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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 <LibGfx/Bitmap.h>
#include <LibGfx/PNGWriter.h>
#include <LibWeb/CSS/StyleComputer.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/HTML/CanvasRenderingContext2D.h>
#include <LibWeb/HTML/HTMLCanvasElement.h>
#include <LibWeb/Layout/CanvasBox.h>
namespace Web::HTML {
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;
unsigned HTMLCanvasElement::width() const
{
return attribute(HTML::AttributeNames::width).to_uint().value_or(300);
}
unsigned HTMLCanvasElement::height() const
{
return attribute(HTML::AttributeNames::height).to_uint().value_or(150);
}
void HTMLCanvasElement::reset_context_to_default_state()
{
m_context.visit(
[](NonnullRefPtr<CanvasRenderingContext2D>& context) {
context->reset_to_default_state();
},
[](NonnullRefPtr<WebGL::WebGLRenderingContext>&) {
TODO();
},
[](Empty) {
// Do nothing.
});
}
void HTMLCanvasElement::set_width(unsigned value)
{
set_attribute(HTML::AttributeNames::width, String::number(value));
m_bitmap = nullptr;
reset_context_to_default_state();
}
void HTMLCanvasElement::set_height(unsigned value)
{
set_attribute(HTML::AttributeNames::height, String::number(value));
m_bitmap = nullptr;
reset_context_to_default_state();
}
RefPtr<Layout::Node> HTMLCanvasElement::create_layout_node(NonnullRefPtr<CSS::StyleProperties> style)
{
return adopt_ref(*new Layout::CanvasBox(document(), *this, move(style)));
}
HTMLCanvasElement::HasOrCreatedContext HTMLCanvasElement::create_2d_context()
{
if (!m_context.has<Empty>())
return m_context.has<NonnullRefPtr<CanvasRenderingContext2D>>() ? HasOrCreatedContext::Yes : HasOrCreatedContext::No;
m_context = CanvasRenderingContext2D::create(*this);
return HasOrCreatedContext::Yes;
}
JS::ThrowCompletionOr<HTMLCanvasElement::HasOrCreatedContext> HTMLCanvasElement::create_webgl_context(JS::Value options)
{
if (!m_context.has<Empty>())
return m_context.has<NonnullRefPtr<WebGL::WebGLRenderingContext>>() ? HasOrCreatedContext::Yes : HasOrCreatedContext::No;
auto maybe_context = TRY(WebGL::WebGLRenderingContext::create(*this, options));
if (!maybe_context)
return HasOrCreatedContext::No;
m_context = maybe_context.release_nonnull();
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 m_context;
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 m_context;
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::try_create(Gfx::BitmapFormat::BGRA8888, size);
if (bitmap_or_error.is_error())
return false;
m_bitmap = bitmap_or_error.release_value_but_fixme_should_propagate_errors();
}
return m_bitmap;
}
String HTMLCanvasElement::to_data_url(String const& type, [[maybe_unused]] Optional<double> quality) const
{
if (!m_bitmap)
return {};
if (type != "image/png")
return {};
auto encoded_bitmap = Gfx::PNGWriter::encode(*m_bitmap);
return AK::URL::create_with_data(type, encode_base64(encoded_bitmap), true).to_string();
}
void HTMLCanvasElement::present()
{
m_context.visit(
[](NonnullRefPtr<CanvasRenderingContext2D>&) {
// Do nothing, CRC2D writes directly to the canvas bitmap.
},
[](NonnullRefPtr<WebGL::WebGLRenderingContext>& context) {
context->present();
},
[](Empty) {
// Do nothing.
});
}
}
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