1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/src/nsFontMetrics.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,228 @@
1.4 +/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#ifndef NSFONTMETRICS__H__
1.10 +#define NSFONTMETRICS__H__
1.11 +
1.12 +#include <stdint.h> // for uint32_t
1.13 +#include <sys/types.h> // for int32_t
1.14 +#include "gfxFont.h" // for gfxFont, gfxFontGroup
1.15 +#include "mozilla/Assertions.h" // for MOZ_ASSERT_HELPER2
1.16 +#include "nsAutoPtr.h" // for nsRefPtr
1.17 +#include "nsCOMPtr.h" // for nsCOMPtr
1.18 +#include "nsCoord.h" // for nscoord
1.19 +#include "nsError.h" // for nsresult
1.20 +#include "nsFont.h" // for nsFont
1.21 +#include "nsISupports.h" // for NS_INLINE_DECL_REFCOUNTING
1.22 +#include "nscore.h" // for char16_t
1.23 +
1.24 +class gfxUserFontSet;
1.25 +class gfxTextPerfMetrics;
1.26 +class nsDeviceContext;
1.27 +class nsIAtom;
1.28 +class nsRenderingContext;
1.29 +struct nsBoundingMetrics;
1.30 +
1.31 +/**
1.32 + * Font metrics
1.33 + *
1.34 + * This class may be somewhat misnamed. A better name might be
1.35 + * nsFontList. The style system uses the nsFont struct for various
1.36 + * font properties, one of which is font-family, which can contain a
1.37 + * *list* of font names. The nsFont struct is "realized" by asking the
1.38 + * device context to cough up an nsFontMetrics object, which contains
1.39 + * a list of real font handles, one for each font mentioned in
1.40 + * font-family (and for each fallback when we fall off the end of that
1.41 + * list).
1.42 + *
1.43 + * The style system needs to have access to certain metrics, such as
1.44 + * the em height (for the CSS "em" unit), and we use the first Western
1.45 + * font's metrics for that purpose. The platform-specific
1.46 + * implementations are expected to select non-Western fonts that "fit"
1.47 + * reasonably well with the Western font that is loaded at Init time.
1.48 + */
1.49 +class nsFontMetrics MOZ_FINAL
1.50 +{
1.51 +public:
1.52 + nsFontMetrics();
1.53 +
1.54 + NS_INLINE_DECL_REFCOUNTING(nsFontMetrics)
1.55 +
1.56 + /**
1.57 + * Initialize the font metrics. Call this after creating the font metrics.
1.58 + * Font metrics you get from the font cache do NOT need to be initialized
1.59 + *
1.60 + * @see nsDeviceContext#GetMetricsFor()
1.61 + */
1.62 + nsresult Init(const nsFont& aFont, nsIAtom* aLanguage,
1.63 + nsDeviceContext *aContext,
1.64 + gfxUserFontSet *aUserFontSet,
1.65 + gfxTextPerfMetrics *aTextPerf);
1.66 +
1.67 + /**
1.68 + * Destroy this font metrics. This breaks the association between
1.69 + * the font metrics and the device context.
1.70 + */
1.71 + void Destroy();
1.72 +
1.73 + /**
1.74 + * Return the font's x-height.
1.75 + */
1.76 + nscoord XHeight();
1.77 +
1.78 + /**
1.79 + * Return the font's superscript offset (the distance from the
1.80 + * baseline to where a superscript's baseline should be placed).
1.81 + * The value returned will be positive.
1.82 + */
1.83 + nscoord SuperscriptOffset();
1.84 +
1.85 + /**
1.86 + * Return the font's subscript offset (the distance from the
1.87 + * baseline to where a subscript's baseline should be placed).
1.88 + * The value returned will be positive.
1.89 + */
1.90 + nscoord SubscriptOffset();
1.91 +
1.92 + /**
1.93 + * Return the font's strikeout offset (the distance from the
1.94 + * baseline to where a strikeout should be placed) and size.
1.95 + * Positive values are above the baseline, negative below.
1.96 + */
1.97 + void GetStrikeout(nscoord& aOffset, nscoord& aSize);
1.98 +
1.99 + /**
1.100 + * Return the font's underline offset (the distance from the
1.101 + * baseline to where a underline should be placed) and size.
1.102 + * Positive values are above the baseline, negative below.
1.103 + */
1.104 + void GetUnderline(nscoord& aOffset, nscoord& aSize);
1.105 +
1.106 + /**
1.107 + * Returns the amount of internal leading for the font.
1.108 + * This is normally the difference between the max ascent
1.109 + * and the em ascent.
1.110 + */
1.111 + nscoord InternalLeading();
1.112 +
1.113 + /**
1.114 + * Returns the amount of external leading for the font.
1.115 + * em ascent(?) plus external leading is the font designer's
1.116 + * recommended line-height for this font.
1.117 + */
1.118 + nscoord ExternalLeading();
1.119 +
1.120 + /**
1.121 + * Returns the height of the em square.
1.122 + * This is em ascent plus em descent.
1.123 + */
1.124 + nscoord EmHeight();
1.125 +
1.126 + /**
1.127 + * Returns the ascent part of the em square.
1.128 + */
1.129 + nscoord EmAscent();
1.130 +
1.131 + /**
1.132 + * Returns the descent part of the em square.
1.133 + */
1.134 + nscoord EmDescent();
1.135 +
1.136 + /**
1.137 + * Returns the height of the bounding box.
1.138 + * This is max ascent plus max descent.
1.139 + */
1.140 + nscoord MaxHeight();
1.141 +
1.142 + /**
1.143 + * Returns the maximum distance characters in this font extend
1.144 + * above the base line.
1.145 + */
1.146 + nscoord MaxAscent();
1.147 +
1.148 + /**
1.149 + * Returns the maximum distance characters in this font extend
1.150 + * below the base line.
1.151 + */
1.152 + nscoord MaxDescent();
1.153 +
1.154 + /**
1.155 + * Returns the maximum character advance for the font.
1.156 + */
1.157 + nscoord MaxAdvance();
1.158 +
1.159 + /**
1.160 + * Returns the average character width
1.161 + */
1.162 + nscoord AveCharWidth();
1.163 +
1.164 + /**
1.165 + * Returns the often needed width of the space character
1.166 + */
1.167 + nscoord SpaceWidth();
1.168 +
1.169 + /**
1.170 + * Returns the font associated with these metrics. The return value
1.171 + * is only defined after Init() has been called.
1.172 + */
1.173 + const nsFont &Font() { return mFont; }
1.174 +
1.175 + /**
1.176 + * Returns the language associated with these metrics
1.177 + */
1.178 + nsIAtom* Language() { return mLanguage; }
1.179 +
1.180 + int32_t GetMaxStringLength();
1.181 +
1.182 + // Get the width for this string. aWidth will be updated with the
1.183 + // width in points, not twips. Callers must convert it if they
1.184 + // want it in another format.
1.185 + nscoord GetWidth(const char* aString, uint32_t aLength,
1.186 + nsRenderingContext *aContext);
1.187 + nscoord GetWidth(const char16_t* aString, uint32_t aLength,
1.188 + nsRenderingContext *aContext);
1.189 +
1.190 + // Draw a string using this font handle on the surface passed in.
1.191 + void DrawString(const char *aString, uint32_t aLength,
1.192 + nscoord aX, nscoord aY,
1.193 + nsRenderingContext *aContext);
1.194 + void DrawString(const char16_t* aString, uint32_t aLength,
1.195 + nscoord aX, nscoord aY,
1.196 + nsRenderingContext *aContext,
1.197 + nsRenderingContext *aTextRunConstructionContext);
1.198 +
1.199 + nsBoundingMetrics GetBoundingMetrics(const char16_t *aString,
1.200 + uint32_t aLength,
1.201 + nsRenderingContext *aContext);
1.202 +
1.203 + // Returns the LOOSE_INK_EXTENTS bounds of the text for determing the
1.204 + // overflow area of the string.
1.205 + nsBoundingMetrics GetInkBoundsForVisualOverflow(const char16_t *aString,
1.206 + uint32_t aLength,
1.207 + nsRenderingContext *aContext);
1.208 +
1.209 + void SetTextRunRTL(bool aIsRTL) { mTextRunRTL = aIsRTL; }
1.210 + bool GetTextRunRTL() { return mTextRunRTL; }
1.211 +
1.212 + gfxFontGroup* GetThebesFontGroup() { return mFontGroup; }
1.213 + gfxUserFontSet* GetUserFontSet() { return mFontGroup->GetUserFontSet(); }
1.214 +
1.215 + int32_t AppUnitsPerDevPixel() { return mP2A; }
1.216 +
1.217 +private:
1.218 + // Private destructor, to discourage deletion outside of Release():
1.219 + ~nsFontMetrics();
1.220 +
1.221 + const gfxFont::Metrics& GetMetrics() const;
1.222 +
1.223 + nsFont mFont;
1.224 + nsRefPtr<gfxFontGroup> mFontGroup;
1.225 + nsCOMPtr<nsIAtom> mLanguage;
1.226 + nsDeviceContext *mDeviceContext;
1.227 + int32_t mP2A;
1.228 + bool mTextRunRTL;
1.229 +};
1.230 +
1.231 +#endif /* NSFONTMETRICS__H__ */
