Verified Commit 4846c1da authored by Jonathan Kew's avatar Jonathan Kew Committed by ma1
Browse files

Bug 1890204 - Ensure font entry's unitsPerEm and font extents are initialized... 

Bug 1890204 - Ensure font entry's unitsPerEm and font extents are initialized when gfxFont is created. r=gfx-reviewers,lsalzman

This means that by the time we potentially call GetFontExtents() when drawing,
the extents fields are guaranteed to have been been initialized, and there's no
risk of the (read-only) access here racing with setting them in UnitsPerEm().

Differential Revision: https://phabricator.services.mozilla.com/D206920
parent 62619558

gfx/thebes/gfxFont.cpp

+4 −0
Original line number Diff line number Diff line
@@ -952,6 +952,10 @@ gfxFont::gfxFont(const RefPtr<UnscaledFont>& aUnscaledFont, 
  }



  mKerningSet = HasFeatureSet(HB_TAG('k', 'e', 'r', 'n'), mKerningEnabled);



  // Ensure the gfxFontEntry's unitsPerEm and extents fields are initialized,

  // so that GetFontExtents can use them without risk of races.

  Unused << mFontEntry->UnitsPerEm();

}



gfxFont::~gfxFont() {

gfx/thebes/gfxFontEntry.cpp

+16 −6
Original line number Diff line number Diff line
@@ -262,14 +262,22 @@ already_AddRefed<gfxFont> gfxFontEntry::FindOrMakeFont( 
}



uint16_t gfxFontEntry::UnitsPerEm() {

  if (!mUnitsPerEm) {

  {

    AutoReadLock lock(mLock);

    if (mUnitsPerEm) {

      return mUnitsPerEm;

    }

  }



  AutoTable headTable(this, TRUETYPE_TAG('h', 'e', 'a', 'd'));

  AutoWriteLock lock(mLock);



  if (!mUnitsPerEm) {

    if (headTable) {

      uint32_t len;

      const HeadTable* head =

          reinterpret_cast<const HeadTable*>(hb_blob_get_data(headTable, &len));

      if (len >= sizeof(HeadTable)) {

        mUnitsPerEm = head->unitsPerEm;

        if (int16_t(head->xMax) > int16_t(head->xMin) &&

            int16_t(head->yMax) > int16_t(head->yMin)) {

          mXMin = head->xMin;
@@ -277,6 +285,7 @@ uint16_t gfxFontEntry::UnitsPerEm() { 
          mXMax = head->xMax;

          mYMax = head->yMax;

        }

        mUnitsPerEm = head->unitsPerEm;

      }

    }
@@ -286,11 +295,12 @@ uint16_t gfxFontEntry::UnitsPerEm() { 
      mUnitsPerEm = kInvalidUPEM;

    }

  }



  return mUnitsPerEm;

}



bool gfxFontEntry::HasSVGGlyph(uint32_t aGlyphId) {

  NS_ASSERTION(mSVGInitialized,

  MOZ_ASSERT(mSVGInitialized,

             "SVG data has not yet been loaded. TryGetSVGData() first.");

  return GetSVGGlyphs()->HasSVGGlyph(aGlyphId);

}
@@ -309,7 +319,7 @@ bool gfxFontEntry::GetSVGGlyphExtents(DrawTarget* aDrawTarget, 


void gfxFontEntry::RenderSVGGlyph(gfxContext* aContext, uint32_t aGlyphId,

                                  SVGContextPaint* aContextPaint) {

  NS_ASSERTION(mSVGInitialized,

  MOZ_ASSERT(mSVGInitialized,

             "SVG data has not yet been loaded. TryGetSVGData() first.");

  GetSVGGlyphs()->RenderGlyph(aContext, aGlyphId, aContextPaint);

}

gfx/thebes/gfxFontEntry.h

+3 −0
Original line number Diff line number Diff line
@@ -538,6 +538,9 @@ class gfxFontEntry { 


  mozilla::gfx::Rect GetFontExtents(float aFUnitScaleFactor) const {

    // Flip the y-axis here to match the orientation of Gecko's coordinates.

    // We don't need to take a lock here because the min/max fields are inert

    // after initialization, and we make sure to initialize them at gfxFont-

    // creation time.

    return mozilla::gfx::Rect(float(mXMin) * aFUnitScaleFactor,

                              float(-mYMax) * aFUnitScaleFactor,

                              float(mXMax - mXMin) * aFUnitScaleFactor,