Bug 129941. Don't create scrollframes for blockframes (except inline blocks) while printing, and make such blockframes clip their contents instead. r=dbaron

layout/base/nsCSSFrameConstructor.cpp

@@ -4354,14 +4354,24 @@ nsCSSFrameConstructor::FindDisplayData(const nsStyleDisplay* aDisplay,
       PropagateScrollToViewport() == aContent;
   }
 
+  NS_ASSERTION(!propagatedScrollToViewport ||
+               !mPresShell->GetPresContext()->IsPaginated(),
+               "Shouldn't propagate scroll in paginated contexts");
+
   // If the frame is a block-level frame and is scrollable, then wrap it
-  // in a scroll frame.
+  // in a scroll frame.  Except we don't want to do that for paginated contexts
+  // for frames that are block-outside.
+  // The condition on skipping scrollframe construction in the
+  // paginated case needs to match code in ConstructNonScrollableBlock
+  // and in nsFrame::ApplyPaginatedOverflowClipping.
   // XXX Ignore tables for the time being
   // XXXbz it would be nice to combine this with the other block
   // case... Think about how do do this?
   if (aDisplay->IsBlockInside() &&
       aDisplay->IsScrollableOverflow() &&
-      !propagatedScrollToViewport) {
+      !propagatedScrollToViewport &&
+      (!mPresShell->GetPresContext()->IsPaginated() ||
+       !aDisplay->IsBlockOutside())) {
     static const FrameConstructionData sScrollableBlockData =
       FULL_CTOR_FCDATA(0, &nsCSSFrameConstructor::ConstructScrollableBlock);
     return &sScrollableBlockData;
@@ -4489,7 +4499,18 @@ nsCSSFrameConstructor::ConstructNonScrollableBlock(nsFrameConstructorState& aSta
 
   if (aDisplay->IsAbsolutelyPositioned() ||
       aDisplay->IsFloating() ||
-      NS_STYLE_DISPLAY_INLINE_BLOCK == aDisplay->mDisplay) {
+      NS_STYLE_DISPLAY_INLINE_BLOCK == aDisplay->mDisplay ||
+      // This check just needs to be the same as the check for using scrollable
+      // blocks in FindDisplayData and the check for clipping in
+      // nsFrame::ApplyPaginatedOverflowClipping; we want a block formatting
+      // context root in paginated contexts for every block that would be
+      // scrollable in a non-paginated context.  Note that IsPaginated()
+      // implies that no propagation to viewport has taken place, so we don't
+      // need to check for propagation here.
+      (mPresShell->GetPresContext()->IsPaginated() &&
+       aDisplay->IsBlockInside() &&
+       aDisplay->IsScrollableOverflow() &&
+       aDisplay->IsBlockOutside())) {
     *aNewFrame = NS_NewBlockFormattingContext(mPresShell, styleContext);
   } else {
     *aNewFrame = NS_NewBlockFrame(mPresShell, styleContext);

layout/generic/nsFrame.cpp

@@ -1197,7 +1197,7 @@ static PRBool ApplyAbsPosClipping(nsDisplayListBuilder* aBuilder,
  * Returns PR_TRUE if aFrame is overflow:hidden and we should interpret
  * that as -moz-hidden-unscrollable.
  */
-static PRBool ApplyOverflowHiddenClipping(nsIFrame* aFrame,
+static inline PRBool ApplyOverflowHiddenClipping(nsIFrame* aFrame,
                                                  const nsStyleDisplay* aDisp)
 {
   if (aDisp->mOverflowX != NS_STYLE_OVERFLOW_HIDDEN)
@@ -1215,6 +1215,24 @@ static PRBool ApplyOverflowHiddenClipping(nsIFrame* aFrame,
        type == nsGkAtoms::bcTableCellFrame;
 }
 
+static inline PRBool ApplyPaginatedOverflowClipping(nsIFrame* aFrame,
+                                                    const nsStyleDisplay* aDisp)
+{
+  // These conditions on aDisp need to match the conditions for which in
+  // non-paginated contexts we'd create a scrollframe for a block but in a
+  // paginated context we don't.  See nsCSSFrameConstructor::FindDisplayData
+  // for the relevant conditions.  These conditions must also match those in
+  // nsCSSFrameConstructor::ConstructNonScrollableBlock for creating block
+  // formatting context roots for forced-to-be-no-longer scrollable blocks in
+  // paginated contexts.
+  return
+    aFrame->PresContext()->IsPaginated() &&
+    aDisp->IsBlockInside() &&
+    aDisp->IsScrollableOverflow() &&
+    aDisp->IsBlockOutside() &&
+    aFrame->GetType() == nsGkAtoms::blockFrame;
+}
+
 static PRBool ApplyOverflowClipping(nsDisplayListBuilder* aBuilder,
                                     nsIFrame* aFrame,
                                     const nsStyleDisplay* aDisp, nsRect* aRect) {
@@ -1224,8 +1242,10 @@ static PRBool ApplyOverflowClipping(nsDisplayListBuilder* aBuilder,
   // changed -moz-hidden-unscrollable to apply to any kind of frame.
 
   // Only -moz-hidden-unscrollable is handled here (and 'hidden' for table
-  // frames). Other overflow clipping is applied by nsHTML/XULScrollFrame.
-  if (!ApplyOverflowHiddenClipping(aFrame, aDisp)) {
+  // frames, and any non-visible value for blocks in a paginated context).
+  // Other overflow clipping is applied by nsHTML/XULScrollFrame.
+  if (!ApplyOverflowHiddenClipping(aFrame, aDisp) &&
+      !ApplyPaginatedOverflowClipping(aFrame, aDisp)) {
     PRBool clip = aDisp->mOverflowX == NS_STYLE_OVERFLOW_CLIP;
     if (!clip)
       return PR_FALSE;

layout/reftests/printing/129941-1-ref.html

@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<html class="reftest-print" style="margin: 0; padding: 0">
+  <body style="margin: 0; padding: 0">
+    <div style="height: 1.25in; border: 0.25in solid green"></div>
+    <div style="height: 1.25in; border: 0.25in solid green"></div>
+    <div style="height: 1.25in; border: 0.25in solid green; border-bottom: none"></div>
+  </body>
+</html>

layout/reftests/printing/129941-1a.html

@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<html class="reftest-print" style="margin: 0; padding: 0;">
+  <body style="overflow: scroll; height: 5in; margin: 0; padding: 0;">
+    <div style="height: 1.25in; border: 0.25in solid green"></div>
+    <div style="height: 1.25in; border: 0.25in solid green"></div>
+    <div style="height: 1.25in; border: 0.25in solid green"></div>
+  </body>
+</html>

layout/reftests/printing/129941-1b.html

@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<html class="reftest-print" style="margin: 0; padding: 0;">
+  <body style="overflow: -moz-hidden-unscrollable; height: 5in; margin: 0; padding: 0;">
+    <div style="height: 1.25in; border: 0.25in solid green"></div>
+    <div style="height: 1.25in; border: 0.25in solid green"></div>
+    <div style="height: 1.25in; border: 0.25in solid green"></div>
+  </body>
+</html>

layout/reftests/printing/reftest.list

@@ -7,3 +7,5 @@
 == 403669-1.html 403669-1-ref.html
 == 381497-n.html 381497-f.html
 == test-async-print.html 272830-1-ref.html
+== 129941-1a.html 129941-1-ref.html
+== 129941-1b.html 129941-1-ref.html