Bug 1668406 - Fix nsIPrintSettings.showMarginGuides. r=jfkthame

So that:

 * It accounts for @page.
 * It is correctly serialized and deserialized over IPC.
 * It's nicer to use.

Depends on D92004

Differential Revision: https://phabricator.services.mozilla.com/D92005

layout/generic/nsPageFrame.cpp

@@ -491,9 +491,9 @@ static void PaintMarginGuides(nsIFrame* aFrame, DrawTarget* aDrawTarget,
                        /* dash offset */ 0.0f);
   DrawOptions options;
 
-  // FIXME(emilio, bug 1659834): Shouldn't this use the page-specific margins,
-  // which account for @page?
-  const nsMargin& margin = aFrame->PresContext()->GetDefaultPageMargin();
+  MOZ_RELEASE_ASSERT(aFrame->IsPageFrame());
+  const nsMargin& margin =
+      static_cast<nsPageFrame*>(aFrame)->GetUsedPageContentMargin();
   int32_t appUnitsPerDevPx = aFrame->PresContext()->AppUnitsPerDevPixel();
 
   // Get the frame's rect and inset by the margins to get the edges of the
@@ -625,16 +625,13 @@ void nsPageFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
     set.Content()->AppendNewToTop<nsDisplayHeaderFooter>(aBuilder, this);
 
     // For print-preview, show margin guides if requested in the settings.
-    if (pc->Type() == nsPresContext::eContext_PrintPreview) {
-      bool showGuides;
-      if (NS_SUCCEEDED(mPD->mPrintSettings->GetShowMarginGuides(&showGuides)) &&
-          showGuides) {
+    if (pc->Type() == nsPresContext::eContext_PrintPreview &&
+        mPD->mPrintSettings->GetShowMarginGuides()) {
       set.Content()->AppendNewToTop<nsDisplayGeneric>(
           aBuilder, this, PaintMarginGuides, "MarginGuides",
           DisplayItemType::TYPE_MARGIN_GUIDES);
     }
   }
-  }
 
   set.MoveTo(aLists);
 }

layout/generic/nsPageFrame.h

@@ -61,6 +61,10 @@ class nsPageFrame final : public nsContainerFrame {
    */
   void AppendDirectlyOwnedAnonBoxes(nsTArray<OwnedAnonBox>& aResult) override;
 
+  const nsMargin& GetUsedPageContentMargin() const {
+    return mPageContentMargin;
+  }
+
  protected:
   explicit nsPageFrame(ComputedStyle* aStyle, nsPresContext* aPresContext);
   virtual ~nsPageFrame();

toolkit/components/printingui/ipc/PPrintingTypes.ipdlh

@@ -33,6 +33,7 @@ struct PrintData {
   bool printBGColors;
   bool printBGImages;
   bool honorPageRuleMargins;
+  bool showMarginGuides;
   short printRange;
   nsString title;
   nsString docURL;

widget/nsIPrintSettings.idl

@@ -183,6 +183,9 @@ interface nsIPrintSettings : nsISupports
   /** Whether @page rule margins should be honored or not. */
   [infallible] attribute boolean honorPageRuleMargins;
 
+  /** Whether to draw guidelines showing the margin settings */
+  [infallible] attribute boolean showMarginGuides;
+
   attribute short   printRange;
 
   attribute AString title;
@@ -201,7 +204,6 @@ interface nsIPrintSettings : nsISupports
   attribute boolean printSilent;         /* print without putting up the dialog */
   attribute boolean shrinkToFit;         /* shrinks content to fit on page      */
   attribute boolean showPrintProgress;   /* indicates whether the progress dialog should be shown */
-  attribute boolean showMarginGuides;    /* whether to draw guidelines showing the margin settings */
 
   /* Additional XP Related */
   attribute AString paperId;       /* identifier of paper (not display name) */

widget/nsPrintSettingsImpl.cpp

@@ -597,7 +597,6 @@ NS_IMETHODIMP nsPrintSettings::SetShowPrintProgress(bool aShowPrintProgress) {
 }
 
 NS_IMETHODIMP nsPrintSettings::GetShowMarginGuides(bool* aShowMarginGuides) {
-  NS_ENSURE_ARG_POINTER(aShowMarginGuides);
   *aShowMarginGuides = mShowMarginGuides;
   return NS_OK;
 }

widget/nsPrintSettingsService.cpp

@@ -114,6 +114,7 @@ nsPrintSettingsService::SerializeToPrintData(nsIPrintSettings* aSettings,
   data->printBGImages() = aSettings->GetPrintBGImages();
 
   data->honorPageRuleMargins() = aSettings->GetHonorPageRuleMargins();
+  data->showMarginGuides() = aSettings->GetShowMarginGuides();
 
   aSettings->GetPrintRange(&data->printRange());
 
@@ -212,6 +213,7 @@ nsPrintSettingsService::DeserializeToPrintSettings(const PrintData& data,
   settings->SetPrintBGColors(data.printBGColors());
   settings->SetPrintBGImages(data.printBGImages());
   settings->SetHonorPageRuleMargins(data.honorPageRuleMargins());
+  settings->SetShowMarginGuides(data.showMarginGuides());
   settings->SetPrintRange(data.printRange());
 
   settings->SetTitle(data.title());