gecko-dev/layout/generic/nsPageSequenceFrame.h

/* -*- 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/. */
#ifndef nsPageSequenceFrame_h___
#define nsPageSequenceFrame_h___

#include "mozilla/Attributes.h"
#include "mozilla/UniquePtr.h"
#include "nsContainerFrame.h"
#include "nsIPrintSettings.h"

namespace mozilla {

class PresShell;
class PrintedSheetFrame;

namespace dom {

class HTMLCanvasElement;

}  // namespace dom
}  // namespace mozilla

//-----------------------------------------------
// This class is used to manage some static data about the layout
// characteristics of our various "Pages Per Sheet" options.
struct nsPagesPerSheetInfo {
  static const nsPagesPerSheetInfo& LookupInfo(int32_t aPPS);

  uint16_t mNumPages;

  // This is the larger of the row-count vs. column-count for this layout
  // (if they aren't the same). We'll aim to stack this number of pages
  // in the sheet's longer axis.
  uint16_t mLargerNumTracks;
};

/**
 * This class maintains various shared data that is used by printing-related
 * frames. The nsPageSequenceFrame strongly owns an instance of this class,
 * which lives for as long as the nsPageSequenceFrame does.
 */
class nsSharedPageData {
 public:
  nsString mDateTimeStr;
  nsString mPageNumFormat;
  nsString mPageNumAndTotalsFormat;
  nsString mDocTitle;
  nsString mDocURL;
  nsFont mHeadFootFont;

  // Total number of pages (populated by PrintedSheetFrame when it determines
  // that it's reflowed the final page):
  int32_t mRawNumPages = 0;

  // If there's more than one page-range, then its components are stored here
  // as pairs of (start,end).  They're stored in the order provided (not
  // necessarily in ascending order).
  nsTArray<int32_t> mPageRanges;

  // Margin for headers and footers; it defaults to 4/100 of an inch on UNIX
  // and 0 elsewhere; I think it has to do with some inconsistency in page size
  // computations
  nsMargin mEdgePaperMargin;

  nsCOMPtr<nsIPrintSettings> mPrintSettings;

  // The scaling ratio we need to apply to make all pages fit horizontally. It's
  // the minimum "ComputedWidth / OverflowWidth" ratio of all page content
  // frames that overflowed.  It's 1.0 if none overflowed horizontally.
  float mShrinkToFitRatio = 1.0f;

  // The mPagesPerSheet{...} members are only used if
  // PagesPerSheetInfo()->mNumPages > 1.  They're initialized with reasonable
  // defaults here (which correspond to what we do for the regular
  // 1-page-per-sheet scenario, though we don't actually use these members in
  // that case).  If we're in >1 pages-per-sheet scenario, then these members
  // will be assigned "real" values during the reflow of the first
  // PrintedSheetFrame.
  float mPagesPerSheetScale = 1.0f;
  // 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 mPagesPerSheetNumCols = 1;
  nsPoint mPagesPerSheetGridOrigin;

  // Lazy getter, to look up our pages-per-sheet info based on mPrintSettings
  // (if it's available).  The result is stored in our mPagesPerSheetInfo
  // member-var to speed up subsequent lookups.
  // This API is infallible; in failure cases, it just returns the info struct
  // that corresponds to 1 page per sheet.
  const nsPagesPerSheetInfo* PagesPerSheetInfo();

 private:
  const nsPagesPerSheetInfo* mPagesPerSheetInfo = nullptr;
};

// Page sequence frame class. Manages a series of pages, in paginated mode.
// (Strictly speaking, this frame's direct children are PrintedSheetFrame
// instances, and each of those will usually contain one nsPageFrame, depending
// on the "pages-per-sheet" setting and whether the print operation is
// restricted to a custom page range.)
class nsPageSequenceFrame final : public nsContainerFrame {
  using LogicalSize = mozilla::LogicalSize;

 public:
  friend nsPageSequenceFrame* NS_NewPageSequenceFrame(
      mozilla::PresShell* aPresShell, ComputedStyle* aStyle);

  NS_DECL_QUERYFRAME
  NS_DECL_FRAMEARENA_HELPERS(nsPageSequenceFrame)

  // nsIFrame
  void Reflow(nsPresContext* aPresContext, ReflowOutput& aReflowOutput,
              const ReflowInput& aReflowInput,
              nsReflowStatus& aStatus) override;

  void BuildDisplayList(nsDisplayListBuilder* aBuilder,
                        const nsDisplayListSet& aLists) override;

  // For Shrink To Fit
  float GetSTFPercent() const { return mPageData->mShrinkToFitRatio; }

  // Gets the final print preview scale that we're applying to the previewed
  // sheets of paper.
  float GetPrintPreviewScale() const;

  // Async Printing
  nsresult StartPrint(nsPresContext* aPresContext,
                      nsIPrintSettings* aPrintSettings,
                      const nsAString& aDocTitle, const nsAString& aDocURL);
  nsresult PrePrintNextSheet(nsITimerCallback* aCallback, bool* aDone);
  nsresult PrintNextSheet();
  void ResetPrintCanvasList();

  uint32_t GetCurrentSheetIdx() const { return mCurrentSheetIdx; }

  int32_t GetRawNumPages() const { return mPageData->mRawNumPages; }

  uint32_t GetPagesInFirstSheet() const;

  nsresult DoPageEnd();

  // We must allow Print Preview UI to have a background, no matter what the
  // user's settings
  bool HonorPrintBackgroundSettings() const override { return false; }

  bool HasTransformGetter() const override { return true; }

#ifdef DEBUG_FRAME_DUMP
  nsresult GetFrameName(nsAString& aResult) const override;
#endif

 protected:
  nsPageSequenceFrame(ComputedStyle*, nsPresContext*);
  virtual ~nsPageSequenceFrame();

  void SetPageNumberFormat(const char* aPropName, const char* aDefPropVal,
                           bool aPageNumOnly);

  // SharedPageData Helper methods
  void SetDateTimeStr(const nsAString& aDateTimeStr);
  void SetPageNumberFormat(const nsAString& aFormatStr, bool aForPageNumOnly);

  // Print scaling is applied in this function.
  void PopulateReflowOutput(ReflowOutput&, const ReflowInput&);

  // Helper function to compute the offset needed to center a child
  // page-frame's margin-box inside our content-box.
  nscoord ComputeCenteringMargin(nscoord aContainerContentBoxWidth,
                                 nscoord aChildPaddingBoxWidth,
                                 const nsMargin& aChildPhysicalMargin);

  mozilla::PrintedSheetFrame* GetCurrentSheetFrame();

  nsSize mSize;

  // These next two LogicalSize members are used when we're in print-preview to
  // ensure that each previewed sheet will fit in the print-preview scrollport:
  // -------

  // Each component of this LogicalSize represents the maximum length of all
  // our print-previewed sheets in that axis, plus a little extra for the
  // print-preview margin.  Note that this LogicalSize doesn't necessarily
  // correspond to any one particular sheet's size (especially if our sheets
  // have different sizes), since the components are tracked independently such
  // that we end up storing the maximum in each dimension.
  LogicalSize mMaxSheetSize;
  // The size of the scrollport where we're print-previewing sheets.
  LogicalSize mScrollportSize;

  // Data shared by all the nsPageFrames:
  mozilla::UniquePtr<nsSharedPageData> mPageData;

  // The zero-based index of the PrintedSheetFrame child that is being printed
  // (or about-to-be-printed), in an async print operation.
  // This is an index into our PrincipalChildList, effectively.
  uint32_t mCurrentSheetIdx = 0;

  nsTArray<RefPtr<mozilla::dom::HTMLCanvasElement> > mCurrentCanvasList;

  bool mCalledBeginPage;

  bool mCurrentCanvasListSetup;
};

#endif /* nsPageSequenceFrame_h___ */