1 files changed, 98 insertions, 0 deletions
diff --git a/layout/generic/nsBlockReflowContext.h b/layout/generic/nsBlockReflowContext.h
new file mode 100644
index 000000000..4d5541ff6
--- /dev/null
+++ b/layout/generic/nsBlockReflowContext.h
@@ -0,0 +1,98 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+// vim:cindent:ts=2:et:sw=2:
+/* 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 "nsIFrame.h"
+#include "mozilla/ReflowOutput.h"
+
+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& aParentRS);
+  ~nsBlockReflowContext() { }
+
+  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 */,
+                  nsOverflowAreas&         aOverflowAreas,
+                  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 state 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___ */