Source/WebCore/style/StyleFontSizeFunctions.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
  * Copyright (C) 2012 Google Inc. 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 "StyleFontSizeFunctions.h"

 #include "CSSValueKeywords.h"
 #include "Document.h"
 #include "Frame.h"
 #include "RenderStyle.h"
 #include "Settings.h"

 namespace WebCore {

 namespace Style {

 enum class MinimumFontSizeRule {
     None,
     Absolute,
     AbsoluteAndRelative
 };

 static float computedFontSizeFromSpecifiedSize(float specifiedSize, bool isAbsoluteSize, float zoomFactor, MinimumFontSizeRule minimumSizeRule, const Settings& settings)
 {
     // Text with a 0px font size should not be visible and therefore needs to be
     // exempt from minimum font size rules. Acid3 relies on this for pixel-perfect
     // rendering. This is also compatible with other browsers that have minimum
     // font size settings (e.g. Firefox).
     if (fabsf(specifiedSize) < std::numeric_limits<float>::epsilon())
         return 0.0f;

     // We support two types of minimum font size. The first is a hard override that applies to
     // all fonts. This is "minSize." The second type of minimum font size is a "smart minimum"
     // that is applied only when the Web page can't know what size it really asked for, e.g.,
     // when it uses logical sizes like "small" or expresses the font-size as a percentage of
     // the user's default font setting.

     // With the smart minimum, we never want to get smaller than the minimum font size to keep fonts readable.
     // However we always allow the page to set an explicit pixel size that is smaller,
     // since sites will mis-render otherwise (e.g., http://www.gamespot.com with a 9px minimum).

     if (minimumSizeRule == MinimumFontSizeRule::None)
         return specifiedSize;

     int minSize = settings.minimumFontSize();
     int minLogicalSize = settings.minimumLogicalFontSize();
     float zoomedSize = specifiedSize * zoomFactor;

     // Apply the hard minimum first. We only apply the hard minimum if after zooming we're still too small.
     zoomedSize = std::max(zoomedSize, static_cast<float>(minSize));

     // Now apply the smart minimum. This minimum is also only applied if we're still too small
     // after zooming. The font size must either be relative to the user default or the original size
     // must have been acceptable. In other words, we only apply the smart minimum whenever we're positive
     // doing so won't disrupt the layout.
     if (minimumSizeRule == MinimumFontSizeRule::AbsoluteAndRelative && (specifiedSize >= minLogicalSize || !isAbsoluteSize))
         zoomedSize = std::max(zoomedSize, static_cast<float>(minLogicalSize));

     // Also clamp to a reasonable maximum to prevent insane font sizes from causing crashes on various
     // platforms. (I'm looking at you, Windows.)
     return std::min(maximumAllowedFontSize, zoomedSize);
 }

 float computedFontSizeFromSpecifiedSize(float specifiedSize, bool isAbsoluteSize, bool useSVGZoomRules, const RenderStyle* style, const Document& document)
 {
     float zoomFactor = 1.0f;
     if (!useSVGZoomRules) {
         zoomFactor = style->effectiveZoom();
         Frame* frame = document.frame();
         if (frame && style->textZoom() != TextZoom::Reset)
             zoomFactor *= frame->textZoomFactor();
     }
     return computedFontSizeFromSpecifiedSize(specifiedSize, isAbsoluteSize, zoomFactor, useSVGZoomRules ? MinimumFontSizeRule::None : MinimumFontSizeRule::AbsoluteAndRelative, document.settings());
 }

 float computedFontSizeFromSpecifiedSizeForSVGInlineText(float specifiedSize, bool isAbsoluteSize, float zoomFactor, const Document& document)
 {
     return computedFontSizeFromSpecifiedSize(specifiedSize, isAbsoluteSize, zoomFactor, MinimumFontSizeRule::Absolute, document.settings());
 }

 const int fontSizeTableMax = 16;
 const int fontSizeTableMin = 9;
 const int totalKeywords = 8;

 // WinIE/Nav4 table for font sizes. Designed to match the legacy font mapping system of HTML.
 static const int quirksFontSizeTable[fontSizeTableMax - fontSizeTableMin + 1][totalKeywords] =
 {
     { 9,    9,     9,     9,    11,    14,    18,    28 },
     { 9,    9,     9,    10,    12,    15,    20,    31 },
     { 9,    9,     9,    11,    13,    17,    22,    34 },
     { 9,    9,    10,    12,    14,    18,    24,    37 },
     { 9,    9,    10,    13,    16,    20,    26,    40 }, // fixed font default (13)
     { 9,    9,    11,    14,    17,    21,    28,    42 },
     { 9,   10,    12,    15,    17,    23,    30,    45 },
     { 9,   10,    13,    16,    18,    24,    32,    48 } // proportional font default (16)
 };
 // HTML       1      2      3      4      5      6      7
 // CSS  xxs   xs     s      m      l     xl     xxl
 //                          |
 //                      user pref

 // Strict mode table matches MacIE and Mozilla's settings exactly.
 static const int strictFontSizeTable[fontSizeTableMax - fontSizeTableMin + 1][totalKeywords] =
 {
     { 9,    9,     9,     9,    11,    14,    18,    27 },
     { 9,    9,     9,    10,    12,    15,    20,    30 },
     { 9,    9,    10,    11,    13,    17,    22,    33 },
     { 9,    9,    10,    12,    14,    18,    24,    36 },
     { 9,   10,    12,    13,    16,    20,    26,    39 }, // fixed font default (13)
     { 9,   10,    12,    14,    17,    21,    28,    42 },
     { 9,   10,    13,    15,    18,    23,    30,    45 },
     { 9,   10,    13,    16,    18,    24,    32,    48 } // proportional font default (16)
 };
 // HTML       1      2      3      4      5      6      7
 // CSS  xxs   xs     s      m      l     xl     xxl
 //                          |
 //                      user pref

 // For values outside the range of the table, we use Todd Fahrner's suggested scale
 // factors for each keyword value.
 static const float fontSizeFactors[totalKeywords] = { 0.60f, 0.75f, 0.89f, 1.0f, 1.2f, 1.5f, 2.0f, 3.0f };

 float fontSizeForKeyword(unsigned keywordID, bool shouldUseFixedDefaultSize, const Document& document)
 {
     bool quirksMode = document.inQuirksMode();
     int mediumSize = shouldUseFixedDefaultSize ? document.settings().defaultFixedFontSize() : document.settings().defaultFontSize();
     if (mediumSize >= fontSizeTableMin && mediumSize <= fontSizeTableMax) {
         // Look up the entry in the table.
         int row = mediumSize - fontSizeTableMin;
         int col = (keywordID - CSSValueXxSmall);
         return quirksMode ? quirksFontSizeTable[row][col] : strictFontSizeTable[row][col];
     }

     // Value is outside the range of the table. Apply the scale factor instead.
     float minLogicalSize = std::max(document.settings().minimumLogicalFontSize(), 1);
     return std::max(fontSizeFactors[keywordID - CSSValueXxSmall] * mediumSize, minLogicalSize);
 }

 template<typename T>
 static int findNearestLegacyFontSize(int pixelFontSize, const T* table, int multiplier)
 {
     // Ignore table[0] because xx-small does not correspond to any legacy font size.
     for (int i = 1; i < totalKeywords - 1; i++) {
         if (pixelFontSize * 2 < (table[i] + table[i + 1]) * multiplier)
             return i;
     }
     return totalKeywords - 1;
 }

 int legacyFontSizeForPixelSize(int pixelFontSize, bool shouldUseFixedDefaultSize, const Document& document)
 {
     bool quirksMode = document.inQuirksMode();
     int mediumSize = shouldUseFixedDefaultSize ? document.settings().defaultFixedFontSize() : document.settings().defaultFontSize();
     if (mediumSize >= fontSizeTableMin && mediumSize <= fontSizeTableMax) {
         int row = mediumSize - fontSizeTableMin;
         return findNearestLegacyFontSize<int>(pixelFontSize, quirksMode ? quirksFontSizeTable[row] : strictFontSizeTable[row], 1);
     }

     return findNearestLegacyFontSize<float>(pixelFontSize, fontSizeFactors, mediumSize);
 }

 }
 }
	/*
	* Copyright (C) 1999 Lars Knoll (knoll@kde.org)
	* (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
	* Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
	* Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
	* Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
	* Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
	* Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
	* Copyright (c) 2011, Code Aurora Forum. All rights reserved.
	* Copyright (C) Research In Motion Limited 2011. All rights reserved.
	* Copyright (C) 2012 Google Inc. 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 "StyleFontSizeFunctions.h"

	#include "CSSValueKeywords.h"
	#include "Document.h"
	#include "Frame.h"
	#include "RenderStyle.h"
	#include "Settings.h"

	namespace WebCore {

	namespace Style {

	enum class MinimumFontSizeRule {
	None,
	Absolute,
	AbsoluteAndRelative
	};

	static float computedFontSizeFromSpecifiedSize(float specifiedSize, bool isAbsoluteSize, float zoomFactor, MinimumFontSizeRule minimumSizeRule, const Settings& settings)
	{
	// Text with a 0px font size should not be visible and therefore needs to be
	// exempt from minimum font size rules. Acid3 relies on this for pixel-perfect
	// rendering. This is also compatible with other browsers that have minimum
	// font size settings (e.g. Firefox).
	if (fabsf(specifiedSize) < std::numeric_limits<float>::epsilon())
	return 0.0f;

	// We support two types of minimum font size. The first is a hard override that applies to
	// all fonts. This is "minSize." The second type of minimum font size is a "smart minimum"
	// that is applied only when the Web page can't know what size it really asked for, e.g.,
	// when it uses logical sizes like "small" or expresses the font-size as a percentage of
	// the user's default font setting.

	// With the smart minimum, we never want to get smaller than the minimum font size to keep fonts readable.
	// However we always allow the page to set an explicit pixel size that is smaller,
	// since sites will mis-render otherwise (e.g., http://www.gamespot.com with a 9px minimum).

	if (minimumSizeRule == MinimumFontSizeRule::None)
	return specifiedSize;

	int minSize = settings.minimumFontSize();
	int minLogicalSize = settings.minimumLogicalFontSize();
	float zoomedSize = specifiedSize * zoomFactor;

	// Apply the hard minimum first. We only apply the hard minimum if after zooming we're still too small.
	zoomedSize = std::max(zoomedSize, static_cast<float>(minSize));

	// Now apply the smart minimum. This minimum is also only applied if we're still too small
	// after zooming. The font size must either be relative to the user default or the original size
	// must have been acceptable. In other words, we only apply the smart minimum whenever we're positive
	// doing so won't disrupt the layout.
	if (minimumSizeRule == MinimumFontSizeRule::AbsoluteAndRelative && (specifiedSize >= minLogicalSize \|\| !isAbsoluteSize))
	zoomedSize = std::max(zoomedSize, static_cast<float>(minLogicalSize));

	// Also clamp to a reasonable maximum to prevent insane font sizes from causing crashes on various
	// platforms. (I'm looking at you, Windows.)
	return std::min(maximumAllowedFontSize, zoomedSize);
	}

	float computedFontSizeFromSpecifiedSize(float specifiedSize, bool isAbsoluteSize, bool useSVGZoomRules, const RenderStyle* style, const Document& document)
	{
	float zoomFactor = 1.0f;
	if (!useSVGZoomRules) {
	zoomFactor = style->effectiveZoom();
	Frame* frame = document.frame();
	if (frame && style->textZoom() != TextZoom::Reset)
	zoomFactor *= frame->textZoomFactor();
	}
	return computedFontSizeFromSpecifiedSize(specifiedSize, isAbsoluteSize, zoomFactor, useSVGZoomRules ? MinimumFontSizeRule::None : MinimumFontSizeRule::AbsoluteAndRelative, document.settings());
	}

	float computedFontSizeFromSpecifiedSizeForSVGInlineText(float specifiedSize, bool isAbsoluteSize, float zoomFactor, const Document& document)
	{
	return computedFontSizeFromSpecifiedSize(specifiedSize, isAbsoluteSize, zoomFactor, MinimumFontSizeRule::Absolute, document.settings());
	}

	const int fontSizeTableMax = 16;
	const int fontSizeTableMin = 9;
	const int totalKeywords = 8;

	// WinIE/Nav4 table for font sizes. Designed to match the legacy font mapping system of HTML.
	static const int quirksFontSizeTable[fontSizeTableMax - fontSizeTableMin + 1][totalKeywords] =
	{
	{ 9, 9, 9, 9, 11, 14, 18, 28 },
	{ 9, 9, 9, 10, 12, 15, 20, 31 },
	{ 9, 9, 9, 11, 13, 17, 22, 34 },
	{ 9, 9, 10, 12, 14, 18, 24, 37 },
	{ 9, 9, 10, 13, 16, 20, 26, 40 }, // fixed font default (13)
	{ 9, 9, 11, 14, 17, 21, 28, 42 },
	{ 9, 10, 12, 15, 17, 23, 30, 45 },
	{ 9, 10, 13, 16, 18, 24, 32, 48 } // proportional font default (16)
	};
	// HTML 1 2 3 4 5 6 7
	// CSS xxs xs s m l xl xxl
	// \|
	// user pref

	// Strict mode table matches MacIE and Mozilla's settings exactly.
	static const int strictFontSizeTable[fontSizeTableMax - fontSizeTableMin + 1][totalKeywords] =
	{
	{ 9, 9, 9, 9, 11, 14, 18, 27 },
	{ 9, 9, 9, 10, 12, 15, 20, 30 },
	{ 9, 9, 10, 11, 13, 17, 22, 33 },
	{ 9, 9, 10, 12, 14, 18, 24, 36 },
	{ 9, 10, 12, 13, 16, 20, 26, 39 }, // fixed font default (13)
	{ 9, 10, 12, 14, 17, 21, 28, 42 },
	{ 9, 10, 13, 15, 18, 23, 30, 45 },
	{ 9, 10, 13, 16, 18, 24, 32, 48 } // proportional font default (16)
	};
	// HTML 1 2 3 4 5 6 7
	// CSS xxs xs s m l xl xxl
	// \|
	// user pref

	// For values outside the range of the table, we use Todd Fahrner's suggested scale
	// factors for each keyword value.
	static const float fontSizeFactors[totalKeywords] = { 0.60f, 0.75f, 0.89f, 1.0f, 1.2f, 1.5f, 2.0f, 3.0f };

	float fontSizeForKeyword(unsigned keywordID, bool shouldUseFixedDefaultSize, const Document& document)
	{
	bool quirksMode = document.inQuirksMode();
	int mediumSize = shouldUseFixedDefaultSize ? document.settings().defaultFixedFontSize() : document.settings().defaultFontSize();
	if (mediumSize >= fontSizeTableMin && mediumSize <= fontSizeTableMax) {
	// Look up the entry in the table.
	int row = mediumSize - fontSizeTableMin;
	int col = (keywordID - CSSValueXxSmall);
	return quirksMode ? quirksFontSizeTable[row][col] : strictFontSizeTable[row][col];
	}

	// Value is outside the range of the table. Apply the scale factor instead.
	float minLogicalSize = std::max(document.settings().minimumLogicalFontSize(), 1);
	return std::max(fontSizeFactors[keywordID - CSSValueXxSmall] * mediumSize, minLogicalSize);
	}

	template<typename T>
	static int findNearestLegacyFontSize(int pixelFontSize, const T* table, int multiplier)
	{
	// Ignore table[0] because xx-small does not correspond to any legacy font size.
	for (int i = 1; i < totalKeywords - 1; i++) {
	if (pixelFontSize * 2 < (table[i] + table[i + 1]) * multiplier)
	return i;
	}
	return totalKeywords - 1;
	}

	int legacyFontSizeForPixelSize(int pixelFontSize, bool shouldUseFixedDefaultSize, const Document& document)
	{
	bool quirksMode = document.inQuirksMode();
	int mediumSize = shouldUseFixedDefaultSize ? document.settings().defaultFixedFontSize() : document.settings().defaultFontSize();
	if (mediumSize >= fontSizeTableMin && mediumSize <= fontSizeTableMax) {
	int row = mediumSize - fontSizeTableMin;
	return findNearestLegacyFontSize<int>(pixelFontSize, quirksMode ? quirksFontSizeTable[row] : strictFontSizeTable[row], 1);
	}

	return findNearestLegacyFontSize<float>(pixelFontSize, fontSizeFactors, mediumSize);
	}

	}
	}