264 lines
8.6 KiB
C++
264 lines
8.6 KiB
C++
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef NSFONTMETRICS__H__
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#define NSFONTMETRICS__H__
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#include <stdint.h> // for uint32_t
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#include <sys/types.h> // for int32_t
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#include "gfxTextRun.h" // for gfxFont, gfxFontGroup
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#include "mozilla/Assertions.h" // for MOZ_ASSERT_HELPER2
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#include "nsAutoPtr.h" // for nsRefPtr
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#include "nsCOMPtr.h" // for nsCOMPtr
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#include "nsCoord.h" // for nscoord
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#include "nsError.h" // for nsresult
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#include "nsFont.h" // for nsFont
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#include "nsISupports.h" // for NS_INLINE_DECL_REFCOUNTING
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#include "nscore.h" // for char16_t
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class gfxUserFontSet;
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class gfxTextPerfMetrics;
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class nsDeviceContext;
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class nsIAtom;
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class nsRenderingContext;
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struct nsBoundingMetrics;
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/**
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* Font metrics
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*
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* This class may be somewhat misnamed. A better name might be
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* nsFontList. The style system uses the nsFont struct for various
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* font properties, one of which is font-family, which can contain a
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* *list* of font names. The nsFont struct is "realized" by asking the
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* device context to cough up an nsFontMetrics object, which contains
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* a list of real font handles, one for each font mentioned in
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* font-family (and for each fallback when we fall off the end of that
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* list).
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*
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* The style system needs to have access to certain metrics, such as
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* the em height (for the CSS "em" unit), and we use the first Western
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* font's metrics for that purpose. The platform-specific
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* implementations are expected to select non-Western fonts that "fit"
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* reasonably well with the Western font that is loaded at Init time.
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*/
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class nsFontMetrics final
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{
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public:
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nsFontMetrics();
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NS_INLINE_DECL_REFCOUNTING(nsFontMetrics)
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/**
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* Initialize the font metrics. Call this after creating the font metrics.
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* Font metrics you get from the font cache do NOT need to be initialized
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*
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* @see nsDeviceContext#GetMetricsFor()
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*/
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nsresult Init(const nsFont& aFont,
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nsIAtom* aLanguage, bool aExplicitLanguage,
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gfxFont::Orientation aOrientation,
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nsDeviceContext *aContext,
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gfxUserFontSet *aUserFontSet,
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gfxTextPerfMetrics *aTextPerf);
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/**
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* Destroy this font metrics. This breaks the association between
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* the font metrics and the device context.
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*/
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void Destroy();
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/**
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* Return the font's x-height.
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*/
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nscoord XHeight();
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/**
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* Return the font's superscript offset (the distance from the
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* baseline to where a superscript's baseline should be placed).
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* The value returned will be positive.
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*/
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nscoord SuperscriptOffset();
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/**
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* Return the font's subscript offset (the distance from the
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* baseline to where a subscript's baseline should be placed).
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* The value returned will be positive.
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*/
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nscoord SubscriptOffset();
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/**
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* Return the font's strikeout offset (the distance from the
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* baseline to where a strikeout should be placed) and size.
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* Positive values are above the baseline, negative below.
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*/
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void GetStrikeout(nscoord& aOffset, nscoord& aSize);
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/**
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* Return the font's underline offset (the distance from the
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* baseline to where a underline should be placed) and size.
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* Positive values are above the baseline, negative below.
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*/
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void GetUnderline(nscoord& aOffset, nscoord& aSize);
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/**
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* Returns the amount of internal leading for the font.
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* This is normally the difference between the max ascent
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* and the em ascent.
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*/
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nscoord InternalLeading();
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/**
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* Returns the amount of external leading for the font.
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* em ascent(?) plus external leading is the font designer's
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* recommended line-height for this font.
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*/
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nscoord ExternalLeading();
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/**
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* Returns the height of the em square.
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* This is em ascent plus em descent.
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*/
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nscoord EmHeight();
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/**
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* Returns the ascent part of the em square.
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*/
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nscoord EmAscent();
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/**
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* Returns the descent part of the em square.
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*/
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nscoord EmDescent();
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/**
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* Returns the height of the bounding box.
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* This is max ascent plus max descent.
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*/
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nscoord MaxHeight();
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/**
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* Returns the maximum distance characters in this font extend
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* above the base line.
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*/
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nscoord MaxAscent();
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/**
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* Returns the maximum distance characters in this font extend
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* below the base line.
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*/
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nscoord MaxDescent();
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/**
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* Returns the maximum character advance for the font.
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*/
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nscoord MaxAdvance();
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/**
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* Returns the average character width
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*/
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nscoord AveCharWidth();
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/**
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* Returns the often needed width of the space character
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*/
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nscoord SpaceWidth();
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/**
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* Returns the font associated with these metrics. The return value
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* is only defined after Init() has been called.
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*/
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const nsFont &Font() const { return mFont; }
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/**
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* Returns the language associated with these metrics
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*/
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nsIAtom* Language() const { return mLanguage; }
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/**
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* Returns the orientation (horizontal/vertical) of these metrics.
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*/
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gfxFont::Orientation Orientation() const { return mOrientation; }
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int32_t GetMaxStringLength();
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// Get the width for this string. aWidth will be updated with the
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// width in points, not twips. Callers must convert it if they
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// want it in another format.
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nscoord GetWidth(const char* aString, uint32_t aLength,
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nsRenderingContext *aContext);
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nscoord GetWidth(const char16_t* aString, uint32_t aLength,
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nsRenderingContext *aContext);
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// Draw a string using this font handle on the surface passed in.
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void DrawString(const char *aString, uint32_t aLength,
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nscoord aX, nscoord aY,
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nsRenderingContext *aContext);
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void DrawString(const char16_t* aString, uint32_t aLength,
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nscoord aX, nscoord aY,
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nsRenderingContext *aContext,
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nsRenderingContext *aTextRunConstructionContext);
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nsBoundingMetrics GetBoundingMetrics(const char16_t *aString,
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uint32_t aLength,
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nsRenderingContext *aContext);
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// Returns the LOOSE_INK_EXTENTS bounds of the text for determing the
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// overflow area of the string.
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nsBoundingMetrics GetInkBoundsForVisualOverflow(const char16_t *aString,
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uint32_t aLength,
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nsRenderingContext *aContext);
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void SetTextRunRTL(bool aIsRTL) { mTextRunRTL = aIsRTL; }
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bool GetTextRunRTL() const { return mTextRunRTL; }
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void SetVertical(bool aVertical) { mVertical = aVertical; }
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bool GetVertical() const { return mVertical; }
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void SetTextOrientation(uint8_t aTextOrientation)
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{
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mTextOrientation = aTextOrientation;
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}
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uint8_t GetTextOrientation() const { return mTextOrientation; }
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gfxFontGroup* GetThebesFontGroup() const { return mFontGroup; }
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gfxUserFontSet* GetUserFontSet() const
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{
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return mFontGroup->GetUserFontSet();
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}
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int32_t AppUnitsPerDevPixel() const { return mP2A; }
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private:
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// Private destructor, to discourage deletion outside of Release():
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~nsFontMetrics();
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const gfxFont::Metrics& GetMetrics() const {
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return GetMetrics(mOrientation);
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}
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const gfxFont::Metrics&
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GetMetrics(const gfxFont::Orientation aFontOrientation) const;
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nsFont mFont;
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RefPtr<gfxFontGroup> mFontGroup;
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nsCOMPtr<nsIAtom> mLanguage;
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nsDeviceContext *mDeviceContext;
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int32_t mP2A;
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// The font orientation (horizontal or vertical) for which these metrics
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// have been initialized. This determines which line metrics (ascent and
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// descent) they will return.
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gfxFont::Orientation mOrientation;
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// These fields may be set by clients to control the behavior of methods
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// like GetWidth and DrawString according to the writing mode, direction
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// and text-orientation desired.
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bool mTextRunRTL;
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bool mVertical;
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uint8_t mTextOrientation;
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};
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#endif /* NSFONTMETRICS__H__ */
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