The Tor Browser: layout/generic/nsColumnSetFrame.cpp@b8a032363ba2 (annotated)

layout/generic/nsColumnSetFrame.cpp@b8a032363ba2 (annotated)

layout/generic/nsColumnSetFrame.cpp

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
 /* rendering object for css3 multi-column layout */
 #include "nsColumnSetFrame.h"
 #include "nsCSSRendering.h"
 #include "nsDisplayList.h"
 using namespace mozilla;
 using namespace mozilla::layout;
 /**
  * Tracking issues:
  *
  * XXX cursor movement around the top and bottom of colums seems to make the editor
  * lose the caret.
  *
  * XXX should we support CSS columns applied to table elements?
  */
 nsIFrame*
 NS_NewColumnSetFrame(nsIPresShell* aPresShell, nsStyleContext* aContext, nsFrameState aStateFlags)
 {
   nsColumnSetFrame* it = new (aPresShell) nsColumnSetFrame(aContext);
   it->AddStateBits(aStateFlags | NS_BLOCK_MARGIN_ROOT);
   return it;
 }
 NS_IMPL_FRAMEARENA_HELPERS(nsColumnSetFrame)
 nsColumnSetFrame::nsColumnSetFrame(nsStyleContext* aContext)
   : nsContainerFrame(aContext), mLastBalanceHeight(NS_INTRINSICSIZE),
     mLastFrameStatus(NS_FRAME_COMPLETE)
 {
 }
 nsIAtom*
 nsColumnSetFrame::GetType() const
 {
   return nsGkAtoms::columnSetFrame;
 }
 static void
 PaintColumnRule(nsIFrame* aFrame, nsRenderingContext* aCtx,
                 const nsRect& aDirtyRect, nsPoint aPt)
 {
   static_cast<nsColumnSetFrame*>(aFrame)->PaintColumnRule(aCtx, aDirtyRect, aPt);
 }
 void
 nsColumnSetFrame::PaintColumnRule(nsRenderingContext* aCtx,
                                   const nsRect& aDirtyRect,
                                   const nsPoint& aPt)
 {
   nsIFrame* child = mFrames.FirstChild();
   if (!child)
     return;  // no columns
   nsIFrame* nextSibling = child->GetNextSibling();
   if (!nextSibling)
     return;  // 1 column only - this means no gap to draw on
   bool isRTL = StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
   const nsStyleColumn* colStyle = StyleColumn();
   uint8_t ruleStyle;
   // Per spec, inset => ridge and outset => groove
   if (colStyle->mColumnRuleStyle == NS_STYLE_BORDER_STYLE_INSET)
     ruleStyle = NS_STYLE_BORDER_STYLE_RIDGE;
   else if (colStyle->mColumnRuleStyle == NS_STYLE_BORDER_STYLE_OUTSET)
     ruleStyle = NS_STYLE_BORDER_STYLE_GROOVE;
   else
     ruleStyle = colStyle->mColumnRuleStyle;
   nsPresContext* presContext = PresContext();
   nscoord ruleWidth = colStyle->GetComputedColumnRuleWidth();
   if (!ruleWidth)
     return;
   nscolor ruleColor =
     GetVisitedDependentColor(eCSSProperty__moz_column_rule_color);
   // In order to re-use a large amount of code, we treat the column rule as a border.
   // We create a new border style object and fill in all the details of the column rule as
   // the left border. PaintBorder() does all the rendering for us, so we not
   // only save an enormous amount of code but we'll support all the line styles that
   // we support on borders!
   nsStyleBorder border(presContext);
   border.SetBorderWidth(NS_SIDE_LEFT, ruleWidth);
   border.SetBorderStyle(NS_SIDE_LEFT, ruleStyle);
   border.SetBorderColor(NS_SIDE_LEFT, ruleColor);
   // Get our content rect as an absolute coordinate, not relative to
   // our parent (which is what the X and Y normally is)
   nsRect contentRect = GetContentRect() - GetRect().TopLeft() + aPt;
   nsSize ruleSize(ruleWidth, contentRect.height);
   while (nextSibling) {
     // The frame tree goes RTL in RTL
     nsIFrame* leftSibling = isRTL ? nextSibling : child;
     nsIFrame* rightSibling = isRTL ? child : nextSibling;
     // Each child frame's position coordinates is actually relative to this nsColumnSetFrame.
     // linePt will be at the top-left edge to paint the line.
     nsPoint edgeOfLeftSibling = leftSibling->GetRect().TopRight() + aPt;
     nsPoint edgeOfRightSibling = rightSibling->GetRect().TopLeft() + aPt;
     nsPoint linePt((edgeOfLeftSibling.x + edgeOfRightSibling.x - ruleWidth) / 2,
                    contentRect.y);
     nsRect lineRect(linePt, ruleSize);
     nsCSSRendering::PaintBorderWithStyleBorder(presContext, *aCtx, this,
         aDirtyRect, lineRect, border, StyleContext(),
         // Remember, we only have the "left" "border". Skip everything else
         (1 << NS_SIDE_TOP | 1 << NS_SIDE_RIGHT | 1 << NS_SIDE_BOTTOM));
     child = nextSibling;
     nextSibling = nextSibling->GetNextSibling();
   }
 }
 nsresult
 nsColumnSetFrame::SetInitialChildList(ChildListID     aListID,
                                       nsFrameList&    aChildList)
 {
   if (aListID == kAbsoluteList) {
     return nsContainerFrame::SetInitialChildList(aListID, aChildList);
   }
   NS_ASSERTION(aListID == kPrincipalList,
                "Only default child list supported");
   NS_ASSERTION(aChildList.OnlyChild(),
                "initial child list must have exaisRevertingctly one child");
   // Queue up the frames for the content frame
   return nsContainerFrame::SetInitialChildList(kPrincipalList, aChildList);
 }
 static nscoord
 GetAvailableContentWidth(const nsHTMLReflowState& aReflowState)
 {
   if (aReflowState.AvailableWidth() == NS_INTRINSICSIZE) {
     return NS_INTRINSICSIZE;
   }
   nscoord borderPaddingWidth =
     aReflowState.ComputedPhysicalBorderPadding().left +
     aReflowState.ComputedPhysicalBorderPadding().right;
   return std::max(0, aReflowState.AvailableWidth() - borderPaddingWidth);
 }
 nscoord
 nsColumnSetFrame::GetAvailableContentHeight(const nsHTMLReflowState& aReflowState)
 {
   if (aReflowState.AvailableHeight() == NS_INTRINSICSIZE) {
     return NS_INTRINSICSIZE;
   }
   nsMargin bp = aReflowState.ComputedPhysicalBorderPadding();
   ApplySkipSides(bp, &aReflowState);
   bp.bottom = aReflowState.ComputedPhysicalBorderPadding().bottom;
   return std::max(0, aReflowState.AvailableHeight() - bp.TopBottom());
 }
 static nscoord
 GetColumnGap(nsColumnSetFrame*    aFrame,
              const nsStyleColumn* aColStyle)
 {
   if (eStyleUnit_Normal == aColStyle->mColumnGap.GetUnit())
     return aFrame->StyleFont()->mFont.size;
   if (eStyleUnit_Coord == aColStyle->mColumnGap.GetUnit()) {
     nscoord colGap = aColStyle->mColumnGap.GetCoordValue();
     NS_ASSERTION(colGap >= 0, "negative column gap");
     return colGap;
   }
   NS_NOTREACHED("Unknown gap type");
   return 0;
 }
 nsColumnSetFrame::ReflowConfig
 nsColumnSetFrame::ChooseColumnStrategy(const nsHTMLReflowState& aReflowState,
                                        bool aForceAuto = false,
                                        nscoord aFeasibleHeight = NS_INTRINSICSIZE,
                                        nscoord aInfeasibleHeight = 0)
 {
   nscoord knownFeasibleHeight = aFeasibleHeight;
   nscoord knownInfeasibleHeight = aInfeasibleHeight;
   const nsStyleColumn* colStyle = StyleColumn();
   nscoord availContentWidth = GetAvailableContentWidth(aReflowState);
   if (aReflowState.ComputedWidth() != NS_INTRINSICSIZE) {
     availContentWidth = aReflowState.ComputedWidth();
   }
   nscoord consumedHeight = GetConsumedHeight();
   // The effective computed height is the height of the current continuation
   // of the column set frame. This should be the same as the computed height
   // if we have an unconstrained available height.
   nscoord computedHeight = GetEffectiveComputedHeight(aReflowState,
                                                       consumedHeight);
   nscoord colHeight = GetAvailableContentHeight(aReflowState);
   if (aReflowState.ComputedHeight() != NS_INTRINSICSIZE) {
     colHeight = aReflowState.ComputedHeight();
   } else if (aReflowState.ComputedMaxHeight() != NS_INTRINSICSIZE) {
     colHeight = std::min(colHeight, aReflowState.ComputedMaxHeight());
   }
   nscoord colGap = GetColumnGap(this, colStyle);
   int32_t numColumns = colStyle->mColumnCount;
   // If column-fill is set to 'balance', then we want to balance the columns.
   const bool isBalancing = colStyle->mColumnFill == NS_STYLE_COLUMN_FILL_BALANCE
                            && !aForceAuto;
   if (isBalancing) {
     const uint32_t MAX_NESTED_COLUMN_BALANCING = 2;
     uint32_t cnt = 0;
     for (const nsHTMLReflowState* rs = aReflowState.parentReflowState;
          rs && cnt < MAX_NESTED_COLUMN_BALANCING; rs = rs->parentReflowState) {
       if (rs->mFlags.mIsColumnBalancing) {
         ++cnt;
       }
     }
     if (cnt == MAX_NESTED_COLUMN_BALANCING) {
       numColumns = 1;
     }
   }
   nscoord colWidth;
   if (colStyle->mColumnWidth.GetUnit() == eStyleUnit_Coord) {
     colWidth = colStyle->mColumnWidth.GetCoordValue();
     NS_ASSERTION(colWidth >= 0, "negative column width");
     // Reduce column count if necessary to make columns fit in the
     // available width. Compute max number of columns that fit in
     // availContentWidth, satisfying colGap*(maxColumns - 1) +
     // colWidth*maxColumns <= availContentWidth
     if (availContentWidth != NS_INTRINSICSIZE && colGap + colWidth > 0
         && numColumns > 0) {
       // This expression uses truncated rounding, which is what we
       // want
       int32_t maxColumns =
         std::min(nscoord(nsStyleColumn::kMaxColumnCount),
                  (availContentWidth + colGap)/(colGap + colWidth));
       numColumns = std::max(1, std::min(numColumns, maxColumns));
     }
   } else if (numColumns > 0 && availContentWidth != NS_INTRINSICSIZE) {
     nscoord widthMinusGaps = availContentWidth - colGap*(numColumns - 1);
     colWidth = widthMinusGaps/numColumns;
   } else {
     colWidth = NS_INTRINSICSIZE;
   }
   // Take care of the situation where there's only one column but it's
   // still too wide
   colWidth = std::max(1, std::min(colWidth, availContentWidth));
   nscoord expectedWidthLeftOver = 0;
   if (colWidth != NS_INTRINSICSIZE && availContentWidth != NS_INTRINSICSIZE) {
     // distribute leftover space
     // First, determine how many columns will be showing if the column
     // count is auto
     if (numColumns <= 0) {
       // choose so that colGap*(nominalColumnCount - 1) +
       // colWidth*nominalColumnCount is nearly availContentWidth
       // make sure to round down
       if (colGap + colWidth > 0) {
         numColumns = (availContentWidth + colGap)/(colGap + colWidth);
         // The number of columns should never exceed kMaxColumnCount.
         numColumns = std::min(nscoord(nsStyleColumn::kMaxColumnCount),
                               numColumns);
       }
       if (numColumns <= 0) {
         numColumns = 1;
       }
     }
     // Compute extra space and divide it among the columns
     nscoord extraSpace =
       std::max(0, availContentWidth - (colWidth*numColumns + colGap*(numColumns - 1)));
     nscoord extraToColumns = extraSpace/numColumns;
     colWidth += extraToColumns;
     expectedWidthLeftOver = extraSpace - (extraToColumns*numColumns);
   }
   if (isBalancing) {
     if (numColumns <= 0) {
       // Hmm, auto column count, column width or available width is unknown,
       // and balancing is required. Let's just use one column then.
       numColumns = 1;
     }
     colHeight = std::min(mLastBalanceHeight, colHeight);
   } else {
     // This is the case when the column-fill property is set to 'auto'.
     // No balancing, so don't limit the column count
     numColumns = INT32_MAX;
     // XXX_jwir3: If a page's height is set to 0, we could continually
     //            create continuations, resulting in an infinite loop, since
     //            no progress is ever made. This is an issue with the spec
     //            (css3-multicol, css3-page, and css3-break) that is
     //            unresolved as of 27 Feb 2013. For the time being, we set this
     //            to have a minimum of 1 css px. Once a resolution is made
     //            on what minimum to have for a page height, we may need to
     //            change this value to match the appropriate spec(s).
     colHeight = std::max(colHeight, nsPresContext::CSSPixelsToAppUnits(1));
   }
 #ifdef DEBUG_roc
   printf("*** nsColumnSetFrame::ChooseColumnStrategy: numColumns=%d, colWidth=%d, expectedWidthLeftOver=%d, colHeight=%d, colGap=%d\n",
          numColumns, colWidth, expectedWidthLeftOver, colHeight, colGap);
 #endif
   ReflowConfig config = { numColumns, colWidth, expectedWidthLeftOver, colGap,
                           colHeight, isBalancing, knownFeasibleHeight,
                           knownInfeasibleHeight, computedHeight, consumedHeight };
   return config;
 }
 bool
 nsColumnSetFrame::ReflowColumns(nsHTMLReflowMetrics& aDesiredSize,
                                 const nsHTMLReflowState& aReflowState,
                                 nsReflowStatus& aReflowStatus,
                                 ReflowConfig& aConfig,
                                 bool aLastColumnUnbounded,
                                 nsCollapsingMargin* aCarriedOutBottomMargin,
                                 ColumnBalanceData& aColData)
 {
   bool feasible = ReflowChildren(aDesiredSize, aReflowState,
                                  aReflowStatus, aConfig, aLastColumnUnbounded,
                                  aCarriedOutBottomMargin, aColData);
   if (aColData.mHasExcessHeight) {
     aConfig = ChooseColumnStrategy(aReflowState, true);
     // We need to reflow our children again one last time, otherwise we might
     // end up with a stale column height for some of our columns, since we
     // bailed out of balancing.
     feasible = ReflowChildren(aDesiredSize, aReflowState, aReflowStatus,
                               aConfig, aLastColumnUnbounded,
                               aCarriedOutBottomMargin, aColData);
   }
   return feasible;
 }
 static void MoveChildTo(nsIFrame* aParent, nsIFrame* aChild, nsPoint aOrigin) {
   if (aChild->GetPosition() == aOrigin) {
     return;
   }
   aChild->SetPosition(aOrigin);
   nsContainerFrame::PlaceFrameView(aChild);
 }
 nscoord
 nsColumnSetFrame::GetMinWidth(nsRenderingContext *aRenderingContext) {
   nscoord width = 0;
   DISPLAY_MIN_WIDTH(this, width);
   if (mFrames.FirstChild()) {
     width = mFrames.FirstChild()->GetMinWidth(aRenderingContext);
   }
   const nsStyleColumn* colStyle = StyleColumn();
   nscoord colWidth;
   if (colStyle->mColumnWidth.GetUnit() == eStyleUnit_Coord) {
     colWidth = colStyle->mColumnWidth.GetCoordValue();
     // As available width reduces to zero, we reduce our number of columns
     // to one, and don't enforce the column width, so just return the min
     // of the child's min-width with any specified column width.
     width = std::min(width, colWidth);
   } else {
     NS_ASSERTION(colStyle->mColumnCount > 0,
                  "column-count and column-width can't both be auto");
     // As available width reduces to zero, we still have mColumnCount columns,
     // so multiply the child's min-width by the number of columns.
     colWidth = width;
     width *= colStyle->mColumnCount;
     // The multiplication above can make 'width' negative (integer overflow),
     // so use std::max to protect against that.
     width = std::max(width, colWidth);
   }
   // XXX count forced column breaks here? Maybe we should return the child's
   // min-width times the minimum number of columns.
   return width;
 }
 nscoord
 nsColumnSetFrame::GetPrefWidth(nsRenderingContext *aRenderingContext) {
   // Our preferred width is our desired column width, if specified, otherwise
   // the child's preferred width, times the number of columns, plus the width
   // of any required column gaps
   // XXX what about forced column breaks here?
   nscoord result = 0;
   DISPLAY_PREF_WIDTH(this, result);
   const nsStyleColumn* colStyle = StyleColumn();
   nscoord colGap = GetColumnGap(this, colStyle);
   nscoord colWidth;
   if (colStyle->mColumnWidth.GetUnit() == eStyleUnit_Coord) {
     colWidth = colStyle->mColumnWidth.GetCoordValue();
   } else if (mFrames.FirstChild()) {
     colWidth = mFrames.FirstChild()->GetPrefWidth(aRenderingContext);
   } else {
     colWidth = 0;
   }
   int32_t numColumns = colStyle->mColumnCount;
   if (numColumns <= 0) {
     // if column-count is auto, assume one column
     numColumns = 1;
   }
   nscoord width = colWidth*numColumns + colGap*(numColumns - 1);
   // The multiplication above can make 'width' negative (integer overflow),
   // so use std::max to protect against that.
   result = std::max(width, colWidth);
   return result;
 }
 bool
 nsColumnSetFrame::ReflowChildren(nsHTMLReflowMetrics&     aDesiredSize,
                                  const nsHTMLReflowState& aReflowState,
                                  nsReflowStatus&          aStatus,
                                  const ReflowConfig&      aConfig,
                                  bool                     aUnboundedLastColumn,
                                  nsCollapsingMargin*      aBottomMarginCarriedOut,
                                  ColumnBalanceData&       aColData)
 {
   aColData.Reset();
   bool allFit = true;
   bool RTL = StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
   bool shrinkingHeightOnly = !NS_SUBTREE_DIRTY(this) &&
     mLastBalanceHeight > aConfig.mColMaxHeight;
 #ifdef DEBUG_roc
   printf("*** Doing column reflow pass: mLastBalanceHeight=%d, mColMaxHeight=%d, RTL=%d\n, mBalanceColCount=%d, mColWidth=%d, mColGap=%d\n",
          mLastBalanceHeight, aConfig.mColMaxHeight, RTL, aConfig.mBalanceColCount,
          aConfig.mColWidth, aConfig.mColGap);
 #endif
   DrainOverflowColumns();
   const bool colHeightChanged = mLastBalanceHeight != aConfig.mColMaxHeight;
   if (colHeightChanged) {
     mLastBalanceHeight = aConfig.mColMaxHeight;
     // XXX Seems like this could fire if incremental reflow pushed the column set
     // down so we reflow incrementally with a different available height.
     // We need a way to do an incremental reflow and be sure availableHeight
     // changes are taken account of! Right now I think block frames with absolute
     // children might exit early.
     //NS_ASSERTION(aKidReason != eReflowReason_Incremental,
     //             "incremental reflow should not have changed the balance height");
   }
   // get our border and padding
   nsMargin borderPadding = aReflowState.ComputedPhysicalBorderPadding();
   ApplySkipSides(borderPadding, &aReflowState);
   nsRect contentRect(0, 0, 0, 0);
   nsOverflowAreas overflowRects;
   nsIFrame* child = mFrames.FirstChild();
   nsPoint childOrigin = nsPoint(borderPadding.left, borderPadding.top);
   // For RTL, figure out where the last column's left edge should be. Since the
   // columns might not fill the frame exactly, we need to account for the
   // slop. Otherwise we'll waste time moving the columns by some tiny
   // amount unnecessarily.
   if (RTL) {
     nscoord availWidth = aReflowState.AvailableWidth();
     if (aReflowState.ComputedWidth() != NS_INTRINSICSIZE) {
       availWidth = aReflowState.ComputedWidth();
     }
     if (availWidth != NS_INTRINSICSIZE) {
       childOrigin.x += availWidth - aConfig.mColWidth;
 #ifdef DEBUG_roc
       printf("*** childOrigin.x = %d\n", childOrigin.x);
 #endif
     }
   }
   int columnCount = 0;
   int contentBottom = 0;
   bool reflowNext = false;
   while (child) {
     // Try to skip reflowing the child. We can't skip if the child is dirty. We also can't
     // skip if the next column is dirty, because the next column's first line(s)
     // might be pullable back to this column. We can't skip if it's the last child
     // because we need to obtain the bottom margin. We can't skip
     // if this is the last column and we're supposed to assign unbounded
     // height to it, because that could change the available height from
     // the last time we reflowed it and we should try to pull all the
     // content from its next sibling. (Note that it might be the last
     // column, but not be the last child because the desired number of columns
     // has changed.)
     bool skipIncremental = !aReflowState.ShouldReflowAllKids()
       && !NS_SUBTREE_DIRTY(child)
       && child->GetNextSibling()
       && !(aUnboundedLastColumn && columnCount == aConfig.mBalanceColCount - 1)
       && !NS_SUBTREE_DIRTY(child->GetNextSibling());
     // If we need to pull up content from the prev-in-flow then this is not just
     // a height shrink. The prev in flow will have set the dirty bit.
     // Check the overflow rect YMost instead of just the child's content height. The child
     // may have overflowing content that cares about the available height boundary.
     // (It may also have overflowing content that doesn't care about the available height
     // boundary, but if so, too bad, this optimization is defeated.)
     // We want scrollable overflow here since this is a calculation that
     // affects layout.
     bool skipResizeHeightShrink = shrinkingHeightOnly
       && child->GetScrollableOverflowRect().YMost() <= aConfig.mColMaxHeight;
     nscoord childContentBottom = 0;
     if (!reflowNext && (skipIncremental || skipResizeHeightShrink)) {
       // This child does not need to be reflowed, but we may need to move it
       MoveChildTo(this, child, childOrigin);
       // If this is the last frame then make sure we get the right status
       nsIFrame* kidNext = child->GetNextSibling();
       if (kidNext) {
         aStatus = (kidNext->GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER)
                   ? NS_FRAME_OVERFLOW_INCOMPLETE
                   : NS_FRAME_NOT_COMPLETE;
       } else {
         aStatus = mLastFrameStatus;
       }
       childContentBottom = nsLayoutUtils::CalculateContentBottom(child);
 #ifdef DEBUG_roc
       printf("*** Skipping child #%d %p (incremental %d, resize height shrink %d): status = %d\n",
              columnCount, (void*)child, skipIncremental, skipResizeHeightShrink, aStatus);
 #endif
     } else {
       nsSize availSize(aConfig.mColWidth, aConfig.mColMaxHeight);
       if (aUnboundedLastColumn && columnCount == aConfig.mBalanceColCount - 1) {
         availSize.height = GetAvailableContentHeight(aReflowState);
       }
       if (reflowNext)
         child->AddStateBits(NS_FRAME_IS_DIRTY);
       nsHTMLReflowState kidReflowState(PresContext(), aReflowState, child,
                                        availSize, availSize.width,
                                        aReflowState.ComputedHeight());
       kidReflowState.mFlags.mIsTopOfPage = true;
       kidReflowState.mFlags.mTableIsSplittable = false;
       kidReflowState.mFlags.mIsColumnBalancing = aConfig.mBalanceColCount < INT32_MAX;
       // We need to reflow any float placeholders, even if our column height
       // hasn't changed.
       kidReflowState.mFlags.mMustReflowPlaceholders = !colHeightChanged;
 #ifdef DEBUG_roc
       printf("*** Reflowing child #%d %p: availHeight=%d\n",
              columnCount, (void*)child,availSize.height);
 #endif
       // Note if the column's next in flow is not being changed by this incremental reflow.
       // This may allow the current column to avoid trying to pull lines from the next column.
       if (child->GetNextSibling() &&
           !(GetStateBits() & NS_FRAME_IS_DIRTY) &&
         !(child->GetNextSibling()->GetStateBits() & NS_FRAME_IS_DIRTY)) {
         kidReflowState.mFlags.mNextInFlowUntouched = true;
       }
       nsHTMLReflowMetrics kidDesiredSize(aReflowState.GetWritingMode(),
                                          aDesiredSize.mFlags);
       // XXX it would be cool to consult the float manager for the
       // previous block to figure out the region of floats from the
       // previous column that extend into this column, and subtract
       // that region from the new float manager.  So you could stick a
       // really big float in the first column and text in following
       // columns would flow around it.
       // Reflow the frame
       ReflowChild(child, PresContext(), kidDesiredSize, kidReflowState,
                   childOrigin.x + kidReflowState.ComputedPhysicalMargin().left,
                   childOrigin.y + kidReflowState.ComputedPhysicalMargin().top,
 , aStatus);
       reflowNext = (aStatus & NS_FRAME_REFLOW_NEXTINFLOW) != 0;
 #ifdef DEBUG_roc
       printf("*** Reflowed child #%d %p: status = %d, desiredSize=%d,%d CarriedOutBottomMargin=%d\n",
              columnCount, (void*)child, aStatus, kidDesiredSize.Width(), kidDesiredSize.Height(),
              kidDesiredSize.mCarriedOutBottomMargin.get());
 #endif
       NS_FRAME_TRACE_REFLOW_OUT("Column::Reflow", aStatus);
       *aBottomMarginCarriedOut = kidDesiredSize.mCarriedOutBottomMargin;
       FinishReflowChild(child, PresContext(), kidDesiredSize,
                         &kidReflowState, childOrigin.x, childOrigin.y, 0);
       childContentBottom = nsLayoutUtils::CalculateContentBottom(child);
       if (childContentBottom > aConfig.mColMaxHeight) {
         allFit = false;
       }
       if (childContentBottom > availSize.height) {
         aColData.mMaxOverflowingHeight = std::max(childContentBottom,
             aColData.mMaxOverflowingHeight);
       }
     }
     contentRect.UnionRect(contentRect, child->GetRect());
     ConsiderChildOverflow(overflowRects, child);
     contentBottom = std::max(contentBottom, childContentBottom);
     aColData.mLastHeight = childContentBottom;
     aColData.mSumHeight += childContentBottom;
     // Build a continuation column if necessary
     nsIFrame* kidNextInFlow = child->GetNextInFlow();
     if (NS_FRAME_IS_FULLY_COMPLETE(aStatus) && !NS_FRAME_IS_TRUNCATED(aStatus)) {
       NS_ASSERTION(!kidNextInFlow, "next in flow should have been deleted");
       child = nullptr;
       break;
     } else {
       ++columnCount;
       // Make sure that the column has a next-in-flow. If not, we must
       // create one to hold the overflowing stuff, even if we're just
       // going to put it on our overflow list and let *our*
       // next in flow handle it.
       if (!kidNextInFlow) {
         NS_ASSERTION(aStatus & NS_FRAME_REFLOW_NEXTINFLOW,
                      "We have to create a continuation, but the block doesn't want us to reflow it?");
         // We need to create a continuing column
         nsresult rv = CreateNextInFlow(child, kidNextInFlow);
         if (NS_FAILED(rv)) {
           NS_NOTREACHED("Couldn't create continuation");
           child = nullptr;
           break;
         }
       }
       // Make sure we reflow a next-in-flow when it switches between being
       // normal or overflow container
       if (NS_FRAME_OVERFLOW_IS_INCOMPLETE(aStatus)) {
         if (!(kidNextInFlow->GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER)) {
           aStatus |= NS_FRAME_REFLOW_NEXTINFLOW;
           reflowNext = true;
           kidNextInFlow->AddStateBits(NS_FRAME_IS_OVERFLOW_CONTAINER);
         }
       }
       else if (kidNextInFlow->GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER) {
         aStatus |= NS_FRAME_REFLOW_NEXTINFLOW;
         reflowNext = true;
         kidNextInFlow->RemoveStateBits(NS_FRAME_IS_OVERFLOW_CONTAINER);
       }
       if ((contentBottom > aReflowState.ComputedMaxHeight() ||
            contentBottom > aReflowState.ComputedHeight()) &&
            aConfig.mBalanceColCount < INT32_MAX) {
         // We overflowed vertically, but have not exceeded the number of
         // columns. We're going to go into overflow columns now, so balancing
         // no longer applies.
         aColData.mHasExcessHeight = true;
       }
       if (columnCount >= aConfig.mBalanceColCount) {
         // No more columns allowed here. Stop.
         aStatus |= NS_FRAME_REFLOW_NEXTINFLOW;
         kidNextInFlow->AddStateBits(NS_FRAME_IS_DIRTY);
         // Move any of our leftover columns to our overflow list. Our
         // next-in-flow will eventually pick them up.
         const nsFrameList& continuationColumns = mFrames.RemoveFramesAfter(child);
         if (continuationColumns.NotEmpty()) {
           SetOverflowFrames(continuationColumns);
         }
         child = nullptr;
         break;
       }
     }
     if (PresContext()->HasPendingInterrupt()) {
       // Stop the loop now while |child| still points to the frame that bailed
       // out.  We could keep going here and condition a bunch of the code in
       // this loop on whether there's an interrupt, or even just keep going and
       // trying to reflow the blocks (even though we know they'll interrupt
       // right after their first line), but stopping now is conceptually the
       // simplest (and probably fastest) thing.
       break;
     }
     // Advance to the next column
     child = child->GetNextSibling();
     if (child) {
       if (!RTL) {
         childOrigin.x += aConfig.mColWidth + aConfig.mColGap;
       } else {
         childOrigin.x -= aConfig.mColWidth + aConfig.mColGap;
       }
 #ifdef DEBUG_roc
       printf("*** NEXT CHILD ORIGIN.x = %d\n", childOrigin.x);
 #endif
     }
   }
   if (PresContext()->CheckForInterrupt(this) &&
       (GetStateBits() & NS_FRAME_IS_DIRTY)) {
     // Mark all our kids starting with |child| dirty
     // Note that this is a CheckForInterrupt call, not a HasPendingInterrupt,
     // because we might have interrupted while reflowing |child|, and since
     // we're about to add a dirty bit to |child| we need to make sure that
     // |this| is scheduled to have dirty bits marked on it and its ancestors.
     // Otherwise, when we go to mark dirty bits on |child|'s ancestors we'll
     // bail out immediately, since it'll already have a dirty bit.
     for (; child; child = child->GetNextSibling()) {
       child->AddStateBits(NS_FRAME_IS_DIRTY);
     }
   }
   aColData.mMaxHeight = contentBottom;
   contentRect.height = std::max(contentRect.height, contentBottom);
   mLastFrameStatus = aStatus;
   // contentRect included the borderPadding.left,borderPadding.top of the child rects
   contentRect -= nsPoint(borderPadding.left, borderPadding.top);
   nsSize contentSize = nsSize(contentRect.XMost(), contentRect.YMost());
   // Apply computed and min/max values
   if (aConfig.mComputedHeight != NS_INTRINSICSIZE) {
     if (aReflowState.AvailableHeight() != NS_INTRINSICSIZE) {
       contentSize.height = std::min(contentSize.height,
                                     aConfig.mComputedHeight);
     } else {
       contentSize.height = aConfig.mComputedHeight;
     }
   } else {
     // We add the "consumed" height back in so that we're applying
     // constraints to the correct height value, then subtract it again
     // after we've finished with the min/max calculation. This prevents us from
     // having a last continuation that is smaller than the min height. but which
     // has prev-in-flows, trigger a larger height than actually required.
     contentSize.height = aReflowState.ApplyMinMaxHeight(contentSize.height,
                                                         aConfig.mConsumedHeight);
   }
   if (aReflowState.ComputedWidth() != NS_INTRINSICSIZE) {
     contentSize.width = aReflowState.ComputedWidth();
   } else {
     contentSize.width = aReflowState.ApplyMinMaxWidth(contentSize.width);
   }
   aDesiredSize.Height() = contentSize.height +
                         borderPadding.TopBottom();
   aDesiredSize.Width() = contentSize.width +
                        borderPadding.LeftRight();
   aDesiredSize.mOverflowAreas = overflowRects;
   aDesiredSize.UnionOverflowAreasWithDesiredBounds();
 #ifdef DEBUG_roc
   printf("*** DONE PASS feasible=%d\n", allFit && NS_FRAME_IS_FULLY_COMPLETE(aStatus)
          && !NS_FRAME_IS_TRUNCATED(aStatus));
 #endif
   return allFit && NS_FRAME_IS_FULLY_COMPLETE(aStatus)
     && !NS_FRAME_IS_TRUNCATED(aStatus);
 }
 void
 nsColumnSetFrame::DrainOverflowColumns()
 {
   // First grab the prev-in-flows overflows and reparent them to this
   // frame.
   nsPresContext* presContext = PresContext();
   nsColumnSetFrame* prev = static_cast<nsColumnSetFrame*>(GetPrevInFlow());
   if (prev) {
     AutoFrameListPtr overflows(presContext, prev->StealOverflowFrames());
     if (overflows) {
       nsContainerFrame::ReparentFrameViewList(*overflows, prev, this);
       mFrames.InsertFrames(this, nullptr, *overflows);
     }
   }
   // Now pull back our own overflows and append them to our children.
   // We don't need to reparent them since we're already their parent.
   AutoFrameListPtr overflows(presContext, StealOverflowFrames());
   if (overflows) {
     // We're already the parent for these frames, so no need to set
     // their parent again.
     mFrames.AppendFrames(nullptr, *overflows);
   }
 }
 void
 nsColumnSetFrame::FindBestBalanceHeight(const nsHTMLReflowState& aReflowState,
                                         nsPresContext* aPresContext,
                                         ReflowConfig& aConfig,
                                         ColumnBalanceData& aColData,
                                         nsHTMLReflowMetrics& aDesiredSize,
                                         nsCollapsingMargin& aOutMargin,
                                         bool& aUnboundedLastColumn,
                                         bool& aRunWasFeasible,
                                         nsReflowStatus& aStatus)
 {
   bool feasible = aRunWasFeasible;
   nsMargin bp = aReflowState.ComputedPhysicalBorderPadding();
   ApplySkipSides(bp);
   bp.bottom = aReflowState.ComputedPhysicalBorderPadding().bottom;
   nscoord availableContentHeight =
     GetAvailableContentHeight(aReflowState);
   // Termination of the algorithm below is guaranteed because
   // aConfig.knownFeasibleHeight - aConfig.knownInfeasibleHeight decreases in every
   // iteration.
   // We set this flag when we detect that we may contain a frame
   // that can break anywhere (thus foiling the linear decrease-by-one
   // search)
   bool maybeContinuousBreakingDetected = false;
   while (!aPresContext->HasPendingInterrupt()) {
     nscoord lastKnownFeasibleHeight = aConfig.mKnownFeasibleHeight;
     // Record what we learned from the last reflow
     if (feasible) {
       // maxHeight is feasible. Also, mLastBalanceHeight is feasible.
       aConfig.mKnownFeasibleHeight = std::min(aConfig.mKnownFeasibleHeight,
                                               aColData.mMaxHeight);
       aConfig.mKnownFeasibleHeight = std::min(aConfig.mKnownFeasibleHeight,
                                               mLastBalanceHeight);
       // Furthermore, no height less than the height of the last
       // column can ever be feasible. (We might be able to reduce the
       // height of a non-last column by moving content to a later column,
       // but we can't do that with the last column.)
       if (mFrames.GetLength() == aConfig.mBalanceColCount) {
         aConfig.mKnownInfeasibleHeight = std::max(aConfig.mKnownInfeasibleHeight,
                                        aColData.mLastHeight - 1);
       }
     } else {
       aConfig.mKnownInfeasibleHeight = std::max(aConfig.mKnownInfeasibleHeight,
                                                 mLastBalanceHeight);
       // If a column didn't fit in its available height, then its current
       // height must be the minimum height for unbreakable content in
       // the column, and therefore no smaller height can be feasible.
       aConfig.mKnownInfeasibleHeight = std::max(aConfig.mKnownInfeasibleHeight,
                                          aColData.mMaxOverflowingHeight - 1);
       if (aUnboundedLastColumn) {
         // The last column is unbounded, so all content got reflowed, so the
         // mColMaxHeight is feasible.
         aConfig.mKnownFeasibleHeight = std::min(aConfig.mKnownFeasibleHeight,
                                                 aColData.mMaxHeight);
       }
     }
 #ifdef DEBUG_roc
     printf("*** nsColumnSetFrame::Reflow balancing knownInfeasible=%d knownFeasible=%d\n",
            aConfig.mKnownInfeasibleHeight, aConfig.mKnownFeasibleHeight);
 #endif
     if (aConfig.mKnownInfeasibleHeight >= aConfig.mKnownFeasibleHeight - 1) {
       // aConfig.mKnownFeasibleHeight is where we want to be
       break;
     }
     if (aConfig.mKnownInfeasibleHeight >= availableContentHeight) {
       break;
     }
     if (lastKnownFeasibleHeight - aConfig.mKnownFeasibleHeight == 1) {
       // We decreased the feasible height by one twip only. This could
       // indicate that there is a continuously breakable child frame
       // that we are crawling through.
       maybeContinuousBreakingDetected = true;
     }
     nscoord nextGuess = (aConfig.mKnownFeasibleHeight + aConfig.mKnownInfeasibleHeight)/2;
     // The constant of 600 twips is arbitrary. It's about two line-heights.
     if (aConfig.mKnownFeasibleHeight - nextGuess < 600 &&
         !maybeContinuousBreakingDetected) {
       // We're close to our target, so just try shrinking just the
       // minimum amount that will cause one of our columns to break
       // differently.
       nextGuess = aConfig.mKnownFeasibleHeight - 1;
     } else if (aUnboundedLastColumn) {
       // Make a guess by dividing that into N columns. Add some slop
       // to try to make it on the feasible side.  The constant of
       // 600 twips is arbitrary. It's about two line-heights.
       nextGuess = aColData.mSumHeight/aConfig.mBalanceColCount + 600;
       // Sanitize it
       nextGuess = clamped(nextGuess, aConfig.mKnownInfeasibleHeight + 1,
                                      aConfig.mKnownFeasibleHeight - 1);
     } else if (aConfig.mKnownFeasibleHeight == NS_INTRINSICSIZE) {
       // This can happen when we had a next-in-flow so we didn't
       // want to do an unbounded height measuring step. Let's just increase
       // from the infeasible height by some reasonable amount.
       nextGuess = aConfig.mKnownInfeasibleHeight*2 + 600;
     }
     // Don't bother guessing more than our height constraint.
     nextGuess = std::min(availableContentHeight, nextGuess);
 #ifdef DEBUG_roc
     printf("*** nsColumnSetFrame::Reflow balancing choosing next guess=%d\n", nextGuess);
 #endif
     aConfig.mColMaxHeight = nextGuess;
     aUnboundedLastColumn = false;
     AddStateBits(NS_FRAME_IS_DIRTY);
     feasible = ReflowColumns(aDesiredSize, aReflowState, aStatus, aConfig, false,
                              &aOutMargin, aColData);
     if (!aConfig.mIsBalancing) {
       // Looks like we had excess height when balancing, so we gave up on
       // trying to balance.
       break;
     }
   }
   if (aConfig.mIsBalancing && !feasible &&
       !aPresContext->HasPendingInterrupt()) {
     // We may need to reflow one more time at the feasible height to
     // get a valid layout.
     bool skip = false;
     if (aConfig.mKnownInfeasibleHeight >= availableContentHeight) {
       aConfig.mColMaxHeight = availableContentHeight;
       if (mLastBalanceHeight == availableContentHeight) {
         skip = true;
       }
     } else {
       aConfig.mColMaxHeight = aConfig.mKnownFeasibleHeight;
     }
     if (!skip) {
       // If our height is unconstrained, make sure that the last column is
       // allowed to have arbitrary height here, even though we were balancing.
       // Otherwise we'd have to split, and it's not clear what we'd do with
       // that.
       AddStateBits(NS_FRAME_IS_DIRTY);
       feasible = ReflowColumns(aDesiredSize, aReflowState, aStatus, aConfig,
                                availableContentHeight == NS_UNCONSTRAINEDSIZE,
                                &aOutMargin, aColData);
     }
   }
   aRunWasFeasible = feasible;
 }
 nsresult
 nsColumnSetFrame::Reflow(nsPresContext*           aPresContext,
                          nsHTMLReflowMetrics&     aDesiredSize,
                          const nsHTMLReflowState& aReflowState,
                          nsReflowStatus&          aStatus)
 {
   // Don't support interruption in columns
   nsPresContext::InterruptPreventer noInterrupts(aPresContext);
   DO_GLOBAL_REFLOW_COUNT("nsColumnSetFrame");
   DISPLAY_REFLOW(aPresContext, this, aReflowState, aDesiredSize, aStatus);
   // Initialize OUT parameter
   aStatus = NS_FRAME_COMPLETE;
   // Our children depend on our height if we have a fixed height.
   if (aReflowState.ComputedHeight() != NS_AUTOHEIGHT) {
     NS_ASSERTION(aReflowState.ComputedHeight() != NS_INTRINSICSIZE,
                  "Unexpected computed height");
     AddStateBits(NS_FRAME_CONTAINS_RELATIVE_HEIGHT);
   }
   else {
     RemoveStateBits(NS_FRAME_CONTAINS_RELATIVE_HEIGHT);
   }
   //------------ Handle Incremental Reflow -----------------
   ReflowConfig config = ChooseColumnStrategy(aReflowState);
   // If balancing, then we allow the last column to grow to unbounded
   // height during the first reflow. This gives us a way to estimate
   // what the average column height should be, because we can measure
   // the heights of all the columns and sum them up. But don't do this
   // if we have a next in flow because we don't want to suck all its
   // content back here and then have to push it out again!
   nsIFrame* nextInFlow = GetNextInFlow();
   bool unboundedLastColumn = config.mIsBalancing && !nextInFlow;
   nsCollapsingMargin carriedOutBottomMargin;
   ColumnBalanceData colData;
   colData.mHasExcessHeight = false;
   bool feasible = ReflowColumns(aDesiredSize, aReflowState, aStatus, config,
                                 unboundedLastColumn, &carriedOutBottomMargin,
                                 colData);
   // If we're not balancing, then we're already done, since we should have
   // reflown all of our children, and there is no need for a binary search to
   // determine proper column height.
   if (config.mIsBalancing && !aPresContext->HasPendingInterrupt()) {
     FindBestBalanceHeight(aReflowState, aPresContext, config, colData,
                           aDesiredSize, carriedOutBottomMargin,
                           unboundedLastColumn, feasible, aStatus);
   }
   if (aPresContext->HasPendingInterrupt() &&
       aReflowState.AvailableHeight() == NS_UNCONSTRAINEDSIZE) {
     // In this situation, we might be lying about our reflow status, because
     // our last kid (the one that got interrupted) was incomplete.  Fix that.
     aStatus = NS_FRAME_COMPLETE;
   }
   FinishReflowWithAbsoluteFrames(aPresContext, aDesiredSize, aReflowState, aStatus, false);
   aDesiredSize.mCarriedOutBottomMargin = carriedOutBottomMargin;
   NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
   NS_ASSERTION(NS_FRAME_IS_FULLY_COMPLETE(aStatus) ||
                aReflowState.AvailableHeight() != NS_UNCONSTRAINEDSIZE,
                "Column set should be complete if the available height is unconstrained");
   return NS_OK;
 }
 void
 nsColumnSetFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                                    const nsRect&           aDirtyRect,
                                    const nsDisplayListSet& aLists) {
   DisplayBorderBackgroundOutline(aBuilder, aLists);
   if (IsVisibleForPainting(aBuilder)) {
     aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
       nsDisplayGenericOverflow(aBuilder, this, ::PaintColumnRule, "ColumnRule",
                                nsDisplayItem::TYPE_COLUMN_RULE));
   }
   // Our children won't have backgrounds so it doesn't matter where we put them.
   for (nsFrameList::Enumerator e(mFrames); !e.AtEnd(); e.Next()) {
     BuildDisplayListForChild(aBuilder, e.get(), aDirtyRect, aLists);
   }
 }
 nsresult
 nsColumnSetFrame::AppendFrames(ChildListID     aListID,
                                nsFrameList&    aFrameList)
 {
   if (aListID == kAbsoluteList) {
     return nsContainerFrame::AppendFrames(aListID, aFrameList);
   }
   NS_ERROR("unexpected child list");
   return NS_ERROR_INVALID_ARG;
 }
 nsresult
 nsColumnSetFrame::InsertFrames(ChildListID     aListID,
                                nsIFrame*       aPrevFrame,
                                nsFrameList&    aFrameList)
 {
   if (aListID == kAbsoluteList) {
     return nsContainerFrame::InsertFrames(aListID, aPrevFrame, aFrameList);
   }
   NS_ERROR("unexpected child list");
   return NS_ERROR_INVALID_ARG;
 }
 nsresult
 nsColumnSetFrame::RemoveFrame(ChildListID     aListID,
                               nsIFrame*       aOldFrame)
 {
   if (aListID == kAbsoluteList) {
     return nsContainerFrame::RemoveFrame(aListID, aOldFrame);
   }
   NS_ERROR("unexpected child list");
   return NS_ERROR_INVALID_ARG;
 }

The Tor Browser / annotate

layout/generic/nsColumnSetFrame.cpp@b8a032363ba2 (annotated)

layout/generic/nsColumnSetFrame.cpp