Introduce ImageData::get_rect

We use that to send only the pixels that will be actually drawn to the
canvas thread in CanvasRenderingContext2d::PutImageData.

We also make the canvas thread byte swap and premultiply colours in-place.
This commit is contained in:
Anthony Ramine 2018-10-06 01:10:34 +02:00
parent 784fbb2bc1
commit 19f40cdf0b
5 changed files with 52 additions and 55 deletions

View file

@ -9,7 +9,7 @@ use dom::bindings::reflector::{Reflector, reflect_dom_object};
use dom::bindings::root::DomRoot;
use dom::globalscope::GlobalScope;
use dom_struct::dom_struct;
use euclid::Size2D;
use euclid::{Rect, Size2D};
use js::jsapi::{Heap, JSContext, JSObject};
use js::rust::Runtime;
use js::typedarray::{Uint8ClampedArray, CreateWith};
@ -149,9 +149,40 @@ impl ImageData {
}
}
#[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 get_size(&self) -> Size2D<u32> {
Size2D::new(self.Width(), self.Height())
}
pub fn rect(&self) -> Rect<u32> {
Rect::from_size(self.get_size())
}
}
impl ImageDataMethods for ImageData {