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