Struct ImageFormatConstraints

pub struct ImageFormatConstraints {

    pub pixel_format: PixelFormat,
    pub color_spaces_count: u32,
    pub color_space: [ColorSpace; 32],
    pub min_coded_width: u32,
    pub max_coded_width: u32,
    pub min_coded_height: u32,
    pub max_coded_height: u32,
    pub min_bytes_per_row: u32,
    pub max_bytes_per_row: u32,
    pub max_coded_width_times_coded_height: u32,
    pub layers: u32,
    pub coded_width_divisor: u32,
    pub coded_height_divisor: u32,
    pub bytes_per_row_divisor: u32,
    pub start_offset_divisor: u32,
    pub display_width_divisor: u32,
    pub display_height_divisor: u32,
    pub required_min_coded_width: u32,
    pub required_max_coded_width: u32,
    pub required_min_coded_height: u32,
    pub required_max_coded_height: u32,
    pub required_min_bytes_per_row: u32,
    pub required_max_bytes_per_row: u32,
}

Describes constraints on layout of image data in buffers.

This type is deprecated for new code, but is still used by some camera code.

Fields

pixel_format: PixelFormat

The PixelFormat for which the following constraints apply. A participant may have more than one PixelFormat that’s supported, in which case that participant can use a list of ImageFormatConstraints with an entry per PixelFormat. It’s not uncommon for the other fields of ImageFormatConstraints to vary by PixelFormat - for example for a linear format to support smaller max size than a tiled format.

color_spaces_count: u32

Empty is an error. Redundant entries are an error. Arbitrary ordering is not an error.

color_space: [ColorSpace; 32]

min_coded_width: u32

Minimum permitted width in pixels.

For example a video decoder participant may set this field to the minimum coded_width that might potentially be specified by a stream. In contrast, required_min_coded_width would be set to the current coded_width specified by the stream. While min_coded_width aggregates by taking the max, required_min_coded_width aggregates by taking the min.

See also required_min_coded_width.

max_coded_width: u32

Maximum width in pixels. For example Scenic may set this field (directly or via sub-participants) to the maximum width that can be composited. 0 is treated as 0xFFFFFFFF.

min_coded_height: u32

Minimum height in pixels. For example a video decoder participant may set this field to the coded_height specified by a stream.

max_coded_height: u32

Maximum height in pixels. For example Scenic may set this field (directly or via sub-participants) to the maximum height that can be composited. 0 is treated as 0xFFFFFFFF.

min_bytes_per_row: u32

Must be >= the value implied by min_coded_width for plane 0.

max_bytes_per_row: u32

Must be >= the value implied by max_coded_width for plane 0. 0 is treated as 0xFFFFFFFF.

max_coded_width_times_coded_height: u32

The max image area in pixels is limited indirectly via BufferSettings.size_bytes, and can also be enforced directly via this field. 0 is treated as 0xFFFFFFFF.

layers: u32

Number of layers within a multi-layered image. 0 is treated as 1.

coded_width_divisor: u32

coded_width % width_divisor must be 0. 0 is treated as 1.

coded_height_divisor: u32

coded_height % height_divisor must be 0. 0 is treated as 1.

bytes_per_row_divisor: u32

bytes_per_row % bytes_per_row_divisor must be 0. 0 is treated as 1.

start_offset_divisor: u32

vmo_usable_start % start_offset_divisor must be 0. 0 is treated as 1.

display_width_divisor: u32

display_width % display_width_divisor must be 0. 0 is treated as 1.

display_height_divisor: u32

display_height % display_height_divisor must be 0. 0 is treated as 1.

required_min_coded_width: u32

required_ dimension bounds.

In contrast to the corresponding fields without “required_” at the start, these fields (when set to non-zero values) express a requirement that the resulting aggregated non-required_ fields specify a space that fully contain the space expressed by each participant’s required_ fields.

For example, a producer video decoder is perfectly happy for the consumer to be willing to accept anything, and the video decoder doesn’t really want to constrain the potential space of dimensions that might be seen in a stream and may be acceptable to the consumer, but the video decoder needs to ensure that the resulting dimension ranges contain at least the current dimensions decoded from the stream.

Similarly, an initiator with a particular dynamic-dimension scenario in mind may wish to require up front that participants agree to handle at least the range of dimensions expected by the initiator in that scenario (else fail earlier rather than later, maybe trying again with smaller required_ space).

It’s much more common for a producer or initiator to set these fields than for a consumer to set these fields.

While the non-required_ fields aggregate by taking the intersection, the required_ fields aggregate by taking the union.

If set, the required_max_coded_width and required_max_coded_height will cause the allocated buffers to be large enough to hold an image that is required_max_coded_width * required_max_coded_height.

TODO(dustingreen): Make it easier to allocate buffers of minimal size that can (optionally) also handle 90 degree rotated version of the max dimensions / alternate required bounds for another main aspect ratio. 0 is treated as 0xFFFFFFFF.

required_max_coded_width: u32

required_min_coded_height: u32

0 is treated as 0xFFFFFFFF.

required_max_coded_height: u32

required_min_bytes_per_row: u32

0 is treated as 0xFFFFFFFF.

required_max_bytes_per_row: u32

Trait Implementations

impl Clone for ImageFormatConstraints

fn clone(&self) -> ImageFormatConstraints

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ImageFormatConstraints

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<D: ResourceDialect> Decode<ImageFormatConstraints, D> for ImageFormatConstraints

fn new_empty() -> Self

Creates a valid instance of Self. The specific value does not matter, since it will be overwritten by decode.

unsafe fn decode( &mut self, decoder: &mut Decoder<'_, D>, offset: usize, _depth: Depth, ) -> Result<()>

Decodes an object of type T from the decoder’s buffers into self.

impl<D: ResourceDialect> Encode<ImageFormatConstraints, D> for &ImageFormatConstraints

unsafe fn encode( self, encoder: &mut Encoder<'_, D>, offset: usize, _depth: Depth, ) -> Result<()>

Encodes the object into the encoder’s buffers. Any handles stored in the object are swapped for Handle::INVALID.

impl<D: ResourceDialect, T0: Encode<PixelFormat, D>, T1: Encode<u32, D>, T2: Encode<Array<ColorSpace, 32>, D>, T3: Encode<u32, D>, T4: Encode<u32, D>, T5: Encode<u32, D>, T6: Encode<u32, D>, T7: Encode<u32, D>, T8: Encode<u32, D>, T9: Encode<u32, D>, T10: Encode<u32, D>, T11: Encode<u32, D>, T12: Encode<u32, D>, T13: Encode<u32, D>, T14: Encode<u32, D>, T15: Encode<u32, D>, T16: Encode<u32, D>, T17: Encode<u32, D>, T18: Encode<u32, D>, T19: Encode<u32, D>, T20: Encode<u32, D>, T21: Encode<u32, D>, T22: Encode<u32, D>> Encode<ImageFormatConstraints, D> for (T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22)

unsafe fn encode( self, encoder: &mut Encoder<'_, D>, offset: usize, depth: Depth, ) -> Result<()>

Encodes the object into the encoder’s buffers. Any handles stored in the object are swapped for Handle::INVALID.

impl Hash for ImageFormatConstraints

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for ImageFormatConstraints

fn cmp(&self, other: &ImageFormatConstraints) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for ImageFormatConstraints

fn eq(&self, other: &ImageFormatConstraints) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for ImageFormatConstraints

fn partial_cmp(&self, other: &ImageFormatConstraints) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl TypeMarker for ImageFormatConstraints

type Owned = ImageFormatConstraints

The owned Rust type which this FIDL type decodes into.

fn inline_align(_context: Context) -> usize

Returns the minimum required alignment of the inline portion of the encoded object. It must be a (nonzero) power of two.

fn inline_size(_context: Context) -> usize

Returns the size of the inline portion of the encoded object, including padding for alignment. Must be a multiple of inline_align.

fn encode_is_copy() -> bool

Returns true if the memory layout of Self::Owned matches the FIDL wire format and encoding requires no validation. When true, we can optimize encoding arrays and vectors of Self::Owned to a single memcpy.

fn decode_is_copy() -> bool

Returns true if the memory layout of Self::Owned matches the FIDL wire format and decoding requires no validation. When true, we can optimize decoding arrays and vectors of Self::Owned to a single memcpy.

impl ValueTypeMarker for ImageFormatConstraints

type Borrowed<'a> = &'a ImageFormatConstraints

The Rust type to use for encoding. This is a particular Encode<Self> type cheaply obtainable from &Self::Owned. There are three cases:

fn borrow(value: &<Self as TypeMarker>::Owned) -> Self::Borrowed<'_>

Cheaply converts from &Self::Owned to Self::Borrowed.

impl Copy for ImageFormatConstraints

impl Eq for ImageFormatConstraints

impl Persistable for ImageFormatConstraints

impl StructuralPartialEq for ImageFormatConstraints