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