Auto merge of #18592 - MortimerGoro:dom_texture, r=jdm

Implement DOM to texture

<!-- Please describe your changes on the following line: -->

This is a prototype of the WebGL DOMToTexture feature. The API should be fine as a privileged extension for now due to security concerns. The working group has been investigating the viability of unprivileged usage but the spec is not ready yet.

Demo video: https://www.youtube.com/watch?v=hpZqEM5hPao

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- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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6 files changed, 75 insertions, 2 deletions

diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index f7d582ffee8..5c7723f17de 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -110,7 +110,7 @@ use style::stylesheets::keyframes_rule::Keyframe;
 use style::values::specified::Length;
 use time::Duration;
 use uuid::Uuid;
-use webrender_api::ImageKey;
+use webrender_api::{DocumentId, ImageKey};
 use webvr_traits::WebVRGamepadHand;
 
 /// A trait to allow tracing (only) DOM objects.
@@ -397,6 +397,7 @@ unsafe_no_jsmanaged_fields!(OpaqueStyleAndLayoutData);
 unsafe_no_jsmanaged_fields!(PathBuf);
 unsafe_no_jsmanaged_fields!(CSSErrorReporter);
 unsafe_no_jsmanaged_fields!(DrawAPaintImageResult);
+unsafe_no_jsmanaged_fields!(DocumentId);
 unsafe_no_jsmanaged_fields!(ImageKey);
 unsafe_no_jsmanaged_fields!(WebGLBufferId);
 unsafe_no_jsmanaged_fields!(WebGLChan);
diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index c20b2273123..d4624d3eb85 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -6,6 +6,7 @@ use byteorder::{NativeEndian, ReadBytesExt, WriteBytesExt};
 use canvas_traits::canvas::{byte_swap, multiply_u8_pixel};
 use canvas_traits::webgl::{WebGLContextShareMode, WebGLCommand, WebGLError};
 use canvas_traits::webgl::{WebGLFramebufferBindingRequest, WebGLMsg, WebGLMsgSender, WebGLParameter, WebVRCommand};
+use canvas_traits::webgl::DOMToTextureCommand;
 use canvas_traits::webgl::WebGLError::*;
 use canvas_traits::webgl::webgl_channel;
 use core::cell::Ref;
@@ -25,6 +26,7 @@ use dom::bindings::str::DOMString;
 use dom::event::{Event, EventBubbles, EventCancelable};
 use dom::htmlcanvaselement::HTMLCanvasElement;
 use dom::htmlcanvaselement::utils as canvas_utils;
+use dom::htmliframeelement::HTMLIFrameElement;
 use dom::node::{Node, NodeDamage, window_from_node};
 use dom::webgl_extensions::WebGLExtensions;
 use dom::webgl_validations::WebGLValidator;
@@ -3261,6 +3263,45 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
     }
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.8
+    fn TexImageDOM(&self,
+                   target: u32,
+                   level: i32,
+                   internal_format: u32,
+                   width: i32,
+                   height: i32,
+                   format: u32,
+                   data_type: u32,
+                   source: &HTMLIFrameElement) -> Fallible<()> {
+        // Currently DOMToTexture only supports TEXTURE_2D, RGBA, UNSIGNED_BYTE and no levels.
+        if target != constants::TEXTURE_2D || level != 0 || internal_format != constants::RGBA ||
+            format != constants::RGBA || data_type != constants::UNSIGNED_BYTE {
+            return Ok(self.webgl_error(InvalidValue));
+        }
+
+        // Get bound texture
+        let texture = match self.bound_texture(constants::TEXTURE_2D) {
+            Some(texture) => texture,
+            None => {
+                return Ok(self.webgl_error(InvalidOperation));
+            }
+        };
+
+        let pipeline_id = source.pipeline_id().ok_or(Error::InvalidState)?;
+        let document_id  = self.global().downcast::<Window>().ok_or(Error::InvalidState)?.webrender_document();
+
+        texture.set_attached_to_dom();
+
+        let command = DOMToTextureCommand::Attach(self.webgl_sender.context_id(),
+                                                  texture.id(),
+                                                  document_id,
+                                                  pipeline_id.to_webrender(),
+                                                  Size2D::new(width, height));
+        self.webgl_sender.send_dom_to_texture(command).unwrap();
+
+        Ok(())
+    }
+
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.8
     #[allow(unsafe_code)]
     unsafe fn TexSubImage2D(&self,
                      cx: *mut JSContext,
diff --git a/components/script/dom/webgltexture.rs b/components/script/dom/webgltexture.rs
index 59be8681337..6927fd10a48 100644
--- a/components/script/dom/webgltexture.rs
+++ b/components/script/dom/webgltexture.rs
@@ -5,6 +5,7 @@
 // https://www.khronos.org/registry/webgl/specs/latest/1.0/webgl.idl
 
 use canvas_traits::webgl::{webgl_channel, WebGLCommand, WebGLError, WebGLMsgSender, WebGLResult, WebGLTextureId};
+use canvas_traits::webgl::DOMToTextureCommand;
 use dom::bindings::cell::DomRefCell;
 use dom::bindings::codegen::Bindings::WebGLRenderingContextBinding::WebGLRenderingContextConstants as constants;
 use dom::bindings::codegen::Bindings::WebGLTextureBinding;
@@ -45,6 +46,8 @@ pub struct WebGLTexture {
     mag_filter: Cell<Option<u32>>,
     #[ignore_heap_size_of = "Defined in ipc-channel"]
     renderer: WebGLMsgSender,
+    /// True if this texture is used for the DOMToTexture feature.
+    attached_to_dom: Cell<bool>,
 }
 
 impl WebGLTexture {
@@ -62,6 +65,7 @@ impl WebGLTexture {
             mag_filter: Cell::new(None),
             image_info_array: DomRefCell::new([ImageInfo::new(); MAX_LEVEL_COUNT * MAX_FACE_COUNT]),
             renderer: renderer,
+            attached_to_dom: Cell::new(false),
         }
     }
 
@@ -179,6 +183,10 @@ impl WebGLTexture {
     pub fn delete(&self) {
         if !self.is_deleted.get() {
             self.is_deleted.set(true);
+            // Notify WR to release the frame output when using DOMToTexture feature
+            if self.attached_to_dom.get() {
+                let _ = self.renderer.send_dom_to_texture(DOMToTextureCommand::Detach(self.id));
+            }
             let _ = self.renderer.send(WebGLCommand::DeleteTexture(self.id));
         }
     }
@@ -374,6 +382,10 @@ impl WebGLTexture {
 
         Some(self.image_info_at_face(0, self.base_mipmap_level))
     }
+
+    pub fn set_attached_to_dom(&self) {
+        self.attached_to_dom.set(true);
+    }
 }
 
 impl Drop for WebGLTexture {
diff --git a/components/script/dom/webidls/WebGLRenderingContext.webidl b/components/script/dom/webidls/WebGLRenderingContext.webidl
index 885ad9486bb..ec729d1b5fb 100644
--- a/components/script/dom/webidls/WebGLRenderingContext.webidl
+++ b/components/script/dom/webidls/WebGLRenderingContext.webidl
@@ -654,6 +654,9 @@ interface WebGLRenderingContextBase
     [Throws]
     void texImage2D(GLenum target, GLint level, GLenum internalformat,
                     GLenum format, GLenum type, TexImageSource? source); // May throw DOMException
+    [Throws, Pref="dom.webgl.dom_to_texture.enabled"]
+    void texImageDOM(GLenum target, GLint level, GLenum internalformat, GLsizei width, GLsizei height,
+                     GLenum format, GLenum type, HTMLIFrameElement source); // May throw DOMException
 
     void texParameterf(GLenum target, GLenum pname, GLfloat param);
     void texParameteri(GLenum target, GLenum pname, GLint param);
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 1e4bf803427..047cc1678ea 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -123,7 +123,7 @@ use timers::{IsInterval, TimerCallback};
 use tinyfiledialogs::{self, MessageBoxIcon};
 use url::Position;
 use webdriver_handlers::jsval_to_webdriver;
-use webrender_api::ClipId;
+use webrender_api::{ClipId, DocumentId};
 use webvr_traits::WebVRMsg;
 
 /// Current state of the window object
@@ -289,6 +289,9 @@ pub struct Window {
     test_worklet: MutNullableDom<Worklet>,
     /// https://drafts.css-houdini.org/css-paint-api-1/#paint-worklet
     paint_worklet: MutNullableDom<Worklet>,
+    /// The Webrender Document id associated with this window.
+    #[ignore_heap_size_of = "defined in webrender_api"]
+    webrender_document: DocumentId,
 }
 
 impl Window {
@@ -1760,6 +1763,10 @@ impl Window {
             .send(msg)
             .unwrap();
     }
+
+    pub fn webrender_document(&self) -> DocumentId {
+        self.webrender_document
+    }
 }
 
 impl Window {
@@ -1794,6 +1801,7 @@ impl Window {
         webgl_chan: WebGLChan,
         webvr_chan: Option<IpcSender<WebVRMsg>>,
         microtask_queue: Rc<MicrotaskQueue>,
+        webrender_document: DocumentId,
     ) -> DomRoot<Self> {
         let layout_rpc: Box<LayoutRPC + Send> = {
             let (rpc_send, rpc_recv) = channel();
@@ -1868,6 +1876,7 @@ impl Window {
             unminified_js_dir: Default::default(),
             test_worklet: Default::default(),
             paint_worklet: Default::default(),
+            webrender_document,
         });
 
         unsafe {
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 119fe4bec2c..6c722cec865 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -124,6 +124,7 @@ use time::{get_time, precise_time_ns, Tm};
 use url::Position;
 use url::percent_encoding::percent_decode;
 use webdriver_handlers;
+use webrender_api::DocumentId;
 use webvr_traits::{WebVREvent, WebVRMsg};
 
 pub type ImageCacheMsg = (PipelineId, PendingImageResponse);
@@ -495,6 +496,9 @@ pub struct ScriptThread {
 
     /// https://html.spec.whatwg.org/multipage/#custom-element-reactions-stack
     custom_element_reaction_stack: CustomElementReactionStack,
+
+    /// The Webrender Document ID associated with this thread.
+    webrender_document: DocumentId,
 }
 
 /// In the event of thread panic, all data on the stack runs its destructor. However, there
@@ -871,6 +875,8 @@ impl ScriptThread {
             transitioning_nodes: Default::default(),
 
             custom_element_reaction_stack: CustomElementReactionStack::new(),
+
+            webrender_document: state.webrender_document,
         }
     }
 
@@ -2062,6 +2068,7 @@ impl ScriptThread {
             self.webgl_chan.channel(),
             self.webvr_chan.clone(),
             self.microtask_queue.clone(),
+            self.webrender_document,
         );
 
         // Initialize the browsing context for the window.