gecko-dev/accessible/base/AccessibleOrProxy.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=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_a11y_AccessibleOrProxy_h
#define mozilla_a11y_AccessibleOrProxy_h
#include "mozilla/a11y/Accessible.h"
#include "mozilla/a11y/ProxyAccessible.h"
#include "mozilla/a11y/Role.h"
#include <stdint.h>
namespace mozilla {
namespace a11y {
/**
* This class stores an Accessible* or a ProxyAccessible* in a safe manner
* with size sizeof(void*).
*/
class AccessibleOrProxy {
public:
MOZ_IMPLICIT AccessibleOrProxy(Accessible* aAcc)
: mBits(reinterpret_cast<uintptr_t>(aAcc)) {}
MOZ_IMPLICIT AccessibleOrProxy(ProxyAccessible* aProxy)
: mBits(aProxy ? (reinterpret_cast<uintptr_t>(aProxy) | IS_PROXY) : 0) {}
MOZ_IMPLICIT AccessibleOrProxy(decltype(nullptr)) : mBits(0) {}
bool IsProxy() const { return mBits & IS_PROXY; }
ProxyAccessible* AsProxy() const {
if (IsProxy()) {
return reinterpret_cast<ProxyAccessible*>(mBits & ~IS_PROXY);
}
return nullptr;
}
bool IsAccessible() const { return !IsProxy(); }
Accessible* AsAccessible() const {
if (IsAccessible()) {
return reinterpret_cast<Accessible*>(mBits);
}
return nullptr;
}
bool IsNull() const { return mBits == 0; }
uint32_t ChildCount() const {
if (IsProxy()) {
return AsProxy()->ChildrenCount();
}
if (RemoteChildDoc()) {
return 1;
}
return AsAccessible()->ChildCount();
}
/**
* Return the child object either an accessible or a proxied accessible at
* the given index.
*/
AccessibleOrProxy ChildAt(uint32_t aIdx) {
if (IsProxy()) {
return AsProxy()->ChildAt(aIdx);
}
ProxyAccessible* childDoc = RemoteChildDoc();
if (childDoc && aIdx == 0) {
return childDoc;
}
return AsAccessible()->GetChildAt(aIdx);
}
/**
* Return the first child object.
*/
AccessibleOrProxy FirstChild() {
if (IsProxy()) {
return AsProxy()->FirstChild();
}
ProxyAccessible* childDoc = RemoteChildDoc();
if (childDoc) {
return childDoc;
}
return AsAccessible()->FirstChild();
}
/**
* Return the last child object.
*/
AccessibleOrProxy LastChild() {
if (IsProxy()) {
return AsProxy()->LastChild();
}
ProxyAccessible* childDoc = RemoteChildDoc();
if (childDoc) {
return childDoc;
}
return AsAccessible()->LastChild();
}
role Role() const {
if (IsProxy()) {
return AsProxy()->Role();
}
return AsAccessible()->Role();
}
AccessibleOrProxy Parent() const;
AccessibleOrProxy ChildAtPoint(int32_t aX, int32_t aY,
Accessible::EWhichChildAtPoint aWhichChild);
// XXX these are implementation details that ideally would not be exposed.
uintptr_t Bits() const { return mBits; }
void SetBits(uintptr_t aBits) { mBits = aBits; }
private:
/**
* If this is an OuterDocAccessible, return the remote child document.
*/
ProxyAccessible* RemoteChildDoc() const;
uintptr_t mBits;
static const uintptr_t IS_PROXY = 0x1;
};
} // namespace a11y
} // namespace mozilla
#endif