Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 843 insertions, 0 deletions

diff --git a/gfx/thebes/gfxFT2FontBase.cpp b/gfx/thebes/gfxFT2FontBase.cpp
new file mode 100644
index 0000000000..923ece60c3
--- /dev/null
+++ b/gfx/thebes/gfxFT2FontBase.cpp
@@ -0,0 +1,843 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * 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/. */
+
+#include "gfxFT2FontBase.h"
+#include "gfxFT2Utils.h"
+#include "harfbuzz/hb.h"
+#include "mozilla/Likely.h"
+#include "mozilla/StaticPrefs_gfx.h"
+#include "gfxFontConstants.h"
+#include "gfxFontUtils.h"
+#include "gfxHarfBuzzShaper.h"
+#include <algorithm>
+#include <dlfcn.h>
+
+#include FT_TRUETYPE_TAGS_H
+#include FT_TRUETYPE_TABLES_H
+#include FT_ADVANCES_H
+#include FT_MULTIPLE_MASTERS_H
+
+#ifndef FT_LOAD_COLOR
+#  define FT_LOAD_COLOR (1L << 20)
+#endif
+#ifndef FT_FACE_FLAG_COLOR
+#  define FT_FACE_FLAG_COLOR (1L << 14)
+#endif
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+
+gfxFT2FontBase::gfxFT2FontBase(
+    const RefPtr<UnscaledFontFreeType>& aUnscaledFont,
+    RefPtr<mozilla::gfx::SharedFTFace>&& aFTFace, gfxFontEntry* aFontEntry,
+    const gfxFontStyle* aFontStyle, int aLoadFlags, bool aEmbolden)
+    : gfxFont(aUnscaledFont, aFontEntry, aFontStyle, kAntialiasDefault),
+      mFTFace(std::move(aFTFace)),
+      mFTLoadFlags(aLoadFlags | FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH |
+                   FT_LOAD_COLOR),
+      mEmbolden(aEmbolden),
+      mFTSize(0.0) {}
+
+gfxFT2FontBase::~gfxFT2FontBase() { mFTFace->ForgetLockOwner(this); }
+
+FT_Face gfxFT2FontBase::LockFTFace() const
+    MOZ_CAPABILITY_ACQUIRE(mFTFace) MOZ_NO_THREAD_SAFETY_ANALYSIS {
+  if (!mFTFace->Lock(this)) {
+    FT_Set_Transform(mFTFace->GetFace(), nullptr, nullptr);
+
+    FT_F26Dot6 charSize = NS_lround(mFTSize * 64.0);
+    FT_Set_Char_Size(mFTFace->GetFace(), charSize, charSize, 0, 0);
+  }
+  return mFTFace->GetFace();
+}
+
+void gfxFT2FontBase::UnlockFTFace() const
+    MOZ_CAPABILITY_RELEASE(mFTFace) MOZ_NO_THREAD_SAFETY_ANALYSIS {
+  mFTFace->Unlock();
+}
+
+static FT_ULong GetTableSizeFromFTFace(SharedFTFace* aFace,
+                                       uint32_t aTableTag) {
+  if (!aFace) {
+    return 0;
+  }
+  FT_ULong len = 0;
+  if (FT_Load_Sfnt_Table(aFace->GetFace(), aTableTag, 0, nullptr, &len) != 0) {
+    return 0;
+  }
+  return len;
+}
+
+bool gfxFT2FontEntryBase::FaceHasTable(SharedFTFace* aFace,
+                                       uint32_t aTableTag) {
+  return GetTableSizeFromFTFace(aFace, aTableTag) > 0;
+}
+
+nsresult gfxFT2FontEntryBase::CopyFaceTable(SharedFTFace* aFace,
+                                            uint32_t aTableTag,
+                                            nsTArray<uint8_t>& aBuffer) {
+  FT_ULong length = GetTableSizeFromFTFace(aFace, aTableTag);
+  if (!length) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  if (!aBuffer.SetLength(length, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  if (FT_Load_Sfnt_Table(aFace->GetFace(), aTableTag, 0, aBuffer.Elements(),
+                         &length) != 0) {
+    aBuffer.Clear();
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}
+
+uint32_t gfxFT2FontEntryBase::GetGlyph(uint32_t aCharCode,
+                                       gfxFT2FontBase* aFont) {
+  const uint32_t slotIndex = aCharCode % kNumCmapCacheSlots;
+  {
+    // Try to read a cached entry without taking an exclusive lock.
+    AutoReadLock lock(mLock);
+    if (mCmapCache) {
+      const auto& slot = mCmapCache[slotIndex];
+      if (slot.mCharCode == aCharCode) {
+        return slot.mGlyphIndex;
+      }
+    }
+  }
+
+  // Create/update the charcode-to-glyphid cache.
+  AutoWriteLock lock(mLock);
+
+  // This cache algorithm and size is based on what is done in
+  // cairo_scaled_font_text_to_glyphs and pango_fc_font_real_get_glyph.  I
+  // think the concept is that adjacent characters probably come mostly from
+  // one Unicode block.  This assumption is probably not so valid with
+  // scripts with large character sets as used for East Asian languages.
+  if (!mCmapCache) {
+    mCmapCache = mozilla::MakeUnique<CmapCacheSlot[]>(kNumCmapCacheSlots);
+
+    // Invalidate slot 0 by setting its char code to something that would
+    // never end up in slot 0.  All other slots are already invalid
+    // because they have mCharCode = 0 and a glyph for char code 0 will
+    // always be in the slot 0.
+    mCmapCache[0].mCharCode = 1;
+  }
+
+  auto& slot = mCmapCache[slotIndex];
+  if (slot.mCharCode != aCharCode) {
+    slot.mCharCode = aCharCode;
+    slot.mGlyphIndex = gfxFT2LockedFace(aFont).GetGlyph(aCharCode);
+  }
+  return slot.mGlyphIndex;
+}
+
+// aScale is intended for a 16.16 x/y_scale of an FT_Size_Metrics
+static inline FT_Long ScaleRoundDesignUnits(FT_Short aDesignMetric,
+                                            FT_Fixed aScale) {
+  FT_Long fixed26dot6 = FT_MulFix(aDesignMetric, aScale);
+  return ROUND_26_6_TO_INT(fixed26dot6);
+}
+
+// Snap a line to pixels while keeping the center and size of the line as
+// close to the original position as possible.
+//
+// Pango does similar snapping for underline and strikethrough when fonts are
+// hinted, but nsCSSRendering::GetTextDecorationRectInternal always snaps the
+// top and size of lines.  Optimizing the distance between the line and
+// baseline is probably good for the gap between text and underline, but
+// optimizing the center of the line is better for positioning strikethough.
+static void SnapLineToPixels(gfxFloat& aOffset, gfxFloat& aSize) {
+  gfxFloat snappedSize = std::max(floor(aSize + 0.5), 1.0);
+  // Correct offset for change in size
+  gfxFloat offset = aOffset - 0.5 * (aSize - snappedSize);
+  // Snap offset
+  aOffset = floor(offset + 0.5);
+  aSize = snappedSize;
+}
+
+static inline gfxRect ScaleGlyphBounds(const IntRect& aBounds,
+                                       gfxFloat aScale) {
+  return gfxRect(FLOAT_FROM_26_6(aBounds.x) * aScale,
+                 FLOAT_FROM_26_6(aBounds.y) * aScale,
+                 FLOAT_FROM_26_6(aBounds.width) * aScale,
+                 FLOAT_FROM_26_6(aBounds.height) * aScale);
+}
+
+/**
+ * Get extents for a simple character representable by a single glyph.
+ * The return value is the glyph id of that glyph or zero if no such glyph
+ * exists.  aWidth/aBounds is only set when this returns a non-zero glyph id.
+ * This is just for use during initialization, and doesn't use the width cache.
+ */
+uint32_t gfxFT2FontBase::GetCharExtents(uint32_t aChar, gfxFloat* aWidth,
+                                        gfxRect* aBounds) {
+  FT_UInt gid = GetGlyph(aChar);
+  int32_t width;
+  IntRect bounds;
+  if (gid && GetFTGlyphExtents(gid, aWidth ? &width : nullptr,
+                               aBounds ? &bounds : nullptr)) {
+    if (aWidth) {
+      *aWidth = FLOAT_FROM_16_16(width);
+    }
+    if (aBounds) {
+      *aBounds = ScaleGlyphBounds(bounds, GetAdjustedSize() / mFTSize);
+    }
+    return gid;
+  } else {
+    return 0;
+  }
+}
+
+/**
+ * Find the closest available fixed strike size, if applicable, to the
+ * desired font size.
+ */
+static double FindClosestSize(FT_Face aFace, double aSize) {
+  // FT size selection does not actually support sizes smaller than 1 and will
+  // clamp this internally, regardless of what is requested. Do the clamp here
+  // instead so that glyph extents/font matrix scaling will compensate it, as
+  // Cairo normally would.
+  if (aSize < 1.0) {
+    aSize = 1.0;
+  }
+  if (FT_IS_SCALABLE(aFace)) {
+    return aSize;
+  }
+  double bestDist = DBL_MAX;
+  FT_Int bestSize = -1;
+  for (FT_Int i = 0; i < aFace->num_fixed_sizes; i++) {
+    double dist = aFace->available_sizes[i].y_ppem / 64.0 - aSize;
+    // If the previous best is smaller than the desired size, prefer
+    // a bigger size. Otherwise, just choose whatever size is closest.
+    if (bestDist < 0 ? dist >= bestDist : fabs(dist) <= bestDist) {
+      bestDist = dist;
+      bestSize = i;
+    }
+  }
+  if (bestSize < 0) {
+    return aSize;
+  }
+  return aFace->available_sizes[bestSize].y_ppem / 64.0;
+}
+
+void gfxFT2FontBase::InitMetrics() {
+  mFUnitsConvFactor = 0.0;
+
+  if (MOZ_UNLIKELY(mStyle.AdjustedSizeMustBeZero())) {
+    memset(&mMetrics, 0, sizeof(mMetrics));  // zero initialize
+    mSpaceGlyph = GetGlyph(' ');
+    return;
+  }
+
+  if (FontSizeAdjust::Tag(mStyle.sizeAdjustBasis) !=
+          FontSizeAdjust::Tag::None &&
+      mStyle.sizeAdjust >= 0.0 && GetAdjustedSize() > 0.0 && mFTSize == 0.0) {
+    // If font-size-adjust is in effect, we need to get metrics in order to
+    // determine the aspect ratio, then compute the final adjusted size and
+    // re-initialize metrics.
+    // Setting mFTSize nonzero here ensures we will not recurse again; the
+    // actual value will be overridden by FindClosestSize below.
+    mFTSize = 1.0;
+    InitMetrics();
+    // Now do the font-size-adjust calculation and set the final size.
+    gfxFloat aspect;
+    switch (FontSizeAdjust::Tag(mStyle.sizeAdjustBasis)) {
+      default:
+        MOZ_ASSERT_UNREACHABLE("unhandled sizeAdjustBasis?");
+        aspect = 0.0;
+        break;
+      case FontSizeAdjust::Tag::ExHeight:
+        aspect = mMetrics.xHeight / mAdjustedSize;
+        break;
+      case FontSizeAdjust::Tag::CapHeight:
+        aspect = mMetrics.capHeight / mAdjustedSize;
+        break;
+      case FontSizeAdjust::Tag::ChWidth:
+        aspect =
+            mMetrics.zeroWidth > 0.0 ? mMetrics.zeroWidth / mAdjustedSize : 0.5;
+        break;
+      case FontSizeAdjust::Tag::IcWidth:
+      case FontSizeAdjust::Tag::IcHeight: {
+        bool vertical = FontSizeAdjust::Tag(mStyle.sizeAdjustBasis) ==
+                        FontSizeAdjust::Tag::IcHeight;
+        gfxFloat advance = GetCharAdvance(kWaterIdeograph, vertical);
+        aspect = advance > 0.0 ? advance / mAdjustedSize : 1.0;
+        break;
+      }
+    }
+    if (aspect > 0.0) {
+      // If we created a shaper above (to measure glyphs), discard it so we
+      // get a new one for the adjusted scaling.
+      delete mHarfBuzzShaper.exchange(nullptr);
+      mAdjustedSize = mStyle.GetAdjustedSize(aspect);
+      // Ensure the FT_Face will be reconfigured for the new size next time we
+      // need to use it.
+      mFTFace->ForgetLockOwner(this);
+    }
+  }
+
+  // Set mAdjustedSize if it hasn't already been set by a font-size-adjust
+  // computation.
+  mAdjustedSize = GetAdjustedSize();
+
+  // Cairo metrics are normalized to em-space, so that whatever fixed size
+  // might actually be chosen is factored out. They are then later scaled by
+  // the font matrix to the target adjusted size. Stash the chosen closest
+  // size here for later scaling of the metrics.
+  mFTSize = FindClosestSize(mFTFace->GetFace(), GetAdjustedSize());
+
+  // Explicitly lock the face so we can release it early before calling
+  // back into Cairo below.
+  FT_Face face = LockFTFace();
+
+  if (MOZ_UNLIKELY(!face)) {
+    // No face.  This unfortunate situation might happen if the font
+    // file is (re)moved at the wrong time.
+    const gfxFloat emHeight = GetAdjustedSize();
+    mMetrics.emHeight = emHeight;
+    mMetrics.maxAscent = mMetrics.emAscent = 0.8 * emHeight;
+    mMetrics.maxDescent = mMetrics.emDescent = 0.2 * emHeight;
+    mMetrics.maxHeight = emHeight;
+    mMetrics.internalLeading = 0.0;
+    mMetrics.externalLeading = 0.2 * emHeight;
+    const gfxFloat spaceWidth = 0.5 * emHeight;
+    mMetrics.spaceWidth = spaceWidth;
+    mMetrics.maxAdvance = spaceWidth;
+    mMetrics.aveCharWidth = spaceWidth;
+    mMetrics.zeroWidth = spaceWidth;
+    mMetrics.ideographicWidth = emHeight;
+    const gfxFloat xHeight = 0.5 * emHeight;
+    mMetrics.xHeight = xHeight;
+    mMetrics.capHeight = mMetrics.maxAscent;
+    const gfxFloat underlineSize = emHeight / 14.0;
+    mMetrics.underlineSize = underlineSize;
+    mMetrics.underlineOffset = -underlineSize;
+    mMetrics.strikeoutOffset = 0.25 * emHeight;
+    mMetrics.strikeoutSize = underlineSize;
+
+    SanitizeMetrics(&mMetrics, false);
+    UnlockFTFace();
+    return;
+  }
+
+  const FT_Size_Metrics& ftMetrics = face->size->metrics;
+
+  mMetrics.maxAscent = FLOAT_FROM_26_6(ftMetrics.ascender);
+  mMetrics.maxDescent = -FLOAT_FROM_26_6(ftMetrics.descender);
+  mMetrics.maxAdvance = FLOAT_FROM_26_6(ftMetrics.max_advance);
+  gfxFloat lineHeight = FLOAT_FROM_26_6(ftMetrics.height);
+
+  gfxFloat emHeight;
+  // Scale for vertical design metric conversion: pixels per design unit.
+  // If this remains at 0.0, we can't use metrics from OS/2 etc.
+  gfxFloat yScale = 0.0;
+  if (FT_IS_SCALABLE(face)) {
+    // Prefer FT_Size_Metrics::x_scale to x_ppem as x_ppem does not
+    // have subpixel accuracy.
+    //
+    // FT_Size_Metrics::y_scale is in 16.16 fixed point format.  Its
+    // (fractional) value is a factor that converts vertical metrics from
+    // design units to units of 1/64 pixels, so that the result may be
+    // interpreted as pixels in 26.6 fixed point format.
+    mFUnitsConvFactor = FLOAT_FROM_26_6(FLOAT_FROM_16_16(ftMetrics.x_scale));
+    yScale = FLOAT_FROM_26_6(FLOAT_FROM_16_16(ftMetrics.y_scale));
+    emHeight = face->units_per_EM * yScale;
+  } else {  // Not scalable.
+    emHeight = ftMetrics.y_ppem;
+    // FT_Face doc says units_per_EM and a bunch of following fields
+    // are "only relevant to scalable outlines". If it's an sfnt,
+    // we can get units_per_EM from the 'head' table instead; otherwise,
+    // we don't have a unitsPerEm value so we can't compute/use yScale or
+    // mFUnitsConvFactor (x scale).
+    const TT_Header* head =
+        static_cast<TT_Header*>(FT_Get_Sfnt_Table(face, ft_sfnt_head));
+    if (head) {
+      // Bug 1267909 - Even if the font is not explicitly scalable,
+      // if the face has color bitmaps, it should be treated as scalable
+      // and scaled to the desired size. Metrics based on y_ppem need
+      // to be rescaled for the adjusted size. This makes metrics agree
+      // with the scales we pass to Cairo for Fontconfig fonts.
+      if (face->face_flags & FT_FACE_FLAG_COLOR) {
+        emHeight = GetAdjustedSize();
+        gfxFloat adjustScale = emHeight / ftMetrics.y_ppem;
+        mMetrics.maxAscent *= adjustScale;
+        mMetrics.maxDescent *= adjustScale;
+        mMetrics.maxAdvance *= adjustScale;
+        lineHeight *= adjustScale;
+      }
+      gfxFloat emUnit = head->Units_Per_EM;
+      mFUnitsConvFactor = ftMetrics.x_ppem / emUnit;
+      yScale = emHeight / emUnit;
+    }
+  }
+
+  TT_OS2* os2 = static_cast<TT_OS2*>(FT_Get_Sfnt_Table(face, ft_sfnt_os2));
+
+  if (os2 && os2->sTypoAscender && yScale > 0.0) {
+    mMetrics.emAscent = os2->sTypoAscender * yScale;
+    mMetrics.emDescent = -os2->sTypoDescender * yScale;
+    FT_Short typoHeight =
+        os2->sTypoAscender - os2->sTypoDescender + os2->sTypoLineGap;
+    lineHeight = typoHeight * yScale;
+
+    // If the OS/2 fsSelection USE_TYPO_METRICS bit is set,
+    // set maxAscent/Descent from the sTypo* fields instead of hhea.
+    const uint16_t kUseTypoMetricsMask = 1 << 7;
+    if ((os2->fsSelection & kUseTypoMetricsMask) ||
+        // maxAscent/maxDescent get used for frame heights, and some fonts
+        // don't have the HHEA table ascent/descent set (bug 279032).
+        (mMetrics.maxAscent == 0.0 && mMetrics.maxDescent == 0.0)) {
+      // We use NS_round here to parallel the pixel-rounded values that
+      // freetype gives us for ftMetrics.ascender/descender.
+      mMetrics.maxAscent = NS_round(mMetrics.emAscent);
+      mMetrics.maxDescent = NS_round(mMetrics.emDescent);
+    }
+  } else {
+    mMetrics.emAscent = mMetrics.maxAscent;
+    mMetrics.emDescent = mMetrics.maxDescent;
+  }
+
+  // gfxFont::Metrics::underlineOffset is the position of the top of the
+  // underline.
+  //
+  // FT_FaceRec documentation describes underline_position as "the
+  // center of the underlining stem".  This was the original definition
+  // of the PostScript metric, but in the PostScript table of OpenType
+  // fonts the metric is "the top of the underline"
+  // (http://www.microsoft.com/typography/otspec/post.htm), and FreeType
+  // (up to version 2.3.7) doesn't make any adjustment.
+  //
+  // Therefore get the underline position directly from the table
+  // ourselves when this table exists.  Use FreeType's metrics for
+  // other (including older PostScript) fonts.
+  if (face->underline_position && face->underline_thickness && yScale > 0.0) {
+    mMetrics.underlineSize = face->underline_thickness * yScale;
+    TT_Postscript* post =
+        static_cast<TT_Postscript*>(FT_Get_Sfnt_Table(face, ft_sfnt_post));
+    if (post && post->underlinePosition) {
+      mMetrics.underlineOffset = post->underlinePosition * yScale;
+    } else {
+      mMetrics.underlineOffset =
+          face->underline_position * yScale + 0.5 * mMetrics.underlineSize;
+    }
+  } else {  // No underline info.
+    // Imitate Pango.
+    mMetrics.underlineSize = emHeight / 14.0;
+    mMetrics.underlineOffset = -mMetrics.underlineSize;
+  }
+
+  if (os2 && os2->yStrikeoutSize && os2->yStrikeoutPosition && yScale > 0.0) {
+    mMetrics.strikeoutSize = os2->yStrikeoutSize * yScale;
+    mMetrics.strikeoutOffset = os2->yStrikeoutPosition * yScale;
+  } else {  // No strikeout info.
+    mMetrics.strikeoutSize = mMetrics.underlineSize;
+    // Use OpenType spec's suggested position for Roman font.
+    mMetrics.strikeoutOffset =
+        emHeight * 409.0 / 2048.0 + 0.5 * mMetrics.strikeoutSize;
+  }
+  SnapLineToPixels(mMetrics.strikeoutOffset, mMetrics.strikeoutSize);
+
+  if (os2 && os2->sxHeight && yScale > 0.0) {
+    mMetrics.xHeight = os2->sxHeight * yScale;
+  } else {
+    // CSS 2.1, section 4.3.2 Lengths: "In the cases where it is
+    // impossible or impractical to determine the x-height, a value of
+    // 0.5em should be used."
+    mMetrics.xHeight = 0.5 * emHeight;
+  }
+
+  // aveCharWidth is used for the width of text input elements so be
+  // liberal rather than conservative in the estimate.
+  if (os2 && os2->xAvgCharWidth) {
+    // Round to pixels as this is compared with maxAdvance to guess
+    // whether this is a fixed width font.
+    mMetrics.aveCharWidth =
+        ScaleRoundDesignUnits(os2->xAvgCharWidth, ftMetrics.x_scale);
+  } else {
+    mMetrics.aveCharWidth = 0.0;  // updated below
+  }
+
+  if (os2 && os2->sCapHeight && yScale > 0.0) {
+    mMetrics.capHeight = os2->sCapHeight * yScale;
+  } else {
+    mMetrics.capHeight = mMetrics.maxAscent;
+  }
+
+  // Release the face lock to safely load glyphs with GetCharExtents if
+  // necessary without recursively locking.
+  UnlockFTFace();
+
+  gfxFloat width;
+  mSpaceGlyph = GetCharExtents(' ', &width);
+  if (mSpaceGlyph) {
+    mMetrics.spaceWidth = width;
+  } else {
+    mMetrics.spaceWidth = mMetrics.maxAdvance;  // guess
+  }
+
+  if (GetCharExtents('0', &width)) {
+    mMetrics.zeroWidth = width;
+  } else {
+    mMetrics.zeroWidth = -1.0;  // indicates not found
+  }
+
+  if (GetCharExtents(kWaterIdeograph, &width)) {
+    mMetrics.ideographicWidth = width;
+  } else {
+    mMetrics.ideographicWidth = -1.0;
+  }
+
+  // If we didn't get a usable x-height or cap-height above, try measuring
+  // specific glyphs. This can be affected by hinting, leading to erratic
+  // behavior across font sizes and system configuration, so we prefer to
+  // use the metrics directly from the font if possible.
+  // Using glyph bounds for x-height or cap-height may not really be right,
+  // if fonts have fancy swashes etc. For x-height, CSS 2.1 suggests possibly
+  // using the height of an "o", which may be more consistent across fonts,
+  // but then curve-overshoot should also be accounted for.
+  gfxFloat xWidth;
+  gfxRect xBounds;
+  if (mMetrics.xHeight == 0.0) {
+    if (GetCharExtents('x', &xWidth, &xBounds) && xBounds.y < 0.0) {
+      mMetrics.xHeight = -xBounds.y;
+      mMetrics.aveCharWidth = std::max(mMetrics.aveCharWidth, xWidth);
+    }
+  }
+
+  if (mMetrics.capHeight == 0.0) {
+    if (GetCharExtents('H', nullptr, &xBounds) && xBounds.y < 0.0) {
+      mMetrics.capHeight = -xBounds.y;
+    }
+  }
+
+  mMetrics.aveCharWidth = std::max(mMetrics.aveCharWidth, mMetrics.zeroWidth);
+  if (mMetrics.aveCharWidth == 0.0) {
+    mMetrics.aveCharWidth = mMetrics.spaceWidth;
+  }
+  // Apparently hinting can mean that max_advance is not always accurate.
+  mMetrics.maxAdvance = std::max(mMetrics.maxAdvance, mMetrics.aveCharWidth);
+
+  mMetrics.maxHeight = mMetrics.maxAscent + mMetrics.maxDescent;
+
+  // Make the line height an integer number of pixels so that lines will be
+  // equally spaced (rather than just being snapped to pixels, some up and
+  // some down).  Layout calculates line height from the emHeight +
+  // internalLeading + externalLeading, but first each of these is rounded
+  // to layout units.  To ensure that the result is an integer number of
+  // pixels, round each of the components to pixels.
+  mMetrics.emHeight = floor(emHeight + 0.5);
+
+  // maxHeight will normally be an integer, but round anyway in case
+  // FreeType is configured differently.
+  mMetrics.internalLeading =
+      floor(mMetrics.maxHeight - mMetrics.emHeight + 0.5);
+
+  // Text input boxes currently don't work well with lineHeight
+  // significantly less than maxHeight (with Verdana, for example).
+  lineHeight = floor(std::max(lineHeight, mMetrics.maxHeight) + 0.5);
+  mMetrics.externalLeading =
+      lineHeight - mMetrics.internalLeading - mMetrics.emHeight;
+
+  // Ensure emAscent + emDescent == emHeight
+  gfxFloat sum = mMetrics.emAscent + mMetrics.emDescent;
+  mMetrics.emAscent =
+      sum > 0.0 ? mMetrics.emAscent * mMetrics.emHeight / sum : 0.0;
+  mMetrics.emDescent = mMetrics.emHeight - mMetrics.emAscent;
+
+  SanitizeMetrics(&mMetrics, false);
+
+#if 0
+    //    printf("font name: %s %f\n", NS_ConvertUTF16toUTF8(GetName()).get(), GetStyle()->size);
+    //    printf ("pango font %s\n", pango_font_description_to_string (pango_font_describe (font)));
+
+    fprintf (stderr, "Font: %s\n", GetName().get());
+    fprintf (stderr, "    emHeight: %f emAscent: %f emDescent: %f\n", mMetrics.emHeight, mMetrics.emAscent, mMetrics.emDescent);
+    fprintf (stderr, "    maxAscent: %f maxDescent: %f\n", mMetrics.maxAscent, mMetrics.maxDescent);
+    fprintf (stderr, "    internalLeading: %f externalLeading: %f\n", mMetrics.externalLeading, mMetrics.internalLeading);
+    fprintf (stderr, "    spaceWidth: %f aveCharWidth: %f xHeight: %f\n", mMetrics.spaceWidth, mMetrics.aveCharWidth, mMetrics.xHeight);
+    fprintf (stderr, "    ideographicWidth: %f\n", mMetrics.ideographicWidth);
+    fprintf (stderr, "    uOff: %f uSize: %f stOff: %f stSize: %f\n", mMetrics.underlineOffset, mMetrics.underlineSize, mMetrics.strikeoutOffset, mMetrics.strikeoutSize);
+#endif
+}
+
+uint32_t gfxFT2FontBase::GetGlyph(uint32_t unicode,
+                                  uint32_t variation_selector) {
+  if (variation_selector) {
+    uint32_t id =
+        gfxFT2LockedFace(this).GetUVSGlyph(unicode, variation_selector);
+    if (id) {
+      return id;
+    }
+    unicode = gfxFontUtils::GetUVSFallback(unicode, variation_selector);
+    if (unicode) {
+      return GetGlyph(unicode);
+    }
+    return 0;
+  }
+
+  return GetGlyph(unicode);
+}
+
+bool gfxFT2FontBase::ShouldRoundXOffset(cairo_t* aCairo) const {
+  // Force rounding if outputting to a Cairo context or if requested by pref to
+  // disable subpixel positioning. Otherwise, allow subpixel positioning (no
+  // rounding) if rendering a scalable outline font with anti-aliasing.
+  // Monochrome rendering or some bitmap fonts can become too distorted with
+  // subpixel positioning, so force rounding in those cases. Also be careful not
+  // to use subpixel positioning if the user requests full hinting via
+  // Fontconfig, which we detect by checking that neither hinting was disabled
+  // nor light hinting was requested. Allow pref to force subpixel positioning
+  // on even if full hinting was requested.
+  return MOZ_UNLIKELY(
+             StaticPrefs::
+                 gfx_text_subpixel_position_force_disabled_AtStartup()) ||
+         aCairo != nullptr || !mFTFace || !FT_IS_SCALABLE(mFTFace->GetFace()) ||
+         (mFTLoadFlags & FT_LOAD_MONOCHROME) ||
+         !((mFTLoadFlags & FT_LOAD_NO_HINTING) ||
+           FT_LOAD_TARGET_MODE(mFTLoadFlags) == FT_RENDER_MODE_LIGHT ||
+           MOZ_UNLIKELY(
+               StaticPrefs::
+                   gfx_text_subpixel_position_force_enabled_AtStartup()));
+}
+
+FT_Vector gfxFT2FontBase::GetEmboldenStrength(FT_Face aFace) const {
+  FT_Vector strength = {0, 0};
+  if (!mEmbolden) {
+    return strength;
+  }
+
+  // If it's an outline glyph, we'll be using mozilla_glyphslot_embolden_less
+  // (see gfx/wr/webrender/src/platform/unix/font.rs), so we need to match its
+  // emboldening strength here.
+  if (aFace->glyph->format == FT_GLYPH_FORMAT_OUTLINE) {
+    strength.x =
+        FT_MulFix(aFace->units_per_EM, aFace->size->metrics.y_scale) / 48;
+    strength.y = strength.x;
+    return strength;
+  }
+
+  // This is the embolden "strength" used by FT_GlyphSlot_Embolden.
+  strength.x =
+      FT_MulFix(aFace->units_per_EM, aFace->size->metrics.y_scale) / 24;
+  strength.y = strength.x;
+  if (aFace->glyph->format == FT_GLYPH_FORMAT_BITMAP) {
+    strength.x &= -64;
+    if (!strength.x) {
+      strength.x = 64;
+    }
+    strength.y &= -64;
+  }
+  return strength;
+}
+
+bool gfxFT2FontBase::GetFTGlyphExtents(uint16_t aGID, int32_t* aAdvance,
+                                       IntRect* aBounds) {
+  gfxFT2LockedFace face(this);
+  MOZ_ASSERT(face.get());
+  if (!face.get()) {
+    // Failed to get the FT_Face? Give up already.
+    NS_WARNING("failed to get FT_Face!");
+    return false;
+  }
+
+  FT_Int32 flags = mFTLoadFlags;
+  if (!aBounds) {
+    flags |= FT_LOAD_ADVANCE_ONLY;
+  }
+
+  // Whether to disable subpixel positioning
+  bool roundX = ShouldRoundXOffset(nullptr);
+
+  // Workaround for FT_Load_Glyph not setting linearHoriAdvance for SVG glyphs.
+  // See https://gitlab.freedesktop.org/freetype/freetype/-/issues/1156.
+  if (!roundX &&
+      GetFontEntry()->HasFontTable(TRUETYPE_TAG('S', 'V', 'G', ' '))) {
+    flags &= ~FT_LOAD_COLOR;
+  }
+
+  if (Factory::LoadFTGlyph(face.get(), aGID, flags) != FT_Err_Ok) {
+    // FT_Face was somehow broken/invalid? Don't try to access glyph slot.
+    // This probably shouldn't happen, but does: see bug 1440938.
+    NS_WARNING("failed to load glyph!");
+    return false;
+  }
+
+  // Whether to interpret hinting settings (i.e. not printing)
+  bool hintMetrics = ShouldHintMetrics();
+  // No hinting disables X and Y hinting. Light disables only X hinting.
+  bool unhintedY = (mFTLoadFlags & FT_LOAD_NO_HINTING) != 0;
+  bool unhintedX =
+      unhintedY || FT_LOAD_TARGET_MODE(mFTLoadFlags) == FT_RENDER_MODE_LIGHT;
+
+  // Normalize out the loaded FT glyph size and then scale to the actually
+  // desired size, in case these two sizes differ.
+  gfxFloat extentsScale = GetAdjustedSize() / mFTSize;
+
+  FT_Vector bold = GetEmboldenStrength(face.get());
+
+  // Due to freetype bug 52683 we MUST use the linearHoriAdvance field when
+  // dealing with a variation font; also use it for scalable fonts when not
+  // applying hinting. Otherwise, prefer hinted width from glyph->advance.x.
+  if (aAdvance) {
+    FT_Fixed advance;
+    if (!roundX || FT_HAS_MULTIPLE_MASTERS(face.get())) {
+      advance = face.get()->glyph->linearHoriAdvance;
+    } else {
+      advance = face.get()->glyph->advance.x << 10;  // convert 26.6 to 16.16
+    }
+    if (advance) {
+      advance += bold.x << 10;  // convert 26.6 to 16.16
+    }
+    // Hinting was requested, but FT did not apply any hinting to the metrics.
+    // Round the advance here to approximate hinting as Cairo does. This must
+    // happen BEFORE we apply the glyph extents scale, just like FT hinting
+    // would.
+    if (hintMetrics && roundX && unhintedX) {
+      advance = (advance + 0x8000) & 0xffff0000u;
+    }
+    *aAdvance = NS_lround(advance * extentsScale);
+  }
+
+  if (aBounds) {
+    const FT_Glyph_Metrics& metrics = face.get()->glyph->metrics;
+    FT_F26Dot6 x = metrics.horiBearingX;
+    FT_F26Dot6 y = -metrics.horiBearingY;
+    FT_F26Dot6 x2 = x + metrics.width;
+    FT_F26Dot6 y2 = y + metrics.height;
+    // Synthetic bold moves the glyph top and right boundaries.
+    y -= bold.y;
+    x2 += bold.x;
+    if (hintMetrics) {
+      if (roundX && unhintedX) {
+        x &= -64;
+        x2 = (x2 + 63) & -64;
+      }
+      if (unhintedY) {
+        y &= -64;
+        y2 = (y2 + 63) & -64;
+      }
+    }
+    *aBounds = IntRect(x, y, x2 - x, y2 - y);
+
+    // Color fonts may not have reported the right bounds here, if there wasn't
+    // an outline for the nominal glyph ID.
+    // In principle we could use COLRFonts::GetColorGlyphBounds to retrieve the
+    // true bounds of the rendering, but that's more expensive; probably better
+    // to just use the font-wide ascent/descent as a heuristic that will
+    // generally ensure everything gets rendered.
+    if (aBounds->IsEmpty() &&
+        GetFontEntry()->HasFontTable(TRUETYPE_TAG('C', 'O', 'L', 'R'))) {
+      const auto& fm = GetMetrics(nsFontMetrics::eHorizontal);
+      // aBounds is stored as FT_F26Dot6, so scale values from `fm` by 64.
+      aBounds->y = int32_t(-NS_round(fm.maxAscent * 64.0));
+      aBounds->height =
+          int32_t(NS_round((fm.maxAscent + fm.maxDescent) * 64.0));
+      aBounds->x = 0;
+      aBounds->width =
+          int32_t(aAdvance ? *aAdvance : NS_round(fm.maxAdvance * 64.0));
+    }
+  }
+
+  return true;
+}
+
+/**
+ * Get the cached glyph metrics for the glyph id if available. Otherwise, query
+ * FreeType for the glyph extents and initialize the glyph metrics.
+ */
+const gfxFT2FontBase::GlyphMetrics& gfxFT2FontBase::GetCachedGlyphMetrics(
+    uint16_t aGID, IntRect* aBounds) {
+  {
+    // Try to read cached metrics without exclusive locking.
+    AutoReadLock lock(mLock);
+    if (mGlyphMetrics) {
+      if (auto metrics = mGlyphMetrics->Lookup(aGID)) {
+        return metrics.Data();
+      }
+    }
+  }
+
+  // We need to create/update the cache.
+  AutoWriteLock lock(mLock);
+  if (!mGlyphMetrics) {
+    mGlyphMetrics =
+        mozilla::MakeUnique<nsTHashMap<nsUint32HashKey, GlyphMetrics>>(128);
+  }
+
+  return mGlyphMetrics->LookupOrInsertWith(aGID, [&] {
+    GlyphMetrics metrics;
+    IntRect bounds;
+    if (GetFTGlyphExtents(aGID, &metrics.mAdvance, &bounds)) {
+      metrics.SetBounds(bounds);
+      if (aBounds) {
+        *aBounds = bounds;
+      }
+    }
+    return metrics;
+  });
+}
+
+bool gfxFT2FontBase::GetGlyphBounds(uint16_t aGID, gfxRect* aBounds,
+                                    bool aTight) {
+  IntRect bounds;
+  const GlyphMetrics& metrics = GetCachedGlyphMetrics(aGID, &bounds);
+  if (!metrics.HasValidBounds()) {
+    return false;
+  }
+  // Check if there are cached bounds and use those if available. Otherwise,
+  // fall back to directly querying the glyph extents.
+  if (metrics.HasCachedBounds()) {
+    bounds = metrics.GetBounds();
+  } else if (bounds.IsEmpty() && !GetFTGlyphExtents(aGID, nullptr, &bounds)) {
+    return false;
+  }
+  // The bounds are stored unscaled, so must be scaled to the adjusted size.
+  *aBounds = ScaleGlyphBounds(bounds, GetAdjustedSize() / mFTSize);
+  return true;
+}
+
+// For variation fonts, figure out the variation coordinates to be applied
+// for each axis, in freetype's order (which may not match the order of
+// axes in mStyle.variationSettings, so we need to search by axis tag).
+/*static*/
+void gfxFT2FontBase::SetupVarCoords(
+    FT_MM_Var* aMMVar, const nsTArray<gfxFontVariation>& aVariations,
+    FT_Face aFTFace) {
+  if (!aMMVar) {
+    return;
+  }
+
+  nsTArray<FT_Fixed> coords;
+  for (unsigned i = 0; i < aMMVar->num_axis; ++i) {
+    coords.AppendElement(aMMVar->axis[i].def);
+    for (const auto& v : aVariations) {
+      if (aMMVar->axis[i].tag == v.mTag) {
+        FT_Fixed val = v.mValue * 0x10000;
+        val = std::min(val, aMMVar->axis[i].maximum);
+        val = std::max(val, aMMVar->axis[i].minimum);
+        coords[i] = val;
+        break;
+      }
+    }
+  }
+
+  if (!coords.IsEmpty()) {
+#if MOZ_TREE_FREETYPE
+    FT_Set_Var_Design_Coordinates(aFTFace, coords.Length(), coords.Elements());
+#else
+    typedef FT_Error (*SetCoordsFunc)(FT_Face, FT_UInt, FT_Fixed*);
+    static SetCoordsFunc setCoords;
+    static bool firstTime = true;
+    if (firstTime) {
+      firstTime = false;
+      setCoords =
+          (SetCoordsFunc)dlsym(RTLD_DEFAULT, "FT_Set_Var_Design_Coordinates");
+    }
+    if (setCoords) {
+      (*setCoords)(aFTFace, coords.Length(), coords.Elements());
+    }
+#endif
+  }
+}