egui/epaint/src/image.rs
2022-02-04 13:31:06 +01:00

298 lines
8.3 KiB
Rust

use crate::Color32;
/// An image stored in RAM.
///
/// To load an image file, see [`ColorImage::from_rgba_unmultiplied`].
///
/// In order to paint the image on screen, you first need to convert it to
///
/// See also: [`ColorImage`], [`AlphaImage`].
#[derive(Clone, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
pub enum ImageData {
/// RGBA image.
Color(ColorImage),
/// Used for the font texture.
Alpha(AlphaImage),
}
impl ImageData {
pub fn size(&self) -> [usize; 2] {
match self {
Self::Color(image) => image.size,
Self::Alpha(image) => image.size,
}
}
pub fn width(&self) -> usize {
self.size()[0]
}
pub fn height(&self) -> usize {
self.size()[1]
}
pub fn bytes_per_pixel(&self) -> usize {
match self {
Self::Color(_) => 4,
Self::Alpha(_) => 1,
}
}
}
// ----------------------------------------------------------------------------
/// A 2D RGBA color image in RAM.
#[derive(Clone, Default, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
pub struct ColorImage {
/// width, height.
pub size: [usize; 2],
/// The pixels, row by row, from top to bottom.
pub pixels: Vec<Color32>,
}
impl ColorImage {
/// Create an image filled with the given color.
pub fn new(size: [usize; 2], color: Color32) -> Self {
Self {
size,
pixels: vec![color; size[0] * size[1]],
}
}
/// Create an `Image` from flat un-multiplied RGBA data.
///
/// This is usually what you want to use after having loaded an image file.
///
/// Panics if `size[0] * size[1] * 4 != rgba.len()`.
///
/// ## Example using the [`image`](crates.io/crates/image) crate:
/// ``` ignore
/// fn load_image_from_path(path: &std::path::Path) -> Result<egui::ColorImage, image::ImageError> {
/// let image = image::io::Reader::open(path)?.decode()?;
/// let size = [image.width() as _, image.height() as _];
/// let image_buffer = image.to_rgba8();
/// let pixels = image_buffer.as_flat_samples();
/// Ok(egui::ColorImage::from_rgba_unmultiplied(
/// size,
/// pixels.as_slice(),
/// ))
/// }
///
/// fn load_image_from_memory(image_data: &[u8]) -> Result<ColorImage, image::ImageError> {
/// let image = image::load_from_memory(image_data)?;
/// let size = [image.width() as _, image.height() as _];
/// let image_buffer = image.to_rgba8();
/// let pixels = image_buffer.as_flat_samples();
/// Ok(ColorImage::from_rgba_unmultiplied(
/// size,
/// pixels.as_slice(),
/// ))
/// }
/// ```
pub fn from_rgba_unmultiplied(size: [usize; 2], rgba: &[u8]) -> Self {
assert_eq!(size[0] * size[1] * 4, rgba.len());
let pixels = rgba
.chunks_exact(4)
.map(|p| Color32::from_rgba_unmultiplied(p[0], p[1], p[2], p[3]))
.collect();
Self { size, pixels }
}
/// An example color image, useful for tests.
pub fn example() -> Self {
let width = 128;
let height = 64;
let mut img = Self::new([width, height], Color32::TRANSPARENT);
for y in 0..height {
for x in 0..width {
let h = x as f32 / width as f32;
let s = 1.0;
let v = 1.0;
let a = y as f32 / height as f32;
img[(x, y)] = crate::color::Hsva { h, s, v, a }.into();
}
}
img
}
#[inline]
pub fn width(&self) -> usize {
self.size[0]
}
#[inline]
pub fn height(&self) -> usize {
self.size[1]
}
}
impl std::ops::Index<(usize, usize)> for ColorImage {
type Output = Color32;
#[inline]
fn index(&self, (x, y): (usize, usize)) -> &Color32 {
let [w, h] = self.size;
assert!(x < w && y < h);
&self.pixels[y * w + x]
}
}
impl std::ops::IndexMut<(usize, usize)> for ColorImage {
#[inline]
fn index_mut(&mut self, (x, y): (usize, usize)) -> &mut Color32 {
let [w, h] = self.size;
assert!(x < w && y < h);
&mut self.pixels[y * w + x]
}
}
impl From<ColorImage> for ImageData {
#[inline(always)]
fn from(image: ColorImage) -> Self {
Self::Color(image)
}
}
// ----------------------------------------------------------------------------
/// An 8-bit image, representing difference levels of transparent white.
///
/// Used for the font texture
#[derive(Clone, Default, Eq, Hash, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
pub struct AlphaImage {
/// width, height
pub size: [usize; 2],
/// The alpha (linear space 0-255) of something white.
///
/// One byte per pixel. Often you want to use [`Self::srgba_pixels`] instead.
pub pixels: Vec<u8>,
}
impl AlphaImage {
pub fn new(size: [usize; 2]) -> Self {
Self {
size,
pixels: vec![0; size[0] * size[1]],
}
}
#[inline]
pub fn width(&self) -> usize {
self.size[0]
}
#[inline]
pub fn height(&self) -> usize {
self.size[1]
}
/// Returns the textures as `sRGBA` premultiplied pixels, row by row, top to bottom.
///
/// `gamma` should normally be set to 1.0.
/// If you are having problems with text looking skinny and pixelated, try
/// setting a lower gamma, e.g. `0.5`.
pub fn srgba_pixels(
&'_ self,
gamma: f32,
) -> impl ExactSizeIterator<Item = super::Color32> + '_ {
let srgba_from_alpha_lut: Vec<Color32> = (0..=255)
.map(|a| {
let a = super::color::linear_f32_from_linear_u8(a).powf(gamma);
super::Rgba::from_white_alpha(a).into()
})
.collect();
self.pixels
.iter()
.map(move |&a| srgba_from_alpha_lut[a as usize])
}
/// Clone a sub-region as a new image
pub fn region(&self, [x, y]: [usize; 2], [w, h]: [usize; 2]) -> AlphaImage {
assert!(x + w <= self.width());
assert!(y + h <= self.height());
let mut pixels = Vec::with_capacity(w * h);
for y in y..y + h {
let offset = y * self.width() + x;
pixels.extend(&self.pixels[offset..(offset + w)]);
}
assert_eq!(pixels.len(), w * h);
AlphaImage {
size: [w, h],
pixels,
}
}
}
impl std::ops::Index<(usize, usize)> for AlphaImage {
type Output = u8;
#[inline]
fn index(&self, (x, y): (usize, usize)) -> &u8 {
let [w, h] = self.size;
assert!(x < w && y < h);
&self.pixels[y * w + x]
}
}
impl std::ops::IndexMut<(usize, usize)> for AlphaImage {
#[inline]
fn index_mut(&mut self, (x, y): (usize, usize)) -> &mut u8 {
let [w, h] = self.size;
assert!(x < w && y < h);
&mut self.pixels[y * w + x]
}
}
impl From<AlphaImage> for ImageData {
#[inline(always)]
fn from(image: AlphaImage) -> Self {
Self::Alpha(image)
}
}
// ----------------------------------------------------------------------------
/// A change to an image.
///
/// Either a whole new image,
/// or an update to a rectangular region of it.
#[derive(Clone, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
#[must_use = "The painter must take care of this"]
pub struct ImageDelta {
/// What to set the texture to.
pub image: ImageData,
/// If `None`, set the whole texture to [`Self::image`].
/// If `Some(pos)`, update a sub-region of an already allocated texture.
pub pos: Option<[usize; 2]>,
}
impl ImageDelta {
/// Update the whole texture.
pub fn full(image: impl Into<ImageData>) -> Self {
Self {
image: image.into(),
pos: None,
}
}
/// Update a sub-region of an existing texture.
pub fn partial(pos: [usize; 2], image: impl Into<ImageData>) -> Self {
Self {
image: image.into(),
pos: Some(pos),
}
}
/// Is this affecting the whole texture?
/// If `false`, this is a partial (sub-region) update.
pub fn is_whole(&self) -> bool {
self.pos.is_none()
}
}