michael@0: /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef NSFONTMETRICS__H__
michael@0: #define NSFONTMETRICS__H__
michael@0: 
michael@0: #include <stdint.h>                     // for uint32_t
michael@0: #include <sys/types.h>                  // for int32_t
michael@0: #include "gfxFont.h"                    // for gfxFont, gfxFontGroup
michael@0: #include "mozilla/Assertions.h"         // for MOZ_ASSERT_HELPER2
michael@0: #include "nsAutoPtr.h"                  // for nsRefPtr
michael@0: #include "nsCOMPtr.h"                   // for nsCOMPtr
michael@0: #include "nsCoord.h"                    // for nscoord
michael@0: #include "nsError.h"                    // for nsresult
michael@0: #include "nsFont.h"                     // for nsFont
michael@0: #include "nsISupports.h"                // for NS_INLINE_DECL_REFCOUNTING
michael@0: #include "nscore.h"                     // for char16_t
michael@0: 
michael@0: class gfxUserFontSet;
michael@0: class gfxTextPerfMetrics;
michael@0: class nsDeviceContext;
michael@0: class nsIAtom;
michael@0: class nsRenderingContext;
michael@0: struct nsBoundingMetrics;
michael@0: 
michael@0: /**
michael@0:  * Font metrics
michael@0:  *
michael@0:  * This class may be somewhat misnamed. A better name might be
michael@0:  * nsFontList. The style system uses the nsFont struct for various
michael@0:  * font properties, one of which is font-family, which can contain a
michael@0:  * *list* of font names. The nsFont struct is "realized" by asking the
michael@0:  * device context to cough up an nsFontMetrics object, which contains
michael@0:  * a list of real font handles, one for each font mentioned in
michael@0:  * font-family (and for each fallback when we fall off the end of that
michael@0:  * list).
michael@0:  *
michael@0:  * The style system needs to have access to certain metrics, such as
michael@0:  * the em height (for the CSS "em" unit), and we use the first Western
michael@0:  * font's metrics for that purpose. The platform-specific
michael@0:  * implementations are expected to select non-Western fonts that "fit"
michael@0:  * reasonably well with the Western font that is loaded at Init time.
michael@0:  */
michael@0: class nsFontMetrics MOZ_FINAL
michael@0: {
michael@0: public:
michael@0:     nsFontMetrics();
michael@0: 
michael@0:     NS_INLINE_DECL_REFCOUNTING(nsFontMetrics)
michael@0: 
michael@0:     /**
michael@0:      * Initialize the font metrics. Call this after creating the font metrics.
michael@0:      * Font metrics you get from the font cache do NOT need to be initialized
michael@0:      *
michael@0:      * @see nsDeviceContext#GetMetricsFor()
michael@0:      */
michael@0:     nsresult Init(const nsFont& aFont, nsIAtom* aLanguage,
michael@0:                   nsDeviceContext *aContext,
michael@0:                   gfxUserFontSet *aUserFontSet,
michael@0:                   gfxTextPerfMetrics *aTextPerf);
michael@0: 
michael@0:     /**
michael@0:      * Destroy this font metrics. This breaks the association between
michael@0:      * the font metrics and the device context.
michael@0:      */
michael@0:     void Destroy();
michael@0: 
michael@0:     /**
michael@0:      * Return the font's x-height.
michael@0:      */
michael@0:     nscoord XHeight();
michael@0: 
michael@0:     /**
michael@0:      * Return the font's superscript offset (the distance from the
michael@0:      * baseline to where a superscript's baseline should be placed).
michael@0:      * The value returned will be positive.
michael@0:      */
michael@0:     nscoord SuperscriptOffset();
michael@0: 
michael@0:     /**
michael@0:      * Return the font's subscript offset (the distance from the
michael@0:      * baseline to where a subscript's baseline should be placed).
michael@0:      * The value returned will be positive.
michael@0:      */
michael@0:     nscoord SubscriptOffset();
michael@0: 
michael@0:     /**
michael@0:      * Return the font's strikeout offset (the distance from the
michael@0:      * baseline to where a strikeout should be placed) and size.
michael@0:      * Positive values are above the baseline, negative below.
michael@0:      */
michael@0:     void GetStrikeout(nscoord& aOffset, nscoord& aSize);
michael@0: 
michael@0:     /**
michael@0:      * Return the font's underline offset (the distance from the
michael@0:      * baseline to where a underline should be placed) and size.
michael@0:      * Positive values are above the baseline, negative below.
michael@0:      */
michael@0:     void GetUnderline(nscoord& aOffset, nscoord& aSize);
michael@0: 
michael@0:     /**
michael@0:      * Returns the amount of internal leading for the font.
michael@0:      * This is normally the difference between the max ascent
michael@0:      * and the em ascent.
michael@0:      */
michael@0:     nscoord InternalLeading();
michael@0: 
michael@0:     /**
michael@0:      * Returns the amount of external leading for the font.
michael@0:      * em ascent(?) plus external leading is the font designer's
michael@0:      * recommended line-height for this font.
michael@0:      */
michael@0:     nscoord ExternalLeading();
michael@0: 
michael@0:     /**
michael@0:      * Returns the height of the em square.
michael@0:      * This is em ascent plus em descent.
michael@0:      */
michael@0:     nscoord EmHeight();
michael@0: 
michael@0:     /**
michael@0:      * Returns the ascent part of the em square.
michael@0:      */
michael@0:     nscoord EmAscent();
michael@0: 
michael@0:     /**
michael@0:      * Returns the descent part of the em square.
michael@0:      */
michael@0:     nscoord EmDescent();
michael@0: 
michael@0:     /**
michael@0:      * Returns the height of the bounding box.
michael@0:      * This is max ascent plus max descent.
michael@0:      */
michael@0:     nscoord MaxHeight();
michael@0: 
michael@0:     /**
michael@0:      * Returns the maximum distance characters in this font extend
michael@0:      * above the base line.
michael@0:      */
michael@0:     nscoord MaxAscent();
michael@0: 
michael@0:     /**
michael@0:      * Returns the maximum distance characters in this font extend
michael@0:      * below the base line.
michael@0:      */
michael@0:     nscoord MaxDescent();
michael@0: 
michael@0:     /**
michael@0:      * Returns the maximum character advance for the font.
michael@0:      */
michael@0:     nscoord MaxAdvance();
michael@0: 
michael@0:     /**
michael@0:      * Returns the average character width
michael@0:      */
michael@0:     nscoord AveCharWidth();
michael@0: 
michael@0:     /**
michael@0:      * Returns the often needed width of the space character
michael@0:      */
michael@0:     nscoord SpaceWidth();
michael@0: 
michael@0:     /**
michael@0:      * Returns the font associated with these metrics. The return value
michael@0:      * is only defined after Init() has been called.
michael@0:      */
michael@0:     const nsFont &Font() { return mFont; }
michael@0: 
michael@0:     /**
michael@0:      * Returns the language associated with these metrics
michael@0:      */
michael@0:     nsIAtom* Language() { return mLanguage; }
michael@0: 
michael@0:     int32_t GetMaxStringLength();
michael@0: 
michael@0:     // Get the width for this string.  aWidth will be updated with the
michael@0:     // width in points, not twips.  Callers must convert it if they
michael@0:     // want it in another format.
michael@0:     nscoord GetWidth(const char* aString, uint32_t aLength,
michael@0:                      nsRenderingContext *aContext);
michael@0:     nscoord GetWidth(const char16_t* aString, uint32_t aLength,
michael@0:                      nsRenderingContext *aContext);
michael@0: 
michael@0:     // Draw a string using this font handle on the surface passed in.
michael@0:     void DrawString(const char *aString, uint32_t aLength,
michael@0:                     nscoord aX, nscoord aY,
michael@0:                     nsRenderingContext *aContext);
michael@0:     void DrawString(const char16_t* aString, uint32_t aLength,
michael@0:                     nscoord aX, nscoord aY,
michael@0:                     nsRenderingContext *aContext,
michael@0:                     nsRenderingContext *aTextRunConstructionContext);
michael@0: 
michael@0:     nsBoundingMetrics GetBoundingMetrics(const char16_t *aString,
michael@0:                                          uint32_t aLength,
michael@0:                                          nsRenderingContext *aContext);
michael@0: 
michael@0:     // Returns the LOOSE_INK_EXTENTS bounds of the text for determing the
michael@0:     // overflow area of the string.
michael@0:     nsBoundingMetrics GetInkBoundsForVisualOverflow(const char16_t *aString,
michael@0:                                                     uint32_t aLength,
michael@0:                                                     nsRenderingContext *aContext);
michael@0: 
michael@0:     void SetTextRunRTL(bool aIsRTL) { mTextRunRTL = aIsRTL; }
michael@0:     bool GetTextRunRTL() { return mTextRunRTL; }
michael@0: 
michael@0:     gfxFontGroup* GetThebesFontGroup() { return mFontGroup; }
michael@0:     gfxUserFontSet* GetUserFontSet() { return mFontGroup->GetUserFontSet(); }
michael@0: 
michael@0:     int32_t AppUnitsPerDevPixel() { return mP2A; }
michael@0: 
michael@0: private:
michael@0:     // Private destructor, to discourage deletion outside of Release():
michael@0:     ~nsFontMetrics();
michael@0: 
michael@0:     const gfxFont::Metrics& GetMetrics() const;
michael@0: 
michael@0:     nsFont mFont;
michael@0:     nsRefPtr<gfxFontGroup> mFontGroup;
michael@0:     nsCOMPtr<nsIAtom> mLanguage;
michael@0:     nsDeviceContext *mDeviceContext;
michael@0:     int32_t mP2A;
michael@0:     bool mTextRunRTL;
michael@0: };
michael@0: 
michael@0: #endif /* NSFONTMETRICS__H__ */