuffer[i] = characters8[i];
+        characters = characterBuffer;
+    } else {
+        characters = valueString.characters16();
+    }
+
+    SWITCH(characters, valueLength) {
+        CASE("yes") {
+            return CSSValueZoom;
+        }
+        CASE("no") {
+            return CSSValueFixed;
+        }
+        CASE("device-width") {
+            return CSSValueZoom;
+        }
+        CASE("device-height") {
+            return CSSValueZoom;
+        }
+    }
+
+    float value = parsePositiveNumber(propertyString, valueString, float(0), float(1));
+    // Numbers in the range <-1, 1>, and unknown values (represented as 0), are mapped to "fixed".

[apavlov, 2013/07/30 12:06:45]

You should use (-1, 1) to denote the open interval (since 1 and -1 are mapped to
"zoom")

+    // Numbers >= 1, numbers <= -1 are mapped to "zoom"
+    return (value > -1 && value < 1) ? CSSValueFixed : CSSValueZoom;
+}
+
+PassRefPtr<CSSValue> HTMLMetaElement::parseViewportValueAsDPI(const String& propertyString, const String& valueString)
+{
+    const UChar* characters;
+    unsigned valueLength = valueString.length();
+
+    const unsigned longestValueLength = 10;
+    UChar characterBuffer[longestValueLength];
+    if (valueString.is8Bit()) {
+        unsigned length = std::min(longestValueLength, valueLength);
+        const LChar* characters8 = valueString.characters8();
+        for (unsigned i = 0; i < length; ++i)
+            characterBuffer[i] = characters8[i];
+        characters = characterBuffer;
+    } else {
+        characters = valueString.characters16();
+    }
+
+    CSSValueID id = CSSValueAuto; // Fallback for invalid.
+    SWITCH(characters, valueLength) {
+        CASE("device-dpi") {
+            id = CSSValueDevice;
+        }
+        CASE("low-dpi") {
+            id = CSSValueSmall;
+        }
+        CASE("medium-dpi") {
+            id = CSSValueMedium;
+        }
+        CASE("high-dpi") {
+            id = CSSValueLarge;
+        }
+    }
+
+    if (id == CSSValueAuto) {
+        float value = parsePositiveNumber(propertyString, valueString, float(70), float(400));
+
+        if (value >= 70 && value <= 400)
+            return cssValuePool().createValue(value, CSSPrimitiveValue::CSS_NUMBER);
+    }
+
+    return cssValuePool().createIdentifierValue(id);
+}
+
+void HTMLMetaElement::viewportPropertyCollector(HTMLMetaElement* self, MutableStylePropertySet* properties, const String& propertyString, const String& valueString)
+{
+    const UChar* characters;
+    unsigned propertyLength = propertyString.length();
+
+    const unsigned longestPropertyLength = 17;
+    UChar characterBuffer[longestPropertyLength];
+    if (propertyString.is8Bit()) {
+        unsigned length = std::min(longestPropertyLength, propertyLength);
+        const LChar* characters8 = propertyString.characters8();
+        for (unsigned i = 0; i < length; ++i)
+            characterBuffer[i] = characters8[i];
+        characters = characterBuffer;
+    } else {
+        characters = propertyString.characters16();
+    }
+
+    SWITCH(characters, propertyLength) {
+        CASE("width") {
+            RefPtr<CSSValue> value = self->parseViewportValueAsLength(propertyString, valueString);
+            if (!value)
+                return;
+            properties->setProperty(CSSPropertyMinWidth, CSSValueExtendToZoom);
+            properties->setProperty(CSSPropertyMaxWidth, value);
+            return;
+        }
+        CASE("height") {
+            RefPtr<CSSValue> value = self->parseViewportValueAsLength(propertyString, valueString);
+            if (!value)
+                return;
+            properties->setProperty(CSSPropertyMinHeight, CSSValueExtendToZoom);
+            properties->setProperty(CSSPropertyMaxHeight, value);
+            return;
+        }
+        CASE("initial-scale") {
+            if (RefPtr<CSSValue> value = self->parseViewportValueAsZoom(propertyString, valueString))
+                properties->setProperty(CSSPropertyZoom, value);
+            return;
+        }
+        CASE("minimum-scale") {
+            if (RefPtr<CSSValue> value = self->parseViewportValueAsZoom(propertyString, valueString))
+                properties->setProperty(CSSPropertyMinZoom, value);
+            return;
+        }
+        CASE("maximum-scale") {
+            if (RefPtr<CSSValue> value = self->parseViewportValueAsZoom(propertyString, valueString))
+                properties->setProperty(CSSPropertyMaxZoom, value);
+            return;
+        }
+        CASE("user-scalable") {
+            CSSValueID value = self->parseViewportValueAsUserZoom(propertyString, valueString);
+            properties->setProperty(CSSPropertyUserZoom, value);
+            return;
+        }
+        CASE("target-densitydpi") {
+            RefPtr<CSSValue> value = self->parseViewportValueAsDPI(propertyString, valueString);
+            properties->setProperty(CSSPropertyInternalTargetDensity, value);
+            return;
+        }
+    }
+    self->reportError(InvalidPropertyError, propertyString, String());
+}
+
+PassRefPtr<StyleRuleBase> HTMLMetaElement::parseViewportContent(const String& contentValue)
+{
+    RefPtr<StyleRuleViewport> rule = StyleRuleViewport::create();
+    RefPtr<MutableStylePropertySet> properties = MutableStylePropertySet::create(CSSStrictMode);
+    parseContentAttribute(properties.get(), contentValue, &HTMLMetaElement::viewportPropertyCollector);
+
+    // For a viewport META element that translates into an @viewport rule with a
+    // non-"auto" "zoom" declaration and no "width" declaration:
+    // If it adds a "height" descriptor, add: width: auto; Otherwise, add: width: extend-to-zoom;
+    RefPtr<CSSValue> widthValue = properties->getPropertyCSSValue(CSSPropertyMinWidth);
+    RefPtr<CSSValue> zoomValue = properties->getPropertyCSSValue(CSSPropertyZoom);
+
+    if (!widthValue && zoomValue) {
+        RefPtr<CSSValue> heightValue = properties->getPropertyCSSValue(CSSPropertyMinHeight);
+        CSSValueID commonHeightValue = heightValue ? CSSValueAuto : CSSValueExtendToZoom;
+        properties->setProperty(CSSPropertyMinWidth, commonHeightValue);
+        properties->setProperty(CSSPropertyMaxWidth, commonHeightValue);
+    }
+
+    rule->setProperties(properties);
+
+    return rule.release();
+}
+
+PassRefPtr<StyleRuleBase> HTMLMetaElement::parseHandheldFriendlyContent(const String& contentValue)
+{
+    RefPtr<StyleRuleViewport> rule = StyleRuleViewport::create();
+    RefPtr<MutableStylePropertySet> properties = MutableStylePropertySet::create(CSSStrictMode);
+    properties->setProperty(CSSPropertyInternalPriority, cssValuePool().createValue(2, CSSPrimitiveValue::CSS_NUMBER));
+
+    if (equalIgnoringCase(contentValue, "true")) {
+        properties->setProperty(CSSPropertyMinWidth, cssValuePool().createValue(100, CSSPrimitiveValue::CSS_PERCENTAGE));
+        properties->setProperty(CSSPropertyMaxWidth, cssValuePool().createValue(100, CSSPrimitiveValue::CSS_PERCENTAGE));
+    }
+
+    rule->setProperties(properties);
+    return rule.release();
+}
+
+PassRefPtr<StyleRuleBase> HTMLMetaElement::parseMobileOptimizedContent(const String& contentValue)
+{
+    RefPtr<StyleRuleViewport> rule = StyleRuleViewport::create();
+    RefPtr<MutableStylePropertySet> properties = MutableStylePropertySet::create(CSSStrictMode);
+    properties->setProperty(CSSPropertyInternalPriority, cssValuePool().createValue(3, CSSPrimitiveValue::CSS_NUMBER));
+
+    float value = parsePositiveNumber(String(), contentValue, float(0), float(10000));
+    RefPtr<CSSValue> widthValue;
+    if (value > 0)
+        widthValue = cssValuePool().createValue(value, CSSPrimitiveValue::CSS_PX);
+    else
+        widthValue = cssValuePool().createValue(100, CSSPrimitiveValue::CSS_PERCENTAGE);
+
+    properties->setProperty(CSSPropertyMinWidth, CSSValueAuto);
+    properties->setProperty(CSSPropertyMaxWidth, widthValue);
+
+    rule->setProperties(properties);
+    return rule.release();
+}
+
+void HTMLMetaElement::parseAttribute(const QualifiedName& name, const AtomicString& value)
+{
+    if (name == http_equivAttr || name == contentAttr) {
+        process();
+    } else if (name == nameAttr) {
+        // Do nothing.
+    } else {
+        HTMLElement::parseAttribute(name, value);
+    }
+}
+
+void HTMLMetaElement::process()
+{
+    // We always need to clear rules as the meta tag could have been modified.
+    removeStyleSheet();
+
+    if (!inDocument())
+        return;
+
+    // All below situations requires a content attribute (which can be the empty string).
+    const AtomicString& contentValue = fastGetAttribute(contentAttr);
+    if (contentValue.isNull())
+        return;
+
+    const AtomicString& nameValue = fastGetAttribute(nameAttr);
+
+    if (nameValue.isNull()) {
+        // Get the document to process the tag, but only if we're actually part of DOM tree (changing a meta tag while
+        // it's not in the tree shouldn't have any effect on the document)
+        const AtomicString& httpEquivValue = fastGetAttribute(http_equivAttr);
+        if (!httpEquivValue.isNull())
+            document()->processHttpEquiv(httpEquivValue, contentValue);
+        return;
+    }
+
+    if (equalIgnoringCase(nameValue, "viewport")) {
+        addStyleSheetForRule(parseViewportContent(contentValue));
+    } else if (equalIgnoringCase(name(), "handheldfriendly")) {
+        addStyleSheetForRule(parseHandheldFriendlyContent(contentValue));
+    } else if (equalIgnoringCase(name(), "mobileoptimized")) {
+        addStyleSheetForRule(parseMobileOptimizedContent(contentValue));
+    } else if (equalIgnoringCase(name(), "referrer")) {
+        document()->processReferrerPolicy(contentValue);
+    }
+}
+
+void HTMLMetaElement::addStyleSheetForRule(PassRefPtr<StyleRuleBase> rule)
+{
+    ASSERT(inDocument());
+    ASSERT(!m_sheet);
+
+    document()->styleSheetCollection()->addStyleSheetCandidateNode(this, false);
+
+    document()->styleSheetCollection()->addPendingSheet();
+
+    // As the stylesheet has no source URL, the position makes no difference.
+    TextPosition startPosition = TextPosition::minimumPosition();
+
+    m_sheet = CSSStyleSheet::createInline(this, KURL(), startPosition, document()->inputEncoding());
+
+    m_sheet->setMediaQueries(MediaQuerySet::create("screen"));
+    m_sheet->setTitle(title());
+
+    m_sheet->contents()->parserAppendRule(rule);
+
+    document()->styleSheetCollection()->removePendingSheet();
+}
+
+void HTMLMetaElement::removeStyleSheet()
+{
+    if (m_sheet) {
+        document()->styleSheetCollection()->removeStyleSheetCandidateNode(this);
+        m_sheet.release()->clearOwnerNode();
+    }
+
+    // No need to resolve style during teardown.
+    if (document()->renderer())
+        document()->styleResolverChanged(DeferRecalcStyle);
+}
+
+String HTMLMetaElement::content() const
+{
+    return getAttribute(contentAttr);
+}
+
+String HTMLMetaElement::httpEquiv() const
+{
+    return getAttribute(http_equivAttr);
+}
+
+String HTMLMetaElement::name() const
+{
+    return getNameAttribute();
+}
+
+}