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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: sw=2 ts=8 et :
/* 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 */
#ifndef mozilla_ContentCache_h
#define mozilla_ContentCache_h
#include <stdint.h>
#include "mozilla/Assertions.h"
#include "mozilla/CheckedInt.h"
#include "mozilla/EventForwards.h"
#include "mozilla/WritingModes.h"
#include "nsIWidget.h"
#include "nsString.h"
#include "nsTArray.h"
#include "Units.h"
namespace mozilla {
class ContentCacheInParent;
namespace dom {
class BrowserParent;
} // namespace dom
* ContentCache stores various information of the child content.
* This class has members which are necessary both in parent process and
* content process.
class ContentCache {
typedef CopyableTArray<LayoutDeviceIntRect> RectArray;
typedef widget::IMENotification IMENotification;
// Whole text in the target
nsString mText;
// Start offset of the composition string.
uint32_t mCompositionStart;
enum { ePrevCharRect = 1, eNextCharRect = 0 };
struct Selection final {
// Following values are offset in "flat text".
uint32_t mAnchor;
uint32_t mFocus;
WritingMode mWritingMode;
// Character rects at previous and next character of mAnchor and mFocus.
// The reason why ContentCache needs to store each previous character of
// them is IME may query character rect of the last character of a line
// when caret is at the end of the line.
// Note that use ePrevCharRect and eNextCharRect for accessing each item.
LayoutDeviceIntRect mAnchorCharRects[2];
LayoutDeviceIntRect mFocusCharRects[2];
// Whole rect of selected text. This is empty if the selection is collapsed.
LayoutDeviceIntRect mRect;
Selection() : mAnchor(UINT32_MAX), mFocus(UINT32_MAX) {}
void Clear() {
mAnchor = mFocus = UINT32_MAX;
mWritingMode = WritingMode();
void ClearAnchorCharRects() {
for (size_t i = 0; i < ArrayLength(mAnchorCharRects); i++) {
void ClearFocusCharRects() {
for (size_t i = 0; i < ArrayLength(mFocusCharRects); i++) {
bool IsValid() const {
return mAnchor != UINT32_MAX && mFocus != UINT32_MAX;
bool Collapsed() const {
"The caller should check if the selection is valid");
return mFocus == mAnchor;
bool Reversed() const {
"The caller should check if the selection is valid");
return mFocus < mAnchor;
uint32_t StartOffset() const {
"The caller should check if the selection is valid");
return Reversed() ? mFocus : mAnchor;
uint32_t EndOffset() const {
"The caller should check if the selection is valid");
return Reversed() ? mAnchor : mFocus;
uint32_t Length() const {
"The caller should check if the selection is valid");
return Reversed() ? mAnchor - mFocus : mFocus - mAnchor;
LayoutDeviceIntRect StartCharRect() const {
"The caller should check if the selection is valid");
return Reversed() ? mFocusCharRects[eNextCharRect]
: mAnchorCharRects[eNextCharRect];
LayoutDeviceIntRect EndCharRect() const {
"The caller should check if the selection is valid");
return Reversed() ? mAnchorCharRects[eNextCharRect]
: mFocusCharRects[eNextCharRect];
} mSelection;
bool IsSelectionValid() const {
return mSelection.IsValid() && mSelection.EndOffset() <= mText.Length();
// Stores first char rect because Yosemite's Japanese IME sometimes tries
// to query it. If there is no text, this is caret rect.
LayoutDeviceIntRect mFirstCharRect;
struct Caret final {
uint32_t mOffset;
LayoutDeviceIntRect mRect;
Caret() : mOffset(UINT32_MAX) {}
void Clear() {
mOffset = UINT32_MAX;
bool IsValid() const { return mOffset != UINT32_MAX; }
uint32_t Offset() const {
NS_ASSERTION(IsValid(), "The caller should check if the caret is valid");
return mOffset;
} mCaret;
struct TextRectArray final {
uint32_t mStart;
RectArray mRects;
TextRectArray() : mStart(UINT32_MAX) {}
void Clear() {
mStart = UINT32_MAX;
bool IsValid() const {
if (mStart == UINT32_MAX) {
return false;
CheckedInt<uint32_t> endOffset =
CheckedInt<uint32_t>(mStart) + mRects.Length();
return endOffset.isValid();
bool HasRects() const { return IsValid() && !mRects.IsEmpty(); }
uint32_t StartOffset() const {
NS_ASSERTION(IsValid(), "The caller should check if the caret is valid");
return mStart;
uint32_t EndOffset() const {
NS_ASSERTION(IsValid(), "The caller should check if the caret is valid");
if (!IsValid()) {
return UINT32_MAX;
return mStart + mRects.Length();
bool InRange(uint32_t aOffset) const {
return IsValid() && StartOffset() <= aOffset && aOffset < EndOffset();
bool InRange(uint32_t aOffset, uint32_t aLength) const {
CheckedInt<uint32_t> endOffset = CheckedInt<uint32_t>(aOffset) + aLength;
if (NS_WARN_IF(!endOffset.isValid())) {
return false;
return InRange(aOffset) && aOffset + aLength <= EndOffset();
bool IsOverlappingWith(uint32_t aOffset, uint32_t aLength) const {
if (!HasRects() || aOffset == UINT32_MAX || !aLength) {
return false;
CheckedInt<uint32_t> endOffset = CheckedInt<uint32_t>(aOffset) + aLength;
if (NS_WARN_IF(!endOffset.isValid())) {
return false;
return aOffset < EndOffset() && endOffset.value() > mStart;
LayoutDeviceIntRect GetRect(uint32_t aOffset) const;
LayoutDeviceIntRect GetUnionRect(uint32_t aOffset, uint32_t aLength) const;
LayoutDeviceIntRect GetUnionRectAsFarAsPossible(
uint32_t aOffset, uint32_t aLength, bool aRoundToExistingOffset) const;
} mTextRectArray;
LayoutDeviceIntRect mEditorRect;
friend class ContentCacheInParent;
friend struct IPC::ParamTraits<ContentCache>;
class ContentCacheInChild final : public ContentCache {
* When IME loses focus, this should be called and making this forget the
* content for reducing footprint.
void Clear();
* Cache*() retrieves the latest content information and store them.
* Be aware, CacheSelection() calls CacheTextRects(), and also CacheText()
* calls CacheSelection(). So, related data is also retrieved automatically.
bool CacheEditorRect(nsIWidget* aWidget,
const IMENotification* aNotification = nullptr);
bool CacheSelection(nsIWidget* aWidget,
const IMENotification* aNotification = nullptr);
bool CacheText(nsIWidget* aWidget,
const IMENotification* aNotification = nullptr);
bool CacheAll(nsIWidget* aWidget,
const IMENotification* aNotification = nullptr);
* SetSelection() modifies selection with specified raw data. And also this
* tries to retrieve text rects too.
void SetSelection(nsIWidget* aWidget, uint32_t aStartOffset, uint32_t aLength,
bool aReversed, const WritingMode& aWritingMode);
bool QueryCharRect(nsIWidget* aWidget, uint32_t aOffset,
LayoutDeviceIntRect& aCharRect) const;
bool QueryCharRectArray(nsIWidget* aWidget, uint32_t aOffset,
uint32_t aLength, RectArray& aCharRectArray) const;
bool CacheCaret(nsIWidget* aWidget,
const IMENotification* aNotification = nullptr);
bool CacheTextRects(nsIWidget* aWidget,
const IMENotification* aNotification = nullptr);
class ContentCacheInParent final : public ContentCache {
explicit ContentCacheInParent(dom::BrowserParent& aBrowserParent);
* AssignContent() is called when BrowserParent receives ContentCache from
* the content process. This doesn't copy composition information because
* it's managed by BrowserParent itself.
void AssignContent(const ContentCache& aOther, nsIWidget* aWidget,
const IMENotification* aNotification = nullptr);
* HandleQueryContentEvent() sets content data to aEvent.mReply.
* For eQuerySelectedText, fail if the cache doesn't contain the whole
* selected range. (This shouldn't happen because PuppetWidget should have
* already sent the whole selection.)
* For eQueryTextContent, fail only if the cache doesn't overlap with
* the queried range. Note the difference from above. We use
* this behavior because a normal eQueryTextContent event is allowed to
* have out-of-bounds offsets, so that widget can request content without
* knowing the exact length of text. It's up to widget to handle cases when
* the returned offset/length are different from the queried offset/length.
* For eQueryTextRect, fail if cached offset/length aren't equals to input.
* Cocoa widget always queries selected offset, so it works on it.
* For eQueryCaretRect, fail if cached offset isn't equals to input
* For eQueryEditorRect, always success
bool HandleQueryContentEvent(WidgetQueryContentEvent& aEvent,
nsIWidget* aWidget) const;
* OnCompositionEvent() should be called before sending composition string.
* This returns true if the event should be sent. Otherwise, false.
bool OnCompositionEvent(const WidgetCompositionEvent& aCompositionEvent);
* OnSelectionEvent() should be called before sending selection event.
void OnSelectionEvent(const WidgetSelectionEvent& aSelectionEvent);
* OnEventNeedingAckHandled() should be called after the child process
* handles a sent event which needs acknowledging.
* WARNING: This may send notifications to IME. That might cause destroying
* BrowserParent or aWidget. Therefore, the caller must not destroy
* this instance during a call of this method.
void OnEventNeedingAckHandled(nsIWidget* aWidget, EventMessage aMessage);
* RequestIMEToCommitComposition() requests aWidget to commit or cancel
* composition. If it's handled synchronously, this returns true.
* @param aWidget The widget to be requested to commit or cancel
* the composition.
* @param aCancel When the caller tries to cancel the composition, true.
* Otherwise, i.e., tries to commit the composition, false.
* @param aCommittedString The committed string (i.e., the last data of
* dispatched composition events during requesting
* IME to commit composition.
* @return Whether the composition is actually committed
* synchronously.
bool RequestIMEToCommitComposition(nsIWidget* aWidget, bool aCancel,
nsAString& aCommittedString);
* MaybeNotifyIME() may notify IME of the notification. If child process
* hasn't been handled all sending events yet, this stores the notification
* and flush it later.
void MaybeNotifyIME(nsIWidget* aWidget, const IMENotification& aNotification);
IMENotification mPendingSelectionChange;
IMENotification mPendingTextChange;
IMENotification mPendingLayoutChange;
IMENotification mPendingCompositionUpdate;
// Log of event messages to be output to crash report.
nsTArray<EventMessage> mDispatchedEventMessages;
nsTArray<EventMessage> mReceivedEventMessages;
// Log of RequestIMEToCommitComposition() in the last 2 compositions.
enum class RequestIMEToCommitCompositionResult : uint8_t {
const char* ToReadableText(
RequestIMEToCommitCompositionResult aResult) const {
switch (aResult) {
case RequestIMEToCommitCompositionResult::eToOldCompositionReceived:
return "Commit request is not handled because it's for "
"older composition";
case RequestIMEToCommitCompositionResult::eToCommittedCompositionReceived:
return "Commit request is not handled because BrowserParent has "
"already "
"sent commit event for the composition";
case RequestIMEToCommitCompositionResult::eReceivedAfterBrowserParentBlur:
return "Commit request is handled with stored composition string "
"because BrowserParent has already lost focus";
case RequestIMEToCommitCompositionResult::eReceivedButNoTextComposition:
return "Commit request is not handled because there is no "
"TextCompsition instance";
case RequestIMEToCommitCompositionResult::eHandledAsynchronously:
return "Commit request is handled but IME doesn't commit current "
"composition synchronously";
case RequestIMEToCommitCompositionResult::eHandledSynchronously:
return "Commit reqeust is handled synchronously";
return "Unknown reason";
// mBrowserParent is owner of the instance.
dom::BrowserParent& MOZ_NON_OWNING_REF mBrowserParent;
// mCompositionString is composition string which were sent to the remote
// process but not yet committed in the remote process.
nsString mCompositionString;
// This is not nullptr only while the instance is requesting IME to
// composition. Then, data value of dispatched composition events should
// be stored into the instance.
nsAString* mCommitStringByRequest;
// mPendingEventsNeedingAck is increased before sending a composition event or
// a selection event and decreased after they are received in the child
// process.
uint32_t mPendingEventsNeedingAck;
// mCompositionStartInChild stores current composition start offset in the
// remote process.
uint32_t mCompositionStartInChild;
// mPendingCommitLength is commit string length of the first pending
// composition. This is used by relative offset query events when querying
// new composition start offset.
// Note that when mPendingCompositionCount is not 0, i.e., there are 2 or
// more pending compositions, this cache won't be used because in such case,
// anyway ContentCacheInParent cannot return proper character rect.
uint32_t mPendingCommitLength;
// mPendingCompositionCount is number of compositions which started in widget
// but not yet handled in the child process.
uint8_t mPendingCompositionCount;
// mPendingCommitCount is number of eCompositionCommit(AsIs) events which
// were sent to the child process but not yet handled in it.
uint8_t mPendingCommitCount;
// mWidgetHasComposition is true when the widget in this process thinks that
// IME has composition. So, this is set to true when eCompositionStart is
// dispatched and set to false when eCompositionCommit(AsIs) is dispatched.
bool mWidgetHasComposition;
// mIsChildIgnoringCompositionEvents is set to true if the child process
// requests commit composition whose commit has already been sent to it.
// Then, set to false when the child process ignores the commit event.
bool mIsChildIgnoringCompositionEvents;
ContentCacheInParent() = delete;
* When following methods' aRoundToExistingOffset is true, even if specified
* offset or range is out of bounds, the result is computed with the existing
* cache forcibly.
bool GetCaretRect(uint32_t aOffset, bool aRoundToExistingOffset,
LayoutDeviceIntRect& aCaretRect) const;
bool GetTextRect(uint32_t aOffset, bool aRoundToExistingOffset,
LayoutDeviceIntRect& aTextRect) const;
bool GetUnionTextRects(uint32_t aOffset, uint32_t aLength,
bool aRoundToExistingOffset,
LayoutDeviceIntRect& aUnionTextRect) const;
void FlushPendingNotifications(nsIWidget* aWidget);
* Remove unnecessary messages from mDispatchedEventMessages and
* mReceivedEventMessages.
void RemoveUnnecessaryEventMessageLog();
* Append event message log to aLog.
void AppendEventMessageLog(nsACString& aLog) const;
} // namespace mozilla
#endif // mozilla_ContentCache_h