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Avoid copying pixels in ctx.putImageData sometimes

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This commit is contained in:
Anthony Ramine 2018-10-06 02:58:45 +02:00
parent 19f40cdf0b
commit 75e6f5dfaa
6 changed files with 53 additions and 41 deletions
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68
components/script/dom/imagedata.rs
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@ -13,6 +13,7 @@ use euclid::{Rect, Size2D};
use js::jsapi::{Heap, JSContext, JSObject};
use js::rust::Runtime;
use js::typedarray::{Uint8ClampedArray, CreateWith};
use std::borrow::Cow;
use std::default::Default;
use std::ptr;
use std::ptr::NonNull;
@ -137,43 +138,46 @@ impl ImageData {
Self::new_with_jsobject(global, width, opt_height, Some(jsobject))
}
/// Nothing must change the array on the JS side while the slice is live.
#[allow(unsafe_code)]
pub fn get_data_array(&self) -> Vec<u8> {
unsafe {
assert!(!self.data.get().is_null());
let cx = Runtime::get();
assert!(!cx.is_null());
typedarray!(in(cx) let array: Uint8ClampedArray = self.data.get());
let vec = array.unwrap().as_slice().to_vec();
vec
}
pub unsafe fn as_slice(&self) -> &[u8] {
assert!(!self.data.get().is_null());
let cx = Runtime::get();
assert!(!cx.is_null());
typedarray!(in(cx) let array: Uint8ClampedArray = self.data.get());
let array = array.as_ref().unwrap();
// NOTE(nox): This is just as unsafe as `as_slice` itself even though we
// are extending the lifetime of the slice, because the data in
// this ImageData instance will never change. The method is thus unsafe
// because the array may be manipulated from JS while the reference
// is live.
let ptr = array.as_slice() as *const _;
&*ptr
}
#[allow(unsafe_code)]
pub fn get_rect(&self, rect: Rect<u32>) -> Vec<u8> {
unsafe {
assert!(!rect.is_empty());
assert!(self.rect().contains_rect(&rect));
assert!(!self.data.get().is_null());
let cx = Runtime::get();
assert!(!cx.is_null());
typedarray!(in(cx) let array: Uint8ClampedArray = self.data.get());
let slice = array.as_ref().unwrap().as_slice();
let area = rect.size.area() as usize;
let first_column_start = rect.origin.x as usize * 4;
let row_length = self.width as usize * 4;
let first_row_start = rect.origin.y as usize * row_length;
if rect.origin.x == 0 && rect.size.width == self.width || rect.size.height == 1 {
let start = first_column_start + first_row_start;
// FIXME(nox): This should be a borrow.
return slice[start..start + area * 4].into();
}
let mut data = Vec::with_capacity(area * 4);
for row in slice[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
pub fn to_vec(&self) -> Vec<u8> {
unsafe { self.as_slice().into() }
}
#[allow(unsafe_code)]
pub unsafe fn get_rect(&self, rect: Rect<u32>) -> Cow<[u8]> {
assert!(!rect.is_empty());
assert!(self.rect().contains_rect(&rect));
let slice = self.as_slice();
let area = rect.size.area() as usize;
let first_column_start = rect.origin.x as usize * 4;
let row_length = self.width as usize * 4;
let first_row_start = rect.origin.y as usize * row_length;
if rect.origin.x == 0 && rect.size.width == self.width || rect.size.height == 1 {
let start = first_column_start + first_row_start;
return Cow::Borrowed(&slice[start..start + area * 4]);
}
let mut data = Vec::with_capacity(area * 4);
for row in slice[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()
}
pub fn get_size(&self) -> Size2D<u32> {