widget/ContentCache.h
author Chris H-C <chutten@mozilla.com>
Mon, 04 Jul 2016 11:16:05 -0400
changeset 312997 df28918fe2361f0b54ca9ce4773a29c4c0675d06
parent 310197 10ca767648a511eaaee798ec22dbda768407973e
child 317783 8bea9647dc86865e874f346a3fccc14565ce3f65
permissions -rw-r--r--
bug 1218576 - Support remote accumulation via JS histograms. r=gfritzsche The JS histograms, too, need to dispatch their accumulations from child to parent. JSHistograms_Add now only supports histograms that are in gHistogramsMap or that were created in the parent process. After bug 1288745, maybe we'll be able to change this to be less convoluted. MozReview-Commit-ID: 3qTH89YKbGP

/* -*- 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 http://mozilla.org/MPL/2.0/. */

#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;

/**
 * ContentCache stores various information of the child content.
 * This class has members which are necessary both in parent process and
 * content process.
 */

class ContentCache
{
public:
  typedef InfallibleTArray<LayoutDeviceIntRect> RectArray;
  typedef widget::IMENotification IMENotification;

  ContentCache();

protected:
  // 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();
      ClearAnchorCharRects();
      ClearFocusCharRects();
      mRect.SetEmpty();
    }

    void ClearAnchorCharRects()
    {
      for (size_t i = 0; i < ArrayLength(mAnchorCharRects); i++) {
        mAnchorCharRects[i].SetEmpty();
      }
    }
    void ClearFocusCharRects()
    {
      for (size_t i = 0; i < ArrayLength(mFocusCharRects); i++) {
        mFocusCharRects[i].SetEmpty();
      }
    }

    bool IsValid() const
    {
      return mAnchor != UINT32_MAX && mFocus != UINT32_MAX;
    }
    bool Collapsed() const
    {
      NS_ASSERTION(IsValid(),
                   "The caller should check if the selection is valid");
      return mFocus == mAnchor;
    }
    bool Reversed() const
    {
      NS_ASSERTION(IsValid(),
                   "The caller should check if the selection is valid");
      return mFocus < mAnchor;
    }
    uint32_t StartOffset() const
    {
      NS_ASSERTION(IsValid(),
                   "The caller should check if the selection is valid");
      return Reversed() ? mFocus : mAnchor;
    }
    uint32_t EndOffset() const
    {
      NS_ASSERTION(IsValid(),
                   "The caller should check if the selection is valid");
      return Reversed() ? mAnchor : mFocus;
    }
    uint32_t Length() const
    {
      NS_ASSERTION(IsValid(),
                   "The caller should check if the selection is valid");
      return Reversed() ? mAnchor - mFocus : mFocus - mAnchor;
    }
    LayoutDeviceIntRect StartCharRect() const
    {
      NS_ASSERTION(IsValid(),
                   "The caller should check if the selection is valid");
      return Reversed() ? mFocusCharRects[eNextCharRect] :
                          mAnchorCharRects[eNextCharRect];
    }
    LayoutDeviceIntRect EndCharRect() const
    {
      NS_ASSERTION(IsValid(),
                   "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;
      mRect.SetEmpty();
    }

    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;
      mRects.Clear();
    }

    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
{
public:
  ContentCacheInChild();

  /**
   * 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);

private:
  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
{
public:
  ContentCacheInParent();

  /**
   * AssignContent() is called when TabParent receives ContentCache from
   * the content process.  This doesn't copy composition information because
   * it's managed by TabParent 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
   *          TabParent 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);

private:
  IMENotification mPendingSelectionChange;
  IMENotification mPendingTextChange;
  IMENotification mPendingLayoutChange;
  IMENotification mPendingCompositionUpdate;

  // 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;

  bool mIsComposing;

  /**
   * 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);
};

} // namespace mozilla

#endif // mozilla_ContentCache_h