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.
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.
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.
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.
30 #include "core/css/FontSize.h"
32 #include "core/CSSValueKeywords.h"
33 #include "core/dom/Document.h"
34 #include "core/frame/Settings.h"
38 float FontSize::getComputedSizeFromSpecifiedSize(const Document* document, float zoomFactor, bool isAbsoluteSize, float specifiedSize, ESmartMinimumForFontSize useSmartMinimumForFontSize)
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())
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.
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).
57 Settings* settings = document->settings();
61 int minSize = settings->minimumFontSize();
62 int minLogicalSize = settings->minimumLogicalFontSize();
63 float zoomedSize = specifiedSize * zoomFactor;
65 // Apply the hard minimum first. We only apply the hard minimum if after zooming we're still too small.
66 if (zoomedSize < minSize)
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;
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);
81 const int fontSizeTableMax = 16;
82 const int fontSizeTableMin = 9;
83 const int totalKeywords = 8;
85 // WinIE/Nav4 table for font sizes. Designed to match the legacy font mapping system of HTML.
86 static const int quirksFontSizeTable[fontSizeTableMax - fontSizeTableMin + 1][totalKeywords] =
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)
98 // CSS xxs xs s m l xl xxl
102 // Strict mode table matches MacIE and Mozilla's settings exactly.
103 static const int strictFontSizeTable[fontSizeTableMax - fontSizeTableMin + 1][totalKeywords] =
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)
114 // HTML 1 2 3 4 5 6 7
115 // CSS xxs xs s m l xl xxl
119 // For values outside the range of the table, we use Todd Fahrner's suggested scale
120 // factors for each keyword value.
121 static const float fontSizeFactors[totalKeywords] = { 0.60f, 0.75f, 0.89f, 1.0f, 1.2f, 1.5f, 2.0f, 3.0f };
123 static int inline rowFromMediumFontSizeInRange(const Settings* settings, bool quirksMode, FixedPitchFontType fixedPitchFontType, int& mediumSize)
125 mediumSize = fixedPitchFontType == FixedPitchFont ? settings->defaultFixedFontSize() : settings->defaultFontSize();
126 if (mediumSize >= fontSizeTableMin && mediumSize <= fontSizeTableMax)
127 return mediumSize - fontSizeTableMin;
131 float FontSize::fontSizeForKeyword(const Document* document, CSSValueID keyword, FixedPitchFontType fixedPitchFontType)
133 ASSERT(keyword >= CSSValueXxSmall && keyword <= CSSValueWebkitXxxLarge);
134 const Settings* settings = document->settings();
138 bool quirksMode = document->inQuirksMode();
140 int row = rowFromMediumFontSizeInRange(settings, quirksMode, fixedPitchFontType, mediumSize);
142 int col = (keyword - CSSValueXxSmall);
143 return quirksMode ? quirksFontSizeTable[row][col] : strictFontSizeTable[row][col];
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 - CSSValueXxSmall] * mediumSize, minLogicalSize);
154 static int findNearestLegacyFontSize(int pixelFontSize, const T* table, int multiplier)
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)
161 return totalKeywords - 1;
164 int FontSize::legacyFontSize(const Document* document, int pixelFontSize, FixedPitchFontType fixedPitchFontType)
166 const Settings* settings = document->settings();
170 bool quirksMode = document->inQuirksMode();
172 int row = rowFromMediumFontSizeInRange(settings, quirksMode, fixedPitchFontType, mediumSize);
174 return findNearestLegacyFontSize<int>(pixelFontSize, quirksMode ? quirksFontSizeTable[row] : strictFontSizeTable[row], 1);
176 return findNearestLegacyFontSize<float>(pixelFontSize, fontSizeFactors, mediumSize);