1 files changed, 91 insertions, 0 deletions
diff --git a/layout/generic/nsBlockReflowContext.h b/layout/generic/nsBlockReflowContext.h
new file mode 100644
index 0000000000..b7521f0a6e
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+++ b/layout/generic/nsBlockReflowContext.h
@@ -0,0 +1,91 @@
+/* -*- 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/. */
+
+/* class that a parent frame uses to reflow a block frame */
+
+#ifndef nsBlockReflowContext_h___
+#define nsBlockReflowContext_h___
+
+#include "mozilla/ReflowOutput.h"
+
+class nsIFrame;
+class nsLineBox;
+class nsPresContext;
+namespace mozilla {
+class BlockReflowInput;
+}  // namespace mozilla
+
+/**
+ * An encapsulation of the state and algorithm for reflowing block frames.
+ */
+class nsBlockReflowContext {
+  using BlockReflowInput = mozilla::BlockReflowInput;
+  using ReflowInput = mozilla::ReflowInput;
+  using ReflowOutput = mozilla::ReflowOutput;
+
+ public:
+  nsBlockReflowContext(nsPresContext* aPresContext,
+                       const ReflowInput& aParentRI);
+  ~nsBlockReflowContext() = default;
+
+  void ReflowBlock(const mozilla::LogicalRect& aSpace, bool aApplyBStartMargin,
+                   nsCollapsingMargin& aPrevMargin, nscoord aClearance,
+                   bool aIsAdjacentWithBStart, nsLineBox* aLine,
+                   ReflowInput& aReflowInput, nsReflowStatus& aReflowStatus,
+                   BlockReflowInput& aState);
+
+  bool PlaceBlock(const ReflowInput& aReflowInput, bool aForceFit,
+                  nsLineBox* aLine,
+                  nsCollapsingMargin& aBEndMarginResult /* out */,
+                  mozilla::OverflowAreas& aOverflowAreas,
+                  const nsReflowStatus& aReflowStatus);
+
+  nsCollapsingMargin& GetCarriedOutBEndMargin() {
+    return mMetrics.mCarriedOutBEndMargin;
+  }
+
+  const ReflowOutput& GetMetrics() const { return mMetrics; }
+
+  /**
+   * Computes the collapsed block-start margin (in the context's parent's
+   * writing mode) for a block whose reflow input is in aRI.
+   * The computed margin is added into aMargin, whose writing mode is the
+   * parent's mode as found in mMetrics.GetWritingMode(); note this may not be
+   * the block's own writing mode as found in aRI.
+   * If aClearanceFrame is null then this is the first optimistic pass which
+   * shall assume that no frames have clearance, and we clear the HasClearance
+   * on all frames encountered.
+   * If non-null, this is the second pass and the caller has decided
+   * aClearanceFrame needs clearance (and we will therefore stop collapsing
+   * there); also, this function is responsible for marking it with
+   * SetHasClearance.
+   * If in the optimistic pass any frame is encountered that might possibly
+   * need clearance (i.e., if we really needed the optimism assumption) then
+   * we set aMayNeedRetry to true.
+   * We return true if we changed the clearance state of any line and marked it
+   * dirty.
+   */
+  bool ComputeCollapsedBStartMargin(const ReflowInput& aRI,
+                                    nsCollapsingMargin* aMargin,
+                                    nsIFrame* aClearanceFrame,
+                                    bool* aMayNeedRetry,
+                                    bool* aIsEmpty = nullptr);
+
+ protected:
+  nsPresContext* mPresContext;
+  const ReflowInput& mOuterReflowInput;
+
+  nsIFrame* mFrame;
+  mozilla::LogicalRect mSpace;
+
+  nscoord mICoord, mBCoord;
+  nsSize mContainerSize;
+  mozilla::WritingMode mWritingMode;
+  ReflowOutput mMetrics;
+  nsCollapsingMargin mBStartMargin;
+};
+
+#endif /* nsBlockReflowContext_h___ */