1/* 2 * Copyright (C) 1999 Lars Knoll (knoll@kde.org) 3 * (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com) 4 * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com) 5 * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved. 6 * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org> 7 * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org> 8 * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/) 9 * Copyright (c) 2011, Code Aurora Forum. All rights reserved. 10 * Copyright (C) Research In Motion Limited 2011. All rights reserved. 11 * Copyright (C) 2012 Google Inc. All rights reserved. 12 * 13 * This library is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU Library General Public 15 * License as published by the Free Software Foundation; either 16 * version 2 of the License, or (at your option) any later version. 17 * 18 * This library is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 21 * Library General Public License for more details. 22 * 23 * You should have received a copy of the GNU Library General Public License 24 * along with this library; see the file COPYING.LIB. If not, write to 25 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 26 * Boston, MA 02110-1301, USA. 27 */ 28 29#include "config.h" 30#include "core/css/FontSize.h" 31 32#include "core/CSSValueKeywords.h" 33#include "core/dom/Document.h" 34#include "core/frame/Settings.h" 35 36namespace blink { 37 38float FontSize::getComputedSizeFromSpecifiedSize(const Document* document, float zoomFactor, bool isAbsoluteSize, float specifiedSize, ESmartMinimumForFontSize useSmartMinimumForFontSize) 39{ 40 // Text with a 0px font size should not be visible and therefore needs to be 41 // exempt from minimum font size rules. Acid3 relies on this for pixel-perfect 42 // rendering. This is also compatible with other browsers that have minimum 43 // font size settings (e.g. Firefox). 44 if (fabsf(specifiedSize) < std::numeric_limits<float>::epsilon()) 45 return 0.0f; 46 47 // We support two types of minimum font size. The first is a hard override that applies to 48 // all fonts. This is "minSize." The second type of minimum font size is a "smart minimum" 49 // that is applied only when the Web page can't know what size it really asked for, e.g., 50 // when it uses logical sizes like "small" or expresses the font-size as a percentage of 51 // the user's default font setting. 52 53 // With the smart minimum, we never want to get smaller than the minimum font size to keep fonts readable. 54 // However we always allow the page to set an explicit pixel size that is smaller, 55 // since sites will mis-render otherwise (e.g., http://www.gamespot.com with a 9px minimum). 56 57 Settings* settings = document->settings(); 58 if (!settings) 59 return 1.0f; 60 61 int minSize = settings->minimumFontSize(); 62 int minLogicalSize = settings->minimumLogicalFontSize(); 63 float zoomedSize = specifiedSize * zoomFactor; 64 65 // Apply the hard minimum first. We only apply the hard minimum if after zooming we're still too small. 66 if (zoomedSize < minSize) 67 zoomedSize = minSize; 68 69 // Now apply the "smart minimum." This minimum is also only applied if we're still too small 70 // after zooming. The font size must either be relative to the user default or the original size 71 // must have been acceptable. In other words, we only apply the smart minimum whenever we're positive 72 // doing so won't disrupt the layout. 73 if (useSmartMinimumForFontSize && zoomedSize < minLogicalSize && (specifiedSize >= minLogicalSize || !isAbsoluteSize)) 74 zoomedSize = minLogicalSize; 75 76 // Also clamp to a reasonable maximum to prevent insane font sizes from causing crashes on various 77 // platforms (I'm looking at you, Windows.) 78 return std::min(maximumAllowedFontSize, zoomedSize); 79} 80 81const int fontSizeTableMax = 16; 82const int fontSizeTableMin = 9; 83const int totalKeywords = 8; 84 85// WinIE/Nav4 table for font sizes. Designed to match the legacy font mapping system of HTML. 86static const int quirksFontSizeTable[fontSizeTableMax - fontSizeTableMin + 1][totalKeywords] = 87{ 88 { 9, 9, 9, 9, 11, 14, 18, 28 }, 89 { 9, 9, 9, 10, 12, 15, 20, 31 }, 90 { 9, 9, 9, 11, 13, 17, 22, 34 }, 91 { 9, 9, 10, 12, 14, 18, 24, 37 }, 92 { 9, 9, 10, 13, 16, 20, 26, 40 }, // fixed font default (13) 93 { 9, 9, 11, 14, 17, 21, 28, 42 }, 94 { 9, 10, 12, 15, 17, 23, 30, 45 }, 95 { 9, 10, 13, 16, 18, 24, 32, 48 } // proportional font default (16) 96}; 97// HTML 1 2 3 4 5 6 7 98// CSS xxs xs s m l xl xxl 99// | 100// user pref 101 102// Strict mode table matches MacIE and Mozilla's settings exactly. 103static const int strictFontSizeTable[fontSizeTableMax - fontSizeTableMin + 1][totalKeywords] = 104{ 105 { 9, 9, 9, 9, 11, 14, 18, 27 }, 106 { 9, 9, 9, 10, 12, 15, 20, 30 }, 107 { 9, 9, 10, 11, 13, 17, 22, 33 }, 108 { 9, 9, 10, 12, 14, 18, 24, 36 }, 109 { 9, 10, 12, 13, 16, 20, 26, 39 }, // fixed font default (13) 110 { 9, 10, 12, 14, 17, 21, 28, 42 }, 111 { 9, 10, 13, 15, 18, 23, 30, 45 }, 112 { 9, 10, 13, 16, 18, 24, 32, 48 } // proportional font default (16) 113}; 114// HTML 1 2 3 4 5 6 7 115// CSS xxs xs s m l xl xxl 116// | 117// user pref 118 119// For values outside the range of the table, we use Todd Fahrner's suggested scale 120// factors for each keyword value. 121static const float fontSizeFactors[totalKeywords] = { 0.60f, 0.75f, 0.89f, 1.0f, 1.2f, 1.5f, 2.0f, 3.0f }; 122 123static int inline rowFromMediumFontSizeInRange(const Settings* settings, bool quirksMode, FixedPitchFontType fixedPitchFontType, int& mediumSize) 124{ 125 mediumSize = fixedPitchFontType == FixedPitchFont ? settings->defaultFixedFontSize() : settings->defaultFontSize(); 126 if (mediumSize >= fontSizeTableMin && mediumSize <= fontSizeTableMax) 127 return mediumSize - fontSizeTableMin; 128 return -1; 129} 130 131float FontSize::fontSizeForKeyword(const Document* document, unsigned keyword, FixedPitchFontType fixedPitchFontType) 132{ 133 ASSERT(keyword >= 1 && keyword <= 8); 134 const Settings* settings = document->settings(); 135 if (!settings) 136 return 1.0f; 137 138 bool quirksMode = document->inQuirksMode(); 139 int mediumSize = 0; 140 int row = rowFromMediumFontSizeInRange(settings, quirksMode, fixedPitchFontType, mediumSize); 141 if (row >= 0) { 142 int col = (keyword - 1); 143 return quirksMode ? quirksFontSizeTable[row][col] : strictFontSizeTable[row][col]; 144 } 145 146 // Value is outside the range of the table. Apply the scale factor instead. 147 float minLogicalSize = std::max(settings->minimumLogicalFontSize(), 1); 148 return std::max(fontSizeFactors[keyword - 1] * mediumSize, minLogicalSize); 149} 150 151 152 153template<typename T> 154static int findNearestLegacyFontSize(int pixelFontSize, const T* table, int multiplier) 155{ 156 // Ignore table[0] because xx-small does not correspond to any legacy font size. 157 for (int i = 1; i < totalKeywords - 1; i++) { 158 if (pixelFontSize * 2 < (table[i] + table[i + 1]) * multiplier) 159 return i; 160 } 161 return totalKeywords - 1; 162} 163 164int FontSize::legacyFontSize(const Document* document, int pixelFontSize, FixedPitchFontType fixedPitchFontType) 165{ 166 const Settings* settings = document->settings(); 167 if (!settings) 168 return 1; 169 170 bool quirksMode = document->inQuirksMode(); 171 int mediumSize = 0; 172 int row = rowFromMediumFontSizeInRange(settings, quirksMode, fixedPitchFontType, mediumSize); 173 if (row >= 0) 174 return findNearestLegacyFontSize<int>(pixelFontSize, quirksMode ? quirksFontSizeTable[row] : strictFontSizeTable[row], 1); 175 176 return findNearestLegacyFontSize<float>(pixelFontSize, fontSizeFactors, mediumSize); 177} 178 179} // namespace blink 180