The pure arithmetic that turns a laid-out worksheet's extent into the scrollable (virtual) size and scroll granularity. More...

#include <algorithm>
#include <vector>

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Data Structures
struct	TrailingGroupGeometry
	One trailing group cell's geometry, as GetMaxPoint's height walk needs it. More...

struct	WorksheetVirtualSize
	The scrollable size + scroll granularity computed for a worksheet. More...

struct	ScrollCompensation
	Where to scroll to, and how far to shift the document, to keep a point still. More...

class	WorksheetView
	The narrow view surface the worksheet's layout pipeline needs. More...

struct	WorksheetVirtualSizeCache
	Remembers the last virtual size applied, so an unchanged size is a no-op. More...

Functions
int	ComputeWorksheetContentWidth (const std::vector< int > &cellWidthsWithMargins, int baseIndent)
	Compute the worksheet's content width.

int	ComputeWorksheetContentHeight (const std::vector< TrailingGroupGeometry > &trailing, int groupSkip, int baseIndent)
	Compute the worksheet's content height from its trailing cells' geometry.

WorksheetVirtualSize	ComputeWorksheetVirtualSize (bool hasTree, int maxPointWidth, int maxPointHeight, int clientHeight, int currentScrollPixelY)
	Compute a worksheet's virtual size and scroll unit.

ScrollCompensation	ComputeScrollCompensation (int scrollUnitsY, int scrollUnit, int topOffset, int shift)
	Compute the scroll position that keeps a point of the worksheet still on screen.

void	ApplyWorksheetVirtualSize (WorksheetView &view, bool hasTree, int maxWidth, int maxHeight, WorksheetVirtualSizeCache &cache, int &scrollUnit)
	Measure the view, compute the virtual size and apply it, skipping no-ops.

Detailed Description

The pure arithmetic that turns a laid-out worksheet's extent into the scrollable (virtual) size and scroll granularity.

Kept deliberately free of any GUI/wxWidgets dependency so the scroll-range math - historically a source of "the pane won't scroll" bugs - can be unit-tested in isolation. WorksheetLayout::AdjustSize() measures the document (GetMaxPoint) and the window (GetClientSize) and feeds the numbers here, then applies the result with SetVirtualSize()/SetScrollRate().

Function Documentation

◆ ApplyWorksheetVirtualSize()

void ApplyWorksheetVirtualSize	(	WorksheetView &	view,
		bool	hasTree,
		int	maxWidth,
		int	maxHeight,
		WorksheetVirtualSizeCache &	cache,
		int &	scrollUnit
	)

inline

Measure the view, compute the virtual size and apply it, skipping no-ops.

This is the view-facing half of WorksheetLayout::AdjustSize(): it reads the client size and scroll position from view, feeds them (with the already-measured document extent maxWidth / maxHeight) to ComputeWorksheetVirtualSize(), and - only if the result actually changed and is positive - pushes it back to the view and updates the scroll rate.

Parameters

view	The window abstraction (real worksheet or a test mock).
hasTree	Whether the worksheet has content (ignores the extent if not).
maxWidth	The document's right extent (WorksheetLayout::GetMaxPoint x).
maxHeight	The document's bottom extent (WorksheetLayout::GetMaxPoint y).
cache	The last-applied size, updated in place to dedupe.
scrollUnit	Read to turn the scroll position into pixels, and updated to the new granularity. WorksheetLayout keeps it as a member because Worksheet's scroll handlers read it too.

◆ ComputeScrollCompensation()

ScrollCompensation ComputeScrollCompensation	(	int	scrollUnitsY,
		int	scrollUnit,
		int	topOffset,
		int	shift
	)

inline

Compute the scroll position that keeps a point of the worksheet still on screen.

When Maxima appends output to a cell above the cursor, everything below that cell moves down, the cursor with it. Scrolling down by the same amount would put it back - but the view can only scroll in whole scroll units (10 px or more), so on its own that would still leave the cursor jittering by up to one unit on every append. The remainder is absorbed by the worksheet's top offset: an extra top margin of less than one scroll unit that shifts the whole document down. Scrolling one unit further than needed and moving the document down by the excess makes the compensation pixel-exact.

With the scroll position S, the top offset t and the point having moved down by shift pixels, the point stays where it was on screen exactly if the new values S', t' satisfy S' - t' = S + shift - t. This picks the smallest S' that is a multiple of the scroll unit and allows a t' in [0, scrollUnit). Near the top of the document, where S' cannot go below 0, t' is clamped to that range and the compensation is only as good as it can be.

Parameters

scrollUnitsY	The current vertical scroll position, in scroll units.
scrollUnit	The scroll granularity in px (> 0).
topOffset	The current top offset in px.
shift	How far (px) the point to keep still has moved down in the document; negative if it moved up.

Kept GUI-free so it can be unit-tested in isolation - see test_WorksheetSizeMath.

◆ ComputeWorksheetContentHeight()

int ComputeWorksheetContentHeight	(	const std::vector< TrailingGroupGeometry > &	trailing,
		int	groupSkip,
		int	baseIndent
	)

inline

Compute the worksheet's content height from its trailing cells' geometry.

This is the backward walk WorksheetLayout::GetMaxPoint() runs from the last cell: it accumulates the heights of the cells at the bottom whose position is not yet trustworthy (stale-and-unpositioned, or still-being-laid-out) until it reaches an "anchor" - a cell whose size is stale but whose top position (y) is already valid - and pins the total to that anchor's top plus everything accumulated below it. If the walk runs off the top of the document (no such anchor), the height falls back to the document's base indent plus the accumulated heights.

Parameters

trailing	The cells starting at the LAST cell and running backward. The walk stops at (and includes) the first entry that is the anchor, i.e. sizeIsStale && currentY >= 0.
groupSkip	The vertical gap between group cells (Configuration::GetGroupSkip).
baseIndent	The document's top margin (Configuration::GetBaseIndent), used only when there is no anchor.

Kept GUI-free (no Cell/Configuration dependency) so this fiddly stale-cell accounting can be unit-tested in isolation - see test_WorksheetSizeMath.

◆ ComputeWorksheetContentWidth()

int ComputeWorksheetContentWidth	(	const std::vector< int > &	cellWidthsWithMargins,
		int	baseIndent
	)

inline

Compute the worksheet's content width.

That is the document's base indent, widened to fit the widest group cell. Each entry in cellWidthsWithMargins is a cell's width including its left and right margins (WorksheetLayout::GroupCellWidthWithMargins).

Parameters

cellWidthsWithMargins	Per-cell widths (already including margins).
baseIndent	The minimum width (Configuration::GetBaseIndent).

Kept GUI-free (no Cell/Configuration dependency) so it can be unit-tested in isolation - see test_WorksheetSizeMath.

◆ ComputeWorksheetVirtualSize()

WorksheetVirtualSize ComputeWorksheetVirtualSize	(	bool	hasTree,
		int	maxPointWidth,
		int	maxPointHeight,
		int	clientHeight,
		int	currentScrollPixelY
	)

inline

Compute a worksheet's virtual size and scroll unit.

Parameters

hasTree	Whether the worksheet has any content. Without it the result is a small fixed size with a sane scroll unit.
maxPointWidth	The document's right extent (WorksheetLayout::GetMaxPoint x).
maxPointHeight	The document's bottom extent (WorksheetLayout::GetMaxPoint y).
clientHeight	The visible height of the worksheet window.
currentScrollPixelY	The current vertical scroll offset in pixels.

Invariants (that the callers rely on):

a vertical scrollbar always has room to move: height >= clientHeight + 10;
the virtual size never shrinks below what the current scroll position needs (height >= currentScrollPixelY + clientHeight + 10), so wxWidgets does not clamp the scroll position and jump the view;
a little over-scroll past the end is allowed (with the view scrolled fully down the document occupies the top 1/8 of the client area);
the scroll unit is at least 10 px, so scrolling never feels sluggish on hi-res screens nor degenerates on tiny ones.

Data Structures

Functions

Detailed Description

Function Documentation

◆ ApplyWorksheetVirtualSize()

◆ ComputeScrollCompensation()

◆ ComputeWorksheetContentHeight()

◆ ComputeWorksheetContentWidth()

◆ ComputeWorksheetVirtualSize()