gecko-dev/dom/media/MediaMIMETypes.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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/. */

#ifndef MediaMIMETypes_h_
#define MediaMIMETypes_h_

#include "VideoUtils.h"
#include "mozilla/Maybe.h"
#include "nsString.h"

namespace mozilla {

namespace dom {
struct AudioConfiguration;
struct VideoConfiguration;
}  // namespace dom

// Class containing pointing at a media MIME "type/subtype" string literal.
// See IsMediaMIMEType for restrictions.
// Mainly used to help construct a MediaMIMEType through the statically-checked
// MEDIAMIMETYPE macro, or to compare a MediaMIMEType to a literal.
class DependentMediaMIMEType {
 public:
  // Construction from a literal. Checked in debug builds.
  // Use MEDIAMIMETYPE macro instead, for static checking.
  template <size_t N>
  explicit DependentMediaMIMEType(const char (&aType)[N])
      : mMIMEType(aType, N - 1) {
    MOZ_ASSERT(IsMediaMIMEType(aType, N - 1), "Invalid media MIME type");
  }

  // MIME "type/subtype".
  const nsDependentCString& AsDependentString() const { return mMIMEType; }

 private:
  nsDependentCString mMIMEType;
};

// Instantiate a DependentMediaMIMEType from a literal. Statically checked.
#define MEDIAMIMETYPE(LIT)                                          \
  static_cast<const DependentMediaMIMEType&>([]() {                 \
    static_assert(IsMediaMIMEType(LIT), "Invalid media MIME type"); \
    return DependentMediaMIMEType(LIT);                             \
  }())

// Class containing only pre-parsed lowercase media MIME type/subtype.
class MediaMIMEType {
 public:
  // Construction from a DependentMediaMIMEType, with its inherent checks.
  // Implicit so MEDIAMIMETYPE can be used wherever a MediaMIMEType is expected.
  MOZ_IMPLICIT MediaMIMEType(const DependentMediaMIMEType& aType)
      : mMIMEType(aType.AsDependentString()) {}

  // MIME "type/subtype", always lowercase.
  const nsCString& AsString() const { return mMIMEType; }

  // Comparison with DependentMediaMIMEType.
  // Useful to compare to MEDIAMIMETYPE literals.
  bool operator==(const DependentMediaMIMEType& aOther) const {
    return mMIMEType.Equals(aOther.AsDependentString());
  }
  bool operator!=(const DependentMediaMIMEType& aOther) const {
    return !mMIMEType.Equals(aOther.AsDependentString());
  }

  bool operator==(const MediaMIMEType& aOther) const {
    return mMIMEType.Equals(aOther.mMIMEType);
  }
  bool operator!=(const MediaMIMEType& aOther) const {
    return !mMIMEType.Equals(aOther.mMIMEType);
  }

  // True if type starts with "application/".
  bool HasApplicationMajorType() const;
  // True if type starts with "audio/".
  // Note that some audio content could be stored in a "video/..." container!
  bool HasAudioMajorType() const;
  // True if type starts with "video/".
  // Note that this does not guarantee 100% that the content is actually video!
  // (e.g., "video/webm" could contain a vorbis audio track.)
  bool HasVideoMajorType() const;

  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

 private:
  friend Maybe<MediaMIMEType> MakeMediaMIMEType(const nsAString& aType);
  friend class MediaExtendedMIMEType;
  explicit MediaMIMEType(const nsACString& aType);

  nsCString mMIMEType;  // UTF8 MIME "type/subtype".
};

Maybe<MediaMIMEType> MakeMediaMIMEType(const nsAString& aType);
Maybe<MediaMIMEType> MakeMediaMIMEType(const nsACString& aType);
Maybe<MediaMIMEType> MakeMediaMIMEType(const char* aType);

// A list of case-sensitive codecs attached to a MediaExtendedMIMEType.
class MediaCodecs {
 public:
  MediaCodecs() = default;
  // Construction from a comma-separated list of codecs. Unchecked.
  explicit MediaCodecs(const nsAString& aCodecs) : mCodecs(aCodecs) {}
  // Construction from a literal comma-separated list of codecs. Unchecked.
  template <size_t N>
  explicit MediaCodecs(const char (&aCodecs)[N])
      : mCodecs(NS_ConvertUTF8toUTF16(aCodecs, N - 1)) {}

  bool IsEmpty() const { return mCodecs.IsEmpty(); }
  const nsString& AsString() const { return mCodecs; }

  using RangeType =
      const StringListRange<nsString,
                            StringListRangeEmptyItems::ProcessEmptyItems>;

  // Produces a range object with begin()&end(), can be used in range-for loops.
  // This will iterate through all codecs, even empty ones (except if the
  // original list was an empty string). Iterators dereference to
  // 'const nsDependentString', valid for as long as this MediaCodecs object.
  RangeType Range() const { return RangeType(mCodecs); };

  // Does this list of codecs contain the given aCodec?
  bool Contains(const nsAString& aCodec) const;
  // Does this list of codecs contain *all* the codecs in the given list?
  bool ContainsAll(const MediaCodecs& aCodecs) const;

  // Does this list of codecs contain a codec starting with the given prefix?
  bool ContainsPrefix(const nsAString& aCodecPrefix) const;

  template <size_t N>
  bool operator==(const char (&aType)[N]) const {
    return mCodecs.EqualsASCII(aType, N - 1);
  }

  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

 private:
  // UTF16 comma-separated list of codecs.
  // See http://www.rfc-editor.org/rfc/rfc4281.txt for the description
  // of the 'codecs' parameter.
  nsString mCodecs;
};

// Class containing pre-parsed media MIME type parameters, e.g.:
// MIME type/subtype, optional codecs, etc.
class MediaExtendedMIMEType {
 public:
  explicit MediaExtendedMIMEType(const MediaMIMEType& aType);
  explicit MediaExtendedMIMEType(MediaMIMEType&& aType);

  // MIME "type/subtype".
  const MediaMIMEType& Type() const { return mMIMEType; }

  // Was there an explicit 'codecs' parameter provided?
  bool HaveCodecs() const { return mHaveCodecs; }
  // Codecs. May be empty if not provided or explicitly provided as empty.
  const MediaCodecs& Codecs() const { return mCodecs; }

  // Sizes and rates.
  Maybe<int32_t> GetWidth() const { return GetMaybeNumber(mWidth); }
  Maybe<int32_t> GetHeight() const { return GetMaybeNumber(mHeight); }
  Maybe<double> GetFramerate() const { return GetMaybeNumber(mFramerate); }
  Maybe<int32_t> GetBitrate() const { return GetMaybeNumber(mBitrate); }
  Maybe<int32_t> GetChannels() const { return GetMaybeNumber(mChannels); }
  Maybe<int32_t> GetSamplerate() const { return GetMaybeNumber(mSamplerate); }

  // Original string. Note that "type/subtype" may not be lowercase,
  // use Type().AsString() instead to get the normalized "type/subtype".
  const nsCString& OriginalString() const { return mOriginalString; }

  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

  // aFrac is either a floating-point number or a fraction made of two
  // floating-point numbers.
  static Maybe<double> ComputeFractionalString(const nsAString& aFrac);

 private:
  friend Maybe<MediaExtendedMIMEType> MakeMediaExtendedMIMEType(
      const nsAString& aType);
  friend Maybe<MediaExtendedMIMEType> MakeMediaExtendedMIMEType(
      const dom::VideoConfiguration& aConfig);
  friend Maybe<MediaExtendedMIMEType> MakeMediaExtendedMIMEType(
      const dom::AudioConfiguration& aConfig);

  MediaExtendedMIMEType(const nsACString& aOriginalString,
                        const nsACString& aMIMEType, bool aHaveCodecs,
                        const nsAString& aCodecs, int32_t aWidth,
                        int32_t aHeight, double aFramerate, int32_t aBitrate);
  MediaExtendedMIMEType(const nsACString& aOriginalString,
                        const nsACString& aMIMEType, bool aHaveCodecs,
                        const nsAString& aCodecs, int32_t aChannels,
                        int32_t aSamplerate, int32_t aBitrate);

  template <typename T>
  Maybe<T> GetMaybeNumber(T aNumber) const {
    return (aNumber < 0) ? Maybe<T>(Nothing()) : Some(T(aNumber));
  }

  nsCString mOriginalString;  // Original full string.
  MediaMIMEType mMIMEType;    // MIME type/subtype.
  bool mHaveCodecs = false;   // If false, mCodecs must be empty.
  MediaCodecs mCodecs;
  // For video
  int32_t mWidth = -1;     // -1 if not provided.
  int32_t mHeight = -1;    // -1 if not provided.
  double mFramerate = -1;  // -1 if not provided.
  // For audio
  int32_t mChannels = -1;    // -1 if not provided.
  int32_t mSamplerate = -1;  // -1 if not provided.
  // For both audio and video.
  int32_t mBitrate = -1;  // -1 if not provided.
};

Maybe<MediaExtendedMIMEType> MakeMediaExtendedMIMEType(const nsAString& aType);
Maybe<MediaExtendedMIMEType> MakeMediaExtendedMIMEType(const nsACString& aType);
Maybe<MediaExtendedMIMEType> MakeMediaExtendedMIMEType(const char* aType);
Maybe<MediaExtendedMIMEType> MakeMediaExtendedMIMEType(
    const dom::VideoConfiguration& aConfig);
Maybe<MediaExtendedMIMEType> MakeMediaExtendedMIMEType(
    const dom::AudioConfiguration& aConfig);

}  // namespace mozilla

#endif  // MediaMIMETypes_h_