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/// Information describing the binary data of an image.
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub struct ImageInfo {
/// The pixel format of the image data.
pub pixel_format: PixelFormat,
/// The size of the image in pixels
pub size: glam::UVec2,
/// The stride of the image data in bytes for both X and Y.
pub stride: glam::UVec2,
}
/// Supported pixel formats.
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum PixelFormat {
/// 8-bit monochrome data.
Mono8,
/// 8-bit monochrome data with alpha.
MonoAlpha8(Alpha),
/// Interlaced 8-bit BGR data.
Bgr8,
/// Interlaced 8-bit BGRA data.
Bgra8(Alpha),
/// Interlaced 8-bit RGB data.
Rgb8,
/// Interlaced 8-bit RGBA data.
Rgba8(Alpha),
}
/// Possible alpha representations.
///
/// See also: <https://en.wikipedia.org/wiki/Alpha_compositing#Straight_versus_premultiplied>
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum Alpha {
/// The alpha channel is encoded only in the alpha component of the pixel.
Unpremultiplied,
/// The alpha channel is also premultiplied into the other components of the pixel.
Premultiplied,
}
impl ImageInfo {
/// Create a new info struct with the given format, width and height.
///
/// The row stride is automatically calculated based on the image width and pixel format.
/// If you wish to use a different row stride, construct the struct directly.
pub fn new(pixel_format: PixelFormat, width: u32, height: u32) -> Self {
let stride_x = u32::from(pixel_format.bytes_per_pixel());
let stride_y = stride_x * width;
Self {
pixel_format,
size: glam::UVec2::new(width, height),
stride: glam::UVec2::new(stride_x, stride_y),
}
}
/// Create a new info struct for an 8-bit monochrome image with the given width and height.
pub fn mono8(width: u32, height: u32) -> Self {
Self::new(PixelFormat::Mono8, width, height)
}
/// Create a new info struct for an 8-bit monochrome image with with alpha channel and the given width and height.
pub fn mono_alpha8(width: u32, height: u32) -> Self {
Self::new(PixelFormat::MonoAlpha8(Alpha::Unpremultiplied), width, height)
}
/// Create a new info struct for an 8-bit monochrome image with premultiplied alpha channel and the given width and height.
pub fn mono_alpha8_premultiplied(width: u32, height: u32) -> Self {
Self::new(PixelFormat::MonoAlpha8(Alpha::Premultiplied), width, height)
}
/// Create a new info struct for an 8-bit BGR image with the given width and height.
pub fn bgr8(width: u32, height: u32) -> Self {
Self::new(PixelFormat::Bgr8, width, height)
}
/// Create a new info struct for an 8-bit BGRA image with the given width and height.
pub fn bgra8(width: u32, height: u32) -> Self {
Self::new(PixelFormat::Bgra8(Alpha::Unpremultiplied), width, height)
}
/// Create a new info struct for an 8-bit BGRA image with premultiplied alpha channel and the given width and height.
pub fn bgra8_premultiplied(width: u32, height: u32) -> Self {
Self::new(PixelFormat::Bgra8(Alpha::Premultiplied), width, height)
}
/// Create a new info struct for an 8-bit RGB image with the given width and height.
pub fn rgb8(width: u32, height: u32) -> Self {
Self::new(PixelFormat::Rgb8, width, height)
}
/// Create a new info struct for an 8-bit RGBA image with the given width and height.
pub fn rgba8(width: u32, height: u32) -> Self {
Self::new(PixelFormat::Rgba8(Alpha::Unpremultiplied), width, height)
}
/// Create a new info struct for an 8-bit RGBA image with premultiplied alpha channel and the given width and height.
pub fn rgba8_premultiplied(width: u32, height: u32) -> Self {
Self::new(PixelFormat::Rgba8(Alpha::Premultiplied), width, height)
}
/// Get the image size in bytes.
pub fn byte_size(self) -> u64 {
if self.stride.y >= self.stride.x {
u64::from(self.stride.y) * u64::from(self.size.y)
} else {
u64::from(self.stride.x) * u64::from(self.size.x)
}
}
}
impl PixelFormat {
/// Get the number of channels.
pub fn channels(self) -> u8 {
match self {
PixelFormat::Mono8 => 1,
PixelFormat::MonoAlpha8(_) => 1,
PixelFormat::Bgr8 => 3,
PixelFormat::Bgra8(_) => 4,
PixelFormat::Rgb8 => 3,
PixelFormat::Rgba8(_) => 4,
}
}
/// Get the bytes per channel.
const fn byte_depth(self) -> u8 {
1
}
/// Get the bytes per pixel.
pub fn bytes_per_pixel(self) -> u8 {
self.byte_depth() * self.channels()
}
/// Get the alpha representation of the pixel format.
///
/// Returns [`None`], if the pixel format has no alpha channel.
pub fn alpha(self) -> Option<Alpha> {
match self {
PixelFormat::Mono8 => None,
PixelFormat::MonoAlpha8(a) => Some(a),
PixelFormat::Bgr8 => None,
PixelFormat::Bgra8(a) => Some(a),
PixelFormat::Rgb8 => None,
PixelFormat::Rgba8(a) => Some(a),
}
}
}