gecko-dev/gfx/2d/ScaledFontFontconfig.cpp

/* -*- 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 "ScaledFontFontconfig.h"
#include "Logging.h"

#ifdef USE_SKIA
#include "skia/include/ports/SkTypeface_cairo.h"
#endif

#include FT_TRUETYPE_TABLES_H

#include <fontconfig/fcfreetype.h>

namespace mozilla {
namespace gfx {

// On Linux and Android our "platform" font is a cairo_scaled_font_t and we use
// an SkFontHost implementation that allows Skia to render using this.
// This is mainly because FT_Face is not good for sharing between libraries, which
// is a requirement when we consider runtime switchable backends and so on
ScaledFontFontconfig::ScaledFontFontconfig(cairo_scaled_font_t* aScaledFont,
                                           FcPattern* aPattern,
                                           Float aSize)
  : ScaledFontBase(aSize),
    mPattern(aPattern)
{
  SetCairoScaledFont(aScaledFont);
  FcPatternReference(aPattern);
}

ScaledFontFontconfig::~ScaledFontFontconfig()
{
  FcPatternDestroy(mPattern);
}

#ifdef USE_SKIA
SkTypeface* ScaledFontFontconfig::GetSkTypeface()
{
  if (!mTypeface) {
    mTypeface = SkCreateTypefaceFromCairoFTFontWithFontconfig(mScaledFont, mPattern);
  }

  return mTypeface;
}
#endif

bool
ScaledFontFontconfig::GetFontFileData(FontFileDataOutput aDataCallback, void* aBaton)
{
  bool success = false;
  // Lock the Cairo scaled font to force it to resolve the Fontconfig pattern to an FT_Face.
  if (FT_Face face = cairo_ft_scaled_font_lock_face(GetCairoScaledFont())) {
    FT_ULong length = 0;
    // Request the SFNT file. This may not always succeed for all font types.
    if (FT_Load_Sfnt_Table(face, 0, 0, nullptr, &length) == FT_Err_Ok) {
      uint8_t* fontData = new uint8_t[length];
      if (FT_Load_Sfnt_Table(face, 0, 0, fontData, &length) == FT_Err_Ok) {
        aDataCallback(fontData, length, 0, mSize, 0, nullptr, aBaton);
        success = true;
      }
      delete[] fontData;
    }
    cairo_ft_scaled_font_unlock_face(GetCairoScaledFont());
  }
  return success;
}

ScaledFontFontconfig::InstanceData::InstanceData(cairo_scaled_font_t* aScaledFont, FcPattern* aPattern)
  : mFlags(0)
  , mHintStyle(FC_HINT_NONE)
  , mSubpixelOrder(FC_RGBA_UNKNOWN)
  , mLcdFilter(FC_LCD_LEGACY)
{
  // Record relevant Fontconfig properties into instance data.
  FcBool autohint;
  if (FcPatternGetBool(aPattern, FC_AUTOHINT, 0, &autohint) == FcResultMatch && autohint) {
    mFlags |= AUTOHINT;
  }
  FcBool bitmap;
  if (FcPatternGetBool(aPattern, FC_EMBEDDED_BITMAP, 0, &bitmap) == FcResultMatch && bitmap) {
    mFlags |= EMBEDDED_BITMAP;
  }
  FcBool embolden;
  if (FcPatternGetBool(aPattern, FC_EMBOLDEN, 0, &embolden) == FcResultMatch && embolden) {
    mFlags |= EMBOLDEN;
  }
  FcBool vertical;
  if (FcPatternGetBool(aPattern, FC_VERTICAL_LAYOUT, 0, &vertical) == FcResultMatch && vertical) {
    mFlags |= VERTICAL_LAYOUT;
  }

  FcBool antialias;
  if (FcPatternGetBool(aPattern, FC_ANTIALIAS, 0, &antialias) != FcResultMatch || antialias) {
    mFlags |= ANTIALIAS;

    // Only record subpixel order and lcd filtering if antialiasing is enabled.
    int rgba;
    if (FcPatternGetInteger(aPattern, FC_RGBA, 0, &rgba) == FcResultMatch) {
      mSubpixelOrder = rgba;
    }
    int filter;
    if (FcPatternGetInteger(aPattern, FC_LCD_FILTER, 0, &filter) == FcResultMatch) {
      mLcdFilter = filter;
    }
  }

  cairo_font_options_t* fontOptions = cairo_font_options_create();
  cairo_scaled_font_get_font_options(aScaledFont, fontOptions);
  // For printer fonts, Cairo hint metrics and hinting will be disabled.
  // For other fonts, allow hint metrics and hinting.
  if (cairo_font_options_get_hint_metrics(fontOptions) != CAIRO_HINT_METRICS_OFF) {
    mFlags |= HINT_METRICS;

    FcBool hinting;
    if (FcPatternGetBool(aPattern, FC_HINTING, 0, &hinting) != FcResultMatch || hinting) {
      int hintstyle;
      if (FcPatternGetInteger(aPattern, FC_HINT_STYLE, 0, &hintstyle) != FcResultMatch) {
        hintstyle = FC_HINT_FULL;
      }
      mHintStyle = hintstyle;
    }
  }
  cairo_font_options_destroy(fontOptions);

  // Some fonts supply an adjusted size or otherwise use the font matrix for italicization.
  // Record the scale and the skew to accomodate both of these cases.
  cairo_matrix_t fontMatrix;
  cairo_scaled_font_get_font_matrix(aScaledFont, &fontMatrix);
  mScale = Float(fontMatrix.xx);
  mSkew = Float(fontMatrix.xy);
}

void
ScaledFontFontconfig::InstanceData::SetupPattern(FcPattern* aPattern) const
{
  if (mFlags & AUTOHINT) {
    FcPatternAddBool(aPattern, FC_AUTOHINT, FcTrue);
  }
  if (mFlags & EMBEDDED_BITMAP) {
    FcPatternAddBool(aPattern, FC_EMBEDDED_BITMAP, FcTrue);
  }
  if (mFlags & EMBOLDEN) {
    FcPatternAddBool(aPattern, FC_EMBOLDEN, FcTrue);
  }
  if (mFlags & VERTICAL_LAYOUT) {
    FcPatternAddBool(aPattern, FC_VERTICAL_LAYOUT, FcTrue);
  }

  if (mFlags & ANTIALIAS) {
    FcPatternAddBool(aPattern, FC_ANTIALIAS, FcTrue);
    if (mSubpixelOrder != FC_RGBA_UNKNOWN) {
      FcPatternAddInteger(aPattern, FC_RGBA, mSubpixelOrder);
    }
    if (mLcdFilter != FC_LCD_LEGACY) {
      FcPatternAddInteger(aPattern, FC_LCD_FILTER, mLcdFilter);
    }
  } else {
    FcPatternAddBool(aPattern, FC_ANTIALIAS, FcFalse);
  }

  if (mHintStyle) {
    FcPatternAddBool(aPattern, FC_HINTING, FcTrue);
    FcPatternAddInteger(aPattern, FC_HINT_STYLE, mHintStyle);
  } else {
    FcPatternAddBool(aPattern, FC_HINTING, FcFalse);
  }
}

void
ScaledFontFontconfig::InstanceData::SetupFontOptions(cairo_font_options_t* aFontOptions) const
{
  // Try to build a sane initial set of Cairo font options based on the Fontconfig
  // pattern.
  if (mFlags & HINT_METRICS) {
    // For regular (non-printer) fonts, enable hint metrics as well as hinting
    // and (possibly subpixel) antialiasing.
    cairo_font_options_set_hint_metrics(aFontOptions, CAIRO_HINT_METRICS_ON);

    cairo_hint_style_t hinting;
    switch (mHintStyle) {
    case FC_HINT_NONE:
      hinting = CAIRO_HINT_STYLE_NONE;
      break;
    case FC_HINT_SLIGHT:
      hinting = CAIRO_HINT_STYLE_SLIGHT;
      break;
    case FC_HINT_MEDIUM:
    default:
      hinting = CAIRO_HINT_STYLE_MEDIUM;
      break;
    case FC_HINT_FULL:
      hinting = CAIRO_HINT_STYLE_FULL;
      break;
    }
    cairo_font_options_set_hint_style(aFontOptions, hinting);

    if (mFlags & ANTIALIAS) {
      cairo_subpixel_order_t subpixel = CAIRO_SUBPIXEL_ORDER_DEFAULT;
      switch (mSubpixelOrder) {
      case FC_RGBA_RGB:
        subpixel = CAIRO_SUBPIXEL_ORDER_RGB;
        break;
      case FC_RGBA_BGR:
        subpixel = CAIRO_SUBPIXEL_ORDER_BGR;
        break;
      case FC_RGBA_VRGB:
        subpixel = CAIRO_SUBPIXEL_ORDER_VRGB;
        break;
      case FC_RGBA_VBGR:
        subpixel = CAIRO_SUBPIXEL_ORDER_VBGR;
        break;
      default:
        break;
      }
      if (subpixel != CAIRO_SUBPIXEL_ORDER_DEFAULT) {
        cairo_font_options_set_antialias(aFontOptions, CAIRO_ANTIALIAS_SUBPIXEL);
        cairo_font_options_set_subpixel_order(aFontOptions, subpixel);
      } else {
        cairo_font_options_set_antialias(aFontOptions, CAIRO_ANTIALIAS_GRAY);
      }
    } else {
      cairo_font_options_set_antialias(aFontOptions, CAIRO_ANTIALIAS_NONE);
    }
  } else {
    // For printer fonts, disable hint metrics and hinting. Don't allow subpixel
    // antialiasing.
    cairo_font_options_set_hint_metrics(aFontOptions, CAIRO_HINT_METRICS_OFF);
    cairo_font_options_set_hint_style(aFontOptions, CAIRO_HINT_STYLE_NONE);
    cairo_font_options_set_antialias(aFontOptions,
      mFlags & ANTIALIAS ? CAIRO_ANTIALIAS_GRAY : CAIRO_ANTIALIAS_NONE);
  }
}

void
ScaledFontFontconfig::InstanceData::SetupFontMatrix(cairo_matrix_t* aFontMatrix) const
{
  // Build a font matrix that will reproduce a possibly adjusted size
  // and any italics/skew. This is just the concatenation of a simple
  // scale matrix with a matrix that skews on the X axis.
  cairo_matrix_init(aFontMatrix, mScale, 0, mSkew, mScale, 0, 0);
}

bool
ScaledFontFontconfig::GetFontInstanceData(FontInstanceDataOutput aCb, void* aBaton)
{
  InstanceData instance(GetCairoScaledFont(), mPattern);

  aCb(reinterpret_cast<uint8_t*>(&instance), sizeof(instance), aBaton);
  return true;
}

bool
ScaledFontFontconfig::GetFontDescriptor(FontDescriptorOutput aCb, void* aBaton)
{
  // Check if the Fontconfig pattern uses a font file and index to specify which
  // font to load. If so, record these as a font descriptor along with any instance
  // data required to rebuild a scaled font from it.
  FcChar8* pathname = nullptr;
  if (FcPatternGetString(mPattern, FC_FILE, 0, &pathname) != FcResultMatch) {
    return false;
  }
  int index = 0;
  FcPatternGetInteger(mPattern, FC_INDEX, 0, &index);
  if (index < 0) {
    return false;
  }

  size_t pathLength = strlen(reinterpret_cast<char*>(pathname)) + 1;
  size_t dataLength = sizeof(FontDescriptor) + pathLength;
  uint8_t* data = new uint8_t[dataLength];
  FontDescriptor* desc = reinterpret_cast<FontDescriptor*>(data);
  desc->mPathLength = pathLength;
  desc->mIndex = index;
  desc->mInstanceData = InstanceData(GetCairoScaledFont(), mPattern);
  memcpy(data + sizeof(FontDescriptor), pathname, pathLength);

  aCb(data, dataLength, mSize, aBaton);
  return true;
}

already_AddRefed<ScaledFont>
ScaledFontFontconfig::CreateFromInstanceData(const InstanceData& aInstanceData,
                                             FT_Face aFace, const char* aPathname, uint32_t aIndex,
                                             Float aSize)

{
  FcPattern* pattern = FcPatternCreate();
  if (!pattern) {
    gfxWarning() << "Failing initializing Fontconfig pattern for scaled font";
    return nullptr;
  }
  if (aFace) {
    FcPatternAddFTFace(pattern, FC_FT_FACE, aFace);
  } else {
    FcPatternAddString(pattern, FC_FILE, reinterpret_cast<const FcChar8*>(aPathname));
    FcPatternAddInteger(pattern, FC_INDEX, aIndex);
  }
  FcPatternAddDouble(pattern, FC_PIXEL_SIZE, aSize);
  aInstanceData.SetupPattern(pattern);

  cairo_font_face_t* font = cairo_ft_font_face_create_for_pattern(pattern);
  if (cairo_font_face_status(font) != CAIRO_STATUS_SUCCESS) {
    gfxWarning() << "Failed creating Cairo font face for Fontconfig pattern";
    FcPatternDestroy(pattern);
    return nullptr;
  }

  cairo_matrix_t sizeMatrix;
  aInstanceData.SetupFontMatrix(&sizeMatrix);

  cairo_matrix_t identityMatrix;
  cairo_matrix_init_identity(&identityMatrix);

  cairo_font_options_t *fontOptions = cairo_font_options_create();
  aInstanceData.SetupFontOptions(fontOptions);

  cairo_scaled_font_t* cairoScaledFont =
    cairo_scaled_font_create(font, &sizeMatrix, &identityMatrix, fontOptions);

  cairo_font_options_destroy(fontOptions);
  cairo_font_face_destroy(font);

  if (cairo_scaled_font_status(cairoScaledFont) != CAIRO_STATUS_SUCCESS) {
    gfxWarning() << "Failed creating Cairo scaled font for font face";
    FcPatternDestroy(pattern);
    return nullptr;
  }

  RefPtr<ScaledFontFontconfig> scaledFont =
    new ScaledFontFontconfig(cairoScaledFont, pattern, aSize);

  FcPatternDestroy(pattern);

  return scaledFont.forget();
}

already_AddRefed<ScaledFont>
ScaledFontFontconfig::CreateFromFontDescriptor(const uint8_t* aData, uint32_t aDataLength, Float aSize)
{
  if (aDataLength < sizeof(FontDescriptor)) {
    gfxWarning() << "Fontconfig font descriptor is truncated.";
    return nullptr;
  }
  const FontDescriptor* desc = reinterpret_cast<const FontDescriptor*>(aData);
  if (desc->mPathLength < 1 ||
      desc->mPathLength > aDataLength - sizeof(FontDescriptor)) {
    gfxWarning() << "Pathname in Fontconfig font descriptor has invalid size.";
    return nullptr;
  }
  const char* pathname = reinterpret_cast<const char*>(aData + sizeof(FontDescriptor));
  if (pathname[desc->mPathLength - 1] != '\0') {
    gfxWarning() << "Pathname in Fontconfig font descriptor is not terminated.";
    return nullptr;
  }
  return CreateFromInstanceData(desc->mInstanceData, nullptr, pathname, desc->mIndex, aSize);
}

} // namespace gfx
} // namespace mozilla