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gfxFontMissingGlyphs.cpp (21054B)


      1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
      2 * This Source Code Form is subject to the terms of the Mozilla Public
      3 * License, v. 2.0. If a copy of the MPL was not distributed with this
      4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      5 
      6 #include "gfxFontMissingGlyphs.h"
      7 
      8 #include "gfxUtils.h"
      9 #include "mozilla/gfx/2D.h"
     10 #include "mozilla/gfx/Helpers.h"
     11 #include "mozilla/gfx/PathHelpers.h"
     12 #include "mozilla/LinkedList.h"
     13 #include "mozilla/RefPtr.h"
     14 #include "nsDeviceContext.h"
     15 #include "nsLayoutUtils.h"
     16 #include "TextDrawTarget.h"
     17 #include "LayerUserData.h"
     18 
     19 using namespace mozilla;
     20 using namespace mozilla::gfx;
     21 
     22 #ifndef MOZ_GFX_OPTIMIZE_MOBILE
     23 #  define X 255
     24 static const uint8_t gMiniFontData[] = {
     25    0, X, 0, 0, X, 0, X, X, X, X, X, X, X, 0, X, X, X, X, X, X, X, X, X, X,
     26    X, X, X, X, X, X, X, X, X, X, X, 0, 0, X, X, X, X, 0, X, X, X, X, X, X,
     27    X, 0, X, 0, X, 0, 0, 0, X, 0, 0, X, X, 0, X, X, 0, 0, X, 0, 0, 0, 0, X,
     28    X, 0, X, X, 0, X, X, 0, X, X, 0, X, X, 0, 0, X, 0, X, X, 0, 0, X, 0, 0,
     29    X, 0, X, 0, X, 0, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, 0, 0, X,
     30    X, X, X, X, X, X, X, X, X, X, X, 0, X, 0, 0, X, 0, X, X, X, X, X, X, X,
     31    X, 0, X, 0, X, 0, X, 0, 0, 0, 0, X, 0, 0, X, 0, 0, X, X, 0, X, 0, 0, X,
     32    X, 0, X, 0, 0, X, X, 0, X, X, 0, X, X, 0, 0, X, 0, X, X, 0, 0, X, 0, 0,
     33    0, X, 0, 0, X, 0, X, X, X, X, X, X, 0, 0, X, X, X, X, X, X, X, 0, 0, X,
     34    X, X, X, 0, 0, X, X, 0, X, X, X, 0, 0, X, X, X, X, 0, X, X, X, X, 0, 0,
     35 };
     36 #  undef X
     37 #endif
     38 
     39 /* Parameters that control the rendering of hexboxes. They look like this:
     40 
     41        BMP codepoints           non-BMP codepoints
     42      (U+0000 - U+FFFF)         (U+10000 - U+10FFFF)
     43 
     44         +---------+              +-------------+
     45         |         |              |             |
     46         | HHH HHH |              | HHH HHH HHH |
     47         | HHH HHH |              | HHH HHH HHH |
     48         | HHH HHH |              | HHH HHH HHH |
     49         | HHH HHH |              | HHH HHH HHH |
     50         | HHH HHH |              | HHH HHH HHH |
     51         |         |              |             |
     52         | HHH HHH |              | HHH HHH HHH |
     53         | HHH HHH |              | HHH HHH HHH |
     54         | HHH HHH |              | HHH HHH HHH |
     55         | HHH HHH |              | HHH HHH HHH |
     56         | HHH HHH |              | HHH HHH HHH |
     57         |         |              |             |
     58         +---------+              +-------------+
     59 */
     60 
     61 /** Width of a minifont glyph (see above) */
     62 static const int MINIFONT_WIDTH = 3;
     63 /** Height of a minifont glyph (see above) */
     64 #ifndef MOZ_GFX_OPTIMIZE_MOBILE
     65 static const int MINIFONT_HEIGHT = 5;
     66 #endif
     67 /**
     68 * Gap between minifont glyphs (both horizontal and vertical) and also
     69 * the minimum desired gap between the box border and the glyphs
     70 */
     71 static const int HEX_CHAR_GAP = 1;
     72 /**
     73 * The amount of space between the vertical edge of the glyphbox and the
     74 * box border. We make this nonzero so that when multiple missing glyphs
     75 * occur consecutively there's a gap between their rendered boxes.
     76 */
     77 static const int BOX_HORIZONTAL_INSET = 1;
     78 /** The width of the border */
     79 static const int BOX_BORDER_WIDTH = 1;
     80 /**
     81 * The scaling factor for the border opacity; this is multiplied by the current
     82 * opacity being used to draw the text.
     83 */
     84 static const Float BOX_BORDER_OPACITY = 0.5;
     85 
     86 #ifndef MOZ_GFX_OPTIMIZE_MOBILE
     87 
     88 class GlyphAtlas {
     89 public:
     90  GlyphAtlas(RefPtr<SourceSurface>&& aSurface, const DeviceColor& aColor)
     91      : mSurface(std::move(aSurface)), mColor(aColor) {}
     92  ~GlyphAtlas() = default;
     93 
     94  already_AddRefed<SourceSurface> Surface() const {
     95    RefPtr surface = mSurface;
     96    return surface.forget();
     97  }
     98  DeviceColor Color() const { return mColor; }
     99 
    100 private:
    101  RefPtr<SourceSurface> mSurface;
    102  DeviceColor mColor;
    103 };
    104 
    105 // This is an owning reference that we will manage via exchange() and
    106 // explicit new/delete operations.
    107 static std::atomic<GlyphAtlas*> gGlyphAtlas;
    108 
    109 /**
    110 * Generates a new colored mini-font atlas from the mini-font mask.
    111 */
    112 static GlyphAtlas* MakeGlyphAtlas(const DeviceColor& aColor) {
    113  RefPtr<DrawTarget> glyphDrawTarget =
    114      gfxPlatform::GetPlatform()->CreateOffscreenContentDrawTarget(
    115          IntSize(MINIFONT_WIDTH * 16, MINIFONT_HEIGHT),
    116          SurfaceFormat::B8G8R8A8);
    117  if (!glyphDrawTarget) {
    118    return nullptr;
    119  }
    120  RefPtr<SourceSurface> glyphMask =
    121      glyphDrawTarget->CreateSourceSurfaceFromData(
    122          const_cast<uint8_t*>(gMiniFontData),
    123          IntSize(MINIFONT_WIDTH * 16, MINIFONT_HEIGHT), MINIFONT_WIDTH * 16,
    124          SurfaceFormat::A8);
    125  if (!glyphMask) {
    126    return nullptr;
    127  }
    128  glyphDrawTarget->MaskSurface(ColorPattern(aColor), glyphMask, Point(0, 0),
    129                               DrawOptions(1.0f, CompositionOp::OP_SOURCE));
    130  RefPtr<SourceSurface> surface = glyphDrawTarget->Snapshot();
    131  if (!surface) {
    132    return nullptr;
    133  }
    134  return new GlyphAtlas(std::move(surface), aColor);
    135 }
    136 
    137 /**
    138 * Reuse the current mini-font atlas if the color matches, otherwise regenerate
    139 * it.
    140 */
    141 static inline already_AddRefed<SourceSurface> GetGlyphAtlas(
    142    const DeviceColor& aColor) {
    143  // Get the opaque color, ignoring any transparency which will be handled
    144  // later.
    145  DeviceColor color(aColor.r, aColor.g, aColor.b);
    146 
    147  // Atomically grab the current GlyphAtlas pointer (if any). Because we
    148  // exchange with nullptr here, no other thread will be able to touch the
    149  // currAtlas record while we're using it; if they try, they'll just see
    150  // the null that we stored.
    151  GlyphAtlas* currAtlas = gGlyphAtlas.exchange(nullptr);
    152 
    153  if (currAtlas && currAtlas->Color() == color) {
    154    // If its color is right, grab a reference to its surface.
    155    RefPtr<SourceSurface> surface = currAtlas->Surface();
    156    // Now put the currAtlas record back in the global. If some other thread
    157    // has stored an atlas there in the meantime, we just discard it.
    158    delete gGlyphAtlas.exchange(currAtlas);
    159    return surface.forget();
    160  }
    161 
    162  // Make a new atlas in the color we want.
    163  GlyphAtlas* atlas = MakeGlyphAtlas(color);
    164  RefPtr<SourceSurface> surface = atlas ? atlas->Surface() : nullptr;
    165 
    166  // Store the newly-created atlas in the global; release any other.
    167  delete gGlyphAtlas.exchange(atlas);
    168  return surface.forget();
    169 }
    170 
    171 /**
    172 * Clear any cached glyph atlas resources.
    173 */
    174 static void PurgeGlyphAtlas() { delete gGlyphAtlas.exchange(nullptr); }
    175 
    176 // WebRender layer manager user data that will get signaled when the layer
    177 // manager is destroyed.
    178 class WRUserData : public layers::LayerUserData,
    179                   public LinkedListElement<WRUserData> {
    180 public:
    181  explicit WRUserData(layers::WebRenderLayerManager* aManager);
    182 
    183  ~WRUserData();
    184 
    185  static void Assign(layers::WebRenderLayerManager* aManager) {
    186    if (!aManager->HasUserData(&sWRUserDataKey)) {
    187      aManager->SetUserData(&sWRUserDataKey, new WRUserData(aManager));
    188    }
    189  }
    190 
    191  void Remove() { mManager->RemoveUserData(&sWRUserDataKey); }
    192 
    193  layers::WebRenderLayerManager* mManager;
    194 
    195  static UserDataKey sWRUserDataKey;
    196 };
    197 
    198 static void DestroyImageKey(void* aClosure) {
    199  auto* key = static_cast<wr::ImageKey*>(aClosure);
    200  delete key;
    201 }
    202 
    203 constinit static RefPtr<SourceSurface> gWRGlyphAtlas[8];
    204 MOZ_RUNINIT static LinkedList<WRUserData> gWRUsers;
    205 UserDataKey WRUserData::sWRUserDataKey;
    206 
    207 /**
    208 * Generates a transformed WebRender mini-font atlas for a given orientation.
    209 */
    210 static already_AddRefed<SourceSurface> MakeWRGlyphAtlas(const Matrix* aMat) {
    211  IntSize size(MINIFONT_WIDTH * 16, MINIFONT_HEIGHT);
    212  // If the orientation is transposed, width/height are swapped.
    213  if (aMat && aMat->_11 == 0) {
    214    std::swap(size.width, size.height);
    215  }
    216  RefPtr<DrawTarget> ref =
    217      gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget();
    218  RefPtr<DrawTarget> dt =
    219      gfxPlatform::GetPlatform()->CreateSimilarSoftwareDrawTarget(
    220          ref, size, SurfaceFormat::B8G8R8A8);
    221  if (!dt) {
    222    return nullptr;
    223  }
    224  if (aMat) {
    225    // Select appropriate transform matrix based on whether the
    226    // orientation is transposed.
    227    dt->SetTransform(aMat->_11 == 0
    228                         ? Matrix(0.0f, copysign(1.0f, aMat->_12),
    229                                  copysign(1.0f, aMat->_21), 0.0f,
    230                                  aMat->_21 < 0 ? MINIFONT_HEIGHT : 0.0f,
    231                                  aMat->_12 < 0 ? MINIFONT_WIDTH * 16 : 0.0f)
    232                         : Matrix(copysign(1.0f, aMat->_11), 0.0f, 0.0f,
    233                                  copysign(1.0f, aMat->_22),
    234                                  aMat->_11 < 0 ? MINIFONT_WIDTH * 16 : 0.0f,
    235                                  aMat->_22 < 0 ? MINIFONT_HEIGHT : 0.0f));
    236  }
    237  RefPtr<SourceSurface> mask = dt->CreateSourceSurfaceFromData(
    238      const_cast<uint8_t*>(gMiniFontData),
    239      IntSize(MINIFONT_WIDTH * 16, MINIFONT_HEIGHT), MINIFONT_WIDTH * 16,
    240      SurfaceFormat::A8);
    241  if (!mask) {
    242    return nullptr;
    243  }
    244  dt->MaskSurface(ColorPattern(DeviceColor::MaskOpaqueWhite()), mask,
    245                  Point(0, 0));
    246  return dt->Snapshot();
    247 }
    248 
    249 /**
    250 * Clear any cached WebRender glyph atlas resources.
    251 */
    252 static void PurgeWRGlyphAtlas() {
    253  // For each WR layer manager, we need go through each atlas orientation
    254  // and see if it has a stashed image key. If it does, remove the image
    255  // from the layer manager.
    256  for (WRUserData* user : gWRUsers) {
    257    auto* manager = user->mManager;
    258    for (size_t i = 0; i < 8; i++) {
    259      if (gWRGlyphAtlas[i]) {
    260        auto* key = static_cast<wr::ImageKey*>(gWRGlyphAtlas[i]->GetUserData(
    261            reinterpret_cast<UserDataKey*>(manager)));
    262        if (key) {
    263          manager->GetRenderRootStateManager()->AddImageKeyForDiscard(*key);
    264        }
    265      }
    266    }
    267  }
    268  // Remove the layer managers' destroy notifications only after processing
    269  // so as not to mess up gWRUsers iteration.
    270  while (!gWRUsers.isEmpty()) {
    271    gWRUsers.popFirst()->Remove();
    272  }
    273  // Finally, clear out the atlases.
    274  for (size_t i = 0; i < 8; i++) {
    275    gWRGlyphAtlas[i] = nullptr;
    276  }
    277 }
    278 
    279 WRUserData::WRUserData(layers::WebRenderLayerManager* aManager)
    280    : mManager(aManager) {
    281  gWRUsers.insertFront(this);
    282 }
    283 
    284 WRUserData::~WRUserData() {
    285  // When the layer manager is destroyed, we need go through each
    286  // atlas and remove any assigned image keys.
    287  if (isInList()) {
    288    for (size_t i = 0; i < 8; i++) {
    289      if (gWRGlyphAtlas[i]) {
    290        gWRGlyphAtlas[i]->RemoveUserData(
    291            reinterpret_cast<UserDataKey*>(mManager));
    292      }
    293    }
    294  }
    295 }
    296 
    297 static already_AddRefed<SourceSurface> GetWRGlyphAtlas(DrawTarget& aDrawTarget,
    298                                                       const Matrix* aMat) {
    299  uint32_t key = 0;
    300  // Encode orientation in the key.
    301  if (aMat) {
    302    if (aMat->_11 == 0) {
    303      key |= 4 | (aMat->_12 < 0 ? 1 : 0) | (aMat->_21 < 0 ? 2 : 0);
    304    } else {
    305      key |= (aMat->_11 < 0 ? 1 : 0) | (aMat->_22 < 0 ? 2 : 0);
    306    }
    307  }
    308 
    309  // Check if an atlas was already created, or create one if necessary.
    310  RefPtr<SourceSurface> atlas = gWRGlyphAtlas[key];
    311  if (!atlas) {
    312    atlas = MakeWRGlyphAtlas(aMat);
    313    gWRGlyphAtlas[key] = atlas;
    314  }
    315 
    316  // The atlas may exist, but an image key may not be assigned for it to
    317  // the given layer manager, or it may no longer be valid.
    318  auto* tdt = static_cast<layout::TextDrawTarget*>(&aDrawTarget);
    319  auto* manager = tdt->WrLayerManager();
    320  auto* imageKey = static_cast<wr::ImageKey*>(
    321      atlas->GetUserData(reinterpret_cast<UserDataKey*>(manager)));
    322  if (!imageKey || !manager->WrBridge()->MatchesNamespace(*imageKey)) {
    323    // No image key, so we need to map the atlas' data for transfer to WR.
    324    RefPtr<DataSourceSurface> dataSurface = atlas->GetDataSurface();
    325    if (!dataSurface) {
    326      return nullptr;
    327    }
    328    DataSourceSurface::ScopedMap map(dataSurface, DataSourceSurface::READ);
    329    if (!map.IsMapped()) {
    330      return nullptr;
    331    }
    332    // Transfer the data and get an image key for it.
    333    Maybe<wr::ImageKey> result = tdt->DefineImage(
    334        atlas->GetSize(), map.GetStride(), atlas->GetFormat(), map.GetData());
    335    if (!result.isSome()) {
    336      return nullptr;
    337    }
    338    // Assign the image key to the atlas.
    339    atlas->AddUserData(reinterpret_cast<UserDataKey*>(manager),
    340                       new wr::ImageKey(result.ref()), DestroyImageKey);
    341    // Create a user data notification for when the layer manager is
    342    // destroyed so we can clean up any assigned image keys.
    343    WRUserData::Assign(manager);
    344  }
    345  return atlas.forget();
    346 }
    347 
    348 static void DrawHexChar(uint32_t aDigit, Float aLeft, Float aTop,
    349                        DrawTarget& aDrawTarget, SourceSurface* aAtlas,
    350                        const DeviceColor& aColor,
    351                        const Matrix* aMat = nullptr) {
    352  Rect dest(aLeft, aTop, MINIFONT_WIDTH, MINIFONT_HEIGHT);
    353  if (aDrawTarget.GetBackendType() == BackendType::WEBRENDER_TEXT) {
    354    // For WR, we need to get the image key assigned to the given WR layer
    355    // manager for referencing the image.
    356    auto* tdt = static_cast<layout::TextDrawTarget*>(&aDrawTarget);
    357    auto* manager = tdt->WrLayerManager();
    358    auto* key = static_cast<wr::ImageKey*>(
    359        aAtlas->GetUserData(reinterpret_cast<UserDataKey*>(manager)));
    360    MOZ_ASSERT(key);
    361    // Transform the bounds of the atlas into the given orientation, and then
    362    // also transform a small clip rect which will be used to select the given
    363    // digit from the atlas.
    364    Rect bounds(aLeft - aDigit * MINIFONT_WIDTH, aTop, MINIFONT_WIDTH * 16,
    365                MINIFONT_HEIGHT);
    366    if (aMat) {
    367      // Width and height may be negative after the transform, so move the rect
    368      // if necessary and fix size.
    369      bounds = aMat->TransformRect(bounds);
    370      bounds.x += std::min(bounds.width, 0.0f);
    371      bounds.y += std::min(bounds.height, 0.0f);
    372      bounds.width = fabs(bounds.width);
    373      bounds.height = fabs(bounds.height);
    374      dest = aMat->TransformRect(dest);
    375      dest.x += std::min(dest.width, 0.0f);
    376      dest.y += std::min(dest.height, 0.0f);
    377      dest.width = fabs(dest.width);
    378      dest.height = fabs(dest.height);
    379    }
    380    // Finally, push the colored image with point filtering.
    381    tdt->PushImage(*key, bounds, dest, wr::ImageRendering::Pixelated,
    382                   wr::ToColorF(aColor));
    383  } else {
    384    // For the normal case, just draw the given digit from the atlas. Point
    385    // filtering is used to ensure the mini-font rectangles stay sharp with any
    386    // scaling. Handle any transparency here as well.
    387    aDrawTarget.DrawSurface(
    388        aAtlas, dest,
    389        Rect(aDigit * MINIFONT_WIDTH, 0, MINIFONT_WIDTH, MINIFONT_HEIGHT),
    390        DrawSurfaceOptions(SamplingFilter::POINT),
    391        DrawOptions(aColor.a, CompositionOp::OP_OVER, AntialiasMode::NONE));
    392  }
    393 }
    394 
    395 void gfxFontMissingGlyphs::Purge() {
    396  PurgeGlyphAtlas();
    397  PurgeWRGlyphAtlas();
    398 }
    399 
    400 #else  // MOZ_GFX_OPTIMIZE_MOBILE
    401 
    402 void gfxFontMissingGlyphs::Purge() {}
    403 
    404 #endif
    405 
    406 void gfxFontMissingGlyphs::Shutdown() { Purge(); }
    407 
    408 void gfxFontMissingGlyphs::DrawMissingGlyph(uint32_t aChar, const Rect& aRect,
    409                                            DrawTarget& aDrawTarget,
    410                                            const Pattern& aPattern,
    411                                            const Matrix* aMat) {
    412  Rect rect(aRect);
    413  // If there is an orientation transform, reorient the bounding rect.
    414  if (aMat) {
    415    rect.MoveBy(-aRect.BottomLeft());
    416    rect = aMat->TransformBounds(rect);
    417    rect.MoveBy(aRect.BottomLeft());
    418  }
    419 
    420  // If we're currently drawing with some kind of pattern, we just draw the
    421  // missing-glyph data in black.
    422  DeviceColor color = aPattern.GetType() == PatternType::COLOR
    423                          ? static_cast<const ColorPattern&>(aPattern).mColor
    424                          : ToDeviceColor(sRGBColor::OpaqueBlack());
    425 
    426  // Stroke a rectangle so that the stroke's left edge is inset one pixel
    427  // from the left edge of the glyph box and the stroke's right edge
    428  // is inset one pixel from the right edge of the glyph box.
    429  Float halfBorderWidth = BOX_BORDER_WIDTH / 2.0;
    430  Float borderLeft = rect.X() + BOX_HORIZONTAL_INSET + halfBorderWidth;
    431  Float borderRight = rect.XMost() - BOX_HORIZONTAL_INSET - halfBorderWidth;
    432  Rect borderStrokeRect(borderLeft, rect.Y() + halfBorderWidth,
    433                        borderRight - borderLeft,
    434                        rect.Height() - 2.0 * halfBorderWidth);
    435  if (!borderStrokeRect.IsEmpty()) {
    436    ColorPattern adjustedColor(color);
    437    adjustedColor.mColor.a *= BOX_BORDER_OPACITY;
    438 #ifdef MOZ_GFX_OPTIMIZE_MOBILE
    439    aDrawTarget.FillRect(borderStrokeRect, adjustedColor);
    440 #else
    441    StrokeOptions strokeOptions(BOX_BORDER_WIDTH);
    442    aDrawTarget.StrokeRect(borderStrokeRect, adjustedColor, strokeOptions);
    443 #endif
    444  }
    445 
    446 #ifndef MOZ_GFX_OPTIMIZE_MOBILE
    447  RefPtr<SourceSurface> atlas =
    448      aDrawTarget.GetBackendType() == BackendType::WEBRENDER_TEXT
    449          ? GetWRGlyphAtlas(aDrawTarget, aMat)
    450          : GetGlyphAtlas(color);
    451  if (!atlas) {
    452    return;
    453  }
    454 
    455  Point center = rect.Center();
    456  Float halfGap = HEX_CHAR_GAP / 2.f;
    457  Float top = -(MINIFONT_HEIGHT + halfGap);
    458 
    459  // Figure out a scaling factor that will fit the glyphs in the target rect
    460  // both horizontally and vertically.
    461  Float width = HEX_CHAR_GAP + MINIFONT_WIDTH + HEX_CHAR_GAP + MINIFONT_WIDTH +
    462                ((aChar < 0x10000) ? 0 : HEX_CHAR_GAP + MINIFONT_WIDTH) +
    463                HEX_CHAR_GAP;
    464  Float height = HEX_CHAR_GAP + MINIFONT_HEIGHT + HEX_CHAR_GAP +
    465                 MINIFONT_HEIGHT + HEX_CHAR_GAP;
    466  Float scaling = std::min(rect.Height() / height, rect.Width() / width);
    467 
    468  // We always want integer scaling, otherwise the "bitmap" glyphs will look
    469  // even uglier than usual when scaled to the target.
    470  int32_t devPixelsPerCSSPx = std::max<int32_t>(1, std::floor(scaling));
    471 
    472  Matrix tempMat;
    473  if (aMat) {
    474    // If there is an orientation transform, since draw target transforms may
    475    // not be supported, scale and translate it so that it can be directly used
    476    // for rendering the mini font without changing the draw target transform.
    477    tempMat = Matrix(*aMat)
    478                  .PostScale(devPixelsPerCSSPx, devPixelsPerCSSPx)
    479                  .PostTranslate(center);
    480    aMat = &tempMat;
    481  } else {
    482    // Otherwise, scale and translate the draw target transform assuming it
    483    // supports that.
    484    tempMat = aDrawTarget.GetTransform();
    485    aDrawTarget.SetTransform(Matrix(tempMat).PreTranslate(center).PreScale(
    486        devPixelsPerCSSPx, devPixelsPerCSSPx));
    487  }
    488 
    489  if (aChar < 0x10000) {
    490    if (rect.Width() >= 2 * (MINIFONT_WIDTH + HEX_CHAR_GAP) &&
    491        rect.Height() >= 2 * MINIFONT_HEIGHT + HEX_CHAR_GAP) {
    492      // Draw 4 digits for BMP
    493      Float left = -(MINIFONT_WIDTH + halfGap);
    494      DrawHexChar((aChar >> 12) & 0xF, left, top, aDrawTarget, atlas, color,
    495                  aMat);
    496      DrawHexChar((aChar >> 8) & 0xF, halfGap, top, aDrawTarget, atlas, color,
    497                  aMat);
    498      DrawHexChar((aChar >> 4) & 0xF, left, halfGap, aDrawTarget, atlas, color,
    499                  aMat);
    500      DrawHexChar(aChar & 0xF, halfGap, halfGap, aDrawTarget, atlas, color,
    501                  aMat);
    502    }
    503  } else {
    504    if (rect.Width() >= 3 * (MINIFONT_WIDTH + HEX_CHAR_GAP) &&
    505        rect.Height() >= 2 * MINIFONT_HEIGHT + HEX_CHAR_GAP) {
    506      // Draw 6 digits for non-BMP
    507      Float first = -(MINIFONT_WIDTH * 1.5 + HEX_CHAR_GAP);
    508      Float second = -(MINIFONT_WIDTH / 2.0);
    509      Float third = (MINIFONT_WIDTH / 2.0 + HEX_CHAR_GAP);
    510      DrawHexChar((aChar >> 20) & 0xF, first, top, aDrawTarget, atlas, color,
    511                  aMat);
    512      DrawHexChar((aChar >> 16) & 0xF, second, top, aDrawTarget, atlas, color,
    513                  aMat);
    514      DrawHexChar((aChar >> 12) & 0xF, third, top, aDrawTarget, atlas, color,
    515                  aMat);
    516      DrawHexChar((aChar >> 8) & 0xF, first, halfGap, aDrawTarget, atlas, color,
    517                  aMat);
    518      DrawHexChar((aChar >> 4) & 0xF, second, halfGap, aDrawTarget, atlas,
    519                  color, aMat);
    520      DrawHexChar(aChar & 0xF, third, halfGap, aDrawTarget, atlas, color, aMat);
    521    }
    522  }
    523 
    524  if (!aMat) {
    525    // The draw target transform was changed, so it must be restored to
    526    // the original value.
    527    aDrawTarget.SetTransform(tempMat);
    528  }
    529 #endif
    530 }
    531 
    532 Float gfxFontMissingGlyphs::GetDesiredMinWidth(uint32_t aChar,
    533                                               uint32_t aAppUnitsPerDevPixel) {
    534  /**
    535   * The minimum desired width for a missing-glyph glyph box. I've laid it out
    536   * like this so you can see what goes where.
    537   */
    538  Float width = BOX_HORIZONTAL_INSET + BOX_BORDER_WIDTH + HEX_CHAR_GAP +
    539                MINIFONT_WIDTH + HEX_CHAR_GAP + MINIFONT_WIDTH +
    540                ((aChar < 0x10000) ? 0 : HEX_CHAR_GAP + MINIFONT_WIDTH) +
    541                HEX_CHAR_GAP + BOX_BORDER_WIDTH + BOX_HORIZONTAL_INSET;
    542  // Note that this will give us floating-point division, so the width will
    543  // -not- be snapped to integer multiples of its basic pixel value
    544  width *= Float(AppUnitsPerCSSPixel()) / aAppUnitsPerDevPixel;
    545  return width;
    546 }