Enum BitMask 

pub enum BitMask {
    AllValid(usize),
    Explicit(BitVec<u8, Msb0>),
}

Validity bitmask matching the C++ BitMask layout.

Two canonical representations:

• BitMask::AllValid — every pixel is valid. No heap allocation; all queries (is_valid, count_valid, is_all_valid) are O(1). This is the canonical form the decoder produces when the blob header reports full validity.
• BitMask::Explicit — per-pixel bits stored MSB-first within each byte, matching the C++ convention: bit k is at byte k >> 3, position (1 << 7) >> (k & 7).

Mutating an AllValid mask via set_invalid transitions it to Explicit in place (one allocation).

Variants

AllValid(usize)

Every pixel is valid. The usize is the pixel count.

Explicit(BitVec<u8, Msb0>)

Explicit per-pixel validity bits.

Implementations

impl BitMask

pub fn new(num_pixels: usize) -> Self

Create a new mask with every pixel marked invalid.

pub fn all_valid(num_pixels: usize) -> Self

Create a new mask with every pixel marked valid — O(1), no allocation.

pub fn from_bytes(data: Vec<u8>, num_pixels: usize) -> Self

Create a mask from raw MSB-first bytes, truncated to num_pixels bits.

pub fn is_valid(&self, k: usize) -> bool

Returns true if pixel k is valid. O(1).

pub fn set_valid(&mut self, k: usize)

Mark pixel k as valid.

No-op for AllValid.

pub fn set_invalid(&mut self, k: usize)

Mark pixel k as invalid.

If the mask is AllValid, this materializes it into Explicit first (one allocation of (num_pixels + 7) / 8 bytes), then clears bit k.

pub fn count_valid(&self) -> usize

Returns the number of valid pixels. O(1) for AllValid; popcount for Explicit.

pub fn is_all_valid(&self) -> bool

Returns true if every pixel is valid.

O(1) for AllValid; O(n) popcount fallback for Explicit (an explicit mask may still have every bit set).

pub fn num_pixels(&self) -> usize

Total pixel count. O(1).

pub fn num_bytes(&self) -> usize

Number of bytes in the raw byte representation (ceil(num_pixels / 8)).

pub fn as_bytes(&self) -> Option<&[u8]>

Borrow the underlying byte storage as a slice.

Returns None for AllValid — no bytes are stored. Callers that need bytes for serialization should first branch on is_all_valid, since the LERC blob format omits the mask section entirely for all-valid bands.

pub fn as_bytes_mut(&mut self) -> Option<&mut [u8]>

Mutably borrow the underlying byte storage.

Returns None for AllValid; convert via a mutation like set_invalid first if you need mutable bytes.

Trait Implementations

impl Clone for BitMask

fn clone(&self) -> BitMask

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for BitMask

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

Formats the value using the given formatter.