script/dom/canvas/
imagedata.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::vec::Vec;
7
8use dom_struct::dom_struct;
9use euclid::default::{Rect, Size2D};
10use js::context::{JSContext, NoGC};
11use js::gc::CustomAutoRooterGuard;
12use js::jsapi::JSObject;
13use js::rust::HandleObject;
14use js::typedarray::{ClampedU8, HeapUint8ClampedArray, TypedArray, Uint8ClampedArray};
15use pixels::{Snapshot, SnapshotAlphaMode, SnapshotPixelFormat};
16use rustc_hash::FxHashMap;
17use script_bindings::reflector::{Reflector, reflect_dom_object_with_proto};
18use script_bindings::trace::RootedTraceableBox;
19use servo_base::generic_channel::GenericSharedMemory;
20use servo_base::id::{ImageDataId, ImageDataIndex};
21use servo_constellation_traits::SerializableImageData;
22
23use crate::dom::bindings::buffer_source::{
24    HeapBufferSource, create_buffer_source, create_heap_buffer_source_with_length,
25};
26use crate::dom::bindings::codegen::Bindings::CanvasRenderingContext2DBinding::{
27    ImageDataMethods, ImageDataPixelFormat, ImageDataSettings, PredefinedColorSpace,
28};
29use crate::dom::bindings::error::{Error, Fallible};
30use crate::dom::bindings::root::DomRoot;
31use crate::dom::bindings::serializable::Serializable;
32use crate::dom::bindings::structuredclone::StructuredData;
33use crate::dom::globalscope::GlobalScope;
34
35#[dom_struct]
36pub(crate) struct ImageData {
37    reflector_: Reflector,
38    width: u32,
39    height: u32,
40    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-data>
41    #[ignore_malloc_size_of = "mozjs"]
42    data: HeapBufferSource<ClampedU8>,
43    pixel_format: ImageDataPixelFormat,
44    color_space: PredefinedColorSpace,
45}
46
47impl ImageData {
48    pub(crate) fn new(
49        cx: &mut JSContext,
50        global: &GlobalScope,
51        width: u32,
52        height: u32,
53        mut data: Option<Vec<u8>>,
54    ) -> Fallible<DomRoot<ImageData>> {
55        let len =
56            pixels::compute_rgba8_byte_length_if_within_limit(width as usize, height as usize)
57                .ok_or(Error::Range(
58                    c"The requested image size exceeds the supported range".to_owned(),
59                ))?;
60
61        let settings = ImageDataSettings {
62            colorSpace: Some(PredefinedColorSpace::Srgb),
63            pixelFormat: ImageDataPixelFormat::Rgba_unorm8,
64        };
65
66        if let Some(ref mut d) = data {
67            d.resize(len as usize, 0);
68
69            rooted!(&in(cx) let mut js_object = std::ptr::null_mut::<JSObject>());
70            let _buffer_source =
71                create_buffer_source::<ClampedU8>(cx, &d[..], js_object.handle_mut())
72                    .map_err(|_| Error::JSFailed)?;
73            auto_root!(&in(cx) let data = TypedArray::<ClampedU8, *mut JSObject>::from(js_object.get()).map_err(|_| Error::JSFailed)?);
74
75            Self::Constructor_(cx, global, None, data, width, Some(height), &settings)
76        } else {
77            Self::Constructor(cx, global, None, width, height, &settings)
78        }
79    }
80
81    #[allow(clippy::too_many_arguments)]
82    /// <https://html.spec.whatwg.org/multipage/#initialize-an-imagedata-object>
83    fn initialize(
84        cx: &mut JSContext,
85        pixels_per_row: u32,
86        rows: u32,
87        settings: &ImageDataSettings,
88        source: Option<CustomAutoRooterGuard<Uint8ClampedArray>>,
89        default_color_space: Option<PredefinedColorSpace>,
90        global: &GlobalScope,
91        proto: Option<HandleObject>,
92    ) -> Fallible<DomRoot<ImageData>> {
93        // 1. If source was given:
94        let data = if let Some(source) = source {
95            // 1. If settings["pixelFormat"] equals "rgba-unorm8" and source is not a Uint8ClampedArray,
96            // then throw an "InvalidStateError" DOMException.
97            // 2. If settings["pixelFormat"] is "rgba-float16" and source is not a Float16Array,
98            // then throw an "InvalidStateError" DOMException.
99            if !matches!(settings.pixelFormat, ImageDataPixelFormat::Rgba_unorm8) {
100                // we currently support only rgba-unorm8
101                return Err(Error::InvalidState(None));
102            }
103            // 3. Initialize the data attribute of imageData to source.
104            HeapBufferSource::<ClampedU8>::from_view(cx, source)
105        } else {
106            // 2. Otherwise (source was not given):
107            match settings.pixelFormat {
108                ImageDataPixelFormat::Rgba_unorm8 => {
109                    // 1. If settings["pixelFormat"] is "rgba-unorm8",
110                    // then initialize the data attribute of imageData to a new Uint8ClampedArray object.
111                    // The Uint8ClampedArray object must use a new ArrayBuffer for its storage,
112                    // and must have a zero byte offset and byte length equal to the length of its storage, in bytes.
113                    // The storage ArrayBuffer must have a length of 4 × rows × pixelsPerRow bytes.
114                    // 3. If the storage ArrayBuffer could not be allocated,
115                    // then rethrow the RangeError thrown by JavaScript, and return.
116                    create_heap_buffer_source_with_length(cx, 4 * rows * pixels_per_row)?
117                },
118                // 3. Otherwise, if settings["pixelFormat"] is "rgba-float16",
119                // then initialize the data attribute of imageData to a new Float16Array object.
120                // The Float16Array object must use a new ArrayBuffer for its storage,
121                // and must have a zero byte offset and byte length equal to the length of its storage, in bytes.
122                // The storage ArrayBuffer must have a length of 8 × rows × pixelsPerRow bytes.
123                // not implemented yet
124            }
125        };
126        // 3. Initialize the width attribute of imageData to pixelsPerRow.
127        let width = pixels_per_row;
128        // 4. Initialize the height attribute of imageData to rows.
129        let height = rows;
130        // 5. Initialize the pixelFormat attribute of imageData to settings["pixelFormat"].
131        let pixel_format = settings.pixelFormat;
132        // 6. If settings["colorSpace"] exists,
133        // then initialize the colorSpace attribute of imageData to settings["colorSpace"].
134        let color_space = settings
135            .colorSpace
136            // 7. Otherwise, if defaultColorSpace was given,
137            // then initialize the colorSpace attribute of imageData to defaultColorSpace.
138            .or(default_color_space)
139            // 8. Otherwise, initialize the colorSpace attribute of imageData to "srgb".
140            .unwrap_or(PredefinedColorSpace::Srgb);
141
142        Ok(reflect_dom_object_with_proto(
143            cx,
144            Box::new(ImageData {
145                reflector_: Reflector::new(),
146                width,
147                height,
148                data: *data.into_box(),
149                pixel_format,
150                color_space,
151            }),
152            global,
153            proto,
154        ))
155    }
156
157    pub(crate) fn is_detached(&self, cx: &mut JSContext) -> bool {
158        self.data.is_detached_buffer(cx)
159    }
160
161    pub(crate) fn get_size(&self) -> Size2D<u32> {
162        Size2D::new(self.Width(), self.Height())
163    }
164
165    /// Nothing must change the array on the JS side while the slice is live.
166    #[expect(unsafe_code)]
167    pub(crate) unsafe fn as_slice(&self, no_gc: &NoGC) -> &[u8] {
168        assert!(self.data.is_initialized());
169        let internal_data = self
170            .data
171            .get_typed_array()
172            .expect("Failed to get Data from ImageData.");
173        // NOTE(nox): This is just as unsafe as `as_slice` itself even though we
174        // are extending the lifetime of the slice, because the data in
175        // this ImageData instance will never change. The method is thus unsafe
176        // because the array may be manipulated from JS while the reference
177        // is live.
178        unsafe {
179            let ptr: *const [u8] = internal_data.as_slice_safe(no_gc).unwrap_or(&[]) as *const _;
180            &*ptr
181        }
182    }
183
184    /// Nothing must change the array on the JS side while the slice is live.
185    #[expect(unsafe_code)]
186    pub(crate) unsafe fn get_rect(&self, no_gc: &NoGC, rect: Rect<u32>) -> Cow<'_, [u8]> {
187        pixels::rgba8_get_rect(
188            unsafe { self.as_slice(no_gc) },
189            self.get_size().to_u32(),
190            rect,
191        )
192    }
193
194    #[expect(unsafe_code)]
195    pub(crate) fn get_snapshot_rect(&self, no_gc: &NoGC, rect: Rect<u32>) -> Snapshot {
196        Snapshot::from_vec(
197            rect.size,
198            SnapshotPixelFormat::RGBA,
199            SnapshotAlphaMode::Transparent {
200                premultiplied: false,
201            },
202            unsafe { self.get_rect(no_gc, rect).into_owned() },
203        )
204    }
205
206    #[expect(unsafe_code)]
207    pub(crate) fn get_snapshot(&self, no_gc: &NoGC) -> Snapshot {
208        Snapshot::from_vec(
209            self.get_size(),
210            SnapshotPixelFormat::RGBA,
211            SnapshotAlphaMode::Transparent {
212                premultiplied: false,
213            },
214            unsafe { self.as_slice(no_gc).to_vec() },
215        )
216    }
217
218    #[expect(unsafe_code)]
219    pub(crate) fn to_shared_memory(&self, no_gc: &NoGC) -> GenericSharedMemory {
220        // This is safe because we copy the slice content
221        GenericSharedMemory::from_bytes(unsafe { self.as_slice(no_gc) })
222    }
223
224    #[expect(unsafe_code)]
225    pub(crate) fn to_vec(&self, no_gc: &NoGC) -> Vec<u8> {
226        // This is safe because we copy the slice content
227        unsafe { self.as_slice(no_gc) }.to_vec()
228    }
229}
230
231impl Serializable for ImageData {
232    type Index = ImageDataIndex;
233    type Data = SerializableImageData;
234
235    /// <https://html.spec.whatwg.org/multipage/#the-imagedata-interface:serializable-objects>
236    fn serialize(&self, no_gc: &NoGC) -> Result<(ImageDataId, Self::Data), ()> {
237        // Step 1 Set serialized.[[Data]] to the sub-serialization of the value of value's data attribute.
238        let data = self.to_vec(no_gc);
239
240        // Step 2 Set serialized.[[Width]] to the value of value's width attribute.
241        // Step 3 Set serialized.[[Height]] to the value of value's height attribute.
242        // Step 4 Set serialized.[[ColorSpace]] to the value of value's colorSpace attribute.
243        // Step 5 Set serialized.[[PixelFormat]] to the value of value's pixelFormat attribute.
244        // Note: Since we don't support Float16Array and display-p3 color space
245        // we don't need to serialize colorSpace and pixelFormat
246        let serialized = SerializableImageData {
247            data,
248            width: self.width,
249            height: self.height,
250        };
251        Ok((ImageDataId::new(), serialized))
252    }
253
254    /// <https://html.spec.whatwg.org/multipage/#the-imagedata-interface:deserialization-steps>
255    fn deserialize(
256        cx: &mut JSContext,
257        owner: &GlobalScope,
258        serialized: Self::Data,
259    ) -> Result<DomRoot<Self>, ()> {
260        // Step 1 Initialize value's data attribute to the sub-deserialization of serialized.[[Data]].
261        // Step 2 Initialize value's width attribute to serialized.[[Width]].
262        // Step 3 Initialize value's height attribute to serialized.[[Height]].
263        // Step 4 Initialize value's colorSpace attribute to serialized.[[ColorSpace]].
264        // Step 5 Initialize value's pixelFormat attribute to serialized.[[PixelFormat]].
265        ImageData::new(
266            cx,
267            owner,
268            serialized.width,
269            serialized.height,
270            Some(serialized.data),
271        )
272        .map_err(|_| ())
273    }
274
275    fn serialized_storage<'a>(
276        reader: StructuredData<'a, '_>,
277    ) -> &'a mut Option<FxHashMap<ImageDataId, Self::Data>> {
278        match reader {
279            StructuredData::Reader(r) => &mut r.image_data,
280            StructuredData::Writer(w) => &mut w.image_data,
281        }
282    }
283}
284
285impl ImageDataMethods<crate::DomTypeHolder> for ImageData {
286    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata>
287    fn Constructor(
288        cx: &mut JSContext,
289        global: &GlobalScope,
290        proto: Option<HandleObject>,
291        sw: u32,
292        sh: u32,
293        settings: &ImageDataSettings,
294    ) -> Fallible<DomRoot<Self>> {
295        // 1. If one or both of sw and sh are zero, then throw an "IndexSizeError" DOMException.
296        if sw == 0 || sh == 0 {
297            return Err(Error::IndexSize(None));
298        }
299
300        // When a constructor is called for an ImageData that is too large, other browsers throw
301        // IndexSizeError rather than RangeError here, so we do the same.
302        pixels::compute_rgba8_byte_length_if_within_limit(sw as usize, sh as usize)
303            .ok_or(Error::IndexSize(None))?;
304
305        // 2. Initialize this given sw, sh, and settings.
306        // 3. Initialize the image data of this to transparent black.
307        Self::initialize(cx, sw, sh, settings, None, None, global, proto)
308    }
309
310    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-with-data>
311    fn Constructor_(
312        cx: &mut JSContext,
313        global: &GlobalScope,
314        proto: Option<HandleObject>,
315        data: CustomAutoRooterGuard<Uint8ClampedArray>,
316        sw: u32,
317        sh: Option<u32>,
318        settings: &ImageDataSettings,
319    ) -> Fallible<DomRoot<Self>> {
320        // 1. Let bytesPerPixel be 4 if settings["pixelFormat"] is "rgba-unorm8"; otherwise 8.
321        let bytes_per_pixel = match settings.pixelFormat {
322            ImageDataPixelFormat::Rgba_unorm8 => 4,
323        };
324        // 2. Let length be the buffer source byte length of data.
325        let length = data.len();
326        if length == 0 {
327            return Err(Error::InvalidState(None));
328        }
329        // 3. If length is not a nonzero integral multiple of bytesPerPixel,
330        // then throw an "InvalidStateError" DOMException.
331        if !length.is_multiple_of(bytes_per_pixel) {
332            return Err(Error::InvalidState(None));
333        }
334        // 4. Let length be length divided by bytesPerPixel.
335        let length = length / bytes_per_pixel;
336        // 5. If length is not an integral multiple of sw, then throw an "IndexSizeError" DOMException.
337        if sw == 0 || !length.is_multiple_of(sw as usize) {
338            return Err(Error::IndexSize(None));
339        }
340        // 6. Let height be length divided by sw.
341        let height = length / sw as usize;
342        // 7. If sh was given and its value is not equal to height, then throw an "IndexSizeError" DOMException.
343        if sh.is_some_and(|x| height != x as usize) {
344            return Err(Error::IndexSize(None));
345        }
346        // 8. Initialize this given sw, sh, settings, and source set to data.
347        Self::initialize(
348            cx,
349            sw,
350            height as u32,
351            settings,
352            Some(data),
353            None,
354            global,
355            proto,
356        )
357    }
358
359    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-width>
360    fn Width(&self) -> u32 {
361        self.width
362    }
363
364    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-height>
365    fn Height(&self) -> u32 {
366        self.height
367    }
368
369    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-data>
370    fn GetData(&self) -> Fallible<RootedTraceableBox<HeapUint8ClampedArray>> {
371        self.data.get_typed_array().map_err(|_| Error::JSFailed)
372    }
373
374    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-pixelformat>
375    fn PixelFormat(&self) -> ImageDataPixelFormat {
376        self.pixel_format
377    }
378
379    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-colorspace>
380    fn ColorSpace(&self) -> PredefinedColorSpace {
381        self.color_space
382    }
383}
script/dom/canvas/imagedata.rs

script/dom/canvas/
imagedata.rs
