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98 lines
3.3 KiB
Rust
98 lines
3.3 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 ipc_channel::ipc::IpcSharedMemory;
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use piston_image::{self, DynamicImage, GenericImage};
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use stb_image::image as stb_image2;
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use util::vec::byte_swap;
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pub use msg::constellation_msg::{Image, PixelFormat};
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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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// 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 (0..length).step_by(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.is_empty() {
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return None;
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}
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if is_jpeg(buffer) {
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// For JPEG images, we use stb_image because piston_image does not yet support progressive
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// JPEG.
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// Can't remember why we do this. Maybe it's what cairo wants
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static FORCE_DEPTH: usize = 4;
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match stb_image2::load_from_memory_with_depth(buffer, FORCE_DEPTH, true) {
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stb_image2::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(&mut image.data);
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} else {
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byte_swap(&mut image.data);
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}
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Some(Image {
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width: image.width as u32,
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height: image.height as u32,
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format: PixelFormat::RGBA8,
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bytes: IpcSharedMemory::from_bytes(&image.data[..]),
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})
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}
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stb_image2::LoadResult::ImageF32(_image) => {
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debug!("HDR images not implemented");
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None
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}
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stb_image2::LoadResult::Error(e) => {
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debug!("stb_image failed: {}", e);
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None
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}
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}
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} else {
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match piston_image::load_from_memory(buffer) {
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Ok(image) => {
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let mut rgba = match image {
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DynamicImage::ImageRgba8(rgba) => rgba,
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image => image.to_rgba()
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};
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byte_swap_and_premultiply(&mut *rgba);
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Some(Image {
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width: rgba.width(),
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height: rgba.height(),
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format: PixelFormat::RGBA8,
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bytes: IpcSharedMemory::from_bytes(&*rgba),
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})
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}
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Err(e) => {
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debug!("Image decoding error: {:?}", 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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fn is_jpeg(buffer: &[u8]) -> bool {
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buffer.starts_with(&[0xff, 0xd8, 0xff])
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}
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