diff -r 000000000000 -r 6474c204b198 gfx/src/nsFontMetrics.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/gfx/src/nsFontMetrics.h Wed Dec 31 06:09:35 2014 +0100 @@ -0,0 +1,228 @@ +/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* 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 // for uint32_t +#include // for int32_t +#include "gfxFont.h" // for gfxFont, gfxFontGroup +#include "mozilla/Assertions.h" // for MOZ_ASSERT_HELPER2 +#include "nsAutoPtr.h" // for nsRefPtr +#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 "nscore.h" // for char16_t + +class gfxUserFontSet; +class gfxTextPerfMetrics; +class nsDeviceContext; +class nsIAtom; +class nsRenderingContext; +struct nsBoundingMetrics; + +/** + * 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 + * device 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 MOZ_FINAL +{ +public: + nsFontMetrics(); + + NS_INLINE_DECL_REFCOUNTING(nsFontMetrics) + + /** + * Initialize the font metrics. Call this after creating the font metrics. + * Font metrics you get from the font cache do NOT need to be initialized + * + * @see nsDeviceContext#GetMetricsFor() + */ + nsresult Init(const nsFont& aFont, nsIAtom* aLanguage, + nsDeviceContext *aContext, + gfxUserFontSet *aUserFontSet, + gfxTextPerfMetrics *aTextPerf); + + /** + * Destroy this font metrics. This breaks the association between + * the font metrics and the device context. + */ + void Destroy(); + + /** + * Return the font's x-height. + */ + nscoord XHeight(); + + /** + * 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(); + + /** + * 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(); + + /** + * 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); + + /** + * 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); + + /** + * Returns the amount of internal leading for the font. + * This is normally the difference between the max ascent + * and the em ascent. + */ + nscoord InternalLeading(); + + /** + * 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(); + + /** + * Returns the height of the em square. + * This is em ascent plus em descent. + */ + nscoord EmHeight(); + + /** + * Returns the ascent part of the em square. + */ + nscoord EmAscent(); + + /** + * Returns the descent part of the em square. + */ + nscoord EmDescent(); + + /** + * Returns the height of the bounding box. + * This is max ascent plus max descent. + */ + nscoord MaxHeight(); + + /** + * Returns the maximum distance characters in this font extend + * above the base line. + */ + nscoord MaxAscent(); + + /** + * Returns the maximum distance characters in this font extend + * below the base line. + */ + nscoord MaxDescent(); + + /** + * Returns the maximum character advance for the font. + */ + nscoord MaxAdvance(); + + /** + * Returns the average character width + */ + nscoord AveCharWidth(); + + /** + * Returns the often needed width of the space character + */ + nscoord SpaceWidth(); + + /** + * Returns the font associated with these metrics. The return value + * is only defined after Init() has been called. + */ + const nsFont &Font() { return mFont; } + + /** + * Returns the language associated with these metrics + */ + nsIAtom* Language() { return mLanguage; } + + int32_t GetMaxStringLength(); + + // 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, + nsRenderingContext *aContext); + nscoord GetWidth(const char16_t* aString, uint32_t aLength, + nsRenderingContext *aContext); + + // Draw a string using this font handle on the surface passed in. + void DrawString(const char *aString, uint32_t aLength, + nscoord aX, nscoord aY, + nsRenderingContext *aContext); + void DrawString(const char16_t* aString, uint32_t aLength, + nscoord aX, nscoord aY, + nsRenderingContext *aContext, + nsRenderingContext *aTextRunConstructionContext); + + nsBoundingMetrics GetBoundingMetrics(const char16_t *aString, + uint32_t aLength, + nsRenderingContext *aContext); + + // Returns the LOOSE_INK_EXTENTS bounds of the text for determing the + // overflow area of the string. + nsBoundingMetrics GetInkBoundsForVisualOverflow(const char16_t *aString, + uint32_t aLength, + nsRenderingContext *aContext); + + void SetTextRunRTL(bool aIsRTL) { mTextRunRTL = aIsRTL; } + bool GetTextRunRTL() { return mTextRunRTL; } + + gfxFontGroup* GetThebesFontGroup() { return mFontGroup; } + gfxUserFontSet* GetUserFontSet() { return mFontGroup->GetUserFontSet(); } + + int32_t AppUnitsPerDevPixel() { return mP2A; } + +private: + // Private destructor, to discourage deletion outside of Release(): + ~nsFontMetrics(); + + const gfxFont::Metrics& GetMetrics() const; + + nsFont mFont; + nsRefPtr mFontGroup; + nsCOMPtr mLanguage; + nsDeviceContext *mDeviceContext; + int32_t mP2A; + bool mTextRunRTL; +}; + +#endif /* NSFONTMETRICS__H__ */