Class ScrollAxisBase

ScrollAxisBase is an abstract base class and implements scrolling logic for both horizontal and vertical scrolling in a ScrollAxisBase. Logical units in the ScrollAxisBase are called "Lines".

ScrollAxisBase has support for frozen header and footer lines, maintaining a scroll position and updating and listening to scrollbars. It also maintains a collection of VisibleLineInfo items for all the lines that are visible in the viewing area. ScrollAxisBase wires itself with a ScrollLinesHost and reacts to changes in line count, line sizes, hidden state and default line size.

Inheritance

System.Object

ScrollAxisBase

LineScrollAxis

PixelScrollAxis

Implements

System.IDisposable

Namespace: Syncfusion.Maui.GridCommon.ScrollAxis

Assembly: Syncfusion.Maui.GridCommon.dll

Syntax

public abstract class ScrollAxisBase : Object, IDisposable

Constructors

ScrollAxisBase(IScrollBar, ILineSizeHost)

Initializes a new instance of the ScrollAxisBase class.

Declaration

public ScrollAxisBase(IScrollBar sb, ILineSizeHost scrollLinesHost)

Parameters

Type	Name	Description
IScrollBar	sb	The sb.
ILineSizeHost	scrollLinesHost	The scroll lines host.

Fields

distances

Declaration

public IDistanceCounterCollection distances

Field Value

Type
IDistanceCounterCollection

distancesHost

Declaration

public IDistancesHost distancesHost

Field Value

Type
IDistancesHost

Properties

Clip

Gets or sets the clipping region. Depending on the orientation of the axis, this is either the left and right or top and bottom values of the clipping rectangle in the parent control.

Declaration

public DoubleSpan Clip { get; set; }

Property Value

Type	Description
DoubleSpan	The clip.

DefaultLineSize

Gets or sets the default size of lines.

Declaration

public abstract double DefaultLineSize { get; set; }

Property Value

Type	Description
System.Double	The default size of lines.

Distances

Gets the distances collection which is used internally for mapping from a point position to a line index and vice versa.

Declaration

public IDistanceCounterCollection Distances { get; }

Property Value

Type	Description
IDistanceCounterCollection	The distances collection.

FirstFooterLineIndex

Gets the index of the first footer line.

Declaration

public int FirstFooterLineIndex { get; }

Property Value

Type	Description
System.Int32	The index of the first footer line.

FooterExtent

Gets the footer extent. This is total height (or width) of the footer lines.

Declaration

public abstract double FooterExtent { get; }

Property Value

Type	Description
System.Double	The footer extent.

FooterLineCount

Gets the footer line count.

Declaration

public virtual int FooterLineCount { get; }

Property Value

Type	Description
System.Int32	The footer line count.

HeaderExtent

Gets the header extent. This is total height (or width) of the header lines.

Declaration

public abstract double HeaderExtent { get; }

Property Value

Type	Description
System.Double	The header extent.

HeaderLineCount

Gets the header line count.

Declaration

public virtual int HeaderLineCount { get; }

Property Value

Type	Description
System.Int32	The header line count.

IsFooterVisible

Gets a value indicating whether footer lines are visible.

Declaration

public bool IsFooterVisible { get; }

Property Value

Type	Description
System.Boolean	true if footer lines are visible; otherwise, false.

IsPixelScroll

Gets a value indicating whether this axis supports pixel scrolling.

Declaration

public abstract bool IsPixelScroll { get; }

Property Value

Type	Description
System.Boolean	true if this instance supports pixel scrolling; otherwise, false.

LastBodyVisibleLine

Gets the last visible line.

Declaration

public VisibleLineInfo LastBodyVisibleLine { get; }

Property Value

Type	Description
VisibleLineInfo	The last visible line.

LastBodyVisibleLineIndex

Gets the index of the last visible line.

Declaration

public int LastBodyVisibleLineIndex { get; }

Property Value

Type	Description
System.Int32	The index of the last visible line.

LineCount

Gets or sets the line count.

Declaration

public abstract int LineCount { get; set; }

Property Value

Type	Description
System.Int32	The line count.

Name

Declaration

public string Name { get; set; }

Property Value

Type
System.String

RenderSize

Gets or sets the size (either height or width) of the parent control.

Declaration

public double RenderSize { get; set; }

Property Value

Type	Description
System.Double	The size of the the parent control.

ScrollBar

Gets the scroll bar state.

Declaration

public IScrollBar ScrollBar { get; }

Property Value

Type	Description
IScrollBar	The scroll bar state.

ScrollLineIndex

Gets or sets the index of the first visible Line in the Body region.

Declaration

public abstract int ScrollLineIndex { get; set; }

Property Value

Type	Description
System.Int32	The index of the scroll line.

ScrollLinesHost

Gets the scroll lines host.

Declaration

public ILineSizeHost ScrollLinesHost { get; }

Property Value

Type	Description
ILineSizeHost	The scroll lines host.

ScrollPageSize

Gets the size (either height or width) of the parent control excluding the area occupied by Header and Footer. This size is used for scrolling down or up one page.

Declaration

public double ScrollPageSize { get; }

Property Value

Type	Description
System.Double	The size of the the parent control.

StartLineIndex

Gets or sets the index of the first line in a parent axis. This is used for shared or nested scroll axis (e.g. a nested grid with shared axis in a covered cell).

Declaration

public virtual int StartLineIndex { get; set; }

Property Value

Type	Description
System.Int32	The index of the first line..

ViewCorner

Gets the view corner which is the point after the last visible line of the body region.

Declaration

public double ViewCorner { get; }

Property Value

Type	Description
System.Double	The view corner.

ViewSize

Gets the view size of the (either height or width) of the parent control. Normally the ViewSize is the same as RenderSize. Only if the parent control has more space then needed to display all lines, the ViewSize will be less. In such case the ViewSize is the total height for all lines.

Declaration

public abstract double ViewSize { get; }

Property Value

Type	Description
System.Double	The size of the view.

Methods

add_Changed(ScrollChangedEventHandler)

Declaration

public void add_Changed(ScrollChangedEventHandler value)

Parameters

Type	Name	Description
ScrollChangedEventHandler	value

AlignScrollLine()

Aligns the scroll line.

Declaration

public abstract void AlignScrollLine()

AnyVisibleLines(Int32, Int32)

Determines if any of the lines with the given absolut line index are visible.

Declaration

public bool AnyVisibleLines(int lineIndex1, int lineIndex2)

Parameters

Type	Name	Description
System.Int32	lineIndex1
System.Int32	lineIndex2

Returns

Type
System.Boolean

Dispose()

Call the Dispose and SuppressFinalize method for dipose the instance of ScrollAxisBase class.

Declaration

public void Dispose()

Dispose(Boolean)

Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

Declaration

protected virtual void Dispose(bool disposing)

Parameters

Type	Name	Description
System.Boolean	disposing	Dispose the instance, if it is True

FreezeVisibleLines()

Declaration

public void FreezeVisibleLines()

GetBorderRangeClipPoints(VisibleLineInfo, VisibleLineInfo)

Returns the clipping area for the specified visible lines. Only if IsClippedOrigin is true for first line or if IsClippedCorner is true for last line then the area will be clipped. Otherwise the whole area from 0 to RenderSize is returned.

Declaration

public DoubleSpan GetBorderRangeClipPoints(VisibleLineInfo firstLine, VisibleLineInfo lastLine)

Parameters

Type	Name	Description
VisibleLineInfo	firstLine	The first line.
VisibleLineInfo	lastLine	The last line.

Returns

Type
DoubleSpan

GetClipPoints(ScrollAxisRegion, Boolean)

Gets the clip points for a region.

Declaration

public DoubleSpan GetClipPoints(ScrollAxisRegion region, bool isRightToLeft = false)

Parameters

Type	Name	Description
ScrollAxisRegion	region	The region.
System.Boolean	isRightToLeft	The boolean value used to calculate visible columns in right to left mode.

Returns

Type
DoubleSpan

GetLineNearCorner(Double, Double)

Gets the line near the given corner point. Use this method for hit-testing row or column lines for resizing cells.

Declaration

public VisibleLineInfo GetLineNearCorner(double point, double hitTestPrecision)

Parameters

Type	Name	Description
System.Double	point	The point.
System.Double	hitTestPrecision	The hit test precision in points.

Returns

Type
VisibleLineInfo

GetLineNearCorner(Double, Double, CornerSide)

Gets the line near the given corner point. Use this method for hit-testing row or column lines for resizing cells.

Declaration

public VisibleLineInfo GetLineNearCorner(double point, double hitTestPrecision, CornerSide side)

Parameters

Type	Name	Description
System.Double	point	The point.
System.Double	hitTestPrecision	The hit test precision in points.
CornerSide	side	The hit test corner.

Returns

Type
VisibleLineInfo

GetLinesAndVisibility(Int32, Int32, Boolean, out Boolean, out Boolean, out VisibleLineInfo, out VisibleLineInfo)

Returns points for given absolut line indexes

Declaration

public void GetLinesAndVisibility(int firstIndex, int lastIndex, bool allowAdjust, out bool firstVisible, out bool lastVisible, out VisibleLineInfo firstLine, out VisibleLineInfo lastLine)

Parameters

Type	Name	Description
System.Int32	firstIndex	The first index.
System.Int32	lastIndex	The last index.
System.Boolean	allowAdjust	if set to true return the first visible line if firstIndex is above viewable area or return last visible line if lastIndex is after viewable area (works also for header and footer).
System.Boolean	firstVisible	if set to true indicates the line with index firstIndex is visible in viewable area.
System.Boolean	lastVisible	if set to true indicates the line with index lastIndex is visible in viewable area..
VisibleLineInfo	firstLine	The first line or null if allowAdjust is false and line is not in viewable area.
VisibleLineInfo	lastLine	The last line or null if allowAdjust is false and line is not in viewable area.

GetLineSize(Int32)

Gets the size of the line.

Declaration

public double GetLineSize(int index)

Parameters

Type	Name	Description
System.Int32	index	The index.

Returns

Type
System.Double

GetLineSize(Int32, out Int32)

Gets size from ScrollLinesHost or if the line is being resized then get temporary value previously set with SetLineResize(Int32, Double)

Declaration

public virtual double GetLineSize(int index, out int repeatSizeCount)

Parameters

Type	Name	Description
System.Int32	index	The index.
System.Int32	repeatSizeCount	The number of subsequent values with same size.

Returns

Type
System.Double

GetNextPage(Int32)

Determines the line one page down from the given line.

Declaration

public int GetNextPage(int lineIndex)

Parameters

Type	Name	Description
System.Int32	lineIndex	The current line.

Returns

Type	Description
System.Int32	The line index of the line one page down

GetNextScrollLineIndex(Int32)

Gets the index of the next scroll line.

Declaration

public abstract int GetNextScrollLineIndex(int lineIndex)

Parameters

Type	Name	Description
System.Int32	lineIndex	Index of the line.

Returns

Type
System.Int32

GetOriginAndCornerOfBodyRegion(out Double, out Double)

Gets the origin and corner points of body region.

Declaration

public void GetOriginAndCornerOfBodyRegion(out double origin, out double corner)

Parameters

Type	Name	Description
System.Double	origin	The origin.
System.Double	corner	The corner.

GetPreviousPage(Int32)

Determines the line one page up from the given line.

Declaration

public int GetPreviousPage(int lineIndex)

Parameters

Type	Name	Description
System.Int32	lineIndex	The current line.

Returns

Type	Description
System.Int32	The line index of the line one page up

GetPreviousScrollLineIndex(Int32)

Gets the index of the previous scroll line.

Declaration

public abstract int GetPreviousScrollLineIndex(int lineIndex)

Parameters

Type	Name	Description
System.Int32	lineIndex	Index of the line.

Returns

Type
System.Int32

GetScrollLineIndex(out Int32, out Double, Boolean)

Gets the index of the scroll line.

Declaration

public abstract void GetScrollLineIndex(out int scrollLindeIndex, out double scrollLineOffset, bool isRightToLeft = false)

Parameters

Type	Name	Description
System.Int32	scrollLindeIndex	Index of the scroll linde.
System.Double	scrollLineOffset	The scroll line offset.
System.Boolean	isRightToLeft	The boolean value used to calculate visible columns in right to left mode.

GetScrollLinesHostSize(Int32, out Int32)

Gets size from ScrollLinesHost or if the line is being resized then get temporary value previously set with SetLineResize(Int32, Double). If size is negative then DefaultLineSize is returned.

Declaration

public double GetScrollLinesHostSize(int index, out int repeatSizeCount)

Parameters

Type	Name	Description
System.Int32	index	The index.
System.Int32	repeatSizeCount	The number of subsequent values with same size.

Returns

Type
System.Double

GetVisibleLineAtLineIndex(Int32)

Gets the visibles line that displays the line with the given absolut line index.

Declaration

public VisibleLineInfo GetVisibleLineAtLineIndex(int lineIndex)

Parameters

Type	Name	Description
System.Int32	lineIndex	Index of the line.

Returns

Type
VisibleLineInfo

GetVisibleLineAtLineIndex(Int32, Boolean)

Gets the visibles line that displays the line with the given absolut line index. If the line is outside the view and you specify allowCreateEmptyLineIfNotVisible then the method will create an empty line and initializes its LineIndex and LineSize.

Declaration

public VisibleLineInfo GetVisibleLineAtLineIndex(int lineIndex, bool allowCreateEmptyLineIfNotVisible)

Parameters

Type	Name	Description
System.Int32	lineIndex	Index of the line.
System.Boolean	allowCreateEmptyLineIfNotVisible	if set to true and if the line is outside the view then the method will create an empty line and initializes its LineIndex and LineSize.

Returns

Type
VisibleLineInfo

GetVisibleLineAtPoint(Double, Boolean, Boolean)

Gets the visible line for a point in the display.

Declaration

public VisibleLineInfo GetVisibleLineAtPoint(double point, bool allowOutSideLines = false, bool isRightToLeft = false)

Parameters

Type	Name	Description
System.Double	point	The point in the display for which the visible line is to be obtained.
System.Boolean	allowOutSideLines	boolean value
System.Boolean	isRightToLeft	The boolean value used to calculate visible columns in right to left mode.

Returns

Type	Description
VisibleLineInfo	The visible line for a point in the display.

GetVisibleLines()

Gets the visible lines collection

Declaration

public VisibleLinesCollection GetVisibleLines()

Returns

Type
VisibleLinesCollection

GetVisibleLines(Boolean)

Gets the visible lines collection

Declaration

public VisibleLinesCollection GetVisibleLines(bool isRightToLeft)

Parameters

Type	Name	Description
System.Boolean	isRightToLeft	The boolean value indicates the right to left mode.

Returns

Type	Description
VisibleLinesCollection	Returns the visible lines collection.

GetVisibleLinesClipPoints(Int32, Int32)

Gets the visible lines clip points (clipped origin of first line and clipped corner of last line). If both lines are above or below viewable area an empty span is returned. If lines are both above and below viewable are then the range for all viewable lines is returned.

Declaration

public DoubleSpan GetVisibleLinesClipPoints(int firstIndex, int lastIndex)

Parameters

Type	Name	Description
System.Int32	firstIndex	The first index.
System.Int32	lastIndex	The last index.

Returns

Type
DoubleSpan

GetVisibleLinesRange(Int32)

Returns the first and last VisibleLine.LineIndex for area identified by section.

Declaration

public Int32Span GetVisibleLinesRange(int section)

Parameters

Type	Name	Description
System.Int32	section	0 - Header, 1 - Body, 2 - Footer

Returns

Type
Int32Span

GetVisibleSection(ScrollAxisRegion, out Int32, out Int32)

Return indexes for VisibleLinesCollection for area identified by section.

Declaration

public void GetVisibleSection(ScrollAxisRegion section, out int start, out int end)

Parameters

Type	Name	Description
ScrollAxisRegion	section	0 - Header, 1 - Body, 2 - Footer
System.Int32	start	The start.
System.Int32	end	The end.

GetVisibleSection(Int32, out Int32, out Int32)

Return indexes for VisibleLinesCollection for area identified by section.

Declaration

public void GetVisibleSection(int section, out int start, out int end)

Parameters

Type	Name	Description
System.Int32	section	0 - Header, 1 - Body, 2 - Footer
System.Int32	start	The start.
System.Int32	end	The end.

IsLineVisible(Int32)

Determines if the line with the given absolut line index is visible.

Declaration

public bool IsLineVisible(int lineIndex)

Parameters

Type	Name	Description
System.Int32	lineIndex	Index of the line.

Returns

Type
System.Boolean

MarkDirty()

Force recalculation of visible lines and scrollbar properties next time GetVisibleLines is called.

Declaration

public void MarkDirty()

MouseWheel(Int32)

This method is called in response to a MouseWheel event.

Declaration

public abstract void MouseWheel(int delta)

Parameters

Type	Name	Description
System.Int32	delta	The delta.

OnLinesInserted(Int32, Int32)

Called when lines were inserted in ScrollLinesHost.

Declaration

protected virtual void OnLinesInserted(int insertAt, int count)

Parameters

Type	Name	Description
System.Int32	insertAt	Index of the first inserted line.
System.Int32	count	The count.

OnLinesRemoved(Int32, Int32)

Called when lines were removed in ScrollLinesHost.

Declaration

protected virtual void OnLinesRemoved(int removeAt, int count)

Parameters

Type	Name	Description
System.Int32	removeAt	Index of the first removed line.
System.Int32	count	The count.

RaiseChanged(ScrollChangedAction)

Raises the changed event.

Declaration

public void RaiseChanged(ScrollChangedAction action)

Parameters

Type	Name	Description
ScrollChangedAction	action

RangeToPoints(ScrollAxisRegion, Int32, Int32, Boolean)

Returns the first and last point for the given lines in a region.

Declaration

public abstract DoubleSpan RangeToPoints(ScrollAxisRegion region, int first, int last, bool allowEstimatesForOutOfViewLines)

Parameters

Type	Name	Description
ScrollAxisRegion	region	The region.
System.Int32	first	The index of the first line.
System.Int32	last	The index of the last line.
System.Boolean	allowEstimatesForOutOfViewLines	if set to true allow estimates for out of view lines.

Returns

Type
DoubleSpan

RangeToRegionPoints(Int32, Int32, Boolean)

Returns an array with 3 ranges indicating the first and last point for the given lines in each region.

Declaration

public abstract DoubleSpan[] RangeToRegionPoints(int first, int last, bool allowEstimatesForOutOfViewLines)

Parameters

Type	Name	Description
System.Int32	first	The index of the first line.
System.Int32	last	The index of the last line.
System.Boolean	allowEstimatesForOutOfViewLines	if set to true allow estimates for out of view lines.

Returns

Type
DoubleSpan[]

remove_Changed(ScrollChangedEventHandler)

Declaration

public void remove_Changed(ScrollChangedEventHandler value)

Parameters

Type	Name	Description
ScrollChangedEventHandler	value

ResetLineResize()

Resets temporary value for line size after a resize operation

Declaration

public virtual void ResetLineResize()

ResetVisibleLines()

Resets the visible lines collection.

Declaration

public void ResetVisibleLines()

ScrollInView(Int32)

Scrolls the line into viewable area.

Declaration

public void ScrollInView(int lineIndex)

Parameters

Type	Name	Description
System.Int32	lineIndex	Index of the line.

ScrollInView(Int32, Double)

Scrolls the line into viewable area.

Declaration

public virtual void ScrollInView(int lineIndex, double lineSize)

Parameters

Type	Name	Description
System.Int32	lineIndex	Index of the line.
System.Double	lineSize	Size of the line.

ScrollToNextLine()

Scrolls to next line.

Declaration

public abstract void ScrollToNextLine()

ScrollToNextPage()

Scrolls to next page.

Declaration

public abstract void ScrollToNextPage()

ScrollToPreviousLine()

Scrolls to previous line.

Declaration

public abstract void ScrollToPreviousLine()

ScrollToPreviousPage()

Scrolls to previous page.

Declaration

public abstract void ScrollToPreviousPage()

SetFooterLineCount(Int32)

Sets the footer line count.

Declaration

protected abstract void SetFooterLineCount(int value)

Parameters

Type	Name	Description
System.Int32	value	The value.

SetHeaderLineCount(Int32)

Sets the header line count.

Declaration

protected abstract void SetHeaderLineCount(int value)

Parameters

Type	Name	Description
System.Int32	value	The value.

SetLineHiddenState(Int32, Int32, Boolean)

Sets the hidden state of the lines.

Declaration

public abstract void SetLineHiddenState(int from, int to, bool hide)

Parameters

Type	Name	Description
System.Int32	from	From.
System.Int32	to	To.
System.Boolean	hide	if set to true [hide].

SetLineResize(Int32, Double)

Set temporary value for a line size during a resize operation without commiting value to SrollLinesHost.

Declaration

public virtual void SetLineResize(int index, double size)

Parameters

Type	Name	Description
System.Int32	index	The index.
System.Double	size	The size.

SetLineSize(Int32, Int32, Double)

Sets the size of the lines.

Declaration

public abstract void SetLineSize(int from, int to, double size)

Parameters

Type	Name	Description
System.Int32	from	From.
System.Int32	to	To.
System.Double	size	The size.

SetScrollLineIndex(Int32, Double)

Sets the index of the scroll line.

Declaration

public abstract void SetScrollLineIndex(int scrollLindeIndex, double scrollLineOffset)

Parameters

Type	Name	Description
System.Int32	scrollLindeIndex	Index of the scroll linde.
System.Double	scrollLineOffset	The scroll line offset.

UnfreezeVisibleLines()

Declaration

public void UnfreezeVisibleLines()

UpdateScrollBar()

Updates the scroll bar.

Declaration

public abstract void UpdateScrollBar()

UpdateScrollBar(Boolean)

Declaration

public void UpdateScrollBar(bool ignorePropertyChange)

Parameters

Type	Name	Description
System.Boolean	ignorePropertyChange

VisiblePointToLineIndex(Double)

Gets the visible line index for a point in the display.

Declaration

public int VisiblePointToLineIndex(double point)

Parameters

Type	Name	Description
System.Double	point	The point.

Returns

Type
System.Int32

VisiblePointToLineIndex(Double, Boolean)

Gets the visible line index for a point in the display.

Declaration

public int VisiblePointToLineIndex(double point, bool allowOutsideLines)

Parameters

Type	Name	Description
System.Double	point	The point.
System.Boolean	allowOutsideLines	Set this true if point can be below corner of last line.

Returns

Type
System.Int32

Events

Changed

Occurs when a property was changed.

Declaration

public event ScrollChangedEventHandler Changed

Event Type

Type
ScrollChangedEventHandler

Implements

System.IDisposable