gecko-dev/layout/mathml/nsMathMLmmultiscriptsFrame.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

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1.8 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 nsMathMLmmultiscriptsFrame_h___
#define nsMathMLmmultiscriptsFrame_h___
#include "mozilla/Attributes.h"
#include "nsMathMLContainerFrame.h"
namespace mozilla {
class PresShell;
} // namespace mozilla
//
// <mmultiscripts> -- attach prescripts and tensor indices to a base
// <msub> -- attach a subscript to a base
// <msubsup> -- attach a subscript-superscript pair to a base
// <msup> -- attach a superscript to a base
//
class nsMathMLmmultiscriptsFrame final : public nsMathMLContainerFrame {
public:
NS_DECL_FRAMEARENA_HELPERS(nsMathMLmmultiscriptsFrame)
friend nsIFrame* NS_NewMathMLmmultiscriptsFrame(
mozilla::PresShell* aPresShell, ComputedStyle* aStyle);
NS_IMETHOD
TransmitAutomaticData() override;
nsresult Place(DrawTarget* aDrawTarget, const PlaceFlags& aFlags,
ReflowOutput& aDesiredSize) override;
static nsresult PlaceMultiScript(
nsPresContext* aPresContext, DrawTarget* aDrawTarget,
const PlaceFlags& aFlags, ReflowOutput& aDesiredSize,
nsMathMLContainerFrame* aFrame, nscoord aUserSubScriptShift,
nscoord aUserSupScriptShift, float aFontSizeInflation);
uint8_t ScriptIncrement(nsIFrame* aFrame) override;
protected:
explicit nsMathMLmmultiscriptsFrame(ComputedStyle* aStyle,
nsPresContext* aPresContext)
: nsMathMLContainerFrame(aStyle, aPresContext, kClassID) {}
virtual ~nsMathMLmmultiscriptsFrame();
};
#endif /* nsMathMLmmultiscriptsFrame_h___ */