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ab4b34d423
This is GIF specific. It's also done when the image is PNG but PNG is handled separately with the PNG crate, whereas GIFs are handled by the stb-image crate and the distinction between alpha and non-alpha-supporting images was missing.
91 lines
3 KiB
Rust
91 lines
3 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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use std::iter::range_step;
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use stb_image::image as stb_image;
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use png;
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use util::vec::byte_swap;
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// FIXME: Images must not be copied every frame. Instead we should atomically
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// reference count them.
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pub type Image = png::Image;
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static TEST_IMAGE: &'static [u8] = include_bytes!("test.jpeg");
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pub fn test_image_bin() -> Vec<u8> {
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TEST_IMAGE.iter().map(|&x| x).collect()
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}
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// TODO(pcwalton): Speed up with SIMD, or better yet, find some way to not do this.
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fn byte_swap_and_premultiply(data: &mut [u8]) {
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let length = data.len();
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for i in range_step(0, length, 4) {
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let r = data[i + 2];
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let g = data[i + 1];
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let b = data[i + 0];
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let a = data[i + 3];
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data[i + 0] = ((r as u32) * (a as u32) / 255) as u8;
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data[i + 1] = ((g as u32) * (a as u32) / 255) as u8;
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data[i + 2] = ((b as u32) * (a as u32) / 255) as u8;
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}
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}
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pub fn load_from_memory(buffer: &[u8]) -> Option<Image> {
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if buffer.len() == 0 {
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return None;
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}
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if png::is_png(buffer) {
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match png::load_png_from_memory(buffer) {
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Ok(mut png_image) => {
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match png_image.pixels {
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png::PixelsByColorType::RGB8(ref mut data) => byte_swap(data.as_mut_slice()),
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png::PixelsByColorType::RGBA8(ref mut data) => {
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byte_swap_and_premultiply(data.as_mut_slice())
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}
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_ => {}
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}
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Some(png_image)
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}
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Err(_err) => None,
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}
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} else {
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// For non-png images, we use stb_image
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// Can't remember why we do this. Maybe it's what cairo wants
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static FORCE_DEPTH: uint = 4;
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match stb_image::load_from_memory_with_depth(buffer, FORCE_DEPTH, true) {
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stb_image::LoadResult::ImageU8(mut image) => {
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assert!(image.depth == 4);
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// handle gif separately because the alpha-channel has to be premultiplied
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if is_gif(buffer) {
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byte_swap_and_premultiply(image.data.as_mut_slice());
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} else {
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byte_swap(image.data.as_mut_slice());
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}
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Some(png::Image {
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width: image.width as u32,
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height: image.height as u32,
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pixels: png::PixelsByColorType::RGBA8(image.data)
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})
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}
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stb_image::LoadResult::ImageF32(_image) => {
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error!("HDR images not implemented");
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None
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}
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stb_image::LoadResult::Error(e) => {
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error!("stb_image failed: {}", e);
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None
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}
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}
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}
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}
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fn is_gif(buffer: &[u8]) -> bool {
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match buffer {
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[b'G',b'I',b'F',b'8', n, b'a', ..] if n == b'7' || n == b'9' => true,
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_ => false
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}
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}
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