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 "StyleFontSizeFunctions.h"
31
32#include "CSSValueKeywords.h"
33#include "Document.h"
34#include "Frame.h"
35#include "RenderStyle.h"
36#include "Settings.h"
37
38namespace WebCore {
39
40namespace Style {
41
42enum ESmartMinimumForFontSize { DoNotUseSmartMinimumForFontSize, UseSmartMinimumForFontFize };
43
44static float computedFontSizeFromSpecifiedSize(float specifiedSize, bool isAbsoluteSize, float zoomFactor, ESmartMinimumForFontSize useSmartMinimumForFontSize, const Settings* settings)
45{
46    // Text with a 0px font size should not be visible and therefore needs to be
47    // exempt from minimum font size rules. Acid3 relies on this for pixel-perfect
48    // rendering. This is also compatible with other browsers that have minimum
49    // font size settings (e.g. Firefox).
50    if (fabsf(specifiedSize) < std::numeric_limits<float>::epsilon())
51        return 0.0f;
52
53    // We support two types of minimum font size. The first is a hard override that applies to
54    // all fonts. This is "minSize." The second type of minimum font size is a "smart minimum"
55    // that is applied only when the Web page can't know what size it really asked for, e.g.,
56    // when it uses logical sizes like "small" or expresses the font-size as a percentage of
57    // the user's default font setting.
58
59    // With the smart minimum, we never want to get smaller than the minimum font size to keep fonts readable.
60    // However we always allow the page to set an explicit pixel size that is smaller,
61    // since sites will mis-render otherwise (e.g., http://www.gamespot.com with a 9px minimum).
62
63    if (!settings)
64        return 1.0f;
65
66    int minSize = settings->minimumFontSize();
67    int minLogicalSize = settings->minimumLogicalFontSize();
68    float zoomedSize = specifiedSize * zoomFactor;
69
70    // Apply the hard minimum first. We only apply the hard minimum if after zooming we're still too small.
71    if (zoomedSize < minSize)
72        zoomedSize = minSize;
73
74    // Now apply the "smart minimum." This minimum is also only applied if we're still too small
75    // after zooming. The font size must either be relative to the user default or the original size
76    // must have been acceptable. In other words, we only apply the smart minimum whenever we're positive
77    // doing so won't disrupt the layout.
78    if (useSmartMinimumForFontSize && zoomedSize < minLogicalSize && (specifiedSize >= minLogicalSize || !isAbsoluteSize))
79        zoomedSize = minLogicalSize;
80
81    // Also clamp to a reasonable maximum to prevent insane font sizes from causing crashes on various
82    // platforms (I'm looking at you, Windows.)
83    return std::min(maximumAllowedFontSize, zoomedSize);
84}
85
86float computedFontSizeFromSpecifiedSize(float specifiedSize, bool isAbsoluteSize, bool useSVGZoomRules, const RenderStyle* style, const Document& document)
87{
88    float zoomFactor = 1.0f;
89    if (!useSVGZoomRules) {
90        zoomFactor = style->effectiveZoom();
91        if (Frame* frame = document.frame())
92            zoomFactor *= frame->textZoomFactor();
93    }
94    return computedFontSizeFromSpecifiedSize(specifiedSize, isAbsoluteSize, zoomFactor, UseSmartMinimumForFontFize, document.settings());
95}
96
97float computedFontSizeFromSpecifiedSizeForSVGInlineText(float specifiedSize, bool isAbsoluteSize, float zoomFactor, const Document& document)
98{
99    return computedFontSizeFromSpecifiedSize(specifiedSize, isAbsoluteSize, zoomFactor, DoNotUseSmartMinimumForFontSize, document.settings());
100}
101
102const int fontSizeTableMax = 16;
103const int fontSizeTableMin = 9;
104const int totalKeywords = 8;
105
106// WinIE/Nav4 table for font sizes. Designed to match the legacy font mapping system of HTML.
107static const int quirksFontSizeTable[fontSizeTableMax - fontSizeTableMin + 1][totalKeywords] =
108{
109    { 9,    9,     9,     9,    11,    14,    18,    28 },
110    { 9,    9,     9,    10,    12,    15,    20,    31 },
111    { 9,    9,     9,    11,    13,    17,    22,    34 },
112    { 9,    9,    10,    12,    14,    18,    24,    37 },
113    { 9,    9,    10,    13,    16,    20,    26,    40 }, // fixed font default (13)
114    { 9,    9,    11,    14,    17,    21,    28,    42 },
115    { 9,   10,    12,    15,    17,    23,    30,    45 },
116    { 9,   10,    13,    16,    18,    24,    32,    48 } // proportional font default (16)
117};
118// HTML       1      2      3      4      5      6      7
119// CSS  xxs   xs     s      m      l     xl     xxl
120//                          |
121//                      user pref
122
123// Strict mode table matches MacIE and Mozilla's settings exactly.
124static const int strictFontSizeTable[fontSizeTableMax - fontSizeTableMin + 1][totalKeywords] =
125{
126    { 9,    9,     9,     9,    11,    14,    18,    27 },
127    { 9,    9,     9,    10,    12,    15,    20,    30 },
128    { 9,    9,    10,    11,    13,    17,    22,    33 },
129    { 9,    9,    10,    12,    14,    18,    24,    36 },
130    { 9,   10,    12,    13,    16,    20,    26,    39 }, // fixed font default (13)
131    { 9,   10,    12,    14,    17,    21,    28,    42 },
132    { 9,   10,    13,    15,    18,    23,    30,    45 },
133    { 9,   10,    13,    16,    18,    24,    32,    48 } // proportional font default (16)
134};
135// HTML       1      2      3      4      5      6      7
136// CSS  xxs   xs     s      m      l     xl     xxl
137//                          |
138//                      user pref
139
140// For values outside the range of the table, we use Todd Fahrner's suggested scale
141// factors for each keyword value.
142static const float fontSizeFactors[totalKeywords] = { 0.60f, 0.75f, 0.89f, 1.0f, 1.2f, 1.5f, 2.0f, 3.0f };
143
144float fontSizeForKeyword(unsigned keywordID, bool shouldUseFixedDefaultSize, const Document& document)
145{
146    Settings* settings = document.settings();
147    if (!settings)
148        return 1.0f;
149
150    bool quirksMode = document.inQuirksMode();
151    int mediumSize = shouldUseFixedDefaultSize ? settings->defaultFixedFontSize() : settings->defaultFontSize();
152    if (mediumSize >= fontSizeTableMin && mediumSize <= fontSizeTableMax) {
153        // Look up the entry in the table.
154        int row = mediumSize - fontSizeTableMin;
155        int col = (keywordID - CSSValueXxSmall);
156        return quirksMode ? quirksFontSizeTable[row][col] : strictFontSizeTable[row][col];
157    }
158
159    // Value is outside the range of the table. Apply the scale factor instead.
160    float minLogicalSize = std::max(settings->minimumLogicalFontSize(), 1);
161    return std::max(fontSizeFactors[keywordID - CSSValueXxSmall] * mediumSize, minLogicalSize);
162}
163
164template<typename T>
165static int findNearestLegacyFontSize(int pixelFontSize, const T* table, int multiplier)
166{
167    // Ignore table[0] because xx-small does not correspond to any legacy font size.
168    for (int i = 1; i < totalKeywords - 1; i++) {
169        if (pixelFontSize * 2 < (table[i] + table[i + 1]) * multiplier)
170            return i;
171    }
172    return totalKeywords - 1;
173}
174
175int legacyFontSizeForPixelSize(int pixelFontSize, bool shouldUseFixedDefaultSize, const Document& document)
176{
177    Settings* settings = document.settings();
178    if (!settings)
179        return 1;
180
181    bool quirksMode = document.inQuirksMode();
182    int mediumSize = shouldUseFixedDefaultSize ? settings->defaultFixedFontSize() : settings->defaultFontSize();
183    if (mediumSize >= fontSizeTableMin && mediumSize <= fontSizeTableMax) {
184        int row = mediumSize - fontSizeTableMin;
185        return findNearestLegacyFontSize<int>(pixelFontSize, quirksMode ? quirksFontSizeTable[row] : strictFontSizeTable[row], 1);
186    }
187
188    return findNearestLegacyFontSize<float>(pixelFontSize, fontSizeFactors, mediumSize);
189}
190
191}
192}
193