gecko-dev/layout/generic/nsColumnSetFrame.h

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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/. */
/* rendering object for css3 multi-column layout */
#include "mozilla/Attributes.h"
#include "nsContainerFrame.h"
class nsColumnSetFrame : public nsContainerFrame {
public:
NS_DECL_FRAMEARENA_HELPERS
nsColumnSetFrame(nsStyleContext* aContext);
virtual nsresult SetInitialChildList(ChildListID aListID,
nsFrameList& aChildList) MOZ_OVERRIDE;
virtual nsresult Reflow(nsPresContext* aPresContext,
nsHTMLReflowMetrics& aDesiredSize,
const nsHTMLReflowState& aReflowState,
nsReflowStatus& aStatus) MOZ_OVERRIDE;
virtual nsresult AppendFrames(ChildListID aListID,
nsFrameList& aFrameList) MOZ_OVERRIDE;
virtual nsresult InsertFrames(ChildListID aListID,
nsIFrame* aPrevFrame,
nsFrameList& aFrameList) MOZ_OVERRIDE;
virtual nsresult RemoveFrame(ChildListID aListID,
nsIFrame* aOldFrame) MOZ_OVERRIDE;
virtual nscoord GetMinWidth(nsRenderingContext *aRenderingContext) MOZ_OVERRIDE;
virtual nscoord GetPrefWidth(nsRenderingContext *aRenderingContext) MOZ_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 GetAvailableContentHeight(const nsHTMLReflowState& aReflowState);
virtual nsIFrame* GetContentInsertionFrame() MOZ_OVERRIDE {
nsIFrame* frame = GetFirstPrincipalChild();
// if no children return nullptr
if (!frame)
return nullptr;
return frame->GetContentInsertionFrame();
}
virtual nsresult StealFrame(nsIFrame* aChild, bool aForceNormal) MOZ_OVERRIDE
{ // nsColumnSetFrame keeps overflow containers in main child list
return nsContainerFrame::StealFrame(aChild, true);
}
virtual bool IsFrameOfType(uint32_t aFlags) const MOZ_OVERRIDE
{
return nsContainerFrame::IsFrameOfType(aFlags &
~(nsIFrame::eCanContainOverflowContainers));
}
virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder,
const nsRect& aDirtyRect,
const nsDisplayListSet& aLists) MOZ_OVERRIDE;
virtual nsIAtom* GetType() const MOZ_OVERRIDE;
virtual void PaintColumnRule(nsRenderingContext* aCtx,
const nsRect& aDirtyRect,
const nsPoint& aPt);
#ifdef DEBUG_FRAME_DUMP
virtual nsresult GetFrameName(nsAString& aResult) const MOZ_OVERRIDE {
return MakeFrameName(NS_LITERAL_STRING("ColumnSet"), aResult);
}
#endif
protected:
nscoord mLastBalanceHeight;
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 width of each individual column.
nscoord mColWidth;
// The amount of width that is expected to be left over after all the
// columns and column gaps are laid out.
nscoord mExpectedWidthLeftOver;
// The width of each column gap.
nscoord mColGap;
// The maximum height of any individual column during a reflow iteration.
// This parameter is set during each iteration of the binary search for
// the best column height.
nscoord mColMaxHeight;
// A boolean controlling whether or not we are balancing. This should be
// equivalent to mBalanceColCount == INT32_MAX.
bool mIsBalancing;
// The last known column height that was 'feasible'. A column height is
// feasible if all child content fits within the specified height.
nscoord mKnownFeasibleHeight;
// The last known height that was 'infeasible'. A column height is
// infeasible if not all child content fits within the specified height.
nscoord mKnownInfeasibleHeight;
// Height of the column set frame
nscoord mComputedHeight;
// The height "consumed" by previous-in-flows.
// The computed height should be equal to the height of the element (i.e.
// the computed height itself) plus the consumed height.
nscoord mConsumedHeight;
};
/**
* Some data that is better calculated during reflow
*/
struct ColumnBalanceData {
// The maximum "content height" of any column
nscoord mMaxHeight;
// The sum of the "content heights" for all columns
nscoord mSumHeight;
// The "content height" of the last column
nscoord mLastHeight;
// The maximum "content height" of all columns that overflowed
// their available height
nscoord mMaxOverflowingHeight;
// This flag determines whether the last reflow of children exceeded the
// computed height of the column set frame. If so, we set the height to
// this maximum allowable height, and continue reflow without balancing.
bool mHasExcessHeight;
void Reset() {
mMaxHeight = mSumHeight = mLastHeight = mMaxOverflowingHeight = 0;
mHasExcessHeight = false;
}
};
/**
* 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();
bool ReflowColumns(nsHTMLReflowMetrics& aDesiredSize,
const nsHTMLReflowState& aReflowState,
nsReflowStatus& aReflowStatus,
ReflowConfig& aConfig,
bool aLastColumnUnbounded,
nsCollapsingMargin* aCarriedOutBottomMargin,
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 nsHTMLReflowState& aReflowState,
bool aForceAuto, nscoord aFeasibleHeight,
nscoord aInfeasibleHeight);
/**
* Perform the binary search for the best balance height for this column set.
*
* @param aReflowState 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 FindBestBalanceHeight(const nsHTMLReflowState& aReflowState,
nsPresContext* aPresContext,
ReflowConfig& aConfig,
ColumnBalanceData& aColData,
nsHTMLReflowMetrics& aDesiredSize,
nsCollapsingMargin& aOutMargin,
bool& aUnboundedLastColumn,
bool& aRunWasFeasible,
nsReflowStatus& aStatus);
/**
* Reflow column children. Returns true iff the content that was reflowed
* fit into the mColMaxHeight.
*/
bool ReflowChildren(nsHTMLReflowMetrics& aDesiredSize,
const nsHTMLReflowState& aReflowState,
nsReflowStatus& aStatus,
const ReflowConfig& aConfig,
bool aLastColumnUnbounded,
nsCollapsingMargin* aCarriedOutBottomMargin,
ColumnBalanceData& aColData);
};