gecko-dev/layout/base/ScrollStyles.cpp
2020-08-02 15:29:15 +00:00

49 lines
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/. */
#include "mozilla/ScrollStyles.h"
#include "nsStyleStruct.h" // for nsStyleDisplay
namespace mozilla {
// https://drafts.csswg.org/css-overflow/#overflow-propagation
// "If `visible` is applied to the viewport, it must be interpreted as `auto`.
// If `clip` is applied to the viewport, it must be interpreted as `hidden`."
static StyleOverflow MapOverflowValueForViewportPropagation(
StyleOverflow aOverflow) {
switch (aOverflow) {
case StyleOverflow::Visible:
return StyleOverflow::Auto;
case StyleOverflow::Clip:
return StyleOverflow::Hidden;
default:
return aOverflow;
}
}
ScrollStyles::ScrollStyles(StyleOverflow aH, StyleOverflow aV)
: mHorizontal(aH), mVertical(aV) {
MOZ_ASSERT(mHorizontal == StyleOverflow::Auto ||
mHorizontal == StyleOverflow::Hidden ||
mHorizontal == StyleOverflow::Scroll);
MOZ_ASSERT(mVertical == StyleOverflow::Auto ||
mVertical == StyleOverflow::Hidden ||
mVertical == StyleOverflow::Scroll);
}
ScrollStyles::ScrollStyles(const nsStyleDisplay& aDisplay,
MapOverflowToValidScrollStyleTag)
: ScrollStyles(
MapOverflowValueForViewportPropagation(aDisplay.mOverflowX),
MapOverflowValueForViewportPropagation(aDisplay.mOverflowY)) {}
bool ScrollStyles::IsHiddenInBothDirections() const {
return mHorizontal == StyleOverflow::Hidden &&
mVertical == StyleOverflow::Hidden;
}
} // namespace mozilla