layout/generic/PrintedSheetFrame.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
   6
   7 /* Rendering object for a printed or print-previewed sheet of paper */
   8
   9 #ifndef LAYOUT_GENERIC_PRINTEDSHEETFRAME_H_
  10 #define LAYOUT_GENERIC_PRINTEDSHEETFRAME_H_
  11
  12 #include "mozilla/gfx/Point.h"
  13 #include "nsContainerFrame.h"
  14 #include "nsHTMLParts.h"
  15
  16 class nsSharedPageData;
  17
  18 namespace mozilla {
  19
  20 class PrintedSheetFrame final : public nsContainerFrame {
  21  public:
  22   using IntSize = mozilla::gfx::IntSize;
  23
  24   NS_DECL_QUERYFRAME
  25   NS_DECL_FRAMEARENA_HELPERS(PrintedSheetFrame)
  26
  27   friend PrintedSheetFrame* ::NS_NewPrintedSheetFrame(
  28       mozilla::PresShell* aPresShell, ComputedStyle* aStyle);
  29
  30   void SetSharedPageData(nsSharedPageData* aPD) { mPD = aPD; }
  31
  32   // XXX: this needs a better name, since it also updates style.
  33   // Invokes MoveOverflowToChildList.
  34   // This is intended for use by callers that need to be able to get our first/
  35   // only nsPageFrame from our child list to examine its computed style just
  36   // **prior** to us being reflowed. (If our first nsPageFrame will come from
  37   // our prev-in-flow, we won't otherwise take ownership of it until we are
  38   // reflowed.)
  39   void ClaimPageFrameFromPrevInFlow();
  40
  41   // nsIFrame overrides
  42   void Reflow(nsPresContext* aPresContext, ReflowOutput& aReflowOutput,
  43               const ReflowInput& aReflowInput,
  44               nsReflowStatus& aStatus) override;
  45
  46   void BuildDisplayList(nsDisplayListBuilder* aBuilder,
  47                         const nsDisplayListSet& aLists) override;
  48
  49 #ifdef DEBUG_FRAME_DUMP
  50   nsresult GetFrameName(nsAString& aResult) const override;
  51 #endif
  52
  53   uint32_t GetNumPages() const { return mNumPages; }
  54
  55   // These methods provide information about the grid that pages should be
  56   // placed into in the case that there are multiple pages-per-sheet.
  57   uint32_t GetGridNumCols() const { return mGridNumCols; }
  58   nsPoint GetGridOrigin() const { return mGridOrigin; }
  59   nscoord GetGridCellWidth() const { return mGridCellWidth; }
  60   nscoord GetGridCellHeight() const { return mGridCellHeight; }
  61
  62   nsSize ComputeSheetSize(const nsPresContext* aPresContext);
  63
  64   /**
  65    * When we're printing one page-per-sheet and `page-orientation` on our
  66    * single nsPageFrame child should cause the page to rotate, then we want to
  67    * essentially rotate the sheet. We implement that by switching the
  68    * dimensions of this sheet (changing its orientation), sizing the
  69    * nsPageFrame to the original dimensions, and then applying the rotation to
  70    * the nsPageFrame child.
  71    *
  72    * This returns the dimensions that this frame would have without any
  73    * dimension swap we may have done to implement `page-orientation`. If
  74    * there is no rotation caused by `page-orientation`, then the value returned
  75    * and mRect.Size() are identical.
  76    */
  77   nsSize GetSizeForChildren() const { return mSizeForChildren; }
  78
  79   /**
  80    * This method returns the dimensions of the physical page that the target
  81    * [pseudo-]printer should create. This may be different from our own
  82    * dimensions in the case where CSS `page-orientation` causes us to be
  83    * rotated, but we only support that if the PrintTarget backend supports
  84    * different page sizes/orientations. That's only the case for our Save-to-PDF
  85    * backends (possibly other save-to-file outputs in future).
  86    *
  87    * The dimensions returned are expected to be passed to
  88    * nsDeviceContext::BeginPage, which will pass them on to
  89    * PrintTarget::BeginPage to use as the physical dimensions of the page.
  90    */
  91   IntSize GetPrintTargetSizeInPoints(
  92       const int32_t aAppUnitsPerPhysicalInch) const;
  93
  94  private:
  95   // Private construtor & destructor, to avoid accidental (non-FrameArena)
  96   // instantiation/deletion:
  97   PrintedSheetFrame(ComputedStyle* aStyle, nsPresContext* aPresContext)
  98       : nsContainerFrame(aStyle, aPresContext, kClassID) {}
  99   ~PrintedSheetFrame() = default;
 100
 101   // Helper function to populate some pages-per-sheet metrics in our
 102   // nsSharedPageData.
 103   // XXXjwatt: We should investigate sharing this function for the single
 104   // page-per-sheet case (bug 1835782). The logic for that case
 105   // (nsPageFrame::ComputePageSizeScale) is somewhat different though, since
 106   // that case uses no sheet margins and uses the user/CSS specified margins on
 107   // the page, with any page scaling reverted to keep the margins unchanged.
 108   // We, on the other hand, use the unwriteable margins for the sheet, unscaled,
 109   // and use the user/CSS margins on the pages and allow them to be scaled
 110   // along with any pages-per-sheet scaling. (This behavior makes maximum use
 111   // of the sheet and, by scaling the default on the pages, results in a
 112   // a sensible amount of spacing between pages.)
 113   void ComputePagesPerSheetGridMetrics(const nsSize& aSheetSize);
 114
 115   // See GetSizeForChildren.
 116   nsSize mSizeForChildren;
 117
 118   // Note: this will be set before reflow, and it's strongly owned by our
 119   // nsPageSequenceFrame, which outlives us.
 120   nsSharedPageData* mPD = nullptr;
 121
 122   // The number of visible pages in this sheet.
 123   uint32_t mNumPages = 0;
 124
 125   // Number of "columns" in our pages-per-sheet layout. For example: if we're
 126   // printing with 6 pages-per-sheet, then this could be either 3 or 2,
 127   // depending on whether we're printing portrait-oriented pages onto a
 128   // landscape-oriented sheet (3 cols) vs. if we're printing landscape-oriented
 129   // pages onto a portrait-oriented sheet (2 cols).
 130   uint32_t mGridNumCols = 1;
 131
 132   // The offset of the start of the multiple pages-per-sheet grid from the
 133   // top-left of the sheet.
 134   nsPoint mGridOrigin;
 135
 136   // The size of each cell on the sheet into which pages are to be placed.
 137   // (The default values are arbitrary.)
 138   nscoord mGridCellWidth = 1;
 139   nscoord mGridCellHeight = 1;
 140 };
 141
 142 }  // namespace mozilla
 143
 144 #endif /* LAYOUT_GENERIC_PRINTEDSHEETFRAME_H_ */