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+/* -*- 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 <stdint.h> // for uint32_t
+#include <sys/types.h> // for int32_t
+#include "gfxTextRun.h" // for gfxFont, gfxFontGroup
+#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 "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 final
+{
+public:
+ typedef gfxTextRun::Range Range;
+ typedef mozilla::gfx::DrawTarget DrawTarget;
+
+ struct Params
+ {
+ nsIAtom* language = nullptr;
+ bool explicitLanguage = false;
+ gfxFont::Orientation orientation = gfxFont::eHorizontal;
+ gfxUserFontSet* userFontSet = nullptr;
+ gfxTextPerfMetrics* textPerf = nullptr;
+ };
+
+ nsFontMetrics(const nsFont& aFont, const Params& aParams,
+ nsDeviceContext *aContext);
+
+ NS_INLINE_DECL_REFCOUNTING(nsFontMetrics)
+
+ /**
+ * 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 cap-height.
+ */
+ nscoord CapHeight();
+
+ /**
+ * 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() const { return mFont; }
+
+ /**
+ * Returns the language associated with these metrics
+ */
+ nsIAtom* Language() const { return mLanguage; }
+
+ /**
+ * Returns the orientation (horizontal/vertical) of these metrics.
+ */
+ gfxFont::Orientation Orientation() const { return mOrientation; }
+
+ 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,
+ DrawTarget* aDrawTarget);
+ nscoord GetWidth(const char16_t* aString, uint32_t aLength,
+ DrawTarget* aDrawTarget);
+
+ // 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,
+ DrawTarget* aTextRunConstructionDrawTarget);
+
+ nsBoundingMetrics GetBoundingMetrics(const char16_t *aString,
+ uint32_t aLength,
+ DrawTarget* aDrawTarget);
+
+ // 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,
+ DrawTarget* aDrawTarget);
+
+ void SetTextRunRTL(bool aIsRTL) { mTextRunRTL = aIsRTL; }
+ bool GetTextRunRTL() const { return mTextRunRTL; }
+
+ void SetVertical(bool aVertical) { mVertical = aVertical; }
+ bool GetVertical() const { return mVertical; }
+
+ void SetTextOrientation(uint8_t aTextOrientation)
+ {
+ mTextOrientation = aTextOrientation;
+ }
+ uint8_t GetTextOrientation() const { return mTextOrientation; }
+
+ gfxFontGroup* GetThebesFontGroup() const { return mFontGroup; }
+ gfxUserFontSet* GetUserFontSet() const
+ {
+ return mFontGroup->GetUserFontSet();
+ }
+
+ int32_t AppUnitsPerDevPixel() const { return mP2A; }
+
+private:
+ // Private destructor, to discourage deletion outside of Release():
+ ~nsFontMetrics();
+
+ const gfxFont::Metrics& GetMetrics() const {
+ return GetMetrics(mOrientation);
+ }
+
+ const gfxFont::Metrics&
+ GetMetrics(const gfxFont::Orientation aFontOrientation) const;
+
+ nsFont mFont;
+ RefPtr<gfxFontGroup> mFontGroup;
+ nsCOMPtr<nsIAtom> mLanguage;
+ nsDeviceContext* mDeviceContext;
+ 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.
+ gfxFont::Orientation mOrientation;
+
+ // 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;
+ uint8_t mTextOrientation;
+};
+
+#endif /* NSFONTMETRICS__H__ */