public/lib/images/fidl/image_info.fidl

module scenic;

// Information about a graphical image (texture) including its format and size.
struct ImageInfo {
  // Specifies how pixels are represented in the image buffer.
  enum PixelFormat {
    // A 32-bit four-component unsigned integer format.
    // Byte order: B, G, R, A (little-endian ARGB packed 32-bit word).
    // Equivalent to Skia |kBGRA_8888_SkColorType| color type.
    // Equivalent to Zircon |ARGB_8888| pixel format on little-endian arch.
    BGRA_8 = 0,
    // A 32-bit component that contains information for 2 pixels:
    // Byte order: Y1, U, Y2, V
    // Unpacks to 2 RGB pixels, where RGB1 = func(Y1, U, V)
    // and RGB2 = func(Y2, U, V)
    // Equivalent to YUV422
    YUY2 = 1,
  };

  // Specifies how pixel color information should be interpreted.
  enum ColorSpace {
    SRGB = 0,
  };

  // Specifies how pixels are arranged in memory.
  enum Tiling {
    // Pixels are packed linearly.
    // Equivalent to |VK_IMAGE_TILING_LINEAR|.
    LINEAR = 0,

    // Pixels are packed in a GPU-dependent optimal format.
    // Equivalent to |VK_IMAGE_TILING_OPTIMAL|.
    GPU_OPTIMAL = 1,
  };

  // Specifies how alpha information should be interpreted.
  enum AlphaFormat {
    // Image is considered to be opaque.  Alpha channel is ignored.
    // Blend function is: src.RGB
    OPAQUE = 0,
    // Color channels have been premultiplied by alpha.
    // Blend function is: src.RGB + (dest.RGB * (1 - src.A))
    PREMULTIPLIED = 1,
    // Color channels have not been premultiplied by alpha.
    // Blend function is: (src.RGB * src.A) + (dest.RGB * (1 - src.A))
    NON_PREMULTIPLIED = 2,
  };

  enum Transform {
    // Pixels are displayed normally.
    NORMAL = 0,

    // Pixels are mirrored left-right.
    FLIP_HORIZONTAL = 1,

    // Pixels are flipped vertically.
    FLIP_VERTICAL = 2,

    // Pixels are flipped vertically and mirrored left-right.
    FLIP_VERTICAL_AND_HORIZONTAL = 3,
  };

  // Specifies if the image should be mirrored before displaying.
  Transform transform = Transform.NORMAL;

  // The width and height of the image in pixels.
  uint32 width;
  uint32 height;

  // The number of bytes per row in the image buffer.
  uint32 stride;

  // The pixel format of the image.
  PixelFormat pixel_format = PixelFormat.BGRA_8;

  // The pixel color space.
  ColorSpace color_space = ColorSpace.SRGB;

  // The pixel arrangement in memory.
  Tiling tiling = Tiling.LINEAR;

  // Specifies the interpretion of the alpha channel, if one exists.
  AlphaFormat alpha_format = AlphaFormat.OPAQUE;
};