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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use euclid::{Point2D, Rect, Size2D};
use std::borrow::Cow;
pub fn get_rect(pixels: &[u8], size: Size2D<u32>, rect: Rect<u32>) -> Cow<[u8]> {
assert!(!rect.is_empty());
assert!(Rect::from_size(size).contains_rect(&rect));
assert_eq!(pixels.len() % 4, 0);
assert_eq!(size.area() as usize, pixels.len() / 4);
let area = rect.size.area() as usize;
let first_column_start = rect.origin.x as usize * 4;
let row_length = size.width as usize * 4;
let first_row_start = rect.origin.y as usize * row_length;
if rect.origin.x == 0 && rect.size.width == size.width || rect.size.height == 1 {
let start = first_column_start + first_row_start;
return Cow::Borrowed(&pixels[start..start + area * 4]);
}
let mut data = Vec::with_capacity(area * 4);
for row in pixels[first_row_start..]
.chunks(row_length)
.take(rect.size.height as usize)
{
data.extend_from_slice(&row[first_column_start..][..rect.size.width as usize * 4]);
}
data.into()
}
// TODO(pcwalton): Speed up with SIMD, or better yet, find some way to not do this.
pub fn byte_swap_colors_inplace(pixels: &mut [u8]) {
assert!(pixels.len() % 4 == 0);
for rgba in pixels.chunks_mut(4) {
let b = rgba[0];
rgba[0] = rgba[2];
rgba[2] = b;
}
}
pub fn byte_swap_and_premultiply_inplace(pixels: &mut [u8]) {
assert!(pixels.len() % 4 == 0);
for rgba in pixels.chunks_mut(4) {
let b = rgba[0];
rgba[0] = multiply_u8_color(rgba[2], rgba[3]);
rgba[1] = multiply_u8_color(rgba[1], rgba[3]);
rgba[2] = multiply_u8_color(b, rgba[3]);
}
}
/// Returns true if the pixels were found to be completely opaque.
pub fn premultiply_inplace(pixels: &mut [u8]) -> bool {
assert!(pixels.len() % 4 == 0);
let mut is_opaque = true;
for rgba in pixels.chunks_mut(4) {
rgba[0] = multiply_u8_color(rgba[0], rgba[3]);
rgba[1] = multiply_u8_color(rgba[1], rgba[3]);
rgba[2] = multiply_u8_color(rgba[2], rgba[3]);
is_opaque = is_opaque && rgba[3] == 255;
}
is_opaque
}
pub fn multiply_u8_color(a: u8, b: u8) -> u8 {
return (a as u32 * b as u32 / 255) as u8;
}
pub fn clip(
mut origin: Point2D<i32>,
mut size: Size2D<u32>,
surface: Size2D<u32>,
) -> Option<Rect<u32>> {
if origin.x < 0 {
size.width = size.width.saturating_sub(-origin.x as u32);
origin.x = 0;
}
if origin.y < 0 {
size.height = size.height.saturating_sub(-origin.y as u32);
origin.y = 0;
}
Rect::new(origin.to_u32(), size)
.intersection(&Rect::from_size(surface))
.filter(|rect| !rect.is_empty())
}
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