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LibWeb: Add <canvas> element and start fleshing out CRC2D

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This patch adds HTMLCanvasElement along with a LayoutCanvas object.
The DOM and layout parts are very similar to <img> elements.

The <canvas> element holds a Gfx::Bitmap which is sized according to
the "width" and "height" attributes on the element.

Calling .getContext("2d") on a <canvas> element gives you a context
object that draws into the underlying Gfx::Bitmap of the <canvas>.
The context weakly points to the <canvas> which allows it to outlive
the canvas element if needed.

This is really quite cool. :^)
This commit is contained in:
Andreas Kling 2020-03-19 19:07:56 +01:00
parent 73d28a0551
commit a37c29e353
19 changed files with 649 additions and 1 deletions
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92
Libraries/LibWeb/DOM/HTMLCanvasElement.cpp Normal file
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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <LibGfx/Bitmap.h>
#include <LibWeb/CSS/StyleResolver.h>
#include <LibWeb/DOM/CanvasRenderingContext2D.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/DOM/HTMLCanvasElement.h>
#include <LibWeb/Layout/LayoutCanvas.h>
namespace Web {
HTMLCanvasElement::HTMLCanvasElement(Document& document, const String& tag_name)
: HTMLElement(document, tag_name)
{
}
HTMLCanvasElement::~HTMLCanvasElement()
{
}
int HTMLCanvasElement::preferred_width() const
{
bool ok = false;
int width = attribute("width").to_int(ok);
if (ok)
return width;
return 300;
}
int HTMLCanvasElement::preferred_height() const
{
bool ok = false;
int height = attribute("height").to_int(ok);
if (ok)
return height;
return 300;
}
RefPtr<LayoutNode> HTMLCanvasElement::create_layout_node(const StyleProperties* parent_style) const
{
auto style = document().style_resolver().resolve_style(*this, parent_style);
auto display = style->string_or_fallback(CSS::PropertyID::Display, "inline");
if (display == "none")
return nullptr;
return adopt(*new LayoutCanvas(*this, move(style)));
}
CanvasRenderingContext2D* HTMLCanvasElement::get_context(String type)
{
ASSERT(type.to_lowercase() == "2d");
dbg() << "get_context with m_context=" << m_context.ptr();
if (!m_context)
m_context = CanvasRenderingContext2D::create(*this);
dbg() << "get_context returning m_context=" << m_context.ptr();
return m_context;
}
Gfx::Bitmap& HTMLCanvasElement::ensure_bitmap()
{
if (!m_bitmap || m_bitmap->size() != Gfx::Size(preferred_width(), preferred_height())) {
m_bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::RGBA32, { preferred_width(), preferred_height() });
}
return *m_bitmap;
}
}