mirror of
https://github.com/servo/servo.git
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107 lines
3.3 KiB
Rust
107 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, ImageFormat};
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use util::opts;
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pub use msg::constellation_msg::{Image, ImageMetadata, 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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// No need to pre-multiply alpha when using direct GPU rendering.
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let premultiply_alpha = !opts::get().use_webrender;
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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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if premultiply_alpha {
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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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} else {
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data[i + 0] = r;
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data[i + 1] = g;
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data[i + 2] = b;
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}
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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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let image_fmt_result = detect_image_format(buffer);
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match image_fmt_result {
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Err(msg) => {
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debug!("{}", msg);
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None
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}
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Ok(_) => {
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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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id: None,
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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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}
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// https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img
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pub fn detect_image_format(buffer: &[u8]) -> Result<ImageFormat, &str> {
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if is_gif(buffer) { Ok(ImageFormat::GIF) }
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else if is_jpeg(buffer) { Ok(ImageFormat::JPEG) }
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else if is_png(buffer) { Ok(ImageFormat::PNG) }
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else if is_bmp(buffer) { Ok(ImageFormat::BMP) }
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else if is_ico(buffer) { Ok(ImageFormat::ICO) }
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else { Err("Image Format Not Supported") }
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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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fn is_png(buffer: &[u8]) -> bool {
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buffer.starts_with(&[0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A])
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}
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fn is_bmp(buffer: &[u8]) -> bool {
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buffer.starts_with(&[0x42, 0x4D])
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}
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fn is_ico(buffer: &[u8]) -> bool {
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buffer.starts_with(&[0x00, 0x00, 0x01, 0x00])
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}
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