gecko-dev/dom/html/HTMLBRElement.h
Masayuki Nakano 23a22c597a Bug 1569902 - part 2: Stop using attribute to consider whether a <br> element is a special node for empty last line or not r=m_kato,smaug
Editor creates a `<br>` element to end of a block if last line
of the block is empty because caret should be placed as there is an empty
line.  Such special `<br>` element has `type` attribute whose value is "_moz".
However, adding/removing the attribute is expensive and such hacky attribute
shouldn't be referred nor changed by web apps.

Therefore, this patch makes `HTMLBRElement` take another specific flag whether
it's a special node for empty last line.  For making the meaning clearer,
this patch calls the such `<br>` elements as "padding `<br>` element for
empty last line" insead of "moz-br".  So, this patch also includes a lot of
renaming methods and variables, and modifying related comments.

Note that with this change, `IMEContentObserver` counts the padding `<br>`
element in `<textarea>` because it's inserted before setting the new flag
and setting the flag does not cause DOM tree mutation.  This issue will be
fixed by the following patches.

Differential Revision: https://phabricator.services.mozilla.com/D39858

--HG--
extra : moz-landing-system : lando
2019-08-02 05:45:18 +00:00

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2.6 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_dom_HTMLBRElement_h
#define mozilla_dom_HTMLBRElement_h
#include "mozilla/Attributes.h"
#include "nsGenericHTMLElement.h"
#include "nsGkAtoms.h"
namespace mozilla {
namespace dom {
#define BR_ELEMENT_FLAG_BIT(n_) \
NODE_FLAG_BIT(ELEMENT_TYPE_SPECIFIC_BITS_OFFSET + (n_))
// BR element specific bits
enum {
// NS_PADDING_FOR_EMPTY_EDITOR is set if the <br> element is created by
// editor for placing caret at proper position in empty editor.
NS_PADDING_FOR_EMPTY_EDITOR = BR_ELEMENT_FLAG_BIT(0),
// NS_PADDING_FOR_EMPTY_LAST_LINE is set if the <br> element is created by
// editor for placing caret at proper position for making empty last line
// in a block or <textarea> element visible.
NS_PADDING_FOR_EMPTY_LAST_LINE = BR_ELEMENT_FLAG_BIT(1),
};
ASSERT_NODE_FLAGS_SPACE(ELEMENT_TYPE_SPECIFIC_BITS_OFFSET + 2);
class HTMLBRElement final : public nsGenericHTMLElement {
public:
explicit HTMLBRElement(already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo);
NS_IMPL_FROMNODE_HTML_WITH_TAG(HTMLBRElement, br)
virtual bool ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
const nsAString& aValue,
nsIPrincipal* aMaybeScriptedPrincipal,
nsAttrValue& aResult) override;
NS_IMETHOD_(bool) IsAttributeMapped(const nsAtom* aAttribute) const override;
virtual nsMapRuleToAttributesFunc GetAttributeMappingFunction()
const override;
virtual nsresult Clone(dom::NodeInfo*, nsINode** aResult) const override;
bool Clear() { return GetBoolAttr(nsGkAtoms::clear); }
void SetClear(const nsAString& aClear, ErrorResult& aError) {
return SetHTMLAttr(nsGkAtoms::clear, aClear, aError);
}
void GetClear(DOMString& aClear) const {
return GetHTMLAttr(nsGkAtoms::clear, aClear);
}
virtual JSObject* WrapNode(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto) override;
bool IsPaddingForEmptyEditor() const {
return HasFlag(NS_PADDING_FOR_EMPTY_EDITOR);
}
bool IsPaddingForEmptyLastLine() const {
return HasFlag(NS_PADDING_FOR_EMPTY_LAST_LINE);
}
private:
virtual ~HTMLBRElement();
static void MapAttributesIntoRule(const nsMappedAttributes* aAttributes,
MappedDeclarations&);
};
} // namespace dom
} // namespace mozilla
#endif