chromium/src/third_party/blink/public/mojom/dwrite_font_proxy/dwrite_font_proxy.mojom

// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

module blink.mojom;

import "mojo/public/mojom/base/file_path.mojom";
import "mojo/public/mojom/base/read_only_file.mojom";
import "mojo/public/mojom/base/shared_memory.mojom";
import "mojo/public/mojom/base/string16.mojom";

struct DWriteStringPair {
  mojo_base.mojom.String16 first;
  mojo_base.mojom.String16 second;
};

struct DWriteFontStyle {
  uint16 font_weight;
  uint8 font_slant;
  uint8 font_stretch;
};

struct FallbackFamilyAndStyle {
  string fallback_family_name;
  uint16 weight;
  uint8 width;
  uint8 slant;
};

struct MapCharactersResult {
  uint32 family_index;
  mojo_base.mojom.String16 family_name;
  uint32 mapped_length;
  float scale;
  DWriteFontStyle font_style;
};

enum UniqueFontLookupMode {
    kRetrieveTable,
    kSingleLookups
};

interface DWriteFontProxy {
  // Locates the index of the specified font family within the system
  // collection.
  [Sync]
  FindFamily(mojo_base.mojom.String16 family_name) => (uint32 out_index);

  // Returns the number of font families in the system collection.
  [Sync]
  GetFamilyCount() => (uint32 out_count);

  // Returns the list of locale and family name pairs for the font family at the
  // specified index.
  [Sync]
  GetFamilyNames(uint32 family_index)
      => (array<DWriteStringPair> out_family_names);

  // Returns the list of font file paths in the system font directory that
  // contain font data for the font family at the specified index.
  [Sync]
  GetFontFiles(uint32 family_index)
     => (array<mojo_base.mojom.FilePath> file_paths,
         array<mojo_base.mojom.ReadOnlyFile> file_handles);

  // Returns which font unique name matching lookup mode is to be used on the
  // current machine. On DirectWrite 10 and above, single lookups can be
  // performed directly against DirectWrite API. On older DirectWrite (Windows
  // 7-8.1), unique font lookups need to be performed against a shared memory
  // region which contains the lookup table. Compare GetUniqueFontLookupTable()
  // for lookup mode kRetrieveTable and MatchUniqueFont for
  // lookup mode kSingleLookups.
  [Sync]
  GetUniqueFontLookupMode() => (UniqueFontLookupMode lookup_mode);

  // On supported Windows versions, matches a unique PostScript or full font
  // name against the installed fonts using DirectWrite API. Returns a file path
  // and ttc_index from which the unique font can be instantiated.  Check which
  // mode is supported using GetFontUniqueNameLookupMode().  Returns empty path
  // and 0 ttc index if no font is found. Must not be called if
  // GetUniqueFontLookupMode() returned kRetrieveTable.
  [Sync]
  MatchUniqueFont(mojo_base.mojom.String16 font_unique_name)
      => (mojo_base.mojom.FilePath file_path, uint32 ttc_index);

  // Synchronously returns a protobuf structured lookup list of
  // (full_font_name|postscript_name) => (font_file + ttc_index) to the
  // renderer process as a ReadOnlySharedMemoryRegion if it is available
  // immediately without any blocking operations. Use FontTableMatcher to
  // perform searches in it. If it is not available without blocking operations,
  // sync_available is false and no shared memory region is provided.
  [Sync]
  GetUniqueNameLookupTableIfAvailable()
      => (bool sync_available,
          mojo_base.mojom.ReadOnlySharedMemoryRegion? font_lookup_table);

  // Asynchronously returns a protobuf structured lookup list of
  // (full_font_name|postscript_name) => (font_file + ttc_index) to the
  // renderer process as a ReadOnlySharedMemoryRegion. The lookup list is built
  // on the first renderer call to retrieving this list. Use FontTableMatcher
  // to perform searches in it. Retrieval may take up to several seconds if the
  // table needs rebuilding on browser side.
  GetUniqueNameLookupTable() =>
  (mojo_base.mojom.ReadOnlySharedMemoryRegion? font_lookup_table);

  // Locates a font family that is able to render the specified text using the
  // specified style. If successful, the family_index and family_name will
  // indicate which family in the system font collection can render the
  // requested text and the mapped_length will indicate how many characters can
  // be rendered. If no font exists that can render the text, family_index will
  // be UINT32_MAX and mapped_length will indicate how many characters cannot be
  // rendered by any installed font.
  [Sync]
  MapCharacters(mojo_base.mojom.String16 text,
                DWriteFontStyle font_style,
                mojo_base.mojom.String16 locale_name,
                uint32 reading_direction,
                mojo_base.mojom.String16 base_family_name)
      => (MapCharactersResult out);

  // For a given base family name, bcp47 language tag, and codepoint to look up,
  // return a font family name that is available on the system to display the
  // given codepoint. This internally calls Skia's
  // SkFontMgr_DirectWrite::matchFamilyStyleCharacter which executes
  // IDWriteTextLayout based fallback code, which cannot be run in the renderer
  // due triggering loading the DWrite system font collection.
  // Use only on Windows 8.0 and earlier - otherwise better fallback API is
  // available through using a proxies IDWriteFontFallback.
  [Sync]
  FallbackFamilyAndStyleForCodepoint(string base_family_name,
                                     string bcp47_language_tag,
                                     uint32 codepoint)
      => (FallbackFamilyAndStyle fallback_result);
};