1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 #ifndef NSFONTMETRICS__H__
7 #define NSFONTMETRICS__H__
9 #include <stdint.h> // for uint32_t
10 #include <sys/types.h> // for int32_t
11 #include "mozilla/Assertions.h" // for MOZ_ASSERT_HELPER2
12 #include "mozilla/RefPtr.h" // for RefPtr
13 #include "nsCOMPtr.h" // for nsCOMPtr
14 #include "nsCoord.h" // for nscoord
15 #include "nsError.h" // for nsresult
16 #include "nsFont.h" // for nsFont
17 #include "nsISupports.h" // for NS_INLINE_DECL_REFCOUNTING
18 #include "nsStyleConsts.h"
19 #include "nscore.h" // for char16_t
24 class gfxTextPerfMetrics
;
27 struct nsBoundingMetrics
;
33 } // namespace mozilla
38 * This class may be somewhat misnamed. A better name might be
39 * nsFontList. The style system uses the nsFont struct for various
40 * font properties, one of which is font-family, which can contain a
41 * *list* of font names. The nsFont struct is "realized" by asking the
42 * pres context to cough up an nsFontMetrics object, which contains
43 * a list of real font handles, one for each font mentioned in
44 * font-family (and for each fallback when we fall off the end of that
47 * The style system needs to have access to certain metrics, such as
48 * the em height (for the CSS "em" unit), and we use the first Western
49 * font's metrics for that purpose. The platform-specific
50 * implementations are expected to select non-Western fonts that "fit"
51 * reasonably well with the Western font that is loaded at Init time.
53 class nsFontMetrics final
{
55 typedef mozilla::gfx::DrawTarget DrawTarget
;
57 enum FontOrientation
{ eHorizontal
, eVertical
};
59 struct MOZ_STACK_CLASS Params
{
60 nsAtom
* language
= nullptr;
61 bool explicitLanguage
= false;
62 FontOrientation orientation
= eHorizontal
;
63 gfxUserFontSet
* userFontSet
= nullptr;
64 gfxTextPerfMetrics
* textPerf
= nullptr;
65 gfxFontFeatureValueSet
* featureValueLookup
= nullptr;
68 nsFontMetrics(const nsFont
& aFont
, const Params
& aParams
,
69 nsPresContext
* aContext
);
72 NS_INLINE_DECL_THREADSAFE_REFCOUNTING(nsFontMetrics
)
75 * Destroy this font metrics. This breaks the association between
76 * the font metrics and the pres context.
81 * Return the font's x-height.
86 * Return the font's cap-height.
91 * Return the font's superscript offset (the distance from the
92 * baseline to where a superscript's baseline should be placed).
93 * The value returned will be positive.
95 nscoord
SuperscriptOffset();
98 * Return the font's subscript offset (the distance from the
99 * baseline to where a subscript's baseline should be placed).
100 * The value returned will be positive.
102 nscoord
SubscriptOffset();
105 * Return the font's strikeout offset (the distance from the
106 * baseline to where a strikeout should be placed) and size.
107 * Positive values are above the baseline, negative below.
109 void GetStrikeout(nscoord
& aOffset
, nscoord
& aSize
);
112 * Return the font's underline offset (the distance from the
113 * baseline to where a underline should be placed) and size.
114 * Positive values are above the baseline, negative below.
116 void GetUnderline(nscoord
& aOffset
, nscoord
& aSize
);
119 * Returns the amount of internal leading for the font.
120 * This is normally the difference between the max ascent
123 nscoord
InternalLeading();
126 * Returns the amount of external leading for the font.
127 * em ascent(?) plus external leading is the font designer's
128 * recommended line-height for this font.
130 nscoord
ExternalLeading();
133 * Returns the height of the em square.
134 * This is em ascent plus em descent.
139 * Returns the ascent part of the em square.
144 * Returns the descent part of the em square.
149 * Returns the height of the bounding box.
150 * This is max ascent plus max descent.
155 * Returns the maximum distance characters in this font extend
156 * above the base line.
161 * Returns the maximum distance characters in this font extend
162 * below the base line.
164 nscoord
MaxDescent();
167 * Returns the maximum character advance for the font.
169 nscoord
MaxAdvance();
172 * Returns the average character width
174 nscoord
AveCharWidth();
177 * Returns the often needed width of the space character
179 nscoord
SpaceWidth();
182 * Returns the font associated with these metrics. The return value
183 * is only defined after Init() has been called.
185 const nsFont
& Font() const { return mFont
; }
188 * Returns the language associated with these metrics
190 nsAtom
* Language() const { return mLanguage
; }
193 * Returns the orientation (horizontal/vertical) of these metrics.
195 FontOrientation
Orientation() const { return mOrientation
; }
197 int32_t GetMaxStringLength();
199 // Get the width for this string. aWidth will be updated with the
200 // width in points, not twips. Callers must convert it if they
201 // want it in another format.
202 nscoord
GetWidth(const char* aString
, uint32_t aLength
,
203 DrawTarget
* aDrawTarget
);
204 nscoord
GetWidth(const char16_t
* aString
, uint32_t aLength
,
205 DrawTarget
* aDrawTarget
);
207 // Draw a string using this font handle on the surface passed in.
208 void DrawString(const char* aString
, uint32_t aLength
, nscoord aX
, nscoord aY
,
209 gfxContext
* aContext
);
210 void DrawString(const char16_t
* aString
, uint32_t aLength
, nscoord aX
,
211 nscoord aY
, gfxContext
* aContext
,
212 DrawTarget
* aTextRunConstructionDrawTarget
);
214 nsBoundingMetrics
GetBoundingMetrics(const char16_t
* aString
,
216 DrawTarget
* aDrawTarget
);
218 // Returns the LOOSE_INK_EXTENTS bounds of the text for determing the
219 // overflow area of the string.
220 nsBoundingMetrics
GetInkBoundsForInkOverflow(const char16_t
* aString
,
222 DrawTarget
* aDrawTarget
);
224 void SetTextRunRTL(bool aIsRTL
) { mTextRunRTL
= aIsRTL
; }
225 bool GetTextRunRTL() const { return mTextRunRTL
; }
227 void SetVertical(bool aVertical
) { mVertical
= aVertical
; }
228 bool GetVertical() const { return mVertical
; }
230 void SetTextOrientation(mozilla::StyleTextOrientation aTextOrientation
) {
231 mTextOrientation
= aTextOrientation
;
233 mozilla::StyleTextOrientation
GetTextOrientation() const {
234 return mTextOrientation
;
237 bool ExplicitLanguage() const { return mExplicitLanguage
; }
239 gfxFontGroup
* GetThebesFontGroup() const { return mFontGroup
; }
240 gfxUserFontSet
* GetUserFontSet() const;
242 int32_t AppUnitsPerDevPixel() const { return mP2A
; }
245 // Private destructor, to discourage deletion outside of Release():
249 RefPtr
<gfxFontGroup
> mFontGroup
;
250 RefPtr
<nsAtom
> mLanguage
;
251 // Pointer to the pres context for which this fontMetrics object was
253 nsPresContext
* MOZ_NON_OWNING_REF mPresContext
;
256 // The font orientation (horizontal or vertical) for which these metrics
257 // have been initialized. This determines which line metrics (ascent and
258 // descent) they will return.
259 FontOrientation mOrientation
;
261 // Whether mLanguage comes from explicit markup (in which case it should be
262 // used to tailor effects like case-conversion) or is an inferred/default
264 bool mExplicitLanguage
;
266 // These fields may be set by clients to control the behavior of methods
267 // like GetWidth and DrawString according to the writing mode, direction
268 // and text-orientation desired.
271 mozilla::StyleTextOrientation mTextOrientation
;
274 #endif /* NSFONTMETRICS__H__ */