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-rw-r--r--layout/generic/ColumnUtils.cpp47
1 files changed, 47 insertions, 0 deletions
diff --git a/layout/generic/ColumnUtils.cpp b/layout/generic/ColumnUtils.cpp
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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 http://mozilla.org/MPL/2.0/. */
+
+/* A namespace class for static muti-column utilities. */
+
+#include "mozilla/ColumnUtils.h"
+
+#include <algorithm>
+
+#include "nsContainerFrame.h"
+#include "nsLayoutUtils.h"
+
+namespace mozilla {
+
+/* static */
+nscoord ColumnUtils::GetColumnGap(const nsContainerFrame* aFrame,
+ nscoord aPercentageBasis) {
+ const auto& columnGap = aFrame->StylePosition()->mColumnGap;
+ if (columnGap.IsNormal()) {
+ return aFrame->StyleFont()->mFont.size.ToAppUnits();
+ }
+ return nsLayoutUtils::ResolveGapToLength(columnGap, aPercentageBasis);
+}
+
+/* static */
+nscoord ColumnUtils::ClampUsedColumnWidth(const Length& aColumnWidth) {
+ // Per spec, used values will be clamped to a minimum of 1px.
+ return std::max(CSSPixel::ToAppUnits(1), aColumnWidth.ToAppUnits());
+}
+
+/* static */
+nscoord ColumnUtils::IntrinsicISize(uint32_t aColCount, nscoord aColGap,
+ nscoord aColISize) {
+ MOZ_ASSERT(aColCount > 0, "Cannot compute with zero columns!");
+
+ // Column box's inline-size times number of columns (n), plus n-1 column gaps.
+ nscoord iSize = aColISize * aColCount + aColGap * (aColCount - 1);
+
+ // The multiplication above can make 'iSize' negative (integer overflow),
+ // so use std::max to protect against that.
+ return std::max(iSize, aColISize);
+}
+
+} // namespace mozilla