зеркало из https://github.com/mozilla/gecko-dev.git
218 строки
6.7 KiB
C++
218 строки
6.7 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* The contents of this file are subject to the Netscape Public
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* License Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.mozilla.org/NPL/
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*
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* Software distributed under the License is distributed on an "AS
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
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* implied. See the License for the specific language governing
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* rights and limitations under the License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All
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* Rights Reserved.
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*
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* Contributor(s):
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*/
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#ifndef nsIFontMetrics_h___
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#define nsIFontMetrics_h___
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#include "nsISupports.h"
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#include "nsCoord.h"
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struct nsFont;
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class nsString;
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class nsIDeviceContext;
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class nsIAtom;
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// IID for the nsIFontMetrics interface
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#define NS_IFONT_METRICS_IID \
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{ 0xc74cb770, 0xa33e, 0x11d1, \
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{ 0xa8, 0x24, 0x00, 0x40, 0x95, 0x9a, 0x28, 0xc9 } }
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//----------------------------------------------------------------------
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/**
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* A native font handle
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*/
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typedef void* nsFontHandle;
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/**
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* Font metrics interface
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*
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* This interface may be somewhat misnamed. A better name might be
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* nsIFontList. The style system uses the nsFont struct for various font
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* properties, one of which is font-family, which can contain a *list* of
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* font names. The nsFont struct is "realized" by asking the device context
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* to cough up an nsIFontMetrics object, which contains a list of real font
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* handles, one for each font mentioned in font-family (and for each fallback
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* when we fall off the end of that list).
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*
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* The style system needs to have access to certain metrics, such as the
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* em height (for the CSS "em" unit), and we use the first Western font's
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* metrics for that purpose. The platform-specific implementations are
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* expected to select non-Western fonts that "fit" reasonably well with the
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* Western font that is loaded at Init time.
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*/
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class nsIFontMetrics : public nsISupports
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{
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public:
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NS_DEFINE_STATIC_IID_ACCESSOR(NS_IFONT_METRICS_IID)
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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 nsIDeviceContext#GetMetricsFor()
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*/
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NS_IMETHOD Init(const nsFont& aFont, nsIAtom* aLangGroup,
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nsIDeviceContext *aContext) = 0;
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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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NS_IMETHOD Destroy() = 0;
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#if defined(MOZ_MATHML) && defined(WIN32)
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// XXX currently implemented only on win32 -- other platforms should implement this
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/**
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* Return the font's italic slope, i.e., the tangent of the italic angle.
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* The slope = 0 for an upright font. It is > 0 for a forward-slanted
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* font (italic style) and is < 0 for a back-slanted font.
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*/
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NS_IMETHOD GetItalicSlope(float& aResult) = 0;
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#endif
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/**
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* Return the font's xheight property, scaled into app-units.
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*/
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NS_IMETHOD GetXHeight(nscoord& aResult) = 0;
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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). The
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* value returned will be a positive value.
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*/
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NS_IMETHOD GetSuperscriptOffset(nscoord& aResult) = 0;
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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). The
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* value returned will be a positive value.
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*/
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NS_IMETHOD GetSubscriptOffset(nscoord& aResult) = 0;
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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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NS_IMETHOD GetStrikeout(nscoord& aOffset, nscoord& aSize) = 0;
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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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NS_IMETHOD GetUnderline(nscoord& aOffset, nscoord& aSize) = 0;
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/**
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* Returns the height (in app units) of the font. This is ascent plus descent
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* plus any internal leading
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*
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* This method will be removed once the callers have been moved over to the
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* new GetEmHeight (and possibly GetMaxHeight).
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*/
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NS_IMETHOD GetHeight(nscoord &aHeight) = 0;
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#if defined(XP_UNIX) || defined(XP_PC) || defined(XP_MAC)
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#define NEW_FONT_HEIGHT_APIS 1
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#endif
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#ifdef NEW_FONT_HEIGHT_APIS
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/**
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* Returns the normal line height (em height + leading).
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*/
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NS_IMETHOD GetNormalLineHeight(nscoord &aHeight) = 0;
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#endif /* NEW_FONT_HEIGHT_APIS */
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/**
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* Returns the amount of internal leading (in app units) for the font. This
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* is computed as the "height - (ascent + descent)"
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*/
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NS_IMETHOD GetLeading(nscoord &aLeading) = 0;
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#ifdef NEW_FONT_HEIGHT_APIS
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/**
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* Returns the height (in app units) of the Western font's em square. This is
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* em ascent plus em descent.
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*/
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NS_IMETHOD GetEmHeight(nscoord &aHeight) = 0;
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/**
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* Returns, in app units, the ascent part of the Western font's em square.
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*/
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NS_IMETHOD GetEmAscent(nscoord &aAscent) = 0;
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/**
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* Returns, in app units, the descent part of the Western font's em square.
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*/
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NS_IMETHOD GetEmDescent(nscoord &aDescent) = 0;
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/**
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* Returns the height (in app units) of the Western font's bounding box.
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* This is max ascent plus max descent.
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*/
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NS_IMETHOD GetMaxHeight(nscoord &aHeight) = 0;
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#endif /* NEW_FONT_HEIGHT_APIS */
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/**
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* Returns, in app units, the maximum distance characters in this font extend
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* above the base line.
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*/
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NS_IMETHOD GetMaxAscent(nscoord &aAscent) = 0;
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/**
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* Returns, in app units, the maximum distance characters in this font extend
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* below the base line.
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*/
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NS_IMETHOD GetMaxDescent(nscoord &aDescent) = 0;
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/**
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* Returns, in app units, the maximum character advance for the font
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*/
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NS_IMETHOD GetMaxAdvance(nscoord &aAdvance) = 0;
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/**
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* Returns the font associated with these metrics
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*/
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NS_IMETHOD GetFont(const nsFont *&aFont) = 0;
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/**
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* Returns the language group associated with these metrics
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*/
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NS_IMETHOD GetLangGroup(nsIAtom** aLangGroup) = 0;
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/**
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* Returns the font handle associated with these metrics
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*/
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NS_IMETHOD GetFontHandle(nsFontHandle &aHandle) = 0;
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#ifdef _WIN32
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/**
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* Returns the average character width
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*/
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NS_IMETHOD GetAveCharWidth(nscoord& aAveCharWidth) = 0;
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#endif
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};
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#endif /* nsIFontMetrics_h___ */
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