1 files changed, 268 insertions, 0 deletions
diff --git a/gfx/src/nsFontMetrics.h b/gfx/src/nsFontMetrics.h
new file mode 100644
index 000000000..f8a2c5b93
--- /dev/null
+++ b/gfx/src/nsFontMetrics.h
@@ -0,0 +1,268 @@
+/* -*- 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__ */