1 files changed, 178 insertions, 0 deletions
diff --git a/layout/generic/nsPageContentFrame.cpp b/layout/generic/nsPageContentFrame.cpp
new file mode 100644
index 0000000000..cb4d46678f
--- /dev/null
+++ b/layout/generic/nsPageContentFrame.cpp
@@ -0,0 +1,178 @@
+/* -*- 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/. */
+#include "nsPageContentFrame.h"
+
+#include "mozilla/PresShell.h"
+#include "mozilla/StaticPrefs_layout.h"
+
+#include "nsContentUtils.h"
+#include "nsCSSFrameConstructor.h"
+#include "nsPresContext.h"
+#include "nsGkAtoms.h"
+#include "nsPageSequenceFrame.h"
+
+using namespace mozilla;
+
+nsPageContentFrame* NS_NewPageContentFrame(PresShell* aPresShell,
+                                           ComputedStyle* aStyle) {
+  return new (aPresShell)
+      nsPageContentFrame(aStyle, aPresShell->GetPresContext());
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsPageContentFrame)
+
+void nsPageContentFrame::Reflow(nsPresContext* aPresContext,
+                                ReflowOutput& aReflowOutput,
+                                const ReflowInput& aReflowInput,
+                                nsReflowStatus& aStatus) {
+  MarkInReflow();
+  DO_GLOBAL_REFLOW_COUNT("nsPageContentFrame");
+  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aReflowOutput, aStatus);
+  MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
+  MOZ_ASSERT(mPD, "Need a pointer to nsSharedPageData before reflow starts");
+
+  if (GetPrevInFlow() && HasAnyStateBits(NS_FRAME_FIRST_REFLOW)) {
+    nsresult rv =
+        aPresContext->PresShell()->FrameConstructor()->ReplicateFixedFrames(
+            this);
+    if (NS_FAILED(rv)) {
+      return;
+    }
+  }
+
+  // Set our size up front, since some parts of reflow depend on it
+  // being already set.  Note that the computed height may be
+  // unconstrained; that's ok.  Consumers should watch out for that.
+  nsSize maxSize(aReflowInput.ComputedWidth(), aReflowInput.ComputedHeight());
+  SetSize(maxSize);
+
+  WritingMode wm = aReflowInput.GetWritingMode();
+  aReflowOutput.ISize(wm) = aReflowInput.ComputedISize();
+  if (aReflowInput.ComputedBSize() != NS_UNCONSTRAINEDSIZE) {
+    aReflowOutput.BSize(wm) = aReflowInput.ComputedBSize();
+  }
+  aReflowOutput.SetOverflowAreasToDesiredBounds();
+
+  // A PageContentFrame must always have one child: the canvas frame.
+  // Resize our frame allowing it only to be as big as we are
+  // XXX Pay attention to the page's border and padding...
+  if (mFrames.NotEmpty()) {
+    nsIFrame* frame = mFrames.FirstChild();
+    WritingMode wm = frame->GetWritingMode();
+    LogicalSize logicalSize(wm, maxSize);
+    ReflowInput kidReflowInput(aPresContext, aReflowInput, frame, logicalSize);
+    kidReflowInput.SetComputedBSize(logicalSize.BSize(wm));
+    ReflowOutput kidReflowOutput(kidReflowInput);
+    ReflowChild(frame, aPresContext, kidReflowOutput, kidReflowInput, 0, 0,
+                ReflowChildFlags::Default, aStatus);
+
+    // The document element's background should cover the entire canvas, so
+    // take into account the combined area and any space taken up by
+    // absolutely positioned elements
+    nsMargin padding(0, 0, 0, 0);
+
+    // XXXbz this screws up percentage padding (sets padding to zero
+    // in the percentage padding case)
+    kidReflowInput.mStylePadding->GetPadding(padding);
+
+    // This is for shrink-to-fit, and therefore we want to use the
+    // scrollable overflow, since the purpose of shrink to fit is to
+    // make the content that ought to be reachable (represented by the
+    // scrollable overflow) fit in the page.
+    if (frame->HasOverflowAreas()) {
+      // The background covers the content area and padding area, so check
+      // for children sticking outside the child frame's padding edge
+      nscoord xmost = kidReflowOutput.ScrollableOverflow().XMost();
+      if (xmost > kidReflowOutput.Width()) {
+        nscoord widthToFit =
+            xmost + padding.right +
+            kidReflowInput.mStyleBorder->GetComputedBorderWidth(eSideRight);
+        float ratio = float(maxSize.width) / widthToFit;
+        NS_ASSERTION(ratio >= 0.0 && ratio < 1.0,
+                     "invalid shrink-to-fit ratio");
+        mPD->mShrinkToFitRatio = std::min(mPD->mShrinkToFitRatio, ratio);
+      }
+      // In the case of pdf.js documents, we also want to consider the height,
+      // so that we don't clip the page in either axis if the aspect ratio of
+      // the PDF doesn't match the destination.
+      if (nsContentUtils::IsPDFJS(PresContext()->Document()->GetPrincipal())) {
+        nscoord ymost = kidReflowOutput.ScrollableOverflow().YMost();
+        if (ymost > kidReflowOutput.Height()) {
+          nscoord heightToFit =
+              ymost + padding.bottom +
+              kidReflowInput.mStyleBorder->GetComputedBorderWidth(eSideBottom);
+          float ratio = float(maxSize.height) / heightToFit;
+          MOZ_ASSERT(ratio >= 0.0 && ratio < 1.0);
+          mPD->mShrinkToFitRatio = std::min(mPD->mShrinkToFitRatio, ratio);
+        }
+
+        // pdf.js pages should never overflow given the scaling above.
+        // nsPrintJob::SetupToPrintContent ignores some ratios close to 1.0
+        // though and doesn't reflow us again in that case, so we need to clear
+        // the overflow area here in case that happens. (bug 1689789)
+        frame->ClearOverflowRects();
+        kidReflowOutput.mOverflowAreas = aReflowOutput.mOverflowAreas;
+      }
+    }
+
+    // Place and size the child
+    FinishReflowChild(frame, aPresContext, kidReflowOutput, &kidReflowInput, 0,
+                      0, ReflowChildFlags::Default);
+
+    NS_ASSERTION(aPresContext->IsDynamic() || !aStatus.IsFullyComplete() ||
+                     !frame->GetNextInFlow(),
+                 "bad child flow list");
+
+    aReflowOutput.mOverflowAreas.UnionWith(kidReflowOutput.mOverflowAreas);
+  }
+
+  FinishAndStoreOverflow(&aReflowOutput);
+
+  // Reflow our fixed frames
+  nsReflowStatus fixedStatus;
+  ReflowAbsoluteFrames(aPresContext, aReflowOutput, aReflowInput, fixedStatus);
+  NS_ASSERTION(fixedStatus.IsComplete(),
+               "fixed frames can be truncated, but not incomplete");
+
+  if (StaticPrefs::layout_display_list_improve_fragmentation() &&
+      mFrames.NotEmpty()) {
+    auto* previous = static_cast<nsPageContentFrame*>(GetPrevContinuation());
+    const nscoord previousPageOverflow =
+        previous ? previous->mRemainingOverflow : 0;
+    const nsSize containerSize(aReflowInput.AvailableWidth(),
+                               aReflowInput.AvailableHeight());
+    const nscoord pageBSize = GetLogicalRect(containerSize).BSize(wm);
+    const nscoord overflowBSize =
+        LogicalRect(wm, ScrollableOverflowRect(), GetSize()).BEnd(wm);
+    const nscoord currentPageOverflow = overflowBSize - pageBSize;
+    nscoord remainingOverflow =
+        std::max(currentPageOverflow, previousPageOverflow - pageBSize);
+
+    if (aStatus.IsFullyComplete() && remainingOverflow > 0) {
+      // If we have ScrollableOverflow off the end of our page, then we report
+      // ourselves as overflow-incomplete in order to produce an additional
+      // content-less page, which we expect to draw our overflow on our behalf.
+      aStatus.SetOverflowIncomplete();
+    }
+
+    mRemainingOverflow = std::max(remainingOverflow, 0);
+  }
+
+  NS_FRAME_SET_TRUNCATION(aStatus, aReflowInput, aReflowOutput);
+}
+
+void nsPageContentFrame::AppendDirectlyOwnedAnonBoxes(
+    nsTArray<OwnedAnonBox>& aResult) {
+  MOZ_ASSERT(mFrames.FirstChild(),
+             "pageContentFrame must have a canvasFrame child");
+  aResult.AppendElement(mFrames.FirstChild());
+}
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult nsPageContentFrame::GetFrameName(nsAString& aResult) const {
+  return MakeFrameName(u"PageContent"_ns, aResult);
+}
+#endif