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Don't create 2D canvas contexts arbitrarily

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Sometimes, the canvas still has no rendering context, in this case it represents
a transparent black rectangle.
This commit is contained in:
Anthony Ramine 2018-09-15 12:28:53 +02:00
parent ed673f8070
commit f1e8eb640c
4 changed files with 107 additions and 90 deletions
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79
components/script/dom/htmlcanvaselement.rs
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@ -37,9 +37,10 @@ use js::jsapi::JSContext;
use js::rust::HandleValue;
use offscreen_gl_context::GLContextAttributes;
use profile_traits::ipc;
use ref_filter_map;
use script_layout_interface::{HTMLCanvasData, HTMLCanvasDataSource};
use servo_config::prefs::PREFS;
use std::iter::repeat;
use std::cell::Ref;
use style::attr::{AttrValue, LengthOrPercentageOrAuto};
const DEFAULT_WIDTH: u32 = 300;
@ -174,18 +175,22 @@ impl LayoutHTMLCanvasElementHelpers for LayoutDom<HTMLCanvasElement> {
impl HTMLCanvasElement {
pub fn get_or_init_2d_context(&self) -> Option<DomRoot<CanvasRenderingContext2D>> {
if self.context.borrow().is_none() {
let window = window_from_node(self);
let size = self.get_size();
let context = CanvasRenderingContext2D::new(window.upcast::<GlobalScope>(), self, size);
*self.context.borrow_mut() = Some(CanvasContext::Context2d(Dom::from_ref(&*context)));
}
pub fn context(&self) -> Option<Ref<CanvasContext>> {
ref_filter_map::ref_filter_map(self.context.borrow(), |ctx| ctx.as_ref())
}
match *self.context.borrow().as_ref().unwrap() {
CanvasContext::Context2d(ref context) => Some(DomRoot::from_ref(&*context)),
_ => None,
fn get_or_init_2d_context(&self) -> Option<DomRoot<CanvasRenderingContext2D>> {
if let Some(ctx) = self.context() {
return match *ctx {
CanvasContext::Context2d(ref ctx) => Some(DomRoot::from_ref(ctx)),
_ => None,
};
}
let window = window_from_node(self);
let size = self.get_size();
let context = CanvasRenderingContext2D::new(window.upcast::<GlobalScope>(), self, size);
*self.context.borrow_mut() = Some(CanvasContext::Context2d(Dom::from_ref(&*context)));
Some(context)
}
#[allow(unsafe_code)]
@ -194,20 +199,18 @@ impl HTMLCanvasElement {
cx: *mut JSContext,
options: HandleValue,
) -> Option<DomRoot<WebGLRenderingContext>> {
if self.context.borrow().is_none() {
let window = window_from_node(self);
let size = self.get_size();
let attrs = Self::get_gl_attributes(cx, options)?;
let maybe_ctx = WebGLRenderingContext::new(&window, self, WebGLVersion::WebGL1, size, attrs);
*self.context.borrow_mut() = maybe_ctx.map( |ctx| CanvasContext::WebGL(Dom::from_ref(&*ctx)));
}
if let Some(CanvasContext::WebGL(ref context)) = *self.context.borrow() {
Some(DomRoot::from_ref(&*context))
} else {
None
if let Some(ctx) = self.context() {
return match *ctx {
CanvasContext::WebGL(ref ctx) => Some(DomRoot::from_ref(ctx)),
_ => None,
};
}
let window = window_from_node(self);
let size = self.get_size();
let attrs = Self::get_gl_attributes(cx, options)?;
let context = WebGLRenderingContext::new(&window, self, WebGLVersion::WebGL1, size, attrs)?;
*self.context.borrow_mut() = Some(CanvasContext::WebGL(Dom::from_ref(&*context)));
Some(context)
}
#[allow(unsafe_code)]
@ -219,20 +222,18 @@ impl HTMLCanvasElement {
if !PREFS.is_webgl2_enabled() {
return None
}
if self.context.borrow().is_none() {
let window = window_from_node(self);
let size = self.get_size();
let attrs = Self::get_gl_attributes(cx, options)?;
let maybe_ctx = WebGL2RenderingContext::new(&window, self, size, attrs);
*self.context.borrow_mut() = maybe_ctx.map( |ctx| CanvasContext::WebGL2(Dom::from_ref(&*ctx)));
}
if let Some(CanvasContext::WebGL2(ref context)) = *self.context.borrow() {
Some(DomRoot::from_ref(&*context))
} else {
None
if let Some(ctx) = self.context() {
return match *ctx {
CanvasContext::WebGL2(ref ctx) => Some(DomRoot::from_ref(ctx)),
_ => None,
};
}
let window = window_from_node(self);
let size = self.get_size();
let attrs = Self::get_gl_attributes(cx, options)?;
let context = WebGL2RenderingContext::new(&window, self, size, attrs)?;
*self.context.borrow_mut() = Some(CanvasContext::WebGL2(Dom::from_ref(&*context)));
Some(context)
}
/// Gets the base WebGLRenderingContext for WebGL or WebGL 2, if exists.
@ -289,9 +290,7 @@ impl HTMLCanvasElement {
// TODO: add a method in WebGL2RenderingContext to get the pixels.
return None;
},
None => {
repeat(0xffu8).take((size.height as usize) * (size.width as usize) * 4).collect()
}
None => vec![0; size.height as usize * size.width as usize * 4]
};
Some((data, size))