tor-browser

nsIMathMLFrame.h (12940B)

---

/* -*- 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 nsIMathMLFrame_h___
#define nsIMathMLFrame_h___

#include "nsMathMLOperators.h"
#include "nsQueryFrame.h"

struct nsPresentationData;
struct nsEmbellishData;
class gfxContext;
class nsIFrame;
namespace mozilla {
class ReflowOutput;
}  // namespace mozilla

// For MathML, this 'type' will be used to determine the spacing between frames
// Subclasses can return a 'type' that will give them a particular spacing
enum class MathMLFrameType {
 Unknown = -1,
 Ordinary,
 OperatorOrdinary,
 OperatorInvisible,
 OperatorUserDefined,
 Inner,
 ItalicIdentifier,
 UprightIdentifier,
 Count
};

// Bits used for the presentation flags -- these bits are set
// in their relevant situation as they become available
enum class MathMLPresentationFlag : uint8_t {
 // This bit is used to emulate TeX rendering.
 // Internal use only, cannot be set by the user with an attribute.
 Compressed,

 // This bit is set if the frame will fire a vertical stretch
 // command on all its (non-empty) children.
 // Tags like <mrow> (or an inferred mrow), mpadded, etc, will fire a
 // vertical stretch command on all their non-empty children
 StretchAllChildrenVertically,

 // This bit is set if the frame will fire a horizontal stretch
 // command on all its (non-empty) children.
 // Tags like munder, mover, munderover, will fire a
 // horizontal stretch command on all their non-empty children
 StretchAllChildrenHorizontally,

 // This bit is set if the frame is "space-like", as defined by the spec.
 SpaceLike,

 // This bit is set if a token frame should be rendered with the dtls font
 // feature setting.
 Dtls,

 // a bit used for debug
 StretchDone,
};
using MathMLPresentationFlags = mozilla::EnumSet<MathMLPresentationFlag>;

// Bits used for the embellish flags -- these bits are set
// in their relevant situation as they become available
enum class MathMLEmbellishFlag : uint8_t {
 // This bit is set if the frame is an embellished operator.
 EmbellishedOperator,

 // This bit is set if the frame is an <mo> frame or an embellihsed
 // operator for which the core <mo> has movablelimits="true"
 MovableLimits,

 // This bit is set if the frame is an <mo> frame or an embellihsed
 // operator for which the core <mo> has accent="true"
 Accent,

 // This bit is set if the frame is an <mover> or <munderover> with
 // an accent frame
 AccentOver,

 // This bit is set if the frame is an <munder> or <munderover> with
 // an accentunder frame
 AccentUnder,

 // This bit is set on the core if it is a fence operator.
 Fence,

 // This bit is set on the core if it is a separator operator.
 Separator,
};
using MathMLEmbellishFlags = mozilla::EnumSet<MathMLEmbellishFlag>;

// Abstract base class that provides additional methods for MathML frames
class nsIMathMLFrame {
public:
 NS_DECL_QUERYFRAME_TARGET(nsIMathMLFrame)

 // helper to check whether the frame is "space-like", as defined by the spec.
 virtual bool IsSpaceLike() = 0;

 /* SUPPORT FOR PRECISE POSITIONING */
 /*====================================================================*/

 /* Metrics that _exactly_ enclose the text of the frame.
  * The frame *must* have *already* being reflowed, before you can call
  * the GetBoundingMetrics() method.
  * Note that for a frame with nested children, the bounding metrics
  * will exactly enclose its children. For example, the bounding metrics
  * of msub is the smallest rectangle that exactly encloses both the
  * base and the subscript.
  */
 NS_IMETHOD
 GetBoundingMetrics(nsBoundingMetrics& aBoundingMetrics) = 0;

 NS_IMETHOD
 SetBoundingMetrics(const nsBoundingMetrics& aBoundingMetrics) = 0;

 NS_IMETHOD
 SetReference(const nsPoint& aReference) = 0;

 virtual MathMLFrameType GetMathMLFrameType() = 0;

 /* SUPPORT FOR STRETCHY ELEMENTS */
 /*====================================================================*/

 /* Stretch :
  * Called to ask a stretchy MathML frame to stretch itself depending
  * on its context.
  *
  * An embellished frame is treated in a special way. When it receives a
  * Stretch() command, it passes the command to its embellished child and
  * the stretched size is bubbled up from the inner-most <mo> frame. In other
  * words, the stretch command descend through the embellished hierarchy.
  *
  * @param aStretchDirection [in] the direction where to attempt to
  *        stretch.
  * @param aContainerSize [in] struct that suggests the maximumn size for
  *        the stretched frame. Only member data of the struct that are
  *        relevant to the direction are used (the rest is ignored).
  * @param aDesiredStretchSize [in/out] On input the current size
  *        of the frame, on output the size after stretching.
  */
 NS_IMETHOD
 Stretch(mozilla::gfx::DrawTarget* aDrawTarget,
         nsStretchDirection aStretchDirection,
         nsBoundingMetrics& aContainerSize,
         mozilla::ReflowOutput& aDesiredStretchSize) = 0;

 /* Get the mEmbellishData member variable. */

 NS_IMETHOD
 GetEmbellishData(nsEmbellishData& aEmbellishData) = 0;

 /* SUPPORT FOR SCRIPTING ELEMENTS */
 /*====================================================================*/

 /* Get the mPresentationData member variable. */

 NS_IMETHOD
 GetPresentationData(nsPresentationData& aPresentationData) = 0;

 /* InheritAutomaticData() / TransmitAutomaticData() :
  * There are precise rules governing each MathML frame and its children.
  * Properties such as the scriptlevel or the embellished nature of a frame
  * depend on those rules. Also, certain properties that we use to emulate
  * TeX rendering rules are frame-dependent too. These two methods are meant
  * to be implemented by frame classes that need to assert specific properties
  * within their subtrees.
  *
  * InheritAutomaticData() is called in a top-down manner [like
  * nsIFrame::Init], as we descend the frame tree, whereas
  * TransmitAutomaticData() is called in a bottom-up manner, as we ascend the
  * tree [like nsIFrame::SetInitialChildList]. However, unlike Init() and
  * SetInitialChildList() which are called only once during the life-time of a
  * frame (when initially constructing the frame tree), these two methods are
  * called to build automatic data after the <math>...</math> subtree has been
  * constructed fully, and are called again as we walk a child's subtree to
  * handle dynamic changes that happen in the content model.
  *
  * As a rule of thumb:
  *
  * 1. Use InheritAutomaticData() to set properties related to your ancestors:
  *    - set properties that are intrinsic to yourself
  *    - set properties that depend on the state that you expect your ancestors
  *      to have already reached in their own InheritAutomaticData().
  *    - set properties that your descendants assume that you would have set in
  *      your InheritAutomaticData() -- this way, they can safely query them
  *      and the process will feed upon itself.
  *
  * 2. Use TransmitAutomaticData() to set properties related to your
  *    descendants:
  *    - set properties that depend on the state that you expect your
  *      descendants to have reached upon processing their own
  *      TransmitAutomaticData().
  *    - transmit properties that your descendants expect that you will
  *      transmit to them in your TransmitAutomaticData() -- this way, they
  *      remain up-to-date.
  *    - set properties that your ancestors expect that you would set in your
  *      TransmitAutomaticData() -- this way, they can safely query them and
  *      the process will feed upon itself.
  */

 NS_IMETHOD
 InheritAutomaticData(nsIFrame* aParent) = 0;

 NS_IMETHOD
 TransmitAutomaticData() = 0;

 /* UpdatePresentationData:
  * Updates the frame's compression flag.
  * A frame becomes "compressed" (or "cramped") according to TeX rendering
  * rules (TeXBook, Ch.17, p.140-141).
  *
  * @param aFlagsValues [in]
  *        The new values (e.g., compress) that are going to be
  *        updated.
  *
  * @param aWhichFlags [in]
  *        The flags that are relevant to this call. Since not all calls
  *        are meant to update all flags at once, aWhichFlags is used
  *        to distinguish flags that need to retain their existing values
  *        from flags that need to be turned on (or turned off). If a bit
  *        is set in aWhichFlags, then the corresponding value (which
  *        can be 0 or 1) is taken from aFlagsValues and applied to the
  *        frame. Therefore, by setting their bits in aWhichFlags, and
  *        setting their desired values in aFlagsValues, it is possible to
  *        update some flags in the frame, leaving the other flags unchanged.
  */
 NS_IMETHOD
 UpdatePresentationData(MathMLPresentationFlags aFlagsValues,
                        MathMLPresentationFlags aWhichFlags) = 0;

 /* UpdatePresentationDataFromChildAt :
  * Sets compression flag on the whole tree. For child frames
  * at aFirstIndex up to aLastIndex, this method sets their
  * compression flags. The update is propagated down the subtrees of each of
  * these child frames.
  *
  * @param aFirstIndex [in]
  *        Index of the first child from where the update is propagated.
  *
  * @param aLastIndex [in]
  *        Index of the last child where to stop the update.
  *        A value of -1 means up to last existing child.
  *
  * @param aFlagsValues [in]
  *        The new values (e.g., compress) that are going to be
  *        assigned in the whole sub-trees.
  *
  * @param aWhichFlags [in]
  *        The flags that are relevant to this call. See
  * UpdatePresentationData() for more details about this parameter.
  */
 NS_IMETHOD
 UpdatePresentationDataFromChildAt(int32_t aFirstIndex, int32_t aLastIndex,
                                   MathMLPresentationFlags aFlagsValues,
                                   MathMLPresentationFlags aWhichFlags) = 0;

 // If aFrame is a child frame, returns the script increment which this frame
 // imposes on the specified frame, ignoring any artificial adjustments to
 // scriptlevel.
 // Returns 0 if the specified frame isn't a child frame.
 virtual uint8_t ScriptIncrement(nsIFrame* aFrame) = 0;

 // Returns true if the frame is considered to be an mrow for layout purposes.
 // This includes inferred mrows, but excludes <mrow> elements with a single
 // child.  In the latter case, the child is to be treated as if it wasn't
 // within an mrow, so we pretend the mrow isn't mrow-like.
 virtual bool IsMrowLike() = 0;
};

// struct used by a container frame to keep track of its embellishments.
// By convention, the data that we keep here is bubbled from the embellished
// hierarchy, and it remains unchanged unless we have to recover from a change
// that occurs in the embellished hierarchy. The struct remains in its nil
// state in those frames that are not part of the embellished hierarchy.
struct nsEmbellishData {
 // bits used to mark certain properties of our embellishments
 MathMLEmbellishFlags flags;

 // pointer on the <mo> frame at the core of the embellished hierarchy
 nsIFrame* coreFrame = nullptr;

 // stretchy direction that the nsMathMLChar owned by the core <mo> supports
 nsStretchDirection direction = NS_STRETCH_DIRECTION_UNSUPPORTED;

 // spacing that may come from <mo> depending on its 'form'. Since
 // the 'form' may also depend on the position of the outermost
 // embellished ancestor, the set up of these values may require
 // looking up the position of our ancestors.
 nscoord leadingSpace = 0;
 nscoord trailingSpace = 0;
};

// struct used by a container frame to modulate its presentation.
// By convention, the data that we keep in this struct can change depending
// on any of our ancestors and/or descendants. If a data can be resolved
// solely from the embellished hierarchy, and it remains immutable once
// resolved, we put it in |nsEmbellishData|. If it can be affected by other
// things, it comes here. This struct is updated as we receive information
// transmitted by our ancestors and is kept in sync with changes in our
// descendants that affects us.
struct nsPresentationData {
 // bits for: compressed, etc
 MathMLPresentationFlags flags;

 // handy pointer on our base child (the 'nucleus' in TeX), but it may be
 // null here (e.g., tags like <mrow>, <mfrac>, <mtable>, etc, won't
 // pick a particular child in their child list to be the base)
 nsIFrame* baseFrame = nullptr;
};

#endif /* nsIMathMLFrame_h___ */