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- /*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
- #include <AK/Base64.h>
- #include <AK/Checked.h>
- #include <AK/MemoryStream.h>
- #include <LibGfx/Bitmap.h>
- #include <LibGfx/ImageFormats/JPEGWriter.h>
- #include <LibGfx/ImageFormats/PNGWriter.h>
- #include <LibWeb/Bindings/ExceptionOrUtils.h>
- #include <LibWeb/Bindings/HTMLCanvasElementPrototype.h>
- #include <LibWeb/CSS/StyleComputer.h>
- #include <LibWeb/CSS/StyleValues/IdentifierStyleValue.h>
- #include <LibWeb/CSS/StyleValues/RatioStyleValue.h>
- #include <LibWeb/CSS/StyleValues/StyleValueList.h>
- #include <LibWeb/DOM/Document.h>
- #include <LibWeb/HTML/CanvasRenderingContext2D.h>
- #include <LibWeb/HTML/HTMLCanvasElement.h>
- #include <LibWeb/HTML/Numbers.h>
- #include <LibWeb/HTML/Scripting/ExceptionReporter.h>
- #include <LibWeb/Layout/CanvasBox.h>
- #include <LibWeb/Platform/EventLoopPlugin.h>
- #include <LibWeb/WebIDL/AbstractOperations.h>
- namespace Web::HTML {
- JS_DEFINE_ALLOCATOR(HTMLCanvasElement);
- static constexpr auto max_canvas_area = 16384 * 16384;
- HTMLCanvasElement::HTMLCanvasElement(DOM::Document& document, DOM::QualifiedName qualified_name)
- : HTMLElement(document, move(qualified_name))
- {
- }
- HTMLCanvasElement::~HTMLCanvasElement() = default;
- void HTMLCanvasElement::initialize(JS::Realm& realm)
- {
- Base::initialize(realm);
- WEB_SET_PROTOTYPE_FOR_INTERFACE(HTMLCanvasElement);
- }
- void HTMLCanvasElement::visit_edges(Cell::Visitor& visitor)
- {
- Base::visit_edges(visitor);
- m_context.visit(
- [&](JS::NonnullGCPtr<CanvasRenderingContext2D>& context) {
- visitor.visit(context);
- },
- [&](JS::NonnullGCPtr<WebGL::WebGLRenderingContext>& context) {
- visitor.visit(context);
- },
- [](Empty) {
- });
- }
- void HTMLCanvasElement::apply_presentational_hints(CSS::StyleProperties& style) const
- {
- // https://html.spec.whatwg.org/multipage/rendering.html#attributes-for-embedded-content-and-images
- // The width and height attributes map to the aspect-ratio property on canvas elements.
- // FIXME: Multiple elements have aspect-ratio presentational hints, make this into a helper function
- // https://html.spec.whatwg.org/multipage/rendering.html#map-to-the-aspect-ratio-property
- // if element has both attributes w and h, and parsing those attributes' values using the rules for parsing non-negative integers doesn't generate an error for either
- auto w = parse_non_negative_integer(get_attribute_value(HTML::AttributeNames::width));
- auto h = parse_non_negative_integer(get_attribute_value(HTML::AttributeNames::height));
- if (w.has_value() && h.has_value())
- // then the user agent is expected to use the parsed integers as a presentational hint for the 'aspect-ratio' property of the form auto w / h.
- style.set_property(CSS::PropertyID::AspectRatio,
- CSS::StyleValueList::create(CSS::StyleValueVector {
- CSS::IdentifierStyleValue::create(CSS::ValueID::Auto),
- CSS::RatioStyleValue::create(CSS::Ratio { static_cast<double>(w.value()), static_cast<double>(h.value()) }) },
- CSS::StyleValueList::Separator::Space));
- }
- unsigned HTMLCanvasElement::width() const
- {
- // https://html.spec.whatwg.org/multipage/canvas.html#obtain-numeric-values
- // The rules for parsing non-negative integers must be used to obtain their numeric values.
- // If an attribute is missing, or if parsing its value returns an error, then the default value must be used instead.
- // The width attribute defaults to 300
- return parse_non_negative_integer(get_attribute_value(HTML::AttributeNames::width)).value_or(300);
- }
- unsigned HTMLCanvasElement::height() const
- {
- // https://html.spec.whatwg.org/multipage/canvas.html#obtain-numeric-values
- // The rules for parsing non-negative integers must be used to obtain their numeric values.
- // If an attribute is missing, or if parsing its value returns an error, then the default value must be used instead.
- // the height attribute defaults to 150
- return parse_non_negative_integer(get_attribute_value(HTML::AttributeNames::height)).value_or(150);
- }
- void HTMLCanvasElement::reset_context_to_default_state()
- {
- m_context.visit(
- [](JS::NonnullGCPtr<CanvasRenderingContext2D>& context) {
- context->reset_to_default_state();
- },
- [](JS::NonnullGCPtr<WebGL::WebGLRenderingContext>&) {
- TODO();
- },
- [](Empty) {
- // Do nothing.
- });
- }
- WebIDL::ExceptionOr<void> HTMLCanvasElement::set_width(unsigned value)
- {
- TRY(set_attribute(HTML::AttributeNames::width, MUST(String::number(value))));
- m_bitmap = nullptr;
- reset_context_to_default_state();
- return {};
- }
- WebIDL::ExceptionOr<void> HTMLCanvasElement::set_height(unsigned value)
- {
- TRY(set_attribute(HTML::AttributeNames::height, MUST(String::number(value))));
- m_bitmap = nullptr;
- reset_context_to_default_state();
- return {};
- }
- JS::GCPtr<Layout::Node> HTMLCanvasElement::create_layout_node(NonnullRefPtr<CSS::StyleProperties> style)
- {
- return heap().allocate_without_realm<Layout::CanvasBox>(document(), *this, move(style));
- }
- HTMLCanvasElement::HasOrCreatedContext HTMLCanvasElement::create_2d_context()
- {
- if (!m_context.has<Empty>())
- return m_context.has<JS::NonnullGCPtr<CanvasRenderingContext2D>>() ? HasOrCreatedContext::Yes : HasOrCreatedContext::No;
- m_context = CanvasRenderingContext2D::create(realm(), *this);
- return HasOrCreatedContext::Yes;
- }
- JS::ThrowCompletionOr<HTMLCanvasElement::HasOrCreatedContext> HTMLCanvasElement::create_webgl_context(JS::Value options)
- {
- if (!m_context.has<Empty>())
- return m_context.has<JS::NonnullGCPtr<WebGL::WebGLRenderingContext>>() ? HasOrCreatedContext::Yes : HasOrCreatedContext::No;
- auto maybe_context = TRY(WebGL::WebGLRenderingContext::create(realm(), *this, options));
- if (!maybe_context)
- return HasOrCreatedContext::No;
- m_context = JS::NonnullGCPtr<WebGL::WebGLRenderingContext>(*maybe_context);
- return HasOrCreatedContext::Yes;
- }
- // https://html.spec.whatwg.org/multipage/canvas.html#dom-canvas-getcontext
- JS::ThrowCompletionOr<HTMLCanvasElement::RenderingContext> HTMLCanvasElement::get_context(String const& type, JS::Value options)
- {
- // 1. If options is not an object, then set options to null.
- if (!options.is_object())
- options = JS::js_null();
- // 2. Set options to the result of converting options to a JavaScript value.
- // NOTE: No-op.
- // 3. Run the steps in the cell of the following table whose column header matches this canvas element's canvas context mode and whose row header matches contextId:
- // NOTE: See the spec for the full table.
- if (type == "2d"sv) {
- if (create_2d_context() == HasOrCreatedContext::Yes)
- return JS::make_handle(*m_context.get<JS::NonnullGCPtr<HTML::CanvasRenderingContext2D>>());
- return Empty {};
- }
- // NOTE: The WebGL spec says "experimental-webgl" is also acceptable and must be equivalent to "webgl". Other engines accept this, so we do too.
- if (type.is_one_of("webgl"sv, "experimental-webgl"sv)) {
- if (TRY(create_webgl_context(options)) == HasOrCreatedContext::Yes)
- return JS::make_handle(*m_context.get<JS::NonnullGCPtr<WebGL::WebGLRenderingContext>>());
- return Empty {};
- }
- return Empty {};
- }
- static Gfx::IntSize bitmap_size_for_canvas(HTMLCanvasElement const& canvas, size_t minimum_width, size_t minimum_height)
- {
- auto width = max(canvas.width(), minimum_width);
- auto height = max(canvas.height(), minimum_height);
- Checked<size_t> area = width;
- area *= height;
- if (area.has_overflow()) {
- dbgln("Refusing to create {}x{} canvas (overflow)", width, height);
- return {};
- }
- if (area.value() > max_canvas_area) {
- dbgln("Refusing to create {}x{} canvas (exceeds maximum size)", width, height);
- return {};
- }
- return Gfx::IntSize(width, height);
- }
- bool HTMLCanvasElement::create_bitmap(size_t minimum_width, size_t minimum_height)
- {
- auto size = bitmap_size_for_canvas(*this, minimum_width, minimum_height);
- if (size.is_empty()) {
- m_bitmap = nullptr;
- return false;
- }
- if (!m_bitmap || m_bitmap->size() != size) {
- auto bitmap_or_error = Gfx::Bitmap::create(Gfx::BitmapFormat::BGRA8888, Gfx::AlphaType::Premultiplied, size);
- if (bitmap_or_error.is_error())
- return false;
- m_bitmap = bitmap_or_error.release_value_but_fixme_should_propagate_errors();
- }
- return m_bitmap;
- }
- struct SerializeBitmapResult {
- ByteBuffer buffer;
- StringView mime_type;
- };
- // https://html.spec.whatwg.org/multipage/canvas.html#a-serialisation-of-the-bitmap-as-a-file
- static ErrorOr<SerializeBitmapResult> serialize_bitmap(Gfx::Bitmap const& bitmap, StringView type, Optional<double> quality)
- {
- // If type is an image format that supports variable quality (such as "image/jpeg"), quality is given, and type is not "image/png", then,
- // if Type(quality) is Number, and quality is in the range 0.0 to 1.0 inclusive, the user agent must treat quality as the desired quality level.
- // Otherwise, the user agent must use its default quality value, as if the quality argument had not been given.
- if (quality.has_value() && !(*quality >= 0.0 && *quality <= 1.0))
- quality = OptionalNone {};
- if (type.equals_ignoring_ascii_case("image/jpeg"sv)) {
- AllocatingMemoryStream file;
- Gfx::JPEGWriter::Options jpeg_options;
- if (quality.has_value())
- jpeg_options.quality = static_cast<int>(quality.value() * 100);
- TRY(Gfx::JPEGWriter::encode(file, bitmap, jpeg_options));
- return SerializeBitmapResult { TRY(file.read_until_eof()), "image/jpeg"sv };
- }
- // User agents must support PNG ("image/png"). User agents may support other types.
- // If the user agent does not support the requested type, then it must create the file using the PNG format. [PNG]
- return SerializeBitmapResult { TRY(Gfx::PNGWriter::encode(bitmap)), "image/png"sv };
- }
- // https://html.spec.whatwg.org/multipage/canvas.html#dom-canvas-todataurl
- String HTMLCanvasElement::to_data_url(StringView type, Optional<double> quality)
- {
- // It is possible the the canvas doesn't have a associated bitmap so create one
- if (!bitmap())
- create_bitmap();
- // FIXME: 1. If this canvas element's bitmap's origin-clean flag is set to false, then throw a "SecurityError" DOMException.
- // 2. If this canvas element's bitmap has no pixels (i.e. either its horizontal dimension or its vertical dimension is zero)
- // then return the string "data:,". (This is the shortest data: URL; it represents the empty string in a text/plain resource.)
- if (!m_bitmap)
- return "data:,"_string;
- // 3. Let file be a serialization of this canvas element's bitmap as a file, passing type and quality if given.
- auto file = serialize_bitmap(*m_bitmap, type, move(quality));
- // 4. If file is null then return "data:,".
- if (file.is_error()) {
- dbgln("HTMLCanvasElement: Failed to encode canvas bitmap to {}: {}", type, file.error());
- return "data:,"_string;
- }
- // 5. Return a data: URL representing file. [RFC2397]
- auto base64_encoded_or_error = encode_base64(file.value().buffer);
- if (base64_encoded_or_error.is_error()) {
- return "data:,"_string;
- }
- return MUST(URL::create_with_data(file.value().mime_type, base64_encoded_or_error.release_value(), true).to_string());
- }
- // https://html.spec.whatwg.org/multipage/canvas.html#dom-canvas-toblob
- WebIDL::ExceptionOr<void> HTMLCanvasElement::to_blob(JS::NonnullGCPtr<WebIDL::CallbackType> callback, StringView type, Optional<double> quality)
- {
- // It is possible the the canvas doesn't have a associated bitmap so create one
- if (!bitmap())
- create_bitmap();
- // FIXME: 1. If this canvas element's bitmap's origin-clean flag is set to false, then throw a "SecurityError" DOMException.
- // 2. Let result be null.
- RefPtr<Gfx::Bitmap> bitmap_result;
- // 3. If this canvas element's bitmap has pixels (i.e., neither its horizontal dimension nor its vertical dimension is zero),
- // then set result to a copy of this canvas element's bitmap.
- if (m_bitmap)
- bitmap_result = TRY_OR_THROW_OOM(vm(), m_bitmap->clone());
- // 4. Run these steps in parallel:
- Platform::EventLoopPlugin::the().deferred_invoke([this, callback, bitmap_result, type, quality] {
- // 1. If result is non-null, then set result to a serialization of result as a file with type and quality if given.
- Optional<SerializeBitmapResult> file_result;
- if (bitmap_result) {
- if (auto result = serialize_bitmap(*bitmap_result, type, move(quality)); !result.is_error())
- file_result = result.release_value();
- }
- // 2. Queue an element task on the canvas blob serialization task source given the canvas element to run these steps:
- queue_an_element_task(Task::Source::CanvasBlobSerializationTask, [this, callback, file_result = move(file_result)] {
- auto maybe_error = Bindings::throw_dom_exception_if_needed(vm(), [&]() -> WebIDL::ExceptionOr<void> {
- // 1. If result is non-null, then set result to a new Blob object, created in the relevant realm of this canvas element, representing result. [FILEAPI]
- JS::GCPtr<FileAPI::Blob> blob_result;
- if (file_result.has_value())
- blob_result = FileAPI::Blob::create(realm(), file_result->buffer, TRY_OR_THROW_OOM(vm(), String::from_utf8(file_result->mime_type)));
- // 2. Invoke callback with « result ».
- TRY(WebIDL::invoke_callback(*callback, {}, move(blob_result)));
- return {};
- });
- if (maybe_error.is_throw_completion())
- report_exception(maybe_error.throw_completion(), realm());
- });
- });
- return {};
- }
- void HTMLCanvasElement::present()
- {
- m_context.visit(
- [](JS::NonnullGCPtr<CanvasRenderingContext2D>&) {
- // Do nothing, CRC2D writes directly to the canvas bitmap.
- },
- [](JS::NonnullGCPtr<WebGL::WebGLRenderingContext>& context) {
- context->present();
- },
- [](Empty) {
- // Do nothing.
- });
- }
- }
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