1 files changed, 123 insertions, 0 deletions
diff --git a/layout/generic/PrintedSheetFrame.h b/layout/generic/PrintedSheetFrame.h
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+++ b/layout/generic/PrintedSheetFrame.h
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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 https://mozilla.org/MPL/2.0/. */
+
+/* Rendering object for a printed or print-previewed sheet of paper */
+
+#ifndef LAYOUT_GENERIC_PRINTEDSHEETFRAME_H_
+#define LAYOUT_GENERIC_PRINTEDSHEETFRAME_H_
+
+#include "nsContainerFrame.h"
+#include "nsHTMLParts.h"
+
+class nsSharedPageData;
+
+namespace mozilla {
+
+class PrintedSheetFrame final : public nsContainerFrame {
+ public:
+  NS_DECL_QUERYFRAME
+  NS_DECL_FRAMEARENA_HELPERS(PrintedSheetFrame)
+
+  friend PrintedSheetFrame* ::NS_NewPrintedSheetFrame(
+      mozilla::PresShell* aPresShell, ComputedStyle* aStyle);
+
+  void SetSharedPageData(nsSharedPageData* aPD) { mPD = aPD; }
+
+  // Invokes MoveOverflowToChildList.
+  // This is intended for use by callers that need to be able to get our first/
+  // only nsPageFrame from our child list to examine its computed style just
+  // **prior** to us being reflowed. (If our first nsPageFrame will come from
+  // our prev-in-flow, we won't otherwise take ownership of it until we are
+  // reflowed.)
+  void ClaimPageFrameFromPrevInFlow();
+
+  // nsIFrame overrides
+  void Reflow(nsPresContext* aPresContext, ReflowOutput& aReflowOutput,
+              const ReflowInput& aReflowInput,
+              nsReflowStatus& aStatus) override;
+
+  void BuildDisplayList(nsDisplayListBuilder* aBuilder,
+                        const nsDisplayListSet& aLists) override;
+
+#ifdef DEBUG_FRAME_DUMP
+  nsresult GetFrameName(nsAString& aResult) const override;
+#endif
+
+  uint32_t GetNumPages() const { return mNumPages; }
+
+  // These methods provide information about the grid that pages should be
+  // placed into in the case that there are multiple pages-per-sheet.
+  uint32_t GetGridNumCols() const { return mGridNumCols; }
+  nsPoint GetGridOrigin() const { return mGridOrigin; }
+  nscoord GetGridCellWidth() const { return mGridCellWidth; }
+  nscoord GetGridCellHeight() const { return mGridCellHeight; }
+
+  /**
+   * A helper that is called just prior to this frame being relfowed to
+   * pre-compute and cache the size that the sheet should be given. This is
+   * called before any child nsPageFrames are reflowed, and it is cached so
+   * that those nsPageFrames can obtain their sheet frame's size while they're
+   * reflowing (the normal reflow code doesn't give the sheet frame its size
+   * until after the nsPageFrames have been reflowed).
+   * If we get rid of nsPageFrame::ComputeSinglePPSPageSizeScale (bug 1835782),
+   * which is the only consumer of GetPrecomputedSheetSize, then we can get rid
+   * of GetPrecomputedSheetSize and the member variable and rename
+   * PrecomputeSheetSize to ComputeSheetSize, which will then only be called
+   * once during reflow.
+   */
+  nsSize PrecomputeSheetSize(const nsPresContext* aPresContext);
+  nsSize GetPrecomputedSheetSize() const { return mPrecomputedSize; }
+
+ private:
+  // Private construtor & destructor, to avoid accidental (non-FrameArena)
+  // instantiation/deletion:
+  PrintedSheetFrame(ComputedStyle* aStyle, nsPresContext* aPresContext)
+      : nsContainerFrame(aStyle, aPresContext, kClassID) {}
+  ~PrintedSheetFrame() = default;
+
+  // Helper function to populate some pages-per-sheet metrics in our
+  // nsSharedPageData.
+  // XXXjwatt: We should investigate sharing this function for the single
+  // page-per-sheet case (bug 1835782). The logic for that case
+  // (nsPageFrame::ComputePageSizeScale) is somewhat different though, since
+  // that case uses no sheet margins and uses the user/CSS specified margins on
+  // the page, with any page scaling reverted to keep the margins unchanged.
+  // We, on the other hand, use the unwriteable margins for the sheet, unscaled,
+  // and use the user/CSS margins on the pages and allow them to be scaled
+  // along with any pages-per-sheet scaling. (This behavior makes maximum use
+  // of the sheet and, by scaling the default on the pages, results in a
+  // a sensible amount of spacing between pages.)
+  void ComputePagesPerSheetGridMetrics(const nsSize& aSheetSize);
+
+  nsSize mPrecomputedSize;
+
+  // Note: this will be set before reflow, and it's strongly owned by our
+  // nsPageSequenceFrame, which outlives us.
+  nsSharedPageData* mPD = nullptr;
+
+  // The number of visible pages in this sheet.
+  uint32_t mNumPages = 0;
+
+  // Number of "columns" in our pages-per-sheet layout. For example: if we're
+  // printing with 6 pages-per-sheet, then this could be either 3 or 2,
+  // depending on whether we're printing portrait-oriented pages onto a
+  // landscape-oriented sheet (3 cols) vs. if we're printing landscape-oriented
+  // pages onto a portrait-oriented sheet (2 cols).
+  uint32_t mGridNumCols = 1;
+
+  // The offset of the start of the multiple pages-per-sheet grid from the
+  // top-left of the sheet.
+  nsPoint mGridOrigin;
+
+  // The size of each cell on the sheet into which pages are to be placed.
+  // (The default values are arbitrary.)
+  nscoord mGridCellWidth = 1;
+  nscoord mGridCellHeight = 1;
+};
+
+}  // namespace mozilla
+
+#endif /* LAYOUT_GENERIC_PRINTEDSHEETFRAME_H_ */