/* -*- 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;
#ifdef XP_WIN
bool allowForceGDIClassic =
true;
#endif
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; }
#ifdef XP_WIN
bool AllowForceGDIClassic()
const {
return mAllowForceGDIClassic; }
#endif
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;
#ifdef XP_WIN
const bool mAllowForceGDIClassic =
true;
#endif
// 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__ */
