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Diffstat (limited to 'gfx/src/nsFontMetrics.h')
| -rw-r--r-- | gfx/src/nsFontMetrics.h | 279 |
1 files changed, 279 insertions, 0 deletions
diff --git a/gfx/src/nsFontMetrics.h b/gfx/src/nsFontMetrics.h new file mode 100644 index 0000000000..55a45f6be1 --- /dev/null +++ b/gfx/src/nsFontMetrics.h @@ -0,0 +1,279 @@ +/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef NSFONTMETRICS__H__ +#define NSFONTMETRICS__H__ + +#include <stdint.h> // for uint32_t +#include <sys/types.h> // for int32_t +#include "mozilla/Assertions.h" // for MOZ_ASSERT_HELPER2 +#include "mozilla/RefPtr.h" // for RefPtr +#include "nsCOMPtr.h" // for nsCOMPtr +#include "nsCoord.h" // for nscoord +#include "nsError.h" // for nsresult +#include "nsFont.h" // for nsFont +#include "nsISupports.h" // for NS_INLINE_DECL_REFCOUNTING +#include "nsStyleConsts.h" +#include "nscore.h" // for char16_t + +class gfxContext; +class gfxFontGroup; +class gfxUserFontSet; +class gfxTextPerfMetrics; +class nsPresContext; +class nsAtom; +struct nsBoundingMetrics; + +namespace mozilla { +namespace gfx { +class DrawTarget; +} // namespace gfx +} // namespace mozilla + +/** + * Font metrics + * + * This class may be somewhat misnamed. A better name might be + * nsFontList. The style system uses the nsFont struct for various + * font properties, one of which is font-family, which can contain a + * *list* of font names. The nsFont struct is "realized" by asking the + * pres context to cough up an nsFontMetrics object, which contains + * a list of real font handles, one for each font mentioned in + * font-family (and for each fallback when we fall off the end of that + * list). + * + * The style system needs to have access to certain metrics, such as + * the em height (for the CSS "em" unit), and we use the first Western + * font's metrics for that purpose. The platform-specific + * implementations are expected to select non-Western fonts that "fit" + * reasonably well with the Western font that is loaded at Init time. + */ +class nsFontMetrics final { + public: + typedef mozilla::gfx::DrawTarget DrawTarget; + + enum FontOrientation { eHorizontal, eVertical }; + + struct MOZ_STACK_CLASS Params { + nsAtom* language = nullptr; + bool explicitLanguage = false; + FontOrientation orientation = eHorizontal; + gfxUserFontSet* userFontSet = nullptr; + gfxTextPerfMetrics* textPerf = nullptr; + gfxFontFeatureValueSet* featureValueLookup = nullptr; + }; + + nsFontMetrics(const nsFont& aFont, const Params& aParams, + nsPresContext* aContext); + + // Used by stylo + NS_INLINE_DECL_THREADSAFE_REFCOUNTING(nsFontMetrics) + + /** + * Destroy this font metrics. This breaks the association between + * the font metrics and the pres context. + */ + void Destroy(); + + /** + * Return the font's x-height. + */ + nscoord XHeight() const; + + /** + * Return the font's cap-height. + */ + nscoord CapHeight() const; + + /** + * Return the font's superscript offset (the distance from the + * baseline to where a superscript's baseline should be placed). + * The value returned will be positive. + */ + nscoord SuperscriptOffset() const; + + /** + * Return the font's subscript offset (the distance from the + * baseline to where a subscript's baseline should be placed). + * The value returned will be positive. + */ + nscoord SubscriptOffset() const; + + /** + * Return the font's strikeout offset (the distance from the + * baseline to where a strikeout should be placed) and size. + * Positive values are above the baseline, negative below. + */ + void GetStrikeout(nscoord& aOffset, nscoord& aSize) const; + + /** + * Return the font's underline offset (the distance from the + * baseline to where a underline should be placed) and size. + * Positive values are above the baseline, negative below. + */ + void GetUnderline(nscoord& aOffset, nscoord& aSize) const; + + /** + * Returns the amount of internal leading for the font. + * This is normally the difference between the max ascent + * and the em ascent. + */ + nscoord InternalLeading() const; + + /** + * Returns the amount of external leading for the font. + * em ascent(?) plus external leading is the font designer's + * recommended line-height for this font. + */ + nscoord ExternalLeading() const; + + /** + * Returns the height of the em square. + * This is em ascent plus em descent. + */ + nscoord EmHeight() const; + + /** + * Returns the ascent part of the em square. + */ + nscoord EmAscent() const; + + /** + * Returns the descent part of the em square. + */ + nscoord EmDescent() const; + + /** + * Returns the height of the bounding box. + * This is max ascent plus max descent. + */ + nscoord MaxHeight() const; + + /** + * Returns the maximum distance characters in this font extend + * above the base line. + */ + nscoord MaxAscent() const; + + /** + * Returns the maximum distance characters in this font extend + * below the base line. + */ + nscoord MaxDescent() const; + + /** + * Returns the maximum character advance for the font. + */ + nscoord MaxAdvance() const; + + /** + * Returns the average character width + */ + nscoord AveCharWidth() const; + + /** + * Returns width of the zero character, or AveCharWidth if no zero present. + */ + nscoord ZeroOrAveCharWidth() const; + + /** + * Returns the often needed width of the space character + */ + nscoord SpaceWidth() const; + + /** + * Returns the font associated with these metrics. The return value + * is only defined after Init() has been called. + */ + const nsFont& Font() const { return mFont; } + + /** + * Returns the language associated with these metrics + */ + nsAtom* Language() const { return mLanguage; } + + /** + * Returns the orientation (horizontal/vertical) of these metrics. + */ + FontOrientation Orientation() const { return mOrientation; } + + int32_t GetMaxStringLength() const; + + // Get the width for this string. aWidth will be updated with the + // width in points, not twips. Callers must convert it if they + // want it in another format. + nscoord GetWidth(const char* aString, uint32_t aLength, + DrawTarget* aDrawTarget) const; + nscoord GetWidth(const char16_t* aString, uint32_t aLength, + DrawTarget* aDrawTarget) const; + + // Draw a string using this font handle on the surface passed in. + void DrawString(const char* aString, uint32_t aLength, nscoord aX, nscoord aY, + gfxContext* aContext) const; + void DrawString(const char16_t* aString, uint32_t aLength, nscoord aX, + nscoord aY, gfxContext* aContext, + DrawTarget* aTextRunConstructionDrawTarget) const; + + nsBoundingMetrics GetBoundingMetrics(const char16_t* aString, + uint32_t aLength, + DrawTarget* aDrawTarget) const; + + // Returns the LOOSE_INK_EXTENTS bounds of the text for determing the + // overflow area of the string. + nsBoundingMetrics GetInkBoundsForInkOverflow(const char16_t* aString, + uint32_t aLength, + DrawTarget* aDrawTarget) const; + + void SetTextRunRTL(bool aIsRTL) { mTextRunRTL = aIsRTL; } + bool GetTextRunRTL() const { return mTextRunRTL; } + + void SetVertical(bool aVertical) { mVertical = aVertical; } + bool GetVertical() const { return mVertical; } + + void SetTextOrientation(mozilla::StyleTextOrientation aTextOrientation) { + mTextOrientation = aTextOrientation; + } + mozilla::StyleTextOrientation GetTextOrientation() const { + return mTextOrientation; + } + + bool ExplicitLanguage() const { return mExplicitLanguage; } + + gfxFontGroup* GetThebesFontGroup() const { return mFontGroup; } + gfxUserFontSet* GetUserFontSet() const; + + int32_t AppUnitsPerDevPixel() const { return mP2A; } + + private: + // Private destructor, to discourage deletion outside of Release(): + ~nsFontMetrics(); + + const nsFont mFont; + RefPtr<gfxFontGroup> mFontGroup; + RefPtr<nsAtom> const mLanguage; + // Pointer to the pres context for which this fontMetrics object was + // created. + nsPresContext* MOZ_NON_OWNING_REF mPresContext; + const int32_t mP2A; + + // The font orientation (horizontal or vertical) for which these metrics + // have been initialized. This determines which line metrics (ascent and + // descent) they will return. + const FontOrientation mOrientation; + + // Whether mLanguage comes from explicit markup (in which case it should be + // used to tailor effects like case-conversion) or is an inferred/default + // value. + const bool mExplicitLanguage; + + // These fields may be set by clients to control the behavior of methods + // like GetWidth and DrawString according to the writing mode, direction + // and text-orientation desired. + bool mTextRunRTL; + bool mVertical; + mozilla::StyleTextOrientation mTextOrientation; +}; + +#endif /* NSFONTMETRICS__H__ */ |