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//! Safe Rust wrapper around the HAP codec C library.
//!
//! HAP is a video codec that stores GPU-compressed DXT/BC texture data
//! (optionally Snappy-compressed). This module decodes HAP frames into
//! raw BC block data suitable for direct GPU upload.
#[allow(non_upper_case_globals)]
#[allow(non_camel_case_types)]
#[allow(non_snake_case)]
#[allow(dead_code)]
mod ffi {
include!(concat!(env!("OUT_DIR"), "/hap_bindings.rs"));
}
use std::fmt;
/// Compressed texture format produced by HAP decoding.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum HapFormat {
/// DXT1 / BC1 — 4 bits per pixel, RGB with 1-bit alpha
Bc1,
/// DXT5 / BC3 — 8 bits per pixel, RGB with full alpha
Bc3,
}
impl HapFormat {
/// Returns the corresponding wgpu texture format.
pub fn wgpu_format(self) -> wgpu::TextureFormat {
match self {
HapFormat::Bc1 => wgpu::TextureFormat::Bc1RgbaUnorm,
HapFormat::Bc3 => wgpu::TextureFormat::Bc3RgbaUnorm,
}
}
/// Bytes per 4x4 block for this format.
pub fn block_bytes(self) -> u32 {
match self {
HapFormat::Bc1 => 8,
HapFormat::Bc3 => 16,
}
}
/// Compute the byte size of a compressed image with the given pixel dimensions.
pub fn compressed_size(self, width: u32, height: u32) -> usize {
let blocks_x = width.div_ceil(4);
let blocks_y = height.div_ceil(4);
(blocks_x * blocks_y * self.block_bytes()) as usize
}
}
impl fmt::Display for HapFormat {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
HapFormat::Bc1 => write!(f, "BC1/DXT1"),
HapFormat::Bc3 => write!(f, "BC3/DXT5"),
}
}
}
/// Error type for HAP decoding operations.
#[derive(Debug)]
pub enum HapError {
BadArguments,
BufferTooSmall,
BadFrame,
InternalError,
UnsupportedFormat(u32),
}
impl fmt::Display for HapError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
HapError::BadArguments => write!(f, "HAP: bad arguments"),
HapError::BufferTooSmall => write!(f, "HAP: buffer too small"),
HapError::BadFrame => write!(f, "HAP: bad frame data"),
HapError::InternalError => write!(f, "HAP: internal error"),
HapError::UnsupportedFormat(fmt) => {
write!(f, "HAP: unsupported texture format 0x{fmt:04x}")
}
}
}
}
impl std::error::Error for HapError {}
fn result_from_code(code: u32) -> Result<(), HapError> {
match code {
0 => Ok(()),
1 => Err(HapError::BadArguments),
2 => Err(HapError::BufferTooSmall),
3 => Err(HapError::BadFrame),
_ => Err(HapError::InternalError),
}
}
fn format_from_raw(raw: u32) -> Result<HapFormat, HapError> {
match raw {
ffi::HapTextureFormat_HapTextureFormat_RGB_DXT1 => Ok(HapFormat::Bc1),
ffi::HapTextureFormat_HapTextureFormat_RGBA_DXT5 => Ok(HapFormat::Bc3),
other => Err(HapError::UnsupportedFormat(other)),
}
}
/// Callback passed to HapDecode for multi-threaded chunk decoding.
/// We decode sequentially (sufficient for our use case).
unsafe extern "C" fn decode_callback(
function: ffi::HapDecodeWorkFunction,
p: *mut std::os::raw::c_void,
count: std::os::raw::c_uint,
_info: *mut std::os::raw::c_void,
) {
if let Some(func) = function {
for i in 0..count {
func(p, i);
}
}
}
/// Decode a HAP video packet into compressed BC texture data.
///
/// `packet_data` is the raw packet data from ffmpeg.
/// `output_buf` is a reusable buffer that will be resized as needed.
///
/// Returns the format and the number of valid bytes written to `output_buf`.
pub fn decode(
packet_data: &[u8],
output_buf: &mut Vec<u8>,
) -> Result<(HapFormat, usize), HapError> {
let mut output_length: u64 = 0;
let mut raw_format: u32 = 0;
let result = unsafe {
ffi::HapDecode(
packet_data.as_ptr() as *const std::os::raw::c_void,
packet_data.len() as u64,
0, // texture index (always 0 for single-texture HAP)
Some(decode_callback),
std::ptr::null_mut(),
output_buf.as_mut_ptr() as *mut std::os::raw::c_void,
output_buf.len() as u64,
&mut output_length,
&mut raw_format,
)
};
result_from_code(result)?;
let format = format_from_raw(raw_format)?;
Ok((format, output_length as usize))
}
/// Detect the texture format of a HAP frame without fully decoding it.
pub fn get_frame_format(packet_data: &[u8]) -> Result<HapFormat, HapError> {
let mut raw_format: u32 = 0;
let result = unsafe {
ffi::HapGetFrameTextureFormat(
packet_data.as_ptr() as *const std::os::raw::c_void,
packet_data.len() as u64,
0,
&mut raw_format,
)
};
result_from_code(result)?;
format_from_raw(raw_format)
}
|
