types/image.proto

types/image.proto
Scalar Value Types

types/image.proto

Image

Image describes a resolution, context, aspect ratio, and source independent image. When selecting an image to display the renderer inspects the properties of each image source to find the combination that best matches the intended output destination.

An image is a visual representation of some subject, for example "A dog chasing it's tail, on grass". The subject does not change when you double the resolution, crop in landscape or square, encode using jpeg or webp, or serve via a url or filesystem path. The choice for each of these properties can only be determined at image display time, i.e. the renderer knows that it doesn't support webp, and the destination area is 480px wide at 1.5x pixel density.

Field	Type	Label	Description
sources	Image.Source	repeated	Possible sources of image data. Each source encodes a possible representation of the image, typically to solve art direction or resolution variation. For example there might be a square source and a portrait source, there might be a source sized 128x128 and one sized 32x32. All sources should represent the same subject.

The renderer should choose the source that best destination criteria, preferring to select a larger image if no exact match is found, selecting lower indexes to break ties. | | description | string | | A description of the image, typically used when the image cannot be displayed or consumed by the observer, i.e. when using a screen reader. |

Image.Content

Content describes the location of the image data.

Field	Type	Label	Description
type	string		A media type for the image, e.g. "image/jpeg". See https://www.iana.org/assignments/media-types/media-types.xhtml#image
body	bytes		The binary content of the image.

Prefer other content options instead of embedding the body, especially if the image has multiple sources and/or content types, providing the byte content for each variation can get large and cause performance issues. | | url | string | | A url that resolves to the image content. | | ref | string | | The image is resolved in a catalog of known images using this identifier. For example in an icon set. | | path | string | | A path on the local file system where the image content is located. |

Image.Source

Source represents a variation on the display of an image. Sources may exist for shape variations, or resolution variations. Sources should not change the core subject of an image.

Field	Type	Label	Description
src	Image.Content	repeated	Where to get the image bytes from in preference order. When displaying the image the renderer will go through each src until it finds one of a type it supports.
width	int32		The intrinsic width of the image.
height	int32		The intrinsic height of the image.
purpose	Image.Source.Purpose		The intended purpose for the image. The purpose informs the user of the image which intended contexts the image has been designed for.

Purpose is inspired by https://w3c.github.io/manifest/#purpose-member |

Image.Source.Purpose

Purpose defines the possible intended context for an image.

Name	Number	Description
PURPOSE_UNSPECIFIED	0	The purpose is unspecified. Renderers may treat this as ANY.
ANY	1	The renderer is free to use the image in any context.
MASKABLE	2	The image has been designed with masks and safe zones in mind. As such any part of the image outside the safe zone may be ignored/hidden/masked by the renderer.

See https://w3c.github.io/manifest/#dfn-safe-zone |

Scalar Value Types

.proto Type	Notes	C++	Java	Python	Go	C#	PHP	Ruby
double		double	double	float	float64	double	float	Float
float		float	float	float	float32	float	float	Float
int32	Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint32 instead.	int32	int	int	int32	int	integer	Bignum or Fixnum (as required)
int64	Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint64 instead.	int64	long	int/long	int64	long	integer/string	Bignum
uint32	Uses variable-length encoding.	uint32	int	int/long	uint32	uint	integer	Bignum or Fixnum (as required)
uint64	Uses variable-length encoding.	uint64	long	int/long	uint64	ulong	integer/string	Bignum or Fixnum (as required)
sint32	Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int32s.	int32	int	int	int32	int	integer	Bignum or Fixnum (as required)
sint64	Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int64s.	int64	long	int/long	int64	long	integer/string	Bignum
fixed32	Always four bytes. More efficient than uint32 if values are often greater than 2^28.	uint32	int	int	uint32	uint	integer	Bignum or Fixnum (as required)
fixed64	Always eight bytes. More efficient than uint64 if values are often greater than 2^56.	uint64	long	int/long	uint64	ulong	integer/string	Bignum
sfixed32	Always four bytes.	int32	int	int	int32	int	integer	Bignum or Fixnum (as required)
sfixed64	Always eight bytes.	int64	long	int/long	int64	long	integer/string	Bignum
bool		bool	boolean	boolean	bool	bool	boolean	TrueClass/FalseClass
string	A string must always contain UTF-8 encoded or 7-bit ASCII text.	string	String	str/unicode	string	string	string	String (UTF-8)
bytes	May contain any arbitrary sequence of bytes.	string	ByteString	str	[]byte	ByteString	string	String (ASCII-8BIT)

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