script/dom/webgpu/
gpucanvascontext.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5use std::borrow::Cow;
6use std::cell::{Cell, RefCell};
7use std::rc::Rc;
8
9use arrayvec::ArrayVec;
10use dom_struct::dom_struct;
11use js::context::JSContext;
12use pixels::Snapshot;
13use script_bindings::cformat;
14use script_bindings::codegen::GenericBindings::WebGPUBinding::{
15    GPUDeviceMethods, GPUTextureFormat, GPUTextureUsageConstants,
16};
17use script_bindings::reflector::{Reflector, reflect_weak_referenceable_dom_object};
18use script_webgpu::gpuconvert::convert_texture_descriptor;
19use servo_base::{Epoch, generic_channel};
20use webgpu_traits::{
21    ContextConfiguration, PRESENTATION_BUFFER_COUNT, PendingTexture, WebGPU, WebGPUContextId,
22    WebGPURequest, id,
23};
24use webrender_api::{ImageFormat, ImageKey};
25
26use super::gputexture::GPUTexture;
27use crate::canvas_context::{CanvasContext, CanvasHelpers, HTMLCanvasElementOrOffscreenCanvas};
28use crate::dom::bindings::codegen::Bindings::WebGPUBinding::GPUTexture_Binding::GPUTextureMethods;
29use crate::dom::bindings::codegen::Bindings::WebGPUBinding::{
30    GPUCanvasAlphaMode, GPUCanvasConfiguration as RootedGPUCanvasConfiguration,
31    GPUCanvasContextMethods, GPUExtent3D, GPUExtent3DDict, GPUObjectDescriptorBase,
32    GPUTextureDescriptor, GPUTextureDimension,
33};
34use crate::dom::bindings::codegen::UnionTypes::HTMLCanvasElementOrOffscreenCanvas as RootedHTMLCanvasElementOrOffscreenCanvas;
35use crate::dom::bindings::error::{Error, Fallible};
36use crate::dom::bindings::reflector::DomGlobal;
37use crate::dom::bindings::root::{Dom, DomRoot, MutNullableDom};
38use crate::dom::bindings::str::USVString;
39use crate::dom::globalscope::GlobalScope;
40use crate::dom::htmlcanvaselement::HTMLCanvasElement;
41use crate::dom::webgpu::gpudevice::GPUDevice;
42
43/// <https://gpuweb.github.io/gpuweb/#supported-context-formats>
44fn supported_context_format(format: GPUTextureFormat) -> bool {
45    // TODO: GPUTextureFormat::Rgba16float
46    matches!(
47        format,
48        GPUTextureFormat::Bgra8unorm | GPUTextureFormat::Rgba8unorm
49    )
50}
51
52#[derive(JSTraceable, MallocSizeOf)]
53struct DroppableGPUCanvasContext {
54    #[no_trace]
55    context_id: WebGPUContextId,
56    #[no_trace]
57    channel: WebGPU,
58}
59
60impl Drop for DroppableGPUCanvasContext {
61    fn drop(&mut self) {
62        if let Err(error) = self.channel.0.send(WebGPURequest::DestroyContext {
63            context_id: self.context_id,
64        }) {
65            warn!(
66                "Failed to send DestroyContext({:?}): {error}",
67                self.context_id,
68            );
69        }
70    }
71}
72
73#[derive(JSTraceable, MallocSizeOf)]
74#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
75struct GPUCanvasConfiguration {
76    alpha_mode: GPUCanvasAlphaMode,
77    device: Dom<GPUDevice>,
78    format: GPUTextureFormat,
79    usage: u32,
80    view_formats: Vec<GPUTextureFormat>,
81}
82
83impl From<&RootedGPUCanvasConfiguration> for GPUCanvasConfiguration {
84    fn from(value: &RootedGPUCanvasConfiguration) -> GPUCanvasConfiguration {
85        GPUCanvasConfiguration {
86            alpha_mode: value.alphaMode,
87            device: value.device.as_traced(),
88            format: value.format,
89            usage: value.usage,
90            view_formats: value.viewFormats.clone(),
91        }
92    }
93}
94
95impl GPUCanvasConfiguration {
96    fn root(&self) -> RootedGPUCanvasConfiguration {
97        RootedGPUCanvasConfiguration {
98            alphaMode: self.alpha_mode,
99            device: self.device.as_rooted(),
100            format: self.format,
101            usage: self.usage,
102            viewFormats: self.view_formats.clone(),
103        }
104    }
105}
106
107#[dom_struct]
108pub(crate) struct GPUCanvasContext {
109    reflector_: Reflector,
110    /// <https://gpuweb.github.io/gpuweb/#dom-gpucanvascontext-canvas>
111    canvas: HTMLCanvasElementOrOffscreenCanvas,
112    /// <https://gpuweb.github.io/gpuweb/#dom-gpucanvascontext-configuration-slot>
113    configuration: RefCell<Option<GPUCanvasConfiguration>>,
114    /// <https://gpuweb.github.io/gpuweb/#dom-gpucanvascontext-texturedescriptor-slot>
115    texture_descriptor: RefCell<Option<GPUTextureDescriptor>>,
116    /// <https://gpuweb.github.io/gpuweb/#dom-gpucanvascontext-currenttexture-slot>
117    current_texture: MutNullableDom<GPUTexture>,
118    /// Set if image is cleared
119    /// (usually done by [`GPUCanvasContext::replace_drawing_buffer`])
120    cleared: Cell<bool>,
121    droppable: DroppableGPUCanvasContext,
122}
123
124impl GPUCanvasContext {
125    #[cfg_attr(crown, expect(crown::unrooted_must_root))]
126    fn new_inherited(
127        global: &GlobalScope,
128        canvas: HTMLCanvasElementOrOffscreenCanvas,
129        channel: WebGPU,
130    ) -> Self {
131        let (sender, receiver) = generic_channel::channel().unwrap();
132        let size = canvas.size().cast().cast_unit();
133        let mut buffer_ids = ArrayVec::<id::BufferId, PRESENTATION_BUFFER_COUNT>::new();
134        for _ in 0..PRESENTATION_BUFFER_COUNT {
135            buffer_ids.push(global.wgpu_id_hub().create_buffer_id());
136        }
137        if let Err(error) = channel.0.send(WebGPURequest::CreateContext {
138            buffer_ids,
139            size,
140            sender,
141        }) {
142            warn!("Failed to send CreateContext ({error:?})");
143        }
144        let context_id = receiver.recv().unwrap();
145
146        Self {
147            reflector_: Reflector::new(),
148            canvas,
149            configuration: RefCell::new(None),
150            texture_descriptor: RefCell::new(None),
151            current_texture: MutNullableDom::default(),
152            cleared: Cell::new(true),
153            droppable: DroppableGPUCanvasContext {
154                context_id,
155                channel,
156            },
157        }
158    }
159
160    pub(crate) fn new(
161        cx: &mut JSContext,
162        global: &GlobalScope,
163        canvas: &HTMLCanvasElement,
164        channel: WebGPU,
165    ) -> DomRoot<Self> {
166        reflect_weak_referenceable_dom_object(
167            cx,
168            Rc::new(GPUCanvasContext::new_inherited(
169                global,
170                HTMLCanvasElementOrOffscreenCanvas::HTMLCanvasElement(Dom::from_ref(canvas)),
171                channel,
172            )),
173            global,
174        )
175    }
176}
177
178// Abstract ops from spec
179impl GPUCanvasContext {
180    pub(crate) fn set_image_key(&self, image_key: ImageKey) {
181        if let Err(error) = self.droppable.channel.0.send(WebGPURequest::SetImageKey {
182            context_id: self.context_id(),
183            image_key,
184        }) {
185            warn!(
186                "Failed to send WebGPURequest::Present({:?}) ({error})",
187                self.context_id()
188            );
189        }
190    }
191
192    /// <https://gpuweb.github.io/gpuweb/#abstract-opdef-updating-the-rendering-of-a-webgpu-canvas>
193    pub(crate) fn update_rendering(&self, canvas_epoch: Epoch) -> bool {
194        // Present by updating the image in WebRender. This will copy the texture into
195        // the presentation buffer and use it for presenting or send a cleared image to WebRender.
196        if let Err(error) = self.droppable.channel.0.send(WebGPURequest::Present {
197            context_id: self.context_id(),
198            pending_texture: self.pending_texture(),
199            size: self.size(),
200            canvas_epoch,
201        }) {
202            warn!(
203                "Failed to send WebGPURequest::Present({:?}) ({error})",
204                self.context_id()
205            );
206        }
207
208        // 1. Expire the current texture of context.
209        self.expire_current_texture(true);
210
211        true
212    }
213
214    /// <https://gpuweb.github.io/gpuweb/#abstract-opdef-gputexturedescriptor-for-the-canvas-and-configuration>
215    fn texture_descriptor_for_canvas_and_configuration(
216        &self,
217        configuration: &RootedGPUCanvasConfiguration,
218    ) -> GPUTextureDescriptor {
219        let size = self.size();
220        GPUTextureDescriptor {
221            size: GPUExtent3D::GPUExtent3DDict(GPUExtent3DDict {
222                width: size.width,
223                height: size.height,
224                depthOrArrayLayers: 1,
225            }),
226            format: configuration.format,
227            // We need to add `COPY_SRC` so we can copy texture to presentation buffer
228            // causes FAIL on webgpu:web_platform,canvas,configure:usage:*
229            usage: configuration.usage | GPUTextureUsageConstants::COPY_SRC,
230            viewFormats: configuration.viewFormats.clone(),
231            // All other members set to their defaults.
232            mipLevelCount: 1,
233            sampleCount: 1,
234            parent: GPUObjectDescriptorBase {
235                label: USVString::default(),
236            },
237            dimension: GPUTextureDimension::_2d,
238        }
239    }
240
241    /// <https://gpuweb.github.io/gpuweb/#abstract-opdef-expire-the-current-texture>
242    fn expire_current_texture(&self, skip_dirty: bool) {
243        // 1. If context.[[currentTexture]] is not null:
244
245        if let Some(current_texture) = self.current_texture.take() {
246            // 1.2 Set context.[[currentTexture]] to null.
247
248            // 1.1 Call context.[[currentTexture]].destroy()
249            // (without destroying context.[[drawingBuffer]])
250            // to terminate write access to the image.
251            current_texture.Destroy()
252            // we can safely destroy content here,
253            // because we already copied content when doing present
254            // or current texture is getting cleared
255        }
256        // We skip marking the canvas as dirty again if we are already
257        // in the process of updating the rendering.
258        if !skip_dirty {
259            // texture is either cleared or applied to canvas
260            self.mark_as_dirty();
261        }
262    }
263
264    /// <https://gpuweb.github.io/gpuweb/#abstract-opdef-replace-the-drawing-buffer>
265    fn replace_drawing_buffer(&self) {
266        // 1. Expire the current texture of context.
267        self.expire_current_texture(false);
268        // 2. Let configuration be context.[[configuration]].
269        // 3. Set context.[[drawingBuffer]] to
270        // a transparent black image of the same size as context.canvas
271        self.cleared.set(true);
272    }
273}
274
275// Internal helper methods
276impl GPUCanvasContext {
277    fn context_configuration(&self) -> Option<ContextConfiguration> {
278        let configuration = self.configuration.borrow();
279        let configuration = configuration.as_ref()?;
280        Some(ContextConfiguration {
281            device_id: configuration.device.id().0,
282            queue_id: configuration.device.queue_id().0,
283            format: match configuration.format {
284                GPUTextureFormat::Bgra8unorm => ImageFormat::BGRA8,
285                GPUTextureFormat::Rgba8unorm => ImageFormat::RGBA8,
286                _ => unreachable!("Configure method should set valid texture format"),
287            },
288            is_opaque: matches!(configuration.alpha_mode, GPUCanvasAlphaMode::Opaque),
289            size: self.size(),
290        })
291    }
292
293    fn pending_texture(&self) -> Option<PendingTexture> {
294        self.current_texture.get().map(|texture| PendingTexture {
295            texture_id: texture.id().0,
296            encoder_id: self.global().wgpu_id_hub().create_command_encoder_id(),
297            command_buffer_id: self.global().wgpu_id_hub().create_command_buffer_id(),
298            configuration: self
299                .context_configuration()
300                .expect("Context should be configured if there is a texture."),
301        })
302    }
303}
304
305impl CanvasContext for GPUCanvasContext {
306    type ID = WebGPUContextId;
307
308    fn context_id(&self) -> WebGPUContextId {
309        self.droppable.context_id
310    }
311
312    /// <https://gpuweb.github.io/gpuweb/#abstract-opdef-update-the-canvas-size>
313    fn resize(&self) {
314        // 1. Replace the drawing buffer of context.
315        self.replace_drawing_buffer();
316        // 2. Let configuration be context.[[configuration]]
317        let configuration = self.configuration.borrow();
318        // 3. If configuration is not null:
319        if let Some(configuration) = configuration.as_ref() {
320            // 3.1. Set context.[[textureDescriptor]] to the
321            // GPUTextureDescriptor for the canvas and configuration(canvas, configuration).
322            self.texture_descriptor.replace(Some(
323                self.texture_descriptor_for_canvas_and_configuration(&configuration.root()),
324            ));
325        }
326    }
327
328    fn reset_bitmap(&self) {
329        warn!("The GPUCanvasContext 'reset_bitmap' is not implemented yet");
330    }
331
332    /// <https://gpuweb.github.io/gpuweb/#ref-for-abstract-opdef-get-a-copy-of-the-image-contents-of-a-context%E2%91%A5>
333    fn get_image_data(&self) -> Option<Snapshot> {
334        // 1. Return a copy of the image contents of context.
335        Some(if self.cleared.get() {
336            Snapshot::cleared(self.size())
337        } else {
338            let (sender, receiver) = generic_channel::channel().unwrap();
339            self.droppable
340                .channel
341                .0
342                .send(WebGPURequest::GetImage {
343                    context_id: self.context_id(),
344                    // We need to read from the pending texture, if one exists.
345                    pending_texture: self.pending_texture(),
346                    sender,
347                })
348                .ok()?;
349            receiver.recv().ok()?.to_owned()
350        })
351    }
352
353    fn canvas(&self) -> Option<RootedHTMLCanvasElementOrOffscreenCanvas> {
354        Some(RootedHTMLCanvasElementOrOffscreenCanvas::from(&self.canvas))
355    }
356
357    fn mark_as_dirty(&self) {
358        self.canvas.mark_as_dirty();
359    }
360}
361
362impl GPUCanvasContextMethods<crate::DomTypeHolder> for GPUCanvasContext {
363    /// <https://gpuweb.github.io/gpuweb/#dom-gpucanvascontext-canvas>
364    fn Canvas(&self) -> RootedHTMLCanvasElementOrOffscreenCanvas {
365        RootedHTMLCanvasElementOrOffscreenCanvas::from(&self.canvas)
366    }
367
368    /// <https://gpuweb.github.io/gpuweb/#dom-gpucanvascontext-configure>
369    fn Configure(&self, configuration: &RootedGPUCanvasConfiguration) -> Fallible<()> {
370        // 1. Let device be configuration.device
371        let device = &configuration.device;
372
373        // 6. Let descriptor be the GPUTextureDescriptor for the canvas and configuration.
374        let descriptor = self.texture_descriptor_for_canvas_and_configuration(configuration);
375
376        // 2. Validate texture format required features of configuration.format with device.[[device]].
377        // 3. Validate texture format required features of each element of configuration.viewFormats with device.[[device]].
378        let (mut wgpu_descriptor, _) =
379            convert_texture_descriptor::<crate::DomTypeHolder>(&descriptor, device)?;
380        wgpu_descriptor.label = Some(Cow::Borrowed(
381            "dummy texture for texture descriptor validation",
382        ));
383
384        // 4. If Supported context formats does not contain configuration.format, throw a TypeError
385        if !supported_context_format(configuration.format) {
386            return Err(Error::Type(cformat!(
387                "Unsupported context format: {:?}",
388                configuration.format
389            )));
390        }
391
392        // 5. If configuration.usage includes the TRANSIENT_ATTACHMENT bit, throw a TypeError.
393        if configuration.usage & GPUTextureUsageConstants::TRANSIENT_ATTACHMENT != 0 {
394            return Err(Error::Type(
395                c"configuration.usage includes the TRANSIENT_ATTACHMENT bit".into(),
396            ));
397        }
398
399        // 7. Let this.[[configuration]] to configuration.
400        self.configuration.replace(Some(configuration.into()));
401
402        // 8. Set this.[[textureDescriptor]] to descriptor.
403        self.texture_descriptor.replace(Some(descriptor));
404
405        // 9. Replace the drawing buffer of this.
406        self.replace_drawing_buffer();
407
408        // 10. Issue the subsequent steps on the Device timeline of device.
409        // 10.1. Validate texture descriptor
410        let texture_id = self.global().wgpu_id_hub().create_texture_id();
411        self.droppable
412            .channel
413            .0
414            .send(WebGPURequest::ValidateTextureDescriptor {
415                device_id: device.id().0,
416                texture_id,
417                descriptor: wgpu_descriptor,
418            })
419            .expect("Failed to create WebGPU SwapChain");
420
421        Ok(())
422    }
423
424    /// <https://gpuweb.github.io/gpuweb/#dom-gpucanvascontext-unconfigure>
425    fn Unconfigure(&self) {
426        // 1. Set this.[[configuration]] to null.
427        self.configuration.take();
428        // 2. Set this.[[textureDescriptor]] to null.
429        self.current_texture.take();
430        // 3. Replace the drawing buffer of this.
431        self.replace_drawing_buffer();
432    }
433
434    /// <https://www.w3.org/TR/webgpu/#dom-gpucanvascontext-getconfiguration>
435    fn GetConfiguration(&self) -> Option<RootedGPUCanvasConfiguration> {
436        self.configuration
437            .borrow()
438            .as_ref()
439            .map(|configuration| configuration.root())
440    }
441
442    /// <https://gpuweb.github.io/gpuweb/#dom-gpucanvascontext-getcurrenttexture>
443    fn GetCurrentTexture(&self, cx: &mut JSContext) -> Fallible<DomRoot<GPUTexture>> {
444        // 1. If this.[[configuration]] is null, throw an InvalidStateError and return.
445        let configuration = self.configuration.borrow();
446        let Some(configuration) = configuration.as_ref() else {
447            return Err(Error::InvalidState(Some(
448                "GPUCanvasContext is not configured".into(),
449            )));
450        };
451        // 2. Assert this.[[textureDescriptor]] is not null.
452        let texture_descriptor = self.texture_descriptor.borrow();
453        let texture_descriptor = texture_descriptor.as_ref().unwrap();
454        // 3. Let device be this.[[configuration]].device.
455        let device = &configuration.device;
456        let current_texture = if let Some(current_texture) = self.current_texture.get() {
457            current_texture
458        } else {
459            // If this.[[currentTexture]] is null:
460            // 4.1. Replace the drawing buffer of this.
461            self.replace_drawing_buffer();
462            // 4.2. Set this.[[currentTexture]] to the result of calling device.createTexture() with this.[[textureDescriptor]],
463            // except with the GPUTexture’s underlying storage pointing to this.[[drawingBuffer]].
464            let current_texture = device.CreateTexture(cx, texture_descriptor)?;
465            self.current_texture.set(Some(&current_texture));
466
467            // The content of the texture is the content of the canvas.
468            self.cleared.set(false);
469
470            current_texture
471        };
472        // 6. Return this.[[currentTexture]].
473        Ok(current_texture)
474    }
475}
script/dom/webgpu/gpucanvascontext.rs

script/dom/webgpu/
gpucanvascontext.rs
