gecko-dev/layout/mathml/nsMathMLmunderoverFrame.h
Frédéric Wang bcc3be9085 Bug 1908069 - Introduce PlaceFlags parameter to MathML layout methods. r=emilio
MathML classes has a few Place*() methods  used for layout and intrinsic
size calculation. These methods have a parameter "aPlaceOrigin"
indicating whether the children and other painted objects should have
their final positions set, or if the method is only called for measuring.
This parameter is typically set to false when doing intrinsic size
calculation or when performing some non-final measurement for operator
stretching.

For intrinsic size calculation, it is generally enough to perform
placement with aPlaceOrigin=false and ignoring the vertical metrics.
Some Place*() methods also have a parameter "aWidthOnly" for special
handling. For example, msqrt stretches a radical symbol vertically to
match the height of the content but when doing intrinsic size
calculation this is approximated to nsMathMLChar::GetMaxWidth() instead.
When we implement border/padding/margin we should also be able to
choose between using IntrinsicISizeOffsets() or GetUsed*() methods.

Finally, some Place*() methods initially call a place routing of a
parent class before further tweaking the layout. For example, msqrt
uses mrow layout on children and adds some radical symbol on top of
them. When we implement border/padding, we should make sure we don't
add the border/padding before the final result.

In order to handle all these placement behaviors, a new EnumSet is
introduced. This commit does not change behavior. Handling of padding,
border and margin will be handled in follow-up patches.

Differential Revision: https://phabricator.services.mozilla.com/D216669
2024-08-07 06:00:43 +00:00

89 lines
2.9 KiB
C++

/* -*- 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 nsMathMLmunderoverFrame_h___
#define nsMathMLmunderoverFrame_h___
#include "mozilla/Attributes.h"
#include "nsIReflowCallback.h"
#include "nsMathMLContainerFrame.h"
namespace mozilla {
class PresShell;
} // namespace mozilla
//
// <munderover> -- attach an underscript-overscript pair to a base
//
class nsMathMLmunderoverFrame final : public nsMathMLContainerFrame,
public nsIReflowCallback {
public:
NS_DECL_FRAMEARENA_HELPERS(nsMathMLmunderoverFrame)
friend nsIFrame* NS_NewMathMLmunderoverFrame(mozilla::PresShell* aPresShell,
ComputedStyle* aStyle);
nsresult Place(DrawTarget* aDrawTarget, const PlaceFlags& aFlags,
ReflowOutput& aDesiredSize) override;
NS_IMETHOD InheritAutomaticData(nsIFrame* aParent) override;
NS_IMETHOD TransmitAutomaticData() override;
NS_IMETHOD UpdatePresentationData(uint32_t aFlagsValues,
uint32_t aFlagsToUpdate) override;
void Destroy(DestroyContext&) override;
nsresult AttributeChanged(int32_t aNameSpaceID, nsAtom* aAttribute,
int32_t aModType) override;
uint8_t ScriptIncrement(nsIFrame* aFrame) override;
// nsIReflowCallback.
bool ReflowFinished() override;
void ReflowCallbackCanceled() override;
protected:
explicit nsMathMLmunderoverFrame(ComputedStyle* aStyle,
nsPresContext* aPresContext)
: nsMathMLContainerFrame(aStyle, aPresContext, kClassID),
mIncrementUnder(false),
mIncrementOver(false) {}
virtual ~nsMathMLmunderoverFrame();
private:
// Helper to set the "increment script level" flag on the element belonging
// to a child frame given by aChildIndex.
//
// When this flag is set, the style system will increment the scriptlevel for
// the child element. This is needed for situations where the style system
// cannot itself determine the scriptlevel (mfrac, munder, mover, munderover).
//
// This should be called during reflow.
//
// We set the flag and if it changed, we request appropriate restyling and
// also queue a post-reflow callback to ensure that restyle and reflow happens
// immediately after the current reflow.
void SetIncrementScriptLevel(uint32_t aChildIndex, bool aIncrement);
void SetPendingPostReflowIncrementScriptLevel();
bool mIncrementUnder;
bool mIncrementOver;
struct SetIncrementScriptLevelCommand {
uint32_t mChildIndex;
bool mDoIncrement;
};
nsTArray<SetIncrementScriptLevelCommand>
mPostReflowIncrementScriptLevelCommands;
};
#endif /* nsMathMLmunderoverFrame_h___ */