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;
19#[cfg(feature = "webgl")]
20use servo_base::generic_channel::GenericSharedMemory;
21use servo_base::id::{ImageDataId, ImageDataIndex};
22use servo_constellation_traits::SerializableImageData;
23
24use crate::dom::bindings::buffer_source::{
25    HeapBufferSource, create_buffer_source, create_heap_buffer_source_with_length,
26};
27use crate::dom::bindings::codegen::Bindings::CanvasRenderingContext2DBinding::{
28    ImageDataMethods, ImageDataPixelFormat, ImageDataSettings, PredefinedColorSpace,
29};
30use crate::dom::bindings::error::{Error, Fallible};
31use crate::dom::bindings::root::DomRoot;
32use crate::dom::bindings::serializable::Serializable;
33use crate::dom::bindings::structuredclone::StructuredData;
34use crate::dom::globalscope::GlobalScope;
35
36#[dom_struct]
37pub(crate) struct ImageData {
38    reflector_: Reflector,
39    width: u32,
40    height: u32,
41    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-data>
42    #[ignore_malloc_size_of = "mozjs"]
43    data: HeapBufferSource<ClampedU8>,
44    pixel_format: ImageDataPixelFormat,
45    color_space: PredefinedColorSpace,
46}
47
48impl ImageData {
49    pub(crate) fn new(
50        cx: &mut JSContext,
51        global: &GlobalScope,
52        width: u32,
53        height: u32,
54        mut data: Option<Vec<u8>>,
55    ) -> Fallible<DomRoot<ImageData>> {
56        let len =
57            pixels::compute_rgba8_byte_length_if_within_limit(width as usize, height as usize)
58                .ok_or(Error::Range(
59                    c"The requested image size exceeds the supported range".to_owned(),
60                ))?;
61
62        let settings = ImageDataSettings {
63            colorSpace: Some(PredefinedColorSpace::Srgb),
64            pixelFormat: ImageDataPixelFormat::Rgba_unorm8,
65        };
66
67        if let Some(ref mut d) = data {
68            d.resize(len as usize, 0);
69
70            rooted!(&in(cx) let mut js_object = std::ptr::null_mut::<JSObject>());
71            let _buffer_source =
72                create_buffer_source::<ClampedU8>(cx, &d[..], js_object.handle_mut())
73                    .map_err(|_| Error::JSFailed)?;
74            auto_root!(&in(cx) let data = TypedArray::<ClampedU8, *mut JSObject>::from(js_object.get()).map_err(|_| Error::JSFailed)?);
75
76            Self::Constructor_(cx, global, None, data, width, Some(height), &settings)
77        } else {
78            Self::Constructor(cx, global, None, width, height, &settings)
79        }
80    }
81
82    #[allow(clippy::too_many_arguments)]
83    /// <https://html.spec.whatwg.org/multipage/#initialize-an-imagedata-object>
84    fn initialize(
85        cx: &mut JSContext,
86        pixels_per_row: u32,
87        rows: u32,
88        settings: &ImageDataSettings,
89        source: Option<CustomAutoRooterGuard<Uint8ClampedArray>>,
90        default_color_space: Option<PredefinedColorSpace>,
91        global: &GlobalScope,
92        proto: Option<HandleObject>,
93    ) -> Fallible<DomRoot<ImageData>> {
94        // 1. If source was given:
95        let data = if let Some(source) = source {
96            // 1. If settings["pixelFormat"] equals "rgba-unorm8" and source is not a Uint8ClampedArray,
97            // then throw an "InvalidStateError" DOMException.
98            // 2. If settings["pixelFormat"] is "rgba-float16" and source is not a Float16Array,
99            // then throw an "InvalidStateError" DOMException.
100            if !matches!(settings.pixelFormat, ImageDataPixelFormat::Rgba_unorm8) {
101                // we currently support only rgba-unorm8
102                return Err(Error::InvalidState(None));
103            }
104            // 3. Initialize the data attribute of imageData to source.
105            HeapBufferSource::<ClampedU8>::from_view(cx, source)
106        } else {
107            // 2. Otherwise (source was not given):
108            match settings.pixelFormat {
109                ImageDataPixelFormat::Rgba_unorm8 => {
110                    // 1. If settings["pixelFormat"] is "rgba-unorm8",
111                    // then initialize the data attribute of imageData to a new Uint8ClampedArray object.
112                    // The Uint8ClampedArray object must use a new ArrayBuffer for its storage,
113                    // and must have a zero byte offset and byte length equal to the length of its storage, in bytes.
114                    // The storage ArrayBuffer must have a length of 4 × rows × pixelsPerRow bytes.
115                    // 3. If the storage ArrayBuffer could not be allocated,
116                    // then rethrow the RangeError thrown by JavaScript, and return.
117                    create_heap_buffer_source_with_length(cx, 4 * rows * pixels_per_row)?
118                },
119                // 3. Otherwise, if settings["pixelFormat"] is "rgba-float16",
120                // then initialize the data attribute of imageData to a new Float16Array object.
121                // The Float16Array object must use a new ArrayBuffer for its storage,
122                // and must have a zero byte offset and byte length equal to the length of its storage, in bytes.
123                // The storage ArrayBuffer must have a length of 8 × rows × pixelsPerRow bytes.
124                // not implemented yet
125            }
126        };
127        // 3. Initialize the width attribute of imageData to pixelsPerRow.
128        let width = pixels_per_row;
129        // 4. Initialize the height attribute of imageData to rows.
130        let height = rows;
131        // 5. Initialize the pixelFormat attribute of imageData to settings["pixelFormat"].
132        let pixel_format = settings.pixelFormat;
133        // 6. If settings["colorSpace"] exists,
134        // then initialize the colorSpace attribute of imageData to settings["colorSpace"].
135        let color_space = settings
136            .colorSpace
137            // 7. Otherwise, if defaultColorSpace was given,
138            // then initialize the colorSpace attribute of imageData to defaultColorSpace.
139            .or(default_color_space)
140            // 8. Otherwise, initialize the colorSpace attribute of imageData to "srgb".
141            .unwrap_or(PredefinedColorSpace::Srgb);
142
143        Ok(reflect_dom_object_with_proto(
144            cx,
145            Box::new(ImageData {
146                reflector_: Reflector::new(),
147                width,
148                height,
149                data: *data.into_box(),
150                pixel_format,
151                color_space,
152            }),
153            global,
154            proto,
155        ))
156    }
157
158    pub(crate) fn is_detached(&self, cx: &mut JSContext) -> bool {
159        self.data.is_detached_buffer(cx)
160    }
161
162    pub(crate) fn get_size(&self) -> Size2D<u32> {
163        Size2D::new(self.Width(), self.Height())
164    }
165
166    /// Nothing must change the array on the JS side while the slice is live.
167    #[expect(unsafe_code)]
168    pub(crate) unsafe fn as_slice(&self, no_gc: &NoGC) -> &[u8] {
169        assert!(self.data.is_initialized());
170        let internal_data = self
171            .data
172            .get_typed_array()
173            .expect("Failed to get Data from ImageData.");
174        // NOTE(nox): This is just as unsafe as `as_slice` itself even though we
175        // are extending the lifetime of the slice, because the data in
176        // this ImageData instance will never change. The method is thus unsafe
177        // because the array may be manipulated from JS while the reference
178        // is live.
179        unsafe {
180            let ptr: *const [u8] = internal_data.as_slice_safe(no_gc).unwrap_or(&[]) as *const _;
181            &*ptr
182        }
183    }
184
185    /// Nothing must change the array on the JS side while the slice is live.
186    #[expect(unsafe_code)]
187    pub(crate) unsafe fn get_rect(&self, no_gc: &NoGC, rect: Rect<u32>) -> Cow<'_, [u8]> {
188        pixels::rgba8_get_rect(
189            unsafe { self.as_slice(no_gc) },
190            self.get_size().to_u32(),
191            rect,
192        )
193    }
194
195    #[expect(unsafe_code)]
196    pub(crate) fn get_snapshot_rect(&self, no_gc: &NoGC, rect: Rect<u32>) -> Snapshot {
197        Snapshot::from_vec(
198            rect.size,
199            SnapshotPixelFormat::RGBA,
200            SnapshotAlphaMode::Transparent {
201                premultiplied: false,
202            },
203            unsafe { self.get_rect(no_gc, rect).into_owned() },
204        )
205    }
206
207    #[expect(unsafe_code)]
208    pub(crate) fn get_snapshot(&self, no_gc: &NoGC) -> Snapshot {
209        Snapshot::from_vec(
210            self.get_size(),
211            SnapshotPixelFormat::RGBA,
212            SnapshotAlphaMode::Transparent {
213                premultiplied: false,
214            },
215            unsafe { self.as_slice(no_gc).to_vec() },
216        )
217    }
218
219    #[expect(unsafe_code)]
220    #[cfg(feature = "webgl")]
221    pub(crate) fn to_shared_memory(&self, no_gc: &NoGC) -> GenericSharedMemory {
222        // This is safe because we copy the slice content
223        GenericSharedMemory::from_bytes(unsafe { self.as_slice(no_gc) })
224    }
225
226    #[expect(unsafe_code)]
227    pub(crate) fn to_vec(&self, no_gc: &NoGC) -> Vec<u8> {
228        // This is safe because we copy the slice content
229        unsafe { self.as_slice(no_gc) }.to_vec()
230    }
231}
232
233impl Serializable for ImageData {
234    type Index = ImageDataIndex;
235    type Data = SerializableImageData;
236
237    /// <https://html.spec.whatwg.org/multipage/#the-imagedata-interface:serializable-objects>
238    fn serialize(&self, no_gc: &NoGC) -> Result<(ImageDataId, Self::Data), ()> {
239        // Step 1 Set serialized.[[Data]] to the sub-serialization of the value of value's data attribute.
240        let data = self.to_vec(no_gc);
241
242        // Step 2 Set serialized.[[Width]] to the value of value's width attribute.
243        // Step 3 Set serialized.[[Height]] to the value of value's height attribute.
244        // Step 4 Set serialized.[[ColorSpace]] to the value of value's colorSpace attribute.
245        // Step 5 Set serialized.[[PixelFormat]] to the value of value's pixelFormat attribute.
246        // Note: Since we don't support Float16Array and display-p3 color space
247        // we don't need to serialize colorSpace and pixelFormat
248        let serialized = SerializableImageData {
249            data,
250            width: self.width,
251            height: self.height,
252        };
253        Ok((ImageDataId::new(), serialized))
254    }
255
256    /// <https://html.spec.whatwg.org/multipage/#the-imagedata-interface:deserialization-steps>
257    fn deserialize(
258        cx: &mut JSContext,
259        owner: &GlobalScope,
260        serialized: Self::Data,
261    ) -> Result<DomRoot<Self>, ()> {
262        // Step 1 Initialize value's data attribute to the sub-deserialization of serialized.[[Data]].
263        // Step 2 Initialize value's width attribute to serialized.[[Width]].
264        // Step 3 Initialize value's height attribute to serialized.[[Height]].
265        // Step 4 Initialize value's colorSpace attribute to serialized.[[ColorSpace]].
266        // Step 5 Initialize value's pixelFormat attribute to serialized.[[PixelFormat]].
267        ImageData::new(
268            cx,
269            owner,
270            serialized.width,
271            serialized.height,
272            Some(serialized.data),
273        )
274        .map_err(|_| ())
275    }
276
277    fn serialized_storage<'a>(
278        reader: StructuredData<'a, '_>,
279    ) -> &'a mut Option<FxHashMap<ImageDataId, Self::Data>> {
280        match reader {
281            StructuredData::Reader(r) => &mut r.image_data,
282            StructuredData::Writer(w) => &mut w.image_data,
283        }
284    }
285}
286
287impl ImageDataMethods<crate::DomTypeHolder> for ImageData {
288    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata>
289    fn Constructor(
290        cx: &mut JSContext,
291        global: &GlobalScope,
292        proto: Option<HandleObject>,
293        sw: u32,
294        sh: u32,
295        settings: &ImageDataSettings,
296    ) -> Fallible<DomRoot<Self>> {
297        // 1. If one or both of sw and sh are zero, then throw an "IndexSizeError" DOMException.
298        if sw == 0 || sh == 0 {
299            return Err(Error::IndexSize(None));
300        }
301
302        // When a constructor is called for an ImageData that is too large, other browsers throw
303        // IndexSizeError rather than RangeError here, so we do the same.
304        pixels::compute_rgba8_byte_length_if_within_limit(sw as usize, sh as usize)
305            .ok_or(Error::IndexSize(None))?;
306
307        // 2. Initialize this given sw, sh, and settings.
308        // 3. Initialize the image data of this to transparent black.
309        Self::initialize(cx, sw, sh, settings, None, None, global, proto)
310    }
311
312    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-with-data>
313    fn Constructor_(
314        cx: &mut JSContext,
315        global: &GlobalScope,
316        proto: Option<HandleObject>,
317        data: CustomAutoRooterGuard<Uint8ClampedArray>,
318        sw: u32,
319        sh: Option<u32>,
320        settings: &ImageDataSettings,
321    ) -> Fallible<DomRoot<Self>> {
322        // 1. Let bytesPerPixel be 4 if settings["pixelFormat"] is "rgba-unorm8"; otherwise 8.
323        let bytes_per_pixel = match settings.pixelFormat {
324            ImageDataPixelFormat::Rgba_unorm8 => 4,
325        };
326        // 2. Let length be the buffer source byte length of data.
327        let length = data.len();
328        if length == 0 {
329            return Err(Error::InvalidState(None));
330        }
331        // 3. If length is not a nonzero integral multiple of bytesPerPixel,
332        // then throw an "InvalidStateError" DOMException.
333        if !length.is_multiple_of(bytes_per_pixel) {
334            return Err(Error::InvalidState(None));
335        }
336        // 4. Let length be length divided by bytesPerPixel.
337        let length = length / bytes_per_pixel;
338        // 5. If length is not an integral multiple of sw, then throw an "IndexSizeError" DOMException.
339        if sw == 0 || !length.is_multiple_of(sw as usize) {
340            return Err(Error::IndexSize(None));
341        }
342        // 6. Let height be length divided by sw.
343        let height = length / sw as usize;
344        // 7. If sh was given and its value is not equal to height, then throw an "IndexSizeError" DOMException.
345        if sh.is_some_and(|x| height != x as usize) {
346            return Err(Error::IndexSize(None));
347        }
348        // 8. Initialize this given sw, sh, settings, and source set to data.
349        Self::initialize(
350            cx,
351            sw,
352            height as u32,
353            settings,
354            Some(data),
355            None,
356            global,
357            proto,
358        )
359    }
360
361    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-width>
362    fn Width(&self) -> u32 {
363        self.width
364    }
365
366    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-height>
367    fn Height(&self) -> u32 {
368        self.height
369    }
370
371    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-data>
372    fn GetData(&self) -> Fallible<RootedTraceableBox<HeapUint8ClampedArray>> {
373        self.data.get_typed_array().map_err(|_| Error::JSFailed)
374    }
375
376    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-pixelformat>
377    fn PixelFormat(&self) -> ImageDataPixelFormat {
378        self.pixel_format
379    }
380
381    /// <https://html.spec.whatwg.org/multipage/#dom-imagedata-colorspace>
382    fn ColorSpace(&self) -> PredefinedColorSpace {
383        self.color_space
384    }
385}
script/dom/canvas/imagedata.rs

script/dom/canvas/
imagedata.rs
