WorksheetLayout Class Reference

The layout/recalculation engine of a worksheet. More...

#include <WorksheetLayout.h>

Public Member Functions
	WorksheetLayout (Configuration *config, WorksheetView &view, std::function< GroupCell *()> getTree, std::function< GroupCell *()> getLastCell)
	Construct the engine.
	WorksheetLayout (const WorksheetLayout &)=delete
WorksheetLayout &	operator= (const WorksheetLayout &)=delete
void	RequestRecalculation (Cell *start)
	Schedule a recalculation of the worksheet starting with the cell start.
bool	RecalculateIfNeeded (bool timeout=false, long timeSliceMs=50)
	Perform the scheduled recalculation, if one is pending.
void	AdjustSize ()
	Adjust the virtual size and scrollbars to the document's extent.
void	GetMaxPoint (int *width, int *height)
	Get the coordinates of the bottom right point of the worksheet.
void	UpdateConfigurationClientSize ()
	Inform the configuration about the view's current client size.
int	GroupCellWidthWithMargins (int cellWidth) const
	The horizontal space a group cell of the given width occupies.
int	GetScrollUnit () const
	The scroll granularity (device px per scroll unit) AdjustSize() last applied.
void	RequestAdjustSize ()
	Flag the virtual (scroll) size as needing re-adjustment.
void	CancelPendingRecalculation ()
	Drop any pending recalculation (e.g. when the document is cleared).

Detailed Description

The layout/recalculation engine of a worksheet.

Talks to the cell tree via the callbacks handed to the constructor, to the window via a WorksheetView and to the Configuration for metrics and the canvas size. Worksheet holds one instance and forwards its layout entry points here; the headless unit test drives an instance without any window.

Constructor & Destructor Documentation

WorksheetLayout()

WorksheetLayout::WorksheetLayout	(	Configuration *	config,
		WorksheetView &	view,
		std::function< GroupCell *()>	getTree,
		std::function< GroupCell *()>	getLastCell
	)

Construct the engine.

Parameters

config	The Configuration supplying metrics, the canvas size and the recalculation drawing context.
view	The window surface (real Worksheet or a test mock). Held by reference: must outlive this object.
getTree	Returns the first GroupCell of the worksheet (or null).
getLastCell	Returns the last GroupCell of the worksheet (or null).

Member Function Documentation

AdjustSize()

void WorksheetLayout::AdjustSize

(

)

Adjust the virtual size and scrollbars to the document's extent.

Defers (via RequestAdjustSize()) while a recalculation is still pending, since the cell positions it reads would be stale - see the implementation comment for the full story.

GetMaxPoint()

void WorksheetLayout::GetMaxPoint	(	int *	width,
		int *	height
	)

Get the coordinates of the bottom right point of the worksheet.

Only valid once no recalculation is pending; asserts on that.

GetScrollUnit()

int WorksheetLayout::GetScrollUnit ( ) const

inline

The scroll granularity (device px per scroll unit) AdjustSize() last applied.

Worksheet's scroll handlers read it to convert scroll positions to pixels.

GroupCellWidthWithMargins()

int WorksheetLayout::GroupCellWidthWithMargins

(

int

cellWidth

)

const

The horizontal space a group cell of the given width occupies.

That is the cell's own width plus the equal left and right margins the worksheet reserves around every group cell. Used both when measuring the document width (GetMaxPoint) and while walking the recalculation.

RecalculateIfNeeded()

bool WorksheetLayout::RecalculateIfNeeded	(	bool	timeout = false,
		long	timeSliceMs = 50
	)

Perform the scheduled recalculation, if one is pending.

One walk from the scheduled start point drives both modes: with timeout set the pass is time-sliced (yields after timeSliceMs, resuming on the next call); otherwise the whole scheduled range is laid out in one go. Ends by adjusting the virtual size once the cell positions are valid.

Returns

true if any layout work was done or remains pending.

RequestAdjustSize()

void WorksheetLayout::RequestAdjustSize ( )

inline

Flag the virtual (scroll) size as needing re-adjustment.

Set when a cell changed height (via the callback Worksheet registers on the Configuration, so cells can flag it without depending on the view) or when layout is scheduled; consumed by RecalculateIfNeeded(), which calls AdjustSize() once the cell positions are valid.

RequestRecalculation()

void WorksheetLayout::RequestRecalculation

(

Cell *

start

)

Schedule a recalculation of the worksheet starting with the cell start.

This only records where the next layout pass has to start (it marks the group dirty and moves m_recalculateStart); it does not size or position any cell. The actual work - and, crucially, AdjustSize() once the cell positions are correct - happens in RecalculateIfNeeded(). Calling AdjustSize() (or otherwise reading cell geometry) right after this, without a RecalculateIfNeeded() in between, reads stale positions.

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The documentation for this class was generated from the following files:

• src/WorksheetLayout.h
• src/WorksheetLayout.cpp