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/* -*- 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 */
#ifndef mozilla_ContentEventHandler_h_
#define mozilla_ContentEventHandler_h_
#include "mozilla/EventForwards.h"
#include "mozilla/dom/Selection.h"
#include "nsCOMPtr.h"
#include "nsIFrame.h"
#include "nsINode.h"
class nsPresContext;
class nsRange;
struct nsRect;
namespace mozilla {
namespace dom {
class Element;
class Text;
} // namespace dom
* Query Content Event Handler
* ContentEventHandler is a helper class for EventStateManager.
* The platforms request some content informations, e.g., the selected text,
* the offset of the selected text and the text for specified range.
* This class answers to NS_QUERY_* events from actual contents.
class MOZ_STACK_CLASS ContentEventHandler {
* RawRange is a helper class of ContentEventHandler class. The caller is
* responsible for making sure the start/end nodes are in document order.
* This is enforced by assertions in DEBUG builds.
class MOZ_STACK_CLASS RawRange final {
RawRange() = default;
void Clear() {
mRoot = nullptr;
mStart = RangeBoundary();
mEnd = RangeBoundary();
bool IsPositioned() const { return mStart.IsSet() && mEnd.IsSet(); }
bool Collapsed() const { return mStart == mEnd && IsPositioned(); }
nsINode* GetStartContainer() const { return mStart.Container(); }
nsINode* GetEndContainer() const { return mEnd.Container(); }
uint32_t StartOffset() const {
return *mStart.Offset(
uint32_t EndOffset() const {
return *mEnd.Offset(RangeBoundary::OffsetFilter::kValidOrInvalidOffsets);
nsIContent* StartRef() const { return mStart.Ref(); }
nsIContent* EndRef() const { return mEnd.Ref(); }
const RangeBoundary& Start() const { return mStart; }
const RangeBoundary& End() const { return mEnd; }
// XXX: Make these use RangeBoundaries...
nsresult CollapseTo(const RawRangeBoundary& aBoundary) {
return SetStartAndEnd(aBoundary, aBoundary);
nsresult SetStart(const RawRangeBoundary& aStart);
nsresult SetEnd(const RawRangeBoundary& aEnd);
// NOTE: These helpers can hide performance problems, as they perform a
// search to find aStartOffset in aStartContainer.
nsresult SetStart(nsINode* aStartContainer, uint32_t aStartOffset) {
return SetStart(RawRangeBoundary(aStartContainer, aStartOffset));
nsresult SetEnd(nsINode* aEndContainer, uint32_t aEndOffset) {
return SetEnd(RawRangeBoundary(aEndContainer, aEndOffset));
nsresult SetEndAfter(nsINode* aEndContainer);
void SetStartAndEnd(const nsRange* aRange);
nsresult SetStartAndEnd(const RawRangeBoundary& aStart,
const RawRangeBoundary& aEnd);
nsresult SelectNodeContents(const nsINode* aNodeToSelectContents);
inline void AssertStartIsBeforeOrEqualToEnd();
nsCOMPtr<nsINode> mRoot;
RangeBoundary mStart;
RangeBoundary mEnd;
using Element = dom::Element;
using Selection = dom::Selection;
explicit ContentEventHandler(nsPresContext* aPresContext);
// Handle aEvent in the current process.
HandleQueryContentEvent(WidgetQueryContentEvent* aEvent);
// eQuerySelectedText event handler
OnQuerySelectedText(WidgetQueryContentEvent* aEvent);
// eQueryTextContent event handler
OnQueryTextContent(WidgetQueryContentEvent* aEvent);
// eQueryCaretRect event handler
MOZ_CAN_RUN_SCRIPT nsresult OnQueryCaretRect(WidgetQueryContentEvent* aEvent);
// eQueryTextRect event handler
MOZ_CAN_RUN_SCRIPT nsresult OnQueryTextRect(WidgetQueryContentEvent* aEvent);
// eQueryTextRectArray event handler
OnQueryTextRectArray(WidgetQueryContentEvent* aEvent);
// eQueryEditorRect event handler
OnQueryEditorRect(WidgetQueryContentEvent* aEvent);
// eQueryContentState event handler
OnQueryContentState(WidgetQueryContentEvent* aEvent);
// eQuerySelectionAsTransferable event handler
OnQuerySelectionAsTransferable(WidgetQueryContentEvent* aEvent);
// eQueryCharacterAtPoint event handler
OnQueryCharacterAtPoint(WidgetQueryContentEvent* aEvent);
// eQueryDOMWidgetHittest event handler
OnQueryDOMWidgetHittest(WidgetQueryContentEvent* aEvent);
// NS_SELECTION_* event
MOZ_CAN_RUN_SCRIPT nsresult OnSelectionEvent(WidgetSelectionEvent* aEvent);
RefPtr<dom::Document> mDocument;
// mSelection is typically normal selection but if OnQuerySelectedText()
// is called, i.e., handling eQuerySelectedText, it's the specified selection
// by WidgetQueryContentEvent::mInput::mSelectionType.
RefPtr<Selection> mSelection;
// mFirstSelectedRawRange is initialized from the first range of mSelection,
// if it exists. Otherwise, it is reset by Clear().
RawRange mFirstSelectedRawRange;
RefPtr<Element> mRootElement;
MOZ_CAN_RUN_SCRIPT nsresult Init(WidgetQueryContentEvent* aEvent);
MOZ_CAN_RUN_SCRIPT nsresult Init(WidgetSelectionEvent* aEvent);
nsresult InitBasic(bool aRequireFlush = true);
InitCommon(EventMessage aEventMessage,
SelectionType aSelectionType = SelectionType::eNormal,
bool aRequireFlush = true);
* InitRootContent() computes the root content of current focused editor.
* @param aNormalSelection This must be a Selection instance whose type is
* SelectionType::eNormal.
InitRootContent(const Selection& aNormalSelection);
// FlatText means the text that is generated from DOM tree. The BR elements
// are replaced to native linefeeds. Other elements are ignored.
// NodePosition stores a pair of node and offset in the node.
// When mNode is an element and mOffset is 0, the start position means after
// the open tag of mNode.
// This is useful to receive one or more sets of them instead of nsRange.
// This type is intended to be used for short-lived operations, and is thus
// marked MOZ_STACK_CLASS.
struct MOZ_STACK_CLASS NodePosition : public RangeBoundary {
// Only when mNode is an element node and mOffset is 0, mAfterOpenTag is
// referred.
bool mAfterOpenTag = true;
NodePosition() = default;
NodePosition(nsINode* aContainer, uint32_t aOffset)
: RangeBoundary(aContainer, aOffset) {}
NodePosition(nsINode* aContainer, nsIContent* aRef)
: RangeBoundary(aContainer, aRef) {}
explicit NodePosition(const nsIFrame::ContentOffsets& aContentOffsets)
: RangeBoundary(aContentOffsets.content, aContentOffsets.offset) {}
bool operator==(const NodePosition& aOther) const {
return RangeBoundary::operator==(aOther) &&
mAfterOpenTag == aOther.mAfterOpenTag;
bool IsBeforeOpenTag() const {
return IsSet() && Container()->IsElement() && !Ref() && !mAfterOpenTag;
bool IsImmediatelyAfterOpenTag() const {
return IsSet() && Container()->IsElement() && !Ref() && mAfterOpenTag;
// NodePositionBefore isn't good name if Container() isn't an element node nor
// Offset() is not 0, though, when Container() is an element node and mOffset
// is 0, this is treated as before the open tag of Container().
struct NodePositionBefore final : public NodePosition {
NodePositionBefore(nsINode* aContainer, uint32_t aOffset)
: NodePosition(aContainer, aOffset) {
mAfterOpenTag = false;
NodePositionBefore(nsINode* aContainer, nsIContent* aRef)
: NodePosition(aContainer, aRef) {
mAfterOpenTag = false;
// Get the flatten text length in the range.
// @param aStartPosition Start node and offset in the node of the range.
// @param aEndPosition End node and offset in the node of the range.
// @param aRootElement The root element of the editor or document.
// aRootElement won't cause any text including
// line breaks.
// @param aLength The result of the flatten text length of the
// range.
// @param aLineBreakType Whether this computes flatten text length with
// native line breakers on the platform or
// with XP line breaker (\n).
// @param aIsRemovingNode Should be true only when this is called from
// nsIMutationObserver::ContentRemoved().
// When this is true, aStartPosition.mNode should
// be the root node of removing nodes and mOffset
// should be 0 and aEndPosition.mNode should be
// same as aStartPosition.mNode and mOffset should
// be number of the children of mNode.
static nsresult GetFlatTextLengthInRange(const NodePosition& aStartPosition,
const NodePosition& aEndPosition,
const Element* aRootElement,
uint32_t* aLength,
LineBreakType aLineBreakType,
bool aIsRemovingNode = false);
// Computes the native text length between aStartOffset and aEndOffset of
// aTextNode.
static uint32_t GetNativeTextLength(const dom::Text& aTextNode,
uint32_t aStartOffset,
uint32_t aEndOffset);
// Get the native text length of aTextNode.
static uint32_t GetNativeTextLength(const dom::Text& aTextNode,
uint32_t aMaxLength = UINT32_MAX);
// Get the text length of aTextNode.
static uint32_t GetTextLength(const dom::Text& aTextNode,
LineBreakType aLineBreakType,
uint32_t aMaxLength = UINT32_MAX);
// Get the text length of a given range of a content node in
// the given line break type.
static uint32_t GetTextLengthInRange(const dom::Text& aTextNode,
uint32_t aXPStartOffset,
uint32_t aXPEndOffset,
LineBreakType aLineBreakType);
// Get the contents in aElement (meaning all children of aElement) as plain
// text. E.g., specifying mRootElement gets whole text in it.
// Note that the result is not same as .textContent. The result is
// optimized for native IMEs. For example, <br> element and some block
// elements causes "\n" (or "\r\n"), see also ShouldBreakLineBefore().
nsresult GenerateFlatTextContent(const Element* aElement, nsString& aString,
LineBreakType aLineBreakType);
// Get the contents of aRange as plain text.
nsresult GenerateFlatTextContent(const RawRange& aRawRange, nsString& aString,
LineBreakType aLineBreakType);
// Get offset of start of aRange. Note that the result includes the length
// of line breaker caused by the start of aContent because aRange never
// includes the line breaker caused by its start node.
nsresult GetStartOffset(const RawRange& aRawRange, uint32_t* aOffset,
LineBreakType aLineBreakType);
// Check if we should insert a line break before aContent.
// This should return false only when aContent is an html element which
// is typically used in a paragraph like <em>.
static bool ShouldBreakLineBefore(const nsIContent& aContent,
const Element* aRootElement);
// Get the line breaker length.
static inline uint32_t GetBRLength(LineBreakType aLineBreakType);
static LineBreakType GetLineBreakType(WidgetQueryContentEvent* aEvent);
static LineBreakType GetLineBreakType(WidgetSelectionEvent* aEvent);
static LineBreakType GetLineBreakType(bool aUseNativeLineBreak);
// Returns focused content (including its descendant documents).
nsIContent* GetFocusedContent();
// QueryContentRect() sets the rect of aContent's frame(s) to aEvent.
nsresult QueryContentRect(nsIContent* aContent,
WidgetQueryContentEvent* aEvent);
// Initialize aRawRange from the offset of FlatText and the text length.
// If aExpandToClusterBoundaries is true, the start offset and the end one are
// expanded to nearest cluster boundaries.
nsresult SetRawRangeFromFlatTextOffset(RawRange* aRawRange, uint32_t aOffset,
uint32_t aLength,
LineBreakType aLineBreakType,
bool aExpandToClusterBoundaries,
uint32_t* aNewOffset = nullptr,
dom::Text** aLastTextNode = nullptr);
// If the aCollapsedRawRange isn't in text node but next to a text node,
// this method modifies it in the text node. Otherwise, not modified.
nsresult AdjustCollapsedRangeMaybeIntoTextNode(RawRange& aCollapsedRawRange);
// Convert the frame relative offset to be relative to the root frame of the
// root presContext (but still measured in appUnits of aFrame's presContext).
nsresult ConvertToRootRelativeOffset(nsIFrame* aFrame, nsRect& aRect);
// Expand aXPOffset to the nearest offset in cluster boundary. aForward is
// true, it is expanded to forward.
// FYI: Due to `nsFrameSelection::GetFrameForNodeOffset()`, this cannot
// take `const dom::Text&`.
nsresult ExpandToClusterBoundary(dom::Text& aTextNode, bool aForward,
uint32_t* aXPOffset) const;
using FontRangeArray = nsTArray<mozilla::FontRange>;
static void AppendFontRanges(FontRangeArray& aFontRanges,
const dom::Text& aTextNode, uint32_t aBaseOffset,
uint32_t aXPStartOffset, uint32_t aXPEndOffset,
LineBreakType aLineBreakType);
nsresult GenerateFlatFontRanges(const RawRange& aRawRange,
FontRangeArray& aFontRanges,
uint32_t& aLength,
LineBreakType aLineBreakType);
nsresult QueryTextRectByRange(const RawRange& aRawRange,
LayoutDeviceIntRect& aRect,
WritingMode& aWritingMode);
struct MOZ_STACK_CLASS FrameAndNodeOffset final {
// mFrame is safe since this can live in only stack class and
// ContentEventHandler doesn't modify layout after
// ContentEventHandler::Init() flushes pending layout. In other words,
// this struct shouldn't be used before calling
// ContentEventHandler::Init().
nsIFrame* mFrame;
// offset in the node of mFrame
int32_t mOffsetInNode;
FrameAndNodeOffset() : mFrame(nullptr), mOffsetInNode(-1) {}
FrameAndNodeOffset(nsIFrame* aFrame, int32_t aStartOffsetInNode)
: mFrame(aFrame), mOffsetInNode(aStartOffsetInNode) {}
nsIFrame* operator->() { return mFrame; }
const nsIFrame* operator->() const { return mFrame; }
operator nsIFrame*() { return mFrame; }
operator const nsIFrame*() const { return mFrame; }
bool IsValid() const { return mFrame && mOffsetInNode >= 0; }
// Get first frame after the start of the given range for computing text rect.
// This returns invalid FrameAndNodeOffset if there is no content which
// should affect to computing text rect in the range. mOffsetInNode is start
// offset in the frame.
FrameAndNodeOffset GetFirstFrameInRangeForTextRect(const RawRange& aRawRange);
// Get last frame before the end of the given range for computing text rect.
// This returns invalid FrameAndNodeOffset if there is no content which
// should affect to computing text rect in the range. mOffsetInNode is end
// offset in the frame.
FrameAndNodeOffset GetLastFrameInRangeForTextRect(const RawRange& aRawRange);
struct MOZ_STACK_CLASS FrameRelativeRect final {
// mRect is relative to the mBaseFrame's position.
nsRect mRect;
nsIFrame* mBaseFrame;
FrameRelativeRect() : mBaseFrame(nullptr) {}
explicit FrameRelativeRect(nsIFrame* aBaseFrame) : mBaseFrame(aBaseFrame) {}
FrameRelativeRect(const nsRect& aRect, nsIFrame* aBaseFrame)
: mRect(aRect), mBaseFrame(aBaseFrame) {}
bool IsValid() const { return mBaseFrame != nullptr; }
// Returns an nsRect relative to aBaseFrame instead of mBaseFrame.
nsRect RectRelativeTo(nsIFrame* aBaseFrame) const;
// Returns a rect for line breaker before the node of aFrame (If aFrame is
// a <br> frame or a block level frame, it causes a line break at its
// element's open tag, see also ShouldBreakLineBefore()). Note that this
// doesn't check if aFrame should cause line break in non-debug build.
FrameRelativeRect GetLineBreakerRectBefore(nsIFrame* aFrame);
// Returns a line breaker rect after aTextNode as there is a line breaker
// immediately after aTextNode. This is useful when following block
// element causes a line break before it and it needs to compute the line
// breaker's rect. For example, if there is |<p>abc</p><p>def</p>|, the
// rect of 2nd <p>'s line breaker should be at right of "c" in the first
// <p>, not the start of 2nd <p>. The result is relative to the last text
// frame which represents the last character of aTextNode.
FrameRelativeRect GuessLineBreakerRectAfter(const dom::Text& aTextNode);
// Returns a guessed first rect. I.e., it may be different from actual
// caret when selection is collapsed at start of aFrame. For example, this
// guess the caret rect only with the content box of aFrame and its font
// height like:
// +-aFrame----------------- (border box)
// |
// | +--------------------- (content box)
// | | I
// ^ guessed caret rect
// However, actual caret is computed with more information like line-height,
// child frames of aFrame etc. But this does not emulate actual caret
// behavior exactly for simpler and faster code because it's difficult and
// we're not sure it's worthwhile to do it with complicated implementation.
FrameRelativeRect GuessFirstCaretRectIn(nsIFrame* aFrame);
// Make aRect non-empty. If width and/or height is 0, these methods set them
// to 1. Note that it doesn't set nsRect's width nor height to one device
// pixel because using nsRect::ToOutsidePixels() makes actual width or height
// to 2 pixels because x and y may not be aligned to device pixels.
void EnsureNonEmptyRect(nsRect& aRect) const;
void EnsureNonEmptyRect(LayoutDeviceIntRect& aRect) const;
} // namespace mozilla
#endif // mozilla_ContentEventHandler_h_