michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /* rendering object for css3 multi-column layout */
michael@0: 
michael@0: #include "mozilla/Attributes.h"
michael@0: #include "nsContainerFrame.h"
michael@0: 
michael@0: class nsColumnSetFrame : public nsContainerFrame {
michael@0: public:
michael@0:   NS_DECL_FRAMEARENA_HELPERS
michael@0: 
michael@0:   nsColumnSetFrame(nsStyleContext* aContext);
michael@0: 
michael@0:   virtual nsresult SetInitialChildList(ChildListID     aListID,
michael@0:                                        nsFrameList&    aChildList) MOZ_OVERRIDE;
michael@0: 
michael@0:   virtual nsresult Reflow(nsPresContext* aPresContext,
michael@0:                           nsHTMLReflowMetrics& aDesiredSize,
michael@0:                           const nsHTMLReflowState& aReflowState,
michael@0:                           nsReflowStatus& aStatus) MOZ_OVERRIDE;
michael@0: 
michael@0:   virtual nsresult  AppendFrames(ChildListID     aListID,
michael@0:                                  nsFrameList&    aFrameList) MOZ_OVERRIDE;
michael@0:   virtual nsresult  InsertFrames(ChildListID     aListID,
michael@0:                                  nsIFrame*       aPrevFrame,
michael@0:                                  nsFrameList&    aFrameList) MOZ_OVERRIDE;
michael@0:   virtual nsresult  RemoveFrame(ChildListID     aListID,
michael@0:                                 nsIFrame*       aOldFrame) MOZ_OVERRIDE;
michael@0: 
michael@0:   virtual nscoord GetMinWidth(nsRenderingContext *aRenderingContext) MOZ_OVERRIDE;
michael@0:   virtual nscoord GetPrefWidth(nsRenderingContext *aRenderingContext) MOZ_OVERRIDE;
michael@0: 
michael@0:   /**
michael@0:    * Retrieve the available height for content of this frame. The available content
michael@0:    * height is the available height for the frame, minus borders and padding.
michael@0:    */
michael@0:   virtual nscoord GetAvailableContentHeight(const nsHTMLReflowState& aReflowState);
michael@0: 
michael@0:   virtual nsIFrame* GetContentInsertionFrame() MOZ_OVERRIDE {
michael@0:     nsIFrame* frame = GetFirstPrincipalChild();
michael@0: 
michael@0:     // if no children return nullptr
michael@0:     if (!frame)
michael@0:       return nullptr;
michael@0: 
michael@0:     return frame->GetContentInsertionFrame();
michael@0:   }
michael@0: 
michael@0:   virtual nsresult StealFrame(nsIFrame* aChild, bool aForceNormal) MOZ_OVERRIDE
michael@0:   { // nsColumnSetFrame keeps overflow containers in main child list
michael@0:     return nsContainerFrame::StealFrame(aChild, true);
michael@0:   }
michael@0: 
michael@0:   virtual bool IsFrameOfType(uint32_t aFlags) const MOZ_OVERRIDE
michael@0:    {
michael@0:      return nsContainerFrame::IsFrameOfType(aFlags &
michael@0:               ~(nsIFrame::eCanContainOverflowContainers));
michael@0:    }
michael@0: 
michael@0:   virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
michael@0:                                 const nsRect&           aDirtyRect,
michael@0:                                 const nsDisplayListSet& aLists) MOZ_OVERRIDE;
michael@0: 
michael@0:   virtual nsIAtom* GetType() const MOZ_OVERRIDE;
michael@0: 
michael@0:   virtual void PaintColumnRule(nsRenderingContext* aCtx,
michael@0:                                const nsRect&        aDirtyRect,
michael@0:                                const nsPoint&       aPt);
michael@0: 
michael@0: #ifdef DEBUG_FRAME_DUMP
michael@0:   virtual nsresult GetFrameName(nsAString& aResult) const MOZ_OVERRIDE {
michael@0:     return MakeFrameName(NS_LITERAL_STRING("ColumnSet"), aResult);
michael@0:   }
michael@0: #endif
michael@0: 
michael@0: protected:
michael@0:   nscoord        mLastBalanceHeight;
michael@0:   nsReflowStatus mLastFrameStatus;
michael@0: 
michael@0:   /**
michael@0:    * These are the parameters that control the layout of columns.
michael@0:    */
michael@0:   struct ReflowConfig {
michael@0:     // The number of columns that we want to balance across. If we're not
michael@0:     // balancing, this will be set to INT32_MAX.
michael@0:     int32_t mBalanceColCount;
michael@0: 
michael@0:     // The width of each individual column.
michael@0:     nscoord mColWidth;
michael@0: 
michael@0:     // The amount of width that is expected to be left over after all the
michael@0:     // columns and column gaps are laid out.
michael@0:     nscoord mExpectedWidthLeftOver;
michael@0: 
michael@0:     // The width of each column gap.
michael@0:     nscoord mColGap;
michael@0: 
michael@0:     // The maximum height of any individual column during a reflow iteration.
michael@0:     // This parameter is set during each iteration of the binary search for
michael@0:     // the best column height.
michael@0:     nscoord mColMaxHeight;
michael@0: 
michael@0:     // A boolean controlling whether or not we are balancing. This should be
michael@0:     // equivalent to mBalanceColCount == INT32_MAX.
michael@0:     bool mIsBalancing;
michael@0: 
michael@0:     // The last known column height that was 'feasible'. A column height is
michael@0:     // feasible if all child content fits within the specified height.
michael@0:     nscoord mKnownFeasibleHeight;
michael@0: 
michael@0:     // The last known height that was 'infeasible'. A column height is
michael@0:     // infeasible if not all child content fits within the specified height.
michael@0:     nscoord mKnownInfeasibleHeight;
michael@0: 
michael@0:     // Height of the column set frame
michael@0:     nscoord mComputedHeight;
michael@0: 
michael@0:     // The height "consumed" by previous-in-flows.
michael@0:     // The computed height should be equal to the height of the element (i.e.
michael@0:     // the computed height itself) plus the consumed height.
michael@0:     nscoord mConsumedHeight;
michael@0:   };
michael@0: 
michael@0:   /**
michael@0:    * Some data that is better calculated during reflow
michael@0:    */
michael@0:   struct ColumnBalanceData {
michael@0:     // The maximum "content height" of any column
michael@0:     nscoord mMaxHeight;
michael@0:     // The sum of the "content heights" for all columns
michael@0:     nscoord mSumHeight;
michael@0:     // The "content height" of the last column
michael@0:     nscoord mLastHeight;
michael@0:     // The maximum "content height" of all columns that overflowed
michael@0:     // their available height
michael@0:     nscoord mMaxOverflowingHeight;
michael@0:     // This flag determines whether the last reflow of children exceeded the
michael@0:     // computed height of the column set frame. If so, we set the height to
michael@0:     // this maximum allowable height, and continue reflow without balancing.
michael@0:     bool mHasExcessHeight;
michael@0: 
michael@0:     void Reset() {
michael@0:       mMaxHeight = mSumHeight = mLastHeight = mMaxOverflowingHeight = 0;
michael@0:       mHasExcessHeight = false;
michael@0:     }
michael@0:   };
michael@0: 
michael@0:   /**
michael@0:    * Similar to nsBlockFrame::DrainOverflowLines. Locate any columns not
michael@0:    * handled by our prev-in-flow, and any columns sitting on our own
michael@0:    * overflow list, and put them in our primary child list for reflowing.
michael@0:    */
michael@0:   void DrainOverflowColumns();
michael@0: 
michael@0:   bool ReflowColumns(nsHTMLReflowMetrics& aDesiredSize,
michael@0:                      const nsHTMLReflowState& aReflowState,
michael@0:                      nsReflowStatus& aReflowStatus,
michael@0:                      ReflowConfig& aConfig,
michael@0:                      bool aLastColumnUnbounded,
michael@0:                      nsCollapsingMargin* aCarriedOutBottomMargin,
michael@0:                      ColumnBalanceData& aColData);
michael@0: 
michael@0:   /**
michael@0:    * The basic reflow strategy is to call this function repeatedly to
michael@0:    * obtain specific parameters that determine the layout of the
michael@0:    * columns. This function will compute those parameters from the CSS
michael@0:    * style. This function will also be responsible for implementing
michael@0:    * the state machine that controls column balancing.
michael@0:    */
michael@0:   ReflowConfig ChooseColumnStrategy(const nsHTMLReflowState& aReflowState,
michael@0:                                     bool aForceAuto, nscoord aFeasibleHeight,
michael@0:                                     nscoord aInfeasibleHeight);
michael@0: 
michael@0:   /**
michael@0:    * Perform the binary search for the best balance height for this column set.
michael@0:    *
michael@0:    * @param aReflowState The input parameters for the current reflow iteration.
michael@0:    * @param aPresContext The presentation context in which the current reflow
michael@0:    *        iteration is occurring.
michael@0:    * @param aConfig The ReflowConfig object associated with this column set
michael@0:    *        frame, generated by ChooseColumnStrategy().
michael@0:    * @param aColData A data structure used to keep track of data needed between
michael@0:    *        successive iterations of the balancing process.
michael@0:    * @param aDesiredSize The final output size of the column set frame (output
michael@0:    *        of reflow procedure).
michael@0:    * @param aOutMargin The bottom margin of the column set frame that may be
michael@0:    *        carried out from reflow (and thus collapsed).
michael@0:    * @param aUnboundedLastColumn A boolean value indicating that the last column
michael@0:    *        can be of any height. Used during the first iteration of the
michael@0:    *        balancing procedure to measure the height of all content in
michael@0:    *        descendant frames of the column set.
michael@0:    * @param aRunWasFeasible An input/output parameter indicating whether or not
michael@0:    *        the last iteration of the balancing loop was a feasible height to
michael@0:    *        fit all content from descendant frames.
michael@0:    * @param aStatus A final reflow status of the column set frame, passed in as
michael@0:    *        an output parameter.
michael@0:    */
michael@0:   void FindBestBalanceHeight(const nsHTMLReflowState& aReflowState,
michael@0:                              nsPresContext* aPresContext,
michael@0:                              ReflowConfig& aConfig,
michael@0:                              ColumnBalanceData& aColData,
michael@0:                              nsHTMLReflowMetrics& aDesiredSize,
michael@0:                              nsCollapsingMargin& aOutMargin,
michael@0:                              bool& aUnboundedLastColumn,
michael@0:                              bool& aRunWasFeasible,
michael@0:                              nsReflowStatus& aStatus);
michael@0:   /**
michael@0:    * Reflow column children. Returns true iff the content that was reflowed
michael@0:    * fit into the mColMaxHeight.
michael@0:    */
michael@0:   bool ReflowChildren(nsHTMLReflowMetrics& aDesiredSize,
michael@0:                         const nsHTMLReflowState& aReflowState,
michael@0:                         nsReflowStatus& aStatus,
michael@0:                         const ReflowConfig& aConfig,
michael@0:                         bool aLastColumnUnbounded,
michael@0:                         nsCollapsingMargin* aCarriedOutBottomMargin,
michael@0:                         ColumnBalanceData& aColData);
michael@0: };