Source/WebCore/dom/ViewportArguments.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2012 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 "ViewportArguments.h"

 #include "Document.h"
 #include "Frame.h"
 #include "IntSize.h"
 #include "RuntimeEnabledFeatures.h"
 #include "ScriptableDocumentParser.h"
 #include "Settings.h"
 #include <wtf/text/TextStream.h>

 namespace WebCore {

 typedef WTF::Function<void(ViewportErrorCode, StringView, StringView)> InternalViewportErrorHandler;

 #if PLATFORM(GTK)
 const float ViewportArguments::deprecatedTargetDPI = 160;
 #endif

 static const float& compareIgnoringAuto(const float& value1, const float& value2, const float& (*compare) (const float&, const float&))
 {
     ASSERT(value1 != ViewportArguments::ValueAuto || value2 != ViewportArguments::ValueAuto);

     if (value1 == ViewportArguments::ValueAuto)
         return value2;

     if (value2 == ViewportArguments::ValueAuto)
         return value1;

     return compare(value1, value2);
 }

 static inline float clampLengthValue(float value)
 {
     ASSERT(value != ViewportArguments::ValueDeviceWidth);
     ASSERT(value != ViewportArguments::ValueDeviceHeight);

     // Limits as defined in the css-device-adapt spec.
     if (value != ViewportArguments::ValueAuto)
         return std::min<float>(10000, std::max<float>(value, 1));
     return value;
 }

 static inline float clampScaleValue(float value)
 {
     ASSERT(value != ViewportArguments::ValueDeviceWidth);
     ASSERT(value != ViewportArguments::ValueDeviceHeight);

     // Limits as defined in the css-device-adapt spec.
     if (value != ViewportArguments::ValueAuto)
         return std::min<float>(10, std::max<float>(value, 0.1));
     return value;
 }

 ViewportAttributes ViewportArguments::resolve(const FloatSize& initialViewportSize, const FloatSize& deviceSize, int defaultWidth) const
 {
     float resultWidth = width;
     float resultMaxWidth = maxWidth;
     float resultMinWidth = minWidth;
     float resultHeight = height;
     float resultMinHeight = minHeight;
     float resultMaxHeight = maxHeight;
     float resultZoom = zoom;
     float resultMinZoom = minZoom;
     float resultMaxZoom = maxZoom;

     switch (int(resultWidth)) {
     case ViewportArguments::ValueDeviceWidth:
         resultWidth = deviceSize.width();
         break;
     case ViewportArguments::ValueDeviceHeight:
         resultWidth = deviceSize.height();
         break;
     }

     switch (int(resultHeight)) {
     case ViewportArguments::ValueDeviceWidth:
         resultHeight = deviceSize.width();
         break;
     case ViewportArguments::ValueDeviceHeight:
         resultHeight = deviceSize.height();
         break;
     }

     if (type == ViewportArguments::CSSDeviceAdaptation) {
         switch (int(resultMinWidth)) {
         case ViewportArguments::ValueDeviceWidth:
             resultMinWidth = deviceSize.width();
             break;
         case ViewportArguments::ValueDeviceHeight:
             resultMinWidth = deviceSize.height();
             break;
         }

         switch (int(resultMaxWidth)) {
         case ViewportArguments::ValueDeviceWidth:
             resultMaxWidth = deviceSize.width();
             break;
         case ViewportArguments::ValueDeviceHeight:
             resultMaxWidth = deviceSize.height();
             break;
         }

         switch (int(resultMinHeight)) {
         case ViewportArguments::ValueDeviceWidth:
             resultMinHeight = deviceSize.width();
             break;
         case ViewportArguments::ValueDeviceHeight:
             resultMinHeight = deviceSize.height();
             break;
         }

         switch (int(resultMaxHeight)) {
         case ViewportArguments::ValueDeviceWidth:
             resultMaxHeight = deviceSize.width();
             break;
         case ViewportArguments::ValueDeviceHeight:
             resultMaxHeight = deviceSize.height();
             break;
         }

         if (resultMinWidth != ViewportArguments::ValueAuto || resultMaxWidth != ViewportArguments::ValueAuto)
             resultWidth = compareIgnoringAuto(resultMinWidth, compareIgnoringAuto(resultMaxWidth, deviceSize.width(), std::min), std::max);

         if (resultMinHeight != ViewportArguments::ValueAuto || resultMaxHeight != ViewportArguments::ValueAuto)
             resultHeight = compareIgnoringAuto(resultMinHeight, compareIgnoringAuto(resultMaxHeight, deviceSize.height(), std::min), std::max);

         if (resultMinZoom != ViewportArguments::ValueAuto && resultMaxZoom != ViewportArguments::ValueAuto)
             resultMaxZoom = std::max(resultMinZoom, resultMaxZoom);

         if (resultZoom != ViewportArguments::ValueAuto)
             resultZoom = compareIgnoringAuto(resultMinZoom, compareIgnoringAuto(resultMaxZoom, resultZoom, std::min), std::max);

         if (resultWidth == ViewportArguments::ValueAuto && resultZoom == ViewportArguments::ValueAuto)
             resultWidth = deviceSize.width();

         if (resultWidth == ViewportArguments::ValueAuto && resultHeight == ViewportArguments::ValueAuto)
             resultWidth = deviceSize.width() / resultZoom;

         if (resultWidth == ViewportArguments::ValueAuto)
             resultWidth = resultHeight * deviceSize.width() / deviceSize.height();

         if (resultHeight == ViewportArguments::ValueAuto)
             resultHeight = resultWidth * deviceSize.height() / deviceSize.width();

         if (resultZoom != ViewportArguments::ValueAuto || resultMaxZoom != ViewportArguments::ValueAuto) {
             resultWidth = compareIgnoringAuto(resultWidth, deviceSize.width() / compareIgnoringAuto(resultZoom, resultMaxZoom, std::min), std::max);
             resultHeight = compareIgnoringAuto(resultHeight, deviceSize.height() / compareIgnoringAuto(resultZoom, resultMaxZoom, std::min), std::max);
         }

         resultWidth = std::max<float>(1, resultWidth);
         resultHeight = std::max<float>(1, resultHeight);
     }

     if (type != ViewportArguments::CSSDeviceAdaptation && type != ViewportArguments::Implicit) {
         // Clamp values to a valid range, but not for @viewport since is
         // not mandated by the specification.
         resultWidth = clampLengthValue(resultWidth);
         resultHeight = clampLengthValue(resultHeight);
         resultZoom = clampScaleValue(resultZoom);
         resultMinZoom = clampScaleValue(resultMinZoom);
         resultMaxZoom = clampScaleValue(resultMaxZoom);
     }

     ViewportAttributes result;

     // Resolve minimum-scale and maximum-scale values according to spec.
     if (resultMinZoom == ViewportArguments::ValueAuto)
         result.minimumScale = float(0.25);
     else
         result.minimumScale = resultMinZoom;

     if (resultMaxZoom == ViewportArguments::ValueAuto) {
         result.maximumScale = 5;
         result.minimumScale = std::min<float>(5, result.minimumScale);
     } else
         result.maximumScale = resultMaxZoom;
     result.maximumScale = std::max(result.minimumScale, result.maximumScale);

     // Resolve initial-scale value.
     result.initialScale = resultZoom;
     if (resultZoom == ViewportArguments::ValueAuto) {
         result.initialScale = initialViewportSize.width() / defaultWidth;
         if (resultWidth != ViewportArguments::ValueAuto)
             result.initialScale = initialViewportSize.width() / resultWidth;
         if (resultHeight != ViewportArguments::ValueAuto) {
             // if 'auto', the initial-scale will be negative here and thus ignored.
             result.initialScale = std::max<float>(result.initialScale, initialViewportSize.height() / resultHeight);
         }
     }

     // Constrain initial-scale value to minimum-scale/maximum-scale range.
     result.initialScale = std::min(result.maximumScale, std::max(result.minimumScale, result.initialScale));

     // Resolve width value.
     if (resultWidth == ViewportArguments::ValueAuto) {
         if (resultZoom == ViewportArguments::ValueAuto)
             resultWidth = defaultWidth;
         else if (resultHeight != ViewportArguments::ValueAuto)
             resultWidth = resultHeight * (initialViewportSize.width() / initialViewportSize.height());
         else
             resultWidth = initialViewportSize.width() / result.initialScale;
     }

     // Resolve height value.
     if (resultHeight == ViewportArguments::ValueAuto)
         resultHeight = resultWidth * (initialViewportSize.height() / initialViewportSize.width());

     if (type == ViewportArguments::ViewportMeta) {
         // Extend width and height to fill the visual viewport for the resolved initial-scale.
         resultWidth = std::max<float>(resultWidth, initialViewportSize.width() / result.initialScale);
         resultHeight = std::max<float>(resultHeight, initialViewportSize.height() / result.initialScale);
     }

     result.layoutSize.setWidth(resultWidth);
     result.layoutSize.setHeight(resultHeight);

     // FIXME: This might affect some ports, but is the right thing to do.
     // Only set initialScale to a value if it was explicitly set.
     // if (resultZoom == ViewportArguments::ValueAuto)
     //    result.initialScale = ViewportArguments::ValueAuto;

     result.userScalable = userZoom;
     result.orientation = orientation;
     result.shrinkToFit = shrinkToFit;
     result.viewportFit = viewportFit;

     return result;
 }

 static FloatSize convertToUserSpace(const FloatSize& deviceSize, float devicePixelRatio)
 {
     FloatSize result = deviceSize;
     if (devicePixelRatio != 1)
         result.scale(1 / devicePixelRatio);
     return result;
 }

 ViewportAttributes computeViewportAttributes(ViewportArguments args, int desktopWidth, int deviceWidth, int deviceHeight, float devicePixelRatio, IntSize visibleViewport)
 {
     FloatSize initialViewportSize = convertToUserSpace(visibleViewport, devicePixelRatio);
     FloatSize deviceSize = convertToUserSpace(FloatSize(deviceWidth, deviceHeight), devicePixelRatio);

     return args.resolve(initialViewportSize, deviceSize, desktopWidth);
 }

 float computeMinimumScaleFactorForContentContained(const ViewportAttributes& result, const IntSize& visibleViewport, const IntSize& contentsSize)
 {
     FloatSize viewportSize(visibleViewport);
     return std::max<float>(result.minimumScale, std::max(viewportSize.width() / contentsSize.width(), viewportSize.height() / contentsSize.height()));
 }

 void restrictMinimumScaleFactorToViewportSize(ViewportAttributes& result, IntSize visibleViewport, float devicePixelRatio)
 {
     FloatSize viewportSize = convertToUserSpace(visibleViewport, devicePixelRatio);

     result.minimumScale = std::max<float>(result.minimumScale, std::max(viewportSize.width() / result.layoutSize.width(), viewportSize.height() / result.layoutSize.height()));
 }

 void restrictScaleFactorToInitialScaleIfNotUserScalable(ViewportAttributes& result)
 {
     if (!result.userScalable)
         result.maximumScale = result.minimumScale = result.initialScale;
 }

 static float numericPrefix(StringView key, StringView value, const InternalViewportErrorHandler& errorHandler, bool* ok = nullptr)
 {
     size_t parsedLength;
     float numericValue;
     if (value.is8Bit())
         numericValue = charactersToFloat(value.characters8(), value.length(), parsedLength);
     else
         numericValue = charactersToFloat(value.characters16(), value.length(), parsedLength);
     if (!parsedLength) {
         errorHandler(UnrecognizedViewportArgumentValueError, value, key);
         if (ok)
             *ok = false;
         return 0;
     }
     if (parsedLength < value.length())
         errorHandler(TruncatedViewportArgumentValueError, value, key);
     if (ok)
         *ok = true;
     return numericValue;
 }

 static float findSizeValue(StringView key, StringView value, const InternalViewportErrorHandler& errorHandler, bool* valueWasExplicit = nullptr)
 {
     // 1) Non-negative number values are translated to px lengths.
     // 2) Negative number values are translated to auto.
     // 3) device-width and device-height are used as keywords.
     // 4) Other keywords and unknown values translate to 0.0.

     if (valueWasExplicit)
         *valueWasExplicit = true;

     if (equalLettersIgnoringASCIICase(value, "device-width"))
         return ViewportArguments::ValueDeviceWidth;

     if (equalLettersIgnoringASCIICase(value, "device-height"))
         return ViewportArguments::ValueDeviceHeight;

     float sizeValue = numericPrefix(key, value, errorHandler);

     if (sizeValue < 0) {
         if (valueWasExplicit)
             *valueWasExplicit = false;
         return ViewportArguments::ValueAuto;
     }

     return sizeValue;
 }

 static float findScaleValue(StringView key, StringView value, const InternalViewportErrorHandler& errorHandler)
 {
     // 1) Non-negative number values are translated to <number> values.
     // 2) Negative number values are translated to auto.
     // 3) yes is translated to 1.0.
     // 4) device-width and device-height are translated to 10.0.
     // 5) no and unknown values are translated to 0.0

     if (equalLettersIgnoringASCIICase(value, "yes"))
         return 1;
     if (equalLettersIgnoringASCIICase(value, "no"))
         return 0;
     if (equalLettersIgnoringASCIICase(value, "device-width"))
         return 10;
     if (equalLettersIgnoringASCIICase(value, "device-height"))
         return 10;

     float numericValue = numericPrefix(key, value, errorHandler);

     if (numericValue < 0)
         return ViewportArguments::ValueAuto;

     if (numericValue > 10.0)
         errorHandler(MaximumScaleTooLargeError, { }, { });

     return numericValue;
 }

 static bool findBooleanValue(StringView key, StringView value, const InternalViewportErrorHandler& errorHandler)
 {
     // yes and no are used as keywords.
     // Numbers >= 1, numbers <= -1, device-width and device-height are mapped to yes.
     // Numbers in the range <-1, 1>, and unknown values, are mapped to no.

     if (equalLettersIgnoringASCIICase(value, "yes"))
         return true;
     if (equalLettersIgnoringASCIICase(value, "no"))
         return false;
     if (equalLettersIgnoringASCIICase(value, "device-width"))
         return true;
     if (equalLettersIgnoringASCIICase(value, "device-height"))
         return true;
     return std::abs(numericPrefix(key, value, errorHandler)) >= 1;
 }

 static ViewportFit parseViewportFitValue(StringView key, StringView value, const InternalViewportErrorHandler& errorHandler)
 {
     if (equalLettersIgnoringASCIICase(value, "auto"))
         return ViewportFit::Auto;
     if (equalLettersIgnoringASCIICase(value, "contain"))
         return ViewportFit::Contain;
     if (equalLettersIgnoringASCIICase(value, "cover"))
         return ViewportFit::Cover;

     errorHandler(UnrecognizedViewportArgumentValueError, value, key);

     return ViewportFit::Auto;
 }

 static const char* viewportErrorMessageTemplate(ViewportErrorCode errorCode)
 {
     static const char* const errors[] = {
         "Viewport argument key \"%replacement1\" not recognized and ignored.",
         "Viewport argument value \"%replacement1\" for key \"%replacement2\" is invalid, and has been ignored.",
         "Viewport argument value \"%replacement1\" for key \"%replacement2\" was truncated to its numeric prefix.",
         "Viewport maximum-scale cannot be larger than 10.0. The maximum-scale will be set to 10.0."
     };

     return errors[errorCode];
 }

 static MessageLevel viewportErrorMessageLevel(ViewportErrorCode errorCode)
 {
     switch (errorCode) {
     case TruncatedViewportArgumentValueError:
         return MessageLevel::Warning;
     case UnrecognizedViewportArgumentKeyError:
     case UnrecognizedViewportArgumentValueError:
     case MaximumScaleTooLargeError:
         return MessageLevel::Error;
     }

     ASSERT_NOT_REACHED();
     return MessageLevel::Error;
 }

 static String viewportErrorMessage(ViewportErrorCode errorCode, StringView replacement1, StringView replacement2)
 {
     String message = viewportErrorMessageTemplate(errorCode);
     if (!replacement1.isNull())
         message.replace("%replacement1", replacement1.toStringWithoutCopying());
     // FIXME: This will do the wrong thing if replacement1 contains the substring "%replacement2".
     if (!replacement2.isNull())
         message.replace("%replacement2", replacement2.toStringWithoutCopying());

     if ((errorCode == UnrecognizedViewportArgumentValueError || errorCode == TruncatedViewportArgumentValueError) && replacement1.contains(';'))
         message.append(" Note that ';' is not a separator in viewport values. The list should be comma-separated.");

     return message;
 }

 static void reportViewportWarning(Document& document, ViewportErrorCode errorCode, const String& message)
 {
     // FIXME: Why is this null check needed? Can't addConsoleMessage deal with this?
     if (!document.frame())
         return;

     // FIXME: This message should be moved off the console once a solution to https://bugs.webkit.org/show_bug.cgi?id=103274 exists.
     document.addConsoleMessage(MessageSource::Rendering, viewportErrorMessageLevel(errorCode), message);
 }

 void setViewportFeature(ViewportArguments& arguments, StringView key, StringView value, bool viewportFitEnabled, const ViewportErrorHandler& errorHandler)
 {
     InternalViewportErrorHandler internalErrorHandler = [&errorHandler] (ViewportErrorCode errorCode, StringView replacement1, StringView replacement2) {
         errorHandler(errorCode, viewportErrorMessage(errorCode, replacement1, replacement2));
     };

     if (equalLettersIgnoringASCIICase(key, "width"))
         arguments.width = findSizeValue(key, value, internalErrorHandler, &arguments.widthWasExplicit);
     else if (equalLettersIgnoringASCIICase(key, "height"))
         arguments.height = findSizeValue(key, value, internalErrorHandler);
     else if (equalLettersIgnoringASCIICase(key, "initial-scale"))
         arguments.zoom = findScaleValue(key, value, internalErrorHandler);
     else if (equalLettersIgnoringASCIICase(key, "minimum-scale"))
         arguments.minZoom = findScaleValue(key, value, internalErrorHandler);
     else if (equalLettersIgnoringASCIICase(key, "maximum-scale"))
         arguments.maxZoom = findScaleValue(key, value, internalErrorHandler);
     else if (equalLettersIgnoringASCIICase(key, "user-scalable"))
         arguments.userZoom = findBooleanValue(key, value, internalErrorHandler);
 #if PLATFORM(IOS_FAMILY)
     else if (equalLettersIgnoringASCIICase(key, "minimal-ui")) {
         // FIXME: Ignore silently for now. This code should eventually be removed
         // so we start giving the warning in the web inspector as for other unimplemented keys.
     }
 #endif
     else if (equalLettersIgnoringASCIICase(key, "shrink-to-fit"))
         arguments.shrinkToFit = findBooleanValue(key, value, internalErrorHandler);
     else if (equalLettersIgnoringASCIICase(key, "viewport-fit") && viewportFitEnabled)
         arguments.viewportFit = parseViewportFitValue(key, value, internalErrorHandler);
     else
         internalErrorHandler(UnrecognizedViewportArgumentKeyError, key, { });
 }

 void setViewportFeature(ViewportArguments& arguments, Document& document, StringView key, StringView value)
 {
     setViewportFeature(arguments, key, value, document.settings().viewportFitEnabled(), [&](ViewportErrorCode errorCode, const String& message) {
         reportViewportWarning(document, errorCode, message);
     });
 }

 TextStream& operator<<(TextStream& ts, const ViewportArguments& viewportArguments)
 {
     TextStream::IndentScope indentScope(ts);

     ts << "\n" << indent << "(width " << viewportArguments.width << ", minWidth " << viewportArguments.minWidth << ", maxWidth " << viewportArguments.maxWidth << ")";
     ts << "\n" << indent << "(height " << viewportArguments.height << ", minHeight " << viewportArguments.minHeight << ", maxHeight " << viewportArguments.maxHeight << ")";
     ts << "\n" << indent << "(zoom " << viewportArguments.zoom << ", minZoom " << viewportArguments.minZoom << ", maxZoom " << viewportArguments.maxZoom << ")";

     return ts;
 }

 } // namespace WebCore
	/*
	* Copyright (C) 1999 Lars Knoll (knoll@kde.org)
	* (C) 1999 Antti Koivisto (koivisto@kde.org)
	* (C) 2001 Dirk Mueller (mueller@kde.org)
	* (C) 2006 Alexey Proskuryakov (ap@webkit.org)
	* Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
	* Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
	* Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
	* Copyright (C) 2012 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 "ViewportArguments.h"

	#include "Document.h"
	#include "Frame.h"
	#include "IntSize.h"
	#include "RuntimeEnabledFeatures.h"
	#include "ScriptableDocumentParser.h"
	#include "Settings.h"
	#include <wtf/text/TextStream.h>

	namespace WebCore {

	typedef WTF::Function<void(ViewportErrorCode, StringView, StringView)> InternalViewportErrorHandler;

	#if PLATFORM(GTK)
	const float ViewportArguments::deprecatedTargetDPI = 160;
	#endif

	static const float& compareIgnoringAuto(const float& value1, const float& value2, const float& (*compare) (const float&, const float&))
	{
	ASSERT(value1 != ViewportArguments::ValueAuto \|\| value2 != ViewportArguments::ValueAuto);

	if (value1 == ViewportArguments::ValueAuto)
	return value2;

	if (value2 == ViewportArguments::ValueAuto)
	return value1;

	return compare(value1, value2);
	}

	static inline float clampLengthValue(float value)
	{
	ASSERT(value != ViewportArguments::ValueDeviceWidth);
	ASSERT(value != ViewportArguments::ValueDeviceHeight);

	// Limits as defined in the css-device-adapt spec.
	if (value != ViewportArguments::ValueAuto)
	return std::min<float>(10000, std::max<float>(value, 1));
	return value;
	}

	static inline float clampScaleValue(float value)
	{
	ASSERT(value != ViewportArguments::ValueDeviceWidth);
	ASSERT(value != ViewportArguments::ValueDeviceHeight);

	// Limits as defined in the css-device-adapt spec.
	if (value != ViewportArguments::ValueAuto)
	return std::min<float>(10, std::max<float>(value, 0.1));
	return value;
	}

	ViewportAttributes ViewportArguments::resolve(const FloatSize& initialViewportSize, const FloatSize& deviceSize, int defaultWidth) const
	{
	float resultWidth = width;
	float resultMaxWidth = maxWidth;
	float resultMinWidth = minWidth;
	float resultHeight = height;
	float resultMinHeight = minHeight;
	float resultMaxHeight = maxHeight;
	float resultZoom = zoom;
	float resultMinZoom = minZoom;
	float resultMaxZoom = maxZoom;

	switch (int(resultWidth)) {
	case ViewportArguments::ValueDeviceWidth:
	resultWidth = deviceSize.width();
	break;
	case ViewportArguments::ValueDeviceHeight:
	resultWidth = deviceSize.height();
	break;
	}

	switch (int(resultHeight)) {
	case ViewportArguments::ValueDeviceWidth:
	resultHeight = deviceSize.width();
	break;
	case ViewportArguments::ValueDeviceHeight:
	resultHeight = deviceSize.height();
	break;
	}

	if (type == ViewportArguments::CSSDeviceAdaptation) {
	switch (int(resultMinWidth)) {
	case ViewportArguments::ValueDeviceWidth:
	resultMinWidth = deviceSize.width();
	break;
	case ViewportArguments::ValueDeviceHeight:
	resultMinWidth = deviceSize.height();
	break;
	}

	switch (int(resultMaxWidth)) {
	case ViewportArguments::ValueDeviceWidth:
	resultMaxWidth = deviceSize.width();
	break;
	case ViewportArguments::ValueDeviceHeight:
	resultMaxWidth = deviceSize.height();
	break;
	}

	switch (int(resultMinHeight)) {
	case ViewportArguments::ValueDeviceWidth:
	resultMinHeight = deviceSize.width();
	break;
	case ViewportArguments::ValueDeviceHeight:
	resultMinHeight = deviceSize.height();
	break;
	}

	switch (int(resultMaxHeight)) {
	case ViewportArguments::ValueDeviceWidth:
	resultMaxHeight = deviceSize.width();
	break;
	case ViewportArguments::ValueDeviceHeight:
	resultMaxHeight = deviceSize.height();
	break;
	}

	if (resultMinWidth != ViewportArguments::ValueAuto \|\| resultMaxWidth != ViewportArguments::ValueAuto)
	resultWidth = compareIgnoringAuto(resultMinWidth, compareIgnoringAuto(resultMaxWidth, deviceSize.width(), std::min), std::max);

	if (resultMinHeight != ViewportArguments::ValueAuto \|\| resultMaxHeight != ViewportArguments::ValueAuto)
	resultHeight = compareIgnoringAuto(resultMinHeight, compareIgnoringAuto(resultMaxHeight, deviceSize.height(), std::min), std::max);

	if (resultMinZoom != ViewportArguments::ValueAuto && resultMaxZoom != ViewportArguments::ValueAuto)
	resultMaxZoom = std::max(resultMinZoom, resultMaxZoom);

	if (resultZoom != ViewportArguments::ValueAuto)
	resultZoom = compareIgnoringAuto(resultMinZoom, compareIgnoringAuto(resultMaxZoom, resultZoom, std::min), std::max);

	if (resultWidth == ViewportArguments::ValueAuto && resultZoom == ViewportArguments::ValueAuto)
	resultWidth = deviceSize.width();

	if (resultWidth == ViewportArguments::ValueAuto && resultHeight == ViewportArguments::ValueAuto)
	resultWidth = deviceSize.width() / resultZoom;

	if (resultWidth == ViewportArguments::ValueAuto)
	resultWidth = resultHeight * deviceSize.width() / deviceSize.height();

	if (resultHeight == ViewportArguments::ValueAuto)
	resultHeight = resultWidth * deviceSize.height() / deviceSize.width();

	if (resultZoom != ViewportArguments::ValueAuto \|\| resultMaxZoom != ViewportArguments::ValueAuto) {
	resultWidth = compareIgnoringAuto(resultWidth, deviceSize.width() / compareIgnoringAuto(resultZoom, resultMaxZoom, std::min), std::max);
	resultHeight = compareIgnoringAuto(resultHeight, deviceSize.height() / compareIgnoringAuto(resultZoom, resultMaxZoom, std::min), std::max);
	}

	resultWidth = std::max<float>(1, resultWidth);
	resultHeight = std::max<float>(1, resultHeight);
	}

	if (type != ViewportArguments::CSSDeviceAdaptation && type != ViewportArguments::Implicit) {
	// Clamp values to a valid range, but not for @viewport since is
	// not mandated by the specification.
	resultWidth = clampLengthValue(resultWidth);
	resultHeight = clampLengthValue(resultHeight);
	resultZoom = clampScaleValue(resultZoom);
	resultMinZoom = clampScaleValue(resultMinZoom);
	resultMaxZoom = clampScaleValue(resultMaxZoom);
	}

	ViewportAttributes result;

	// Resolve minimum-scale and maximum-scale values according to spec.
	if (resultMinZoom == ViewportArguments::ValueAuto)
	result.minimumScale = float(0.25);
	else
	result.minimumScale = resultMinZoom;

	if (resultMaxZoom == ViewportArguments::ValueAuto) {
	result.maximumScale = 5;
	result.minimumScale = std::min<float>(5, result.minimumScale);
	} else
	result.maximumScale = resultMaxZoom;
	result.maximumScale = std::max(result.minimumScale, result.maximumScale);

	// Resolve initial-scale value.
	result.initialScale = resultZoom;
	if (resultZoom == ViewportArguments::ValueAuto) {
	result.initialScale = initialViewportSize.width() / defaultWidth;
	if (resultWidth != ViewportArguments::ValueAuto)
	result.initialScale = initialViewportSize.width() / resultWidth;
	if (resultHeight != ViewportArguments::ValueAuto) {
	// if 'auto', the initial-scale will be negative here and thus ignored.
	result.initialScale = std::max<float>(result.initialScale, initialViewportSize.height() / resultHeight);
	}
	}

	// Constrain initial-scale value to minimum-scale/maximum-scale range.
	result.initialScale = std::min(result.maximumScale, std::max(result.minimumScale, result.initialScale));

	// Resolve width value.
	if (resultWidth == ViewportArguments::ValueAuto) {
	if (resultZoom == ViewportArguments::ValueAuto)
	resultWidth = defaultWidth;
	else if (resultHeight != ViewportArguments::ValueAuto)
	resultWidth = resultHeight * (initialViewportSize.width() / initialViewportSize.height());
	else
	resultWidth = initialViewportSize.width() / result.initialScale;
	}

	// Resolve height value.
	if (resultHeight == ViewportArguments::ValueAuto)
	resultHeight = resultWidth * (initialViewportSize.height() / initialViewportSize.width());

	if (type == ViewportArguments::ViewportMeta) {
	// Extend width and height to fill the visual viewport for the resolved initial-scale.
	resultWidth = std::max<float>(resultWidth, initialViewportSize.width() / result.initialScale);
	resultHeight = std::max<float>(resultHeight, initialViewportSize.height() / result.initialScale);
	}

	result.layoutSize.setWidth(resultWidth);
	result.layoutSize.setHeight(resultHeight);

	// FIXME: This might affect some ports, but is the right thing to do.
	// Only set initialScale to a value if it was explicitly set.
	// if (resultZoom == ViewportArguments::ValueAuto)
	// result.initialScale = ViewportArguments::ValueAuto;

	result.userScalable = userZoom;
	result.orientation = orientation;
	result.shrinkToFit = shrinkToFit;
	result.viewportFit = viewportFit;

	return result;
	}

	static FloatSize convertToUserSpace(const FloatSize& deviceSize, float devicePixelRatio)
	{
	FloatSize result = deviceSize;
	if (devicePixelRatio != 1)
	result.scale(1 / devicePixelRatio);
	return result;
	}

	ViewportAttributes computeViewportAttributes(ViewportArguments args, int desktopWidth, int deviceWidth, int deviceHeight, float devicePixelRatio, IntSize visibleViewport)
	{
	FloatSize initialViewportSize = convertToUserSpace(visibleViewport, devicePixelRatio);
	FloatSize deviceSize = convertToUserSpace(FloatSize(deviceWidth, deviceHeight), devicePixelRatio);

	return args.resolve(initialViewportSize, deviceSize, desktopWidth);
	}

	float computeMinimumScaleFactorForContentContained(const ViewportAttributes& result, const IntSize& visibleViewport, const IntSize& contentsSize)
	{
	FloatSize viewportSize(visibleViewport);
	return std::max<float>(result.minimumScale, std::max(viewportSize.width() / contentsSize.width(), viewportSize.height() / contentsSize.height()));
	}

	void restrictMinimumScaleFactorToViewportSize(ViewportAttributes& result, IntSize visibleViewport, float devicePixelRatio)
	{
	FloatSize viewportSize = convertToUserSpace(visibleViewport, devicePixelRatio);

	result.minimumScale = std::max<float>(result.minimumScale, std::max(viewportSize.width() / result.layoutSize.width(), viewportSize.height() / result.layoutSize.height()));
	}

	void restrictScaleFactorToInitialScaleIfNotUserScalable(ViewportAttributes& result)
	{
	if (!result.userScalable)
	result.maximumScale = result.minimumScale = result.initialScale;
	}

	static float numericPrefix(StringView key, StringView value, const InternalViewportErrorHandler& errorHandler, bool* ok = nullptr)
	{
	size_t parsedLength;
	float numericValue;
	if (value.is8Bit())
	numericValue = charactersToFloat(value.characters8(), value.length(), parsedLength);
	else
	numericValue = charactersToFloat(value.characters16(), value.length(), parsedLength);
	if (!parsedLength) {
	errorHandler(UnrecognizedViewportArgumentValueError, value, key);
	if (ok)
	*ok = false;
	return 0;
	}
	if (parsedLength < value.length())
	errorHandler(TruncatedViewportArgumentValueError, value, key);
	if (ok)
	*ok = true;
	return numericValue;
	}

	static float findSizeValue(StringView key, StringView value, const InternalViewportErrorHandler& errorHandler, bool* valueWasExplicit = nullptr)
	{
	// 1) Non-negative number values are translated to px lengths.
	// 2) Negative number values are translated to auto.
	// 3) device-width and device-height are used as keywords.
	// 4) Other keywords and unknown values translate to 0.0.

	if (valueWasExplicit)
	*valueWasExplicit = true;

	if (equalLettersIgnoringASCIICase(value, "device-width"))
	return ViewportArguments::ValueDeviceWidth;

	if (equalLettersIgnoringASCIICase(value, "device-height"))
	return ViewportArguments::ValueDeviceHeight;

	float sizeValue = numericPrefix(key, value, errorHandler);

	if (sizeValue < 0) {
	if (valueWasExplicit)
	*valueWasExplicit = false;
	return ViewportArguments::ValueAuto;
	}

	return sizeValue;
	}

	static float findScaleValue(StringView key, StringView value, const InternalViewportErrorHandler& errorHandler)
	{
	// 1) Non-negative number values are translated to <number> values.
	// 2) Negative number values are translated to auto.
	// 3) yes is translated to 1.0.
	// 4) device-width and device-height are translated to 10.0.
	// 5) no and unknown values are translated to 0.0

	if (equalLettersIgnoringASCIICase(value, "yes"))
	return 1;
	if (equalLettersIgnoringASCIICase(value, "no"))
	return 0;
	if (equalLettersIgnoringASCIICase(value, "device-width"))
	return 10;
	if (equalLettersIgnoringASCIICase(value, "device-height"))
	return 10;

	float numericValue = numericPrefix(key, value, errorHandler);

	if (numericValue < 0)
	return ViewportArguments::ValueAuto;

	if (numericValue > 10.0)
	errorHandler(MaximumScaleTooLargeError, { }, { });

	return numericValue;
	}

	static bool findBooleanValue(StringView key, StringView value, const InternalViewportErrorHandler& errorHandler)
	{
	// yes and no are used as keywords.
	// Numbers >= 1, numbers <= -1, device-width and device-height are mapped to yes.
	// Numbers in the range <-1, 1>, and unknown values, are mapped to no.

	if (equalLettersIgnoringASCIICase(value, "yes"))
	return true;
	if (equalLettersIgnoringASCIICase(value, "no"))
	return false;
	if (equalLettersIgnoringASCIICase(value, "device-width"))
	return true;
	if (equalLettersIgnoringASCIICase(value, "device-height"))
	return true;
	return std::abs(numericPrefix(key, value, errorHandler)) >= 1;
	}

	static ViewportFit parseViewportFitValue(StringView key, StringView value, const InternalViewportErrorHandler& errorHandler)
	{
	if (equalLettersIgnoringASCIICase(value, "auto"))
	return ViewportFit::Auto;
	if (equalLettersIgnoringASCIICase(value, "contain"))
	return ViewportFit::Contain;
	if (equalLettersIgnoringASCIICase(value, "cover"))
	return ViewportFit::Cover;

	errorHandler(UnrecognizedViewportArgumentValueError, value, key);

	return ViewportFit::Auto;
	}

	static const char* viewportErrorMessageTemplate(ViewportErrorCode errorCode)
	{
	static const char* const errors[] = {
	"Viewport argument key \"%replacement1\" not recognized and ignored.",
	"Viewport argument value \"%replacement1\" for key \"%replacement2\" is invalid, and has been ignored.",
	"Viewport argument value \"%replacement1\" for key \"%replacement2\" was truncated to its numeric prefix.",
	"Viewport maximum-scale cannot be larger than 10.0. The maximum-scale will be set to 10.0."
	};

	return errors[errorCode];
	}

	static MessageLevel viewportErrorMessageLevel(ViewportErrorCode errorCode)
	{
	switch (errorCode) {
	case TruncatedViewportArgumentValueError:
	return MessageLevel::Warning;
	case UnrecognizedViewportArgumentKeyError:
	case UnrecognizedViewportArgumentValueError:
	case MaximumScaleTooLargeError:
	return MessageLevel::Error;
	}

	ASSERT_NOT_REACHED();
	return MessageLevel::Error;
	}

	static String viewportErrorMessage(ViewportErrorCode errorCode, StringView replacement1, StringView replacement2)
	{
	String message = viewportErrorMessageTemplate(errorCode);
	if (!replacement1.isNull())
	message.replace("%replacement1", replacement1.toStringWithoutCopying());
	// FIXME: This will do the wrong thing if replacement1 contains the substring "%replacement2".
	if (!replacement2.isNull())
	message.replace("%replacement2", replacement2.toStringWithoutCopying());

	if ((errorCode == UnrecognizedViewportArgumentValueError \|\| errorCode == TruncatedViewportArgumentValueError) && replacement1.contains(';'))
	message.append(" Note that ';' is not a separator in viewport values. The list should be comma-separated.");

	return message;
	}

	static void reportViewportWarning(Document& document, ViewportErrorCode errorCode, const String& message)
	{
	// FIXME: Why is this null check needed? Can't addConsoleMessage deal with this?
	if (!document.frame())
	return;

	// FIXME: This message should be moved off the console once a solution to https://bugs.webkit.org/show_bug.cgi?id=103274 exists.
	document.addConsoleMessage(MessageSource::Rendering, viewportErrorMessageLevel(errorCode), message);
	}

	void setViewportFeature(ViewportArguments& arguments, StringView key, StringView value, bool viewportFitEnabled, const ViewportErrorHandler& errorHandler)
	{
	InternalViewportErrorHandler internalErrorHandler = [&errorHandler] (ViewportErrorCode errorCode, StringView replacement1, StringView replacement2) {
	errorHandler(errorCode, viewportErrorMessage(errorCode, replacement1, replacement2));
	};

	if (equalLettersIgnoringASCIICase(key, "width"))
	arguments.width = findSizeValue(key, value, internalErrorHandler, &arguments.widthWasExplicit);
	else if (equalLettersIgnoringASCIICase(key, "height"))
	arguments.height = findSizeValue(key, value, internalErrorHandler);
	else if (equalLettersIgnoringASCIICase(key, "initial-scale"))
	arguments.zoom = findScaleValue(key, value, internalErrorHandler);
	else if (equalLettersIgnoringASCIICase(key, "minimum-scale"))
	arguments.minZoom = findScaleValue(key, value, internalErrorHandler);
	else if (equalLettersIgnoringASCIICase(key, "maximum-scale"))
	arguments.maxZoom = findScaleValue(key, value, internalErrorHandler);
	else if (equalLettersIgnoringASCIICase(key, "user-scalable"))
	arguments.userZoom = findBooleanValue(key, value, internalErrorHandler);
	#if PLATFORM(IOS_FAMILY)
	else if (equalLettersIgnoringASCIICase(key, "minimal-ui")) {
	// FIXME: Ignore silently for now. This code should eventually be removed
	// so we start giving the warning in the web inspector as for other unimplemented keys.
	}
	#endif
	else if (equalLettersIgnoringASCIICase(key, "shrink-to-fit"))
	arguments.shrinkToFit = findBooleanValue(key, value, internalErrorHandler);
	else if (equalLettersIgnoringASCIICase(key, "viewport-fit") && viewportFitEnabled)
	arguments.viewportFit = parseViewportFitValue(key, value, internalErrorHandler);
	else
	internalErrorHandler(UnrecognizedViewportArgumentKeyError, key, { });
	}

	void setViewportFeature(ViewportArguments& arguments, Document& document, StringView key, StringView value)
	{
	setViewportFeature(arguments, key, value, document.settings().viewportFitEnabled(), [&](ViewportErrorCode errorCode, const String& message) {
	reportViewportWarning(document, errorCode, message);
	});
	}

	TextStream& operator<<(TextStream& ts, const ViewportArguments& viewportArguments)
	{
	TextStream::IndentScope indentScope(ts);

	ts << "\n" << indent << "(width " << viewportArguments.width << ", minWidth " << viewportArguments.minWidth << ", maxWidth " << viewportArguments.maxWidth << ")";
	ts << "\n" << indent << "(height " << viewportArguments.height << ", minHeight " << viewportArguments.minHeight << ", maxHeight " << viewportArguments.maxHeight << ")";
	ts << "\n" << indent << "(zoom " << viewportArguments.zoom << ", minZoom " << viewportArguments.minZoom << ", maxZoom " << viewportArguments.maxZoom << ")";

	return ts;
	}

	} // namespace WebCore