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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Drawing;
namespace System.Windows.Forms.Layout;
internal partial class TableLayout : LayoutEngine
{
// This code was taken from ndp\clr\src\BCL\System\Array.cs
// This changeset replaced the sorting algorithm when elements with the same
// value are sorted. While Array.Sort() was documented as not a being stable sort,
// we need to preserve the order of same elements as it used to be with the old algorithm since
// some customers are putting more than one control in the same TableLayout cell
// and we rely on this order to resolve the conflict
private static int GetMedian(int low, int hi)
{
// Note both may be negative, if we are dealing with arrays w/ negative lower bounds.
return low + ((hi - low) >> 1);
}
private static void Sort(LayoutInfo[] array, IComparer<LayoutInfo> comparer)
{
ArgumentNullException.ThrowIfNull(array);
if (array.Length > 1)
{
SorterObjectArray sorter = new(array, comparer);
sorter.QuickSort(0, array.Length - 1);
}
}
// End of sorting code
// Singleton instance shared by all containers.
internal static TableLayout Instance { get; } = new();
private static readonly int s_containerInfoProperty = PropertyStore.CreateKey();
private static readonly int s_layoutInfoProperty = PropertyStore.CreateKey();
private static readonly string?[] s_propertiesWhichInvalidateCache =
[
// suspend layout before changing one of the above property will cause the AffectedProperty of LayoutEventArgs to be set to null
null,
PropertyNames.ChildIndex, // Changing Z-order changes the row/column assignments
PropertyNames.Parent, // So does adding/removing controls
PropertyNames.Visible, // as well as visibility
PropertyNames.Items, // Changing toolstrip items collection
PropertyNames.Rows,
PropertyNames.Columns,
PropertyNames.RowStyles,
PropertyNames.ColumnStyles,
// RowSpan, ColumnSpan, TableIndex manually call ClearCachedAssignments.
];
internal static TableLayoutSettings CreateSettings(IArrangedElement owner)
{
return new TableLayoutSettings(owner);
}
internal override void ProcessSuspendedLayoutEventArgs(IArrangedElement container, LayoutEventArgs args)
{
ContainerInfo containerInfo = GetContainerInfo(container);
foreach (string? propertyName in s_propertiesWhichInvalidateCache)
{
if (ReferenceEquals(args.AffectedProperty, propertyName))
{
ClearCachedAssignments(containerInfo);
break;
}
}
}
/// <summary>
/// LayoutCore: EntryPoint from LayoutEngine.
/// Container: IArrangedElement to layout (could be table layout panel but doesn't have to be - eg. ToolStrip)
/// LayoutEventArgs: args created from PerformLayout.
///
/// Summary of algorithm:
/// (1). Determine the row and column assignments of all the children of the container. (This can be cached)
/// (2). Apply column styles, then row styles for all the rows:
/// (a). Create a list of column or row sizes (Strip[]) - initialize absolute columns/rows sizes.
/// (b). Determine the minimum size of all the controls
/// (c). Determine the maximum size of all the controls
/// (d). Distribute the minimum size of the control to the corresponding Strip for column or row
/// (e). Distribute the remaining size to the column or row as according to the Row/Column style.
/// (3). Expand the last row/column to fit the table
/// (4). Set the bounds of the child elements as according to the row/column heights specified in Strip[]
/// (a) Calculate bounds of item
/// (b) Align and stretch item to fill column/row as according to Dock and Anchor properties.
/// </summary>
private protected override bool LayoutCore(IArrangedElement container, LayoutEventArgs args)
{
ProcessSuspendedLayoutEventArgs(container, args);
ContainerInfo containerInfo = GetContainerInfo(container);
EnsureRowAndColumnAssignments(container, containerInfo, doNotCache: false);
int cellBorderWidth = containerInfo.CellBorderWidth;
// shrink the size of the display rectangle so that we have space to draw the border
Size containerSize = container.DisplayRectangle.Size - new Size(cellBorderWidth, cellBorderWidth);
// make sure our sizes are non-negative
containerSize.Width = Math.Max(containerSize.Width, 1);
containerSize.Height = Math.Max(containerSize.Height, 1);
Size usedSpace = ApplyStyles(containerInfo, containerSize, measureOnly: false);
ExpandLastElement(containerInfo, usedSpace, containerSize);
RectangleF displayRect = (RectangleF)container.DisplayRectangle;
displayRect.Inflate(-(cellBorderWidth / 2.0f), -(cellBorderWidth) / 2.0f);
SetElementBounds(containerInfo, displayRect);
// ScrollableControl will first try to get the layoutbounds from the derived control when
// trying to figure out if ScrollBars should be added.
CommonProperties.SetLayoutBounds(containerInfo.Container, new Size(SumStrips(containerInfo.Columns, 0, containerInfo.Columns.Length),
SumStrips(containerInfo.Rows, 0, containerInfo.Rows.Length)));
return CommonProperties.GetAutoSize(container);
}
/// <summary>
/// GetPreferredSize: Called on the container to determine the size that best fits its contents.
/// Container: IArrangedElement to determine preferredSize (could be table layout panel but doesn't have to be - eg. ToolStrip)
/// ProposedConstraints: the suggested size that the table layout should fit into. If either argument is 0,
/// TableLayout pretends it's unconstrained for performance reasons.
///
/// Summary of Algorithm:
/// Similar to LayoutCore. Row/Column assignments are NOT cached. TableLayout uses AGGRESSIVE
/// caching for performance reasons.
/// </summary>
internal override Size GetPreferredSize(IArrangedElement container, Size proposedConstraints)
{
ContainerInfo containerInfo = GetContainerInfo(container);
// PERF: Optimizing nested table layouts.
// The problem: TableLayout asks for GPS(0,0) GPS(1,0) GPS(0,1) and GPS(w,0) and GPS(w,h).
// if the table layout is nested, this becomes pretty nasty, as we don't cache row, column
// assignments in preferred size.
// GPS(0,1) GPS(1,0) should return same as GPS(0,0)- if that's already cached return it.
float oldWidth = -1f;
Size prefSize = containerInfo.GetCachedPreferredSize(proposedConstraints, out bool isCacheValid);
if (isCacheValid)
{
return prefSize;
}
// create a dummy containerInfo and we operate on the dummy containerInfo only
// the reason to do so is that when we call ApplyStyles, we change the information
// in the containerInfo. Specifically it will change the strip size so that the
// size information may no longer be accurate.
ContainerInfo tempInfo = new(containerInfo);
int cellBorderWidth = containerInfo.CellBorderWidth;
// pretend the last column is the size of the container if it is absolutely sized
if (containerInfo.MaxColumns == 1 && containerInfo.ColumnStyles.Count > 0 && containerInfo.ColumnStyles[0].SizeType == SizeType.Absolute)
{
// shrink the size of the display rectangle so that we have space to draw the border
Size containerSize = container.DisplayRectangle.Size - new Size(cellBorderWidth * 2, cellBorderWidth * 2);
// make sure our sizes are non-negative
containerSize.Width = Math.Max(containerSize.Width, 1);
containerSize.Height = Math.Max(containerSize.Height, 1);
oldWidth = containerInfo.ColumnStyles[0].Size;
containerInfo.ColumnStyles[0].SetSize(Math.Max(oldWidth, Math.Min(proposedConstraints.Width, containerSize.Width)));
}
// notice we always assign rows and columns here since the user may change the properties of the table while the layout is
// suspended, so we have no way to know whether the cache is invalid or not here.
EnsureRowAndColumnAssignments(container, tempInfo, doNotCache: true);
// deduct the padding for cell border before doing layout
Size cellBorderSize = new(cellBorderWidth, cellBorderWidth);
proposedConstraints -= cellBorderSize;
proposedConstraints.Width = Math.Max(proposedConstraints.Width, 1);
proposedConstraints.Height = Math.Max(proposedConstraints.Height, 1);
if (tempInfo.Columns is not null && containerInfo.Columns is not null && (tempInfo.Columns.Length != containerInfo.Columns.Length))
{
ClearCachedAssignments(containerInfo);
}
if (tempInfo.Rows is not null && containerInfo.Rows is not null && (tempInfo.Rows.Length != containerInfo.Rows.Length))
{
ClearCachedAssignments(containerInfo);
}
prefSize = ApplyStyles(tempInfo, proposedConstraints, measureOnly: true);
// prefSize = MeasureStyles(tempInfo);
// restores the old strip size
if (oldWidth >= 0)
{
containerInfo.ColumnStyles[0].SetSize(oldWidth);
}
// add back the padding for the cell border
return (prefSize + cellBorderSize);
}
/// <summary>
/// EnsureRowAndColumnAssignments: Sets up Row/Column assignments for all the children of the container
/// - Does nothing if Cache is valid
/// - sets RowStart,RowSpan,ColumnStart,ColumnSpan into the LayoutInfo[] collection (containerInfo.ChildrenInfo)
/// </summary>
private static void EnsureRowAndColumnAssignments(IArrangedElement container, ContainerInfo containerInfo, bool doNotCache)
{
// Assign new rows and columns if the cache is invalid or if we are in GetPreferredSize
if (!HasCachedAssignments(containerInfo) || doNotCache)
{
AssignRowsAndColumns(containerInfo);
}
Debug_VerifyAssignmentsAreCurrent(container, containerInfo);
}
/// <summary>
/// ExpandLastElement: expands the row/column to fill the rest of the space in the container.
/// </summary>
private static void ExpandLastElement(ContainerInfo containerInfo, Size usedSpace, Size totalSpace)
{
Strip[] rows = containerInfo.Rows;
Strip[] cols = containerInfo.Columns;
if (cols.Length != 0 && totalSpace.Width > usedSpace.Width)
{
cols[^1].MinSize += totalSpace.Width - usedSpace.Width;
}
if (rows.Length != 0 && totalSpace.Height > usedSpace.Height)
{
rows[^1].MinSize += totalSpace.Height - usedSpace.Height;
}
}
/// <summary>
/// AssignRowsAndColumns: part of EnsureRowAndColumnAssignments.
/// determines the number of rows and columns we need to create
/// </summary>
private static void AssignRowsAndColumns(ContainerInfo containerInfo)
{
int numCols = containerInfo.MaxColumns;
int numRows = containerInfo.MaxRows;
// forces iteration over child collection - this is cached and
// sets containerInfo MinRowsAndColumns and MinColumns/MinRows
LayoutInfo[] childrenInfo = containerInfo.ChildrenInfo;
int minSpace = containerInfo.MinRowsAndColumns;
int minColumn = containerInfo.MinColumns;
int minRow = containerInfo.MinRows;
TableLayoutPanelGrowStyle growStyle = containerInfo.GrowStyle;
if (growStyle == TableLayoutPanelGrowStyle.FixedSize)
{
// if we're a fixed size - check to see if we have enough room
if (containerInfo.MinRowsAndColumns > numCols * numRows)
{
throw new ArgumentException(SR.TableLayoutPanelFullDesc);
}
if ((minColumn > numCols) || (minRow > numRows))
{
throw new ArgumentException(SR.TableLayoutPanelSpanDesc);
}
numRows = Math.Max(1, numRows);
numCols = Math.Max(1, numCols);
// numRows = numRows - numRows indicates that columns are specified and rows should grow
}
else if (growStyle == TableLayoutPanelGrowStyle.AddRows)
{
numRows = 0; // indicates that columns are specified and rows should grow
}
else
{// must be addcolumns
numCols = 0; // indicates that rows are specified and columns should grow
}
if (numCols > 0)
{
// The user specified the number of column (the simple/fast case)
xAssignRowsAndColumns(containerInfo, childrenInfo, numCols, numRows == 0 ? int.MaxValue : numRows, growStyle);
}
else if (numRows > 0)
{
// The user specified rows only (we need to compute the number of columns)
int estimatedCols = Math.Max((int)Math.Ceiling((float)minSpace / numRows), minColumn);
// make sure that estimatedCols is positive
estimatedCols = Math.Max(estimatedCols, 1);
while (!xAssignRowsAndColumns(containerInfo, childrenInfo, estimatedCols, numRows, growStyle))
{
// I am assuming that the division will put us pretty close to the right
// number of columns. If this assumption is wrong, a binary search
// between the number we get by dividing and `childrenInfo.Count`
// could be more efficient. It would certainly degenerate better.
estimatedCols++;
}
}
else
{
// No rows or columns specified, just do a vertical stack.
xAssignRowsAndColumns(containerInfo, childrenInfo, maxColumns: Math.Max(minColumn, 1), maxRows: int.MaxValue, growStyle);
}
}
/// <summary>
/// xAssignRowsAndColumns: part of AssignRowsAndColumns.
/// def: fixed element: has a specific row/column assignment (assigned by SetRow,SetColumn, or Add(c,row,column)
/// def: flow element: does NOT have a specific row/column assignment.
///
/// Determines the placement of fixed and flow elements. Walks through the rows/columns - if there's a
/// spot for the fixed element, place it, else place the next flow element.
/// </summary>
private static bool xAssignRowsAndColumns(ContainerInfo containerInfo, LayoutInfo[] childrenInfo, int maxColumns, int maxRows, TableLayoutPanelGrowStyle growStyle)
{
Debug.Assert(maxColumns > 0, "maxColumn must be positive");
int numColumns = 0;
int numRows = 0;
ReservationGrid reservationGrid = new();
int currentRow = 0;
int currentCol = 0;
int fixedElementIndex = -1;
int flowElementIndex = -1;
// make sure to snap these two collections as we're not in a "containerInfo.Valid" state
// so we'll wind up building up the lists over and over again.
LayoutInfo[] fixedChildrenInfo = containerInfo.FixedChildrenInfo;
// the element at the head of the absolutely positioned element queue
LayoutInfo? fixedElement = GetNextLayoutInfo(fixedChildrenInfo, ref fixedElementIndex, absolutelyPositioned: true);
// the element at the head of the non-absolutely positioned element queue
LayoutInfo? flowElement = GetNextLayoutInfo(childrenInfo, ref flowElementIndex, absolutelyPositioned: false);
while (fixedElement is not null || flowElement is not null)
{
int colStop = currentCol;
int rowStop;
if (flowElement is not null)
{
flowElement.RowStart = currentRow;
flowElement.ColumnStart = currentCol;
// try to layout the flowElement to see if it overlaps with the fixedElement
AdvanceUntilFits(maxColumns, reservationGrid, flowElement, out colStop);
// we have exceeded the row limit. just return
if (flowElement.RowStart >= maxRows)
{
return false;
}
}
// test to see if either the absolutely positioned element is null or it fits.
if (flowElement is not null && (fixedElement is null || (!IsCursorPastInsertionPoint(fixedElement, flowElement.RowStart, colStop) && !IsOverlappingWithReservationGrid(fixedElement, reservationGrid, currentRow))))
{
// Place the flow element.
// advance the rows in reservation grid
for (int j = 0; j < flowElement.RowStart - currentRow; j++)
{
reservationGrid.AdvanceRow();
}
currentRow = flowElement.RowStart;
rowStop = Math.Min(currentRow + flowElement.RowSpan, maxRows);
// reserve spaces in the reservationGrid
reservationGrid.ReserveAll(flowElement, rowStop, colStop);
flowElement = GetNextLayoutInfo(childrenInfo, ref flowElementIndex, absolutelyPositioned: false);
}
else
{
//
// otherwise we place the fixed element.
//
if (currentCol >= maxColumns)
{
// We have already passed the boundary. Go to next row.
currentCol = 0;
currentRow++;
reservationGrid.AdvanceRow();
}
// Set the rowStart and columnStart to fixedElement's specified position.
fixedElement!.RowStart = Math.Min(fixedElement.RowPosition, maxRows - 1);
fixedElement.ColumnStart = Math.Min(fixedElement.ColumnPosition, maxColumns - 1);
if (currentRow > fixedElement.RowStart)
{
// We have already passed the specified position. set the start column to the current column.
fixedElement.ColumnStart = currentCol;
}
else if (currentRow == fixedElement.RowStart)
{
// Set the start column to be the max of the specified column and current column.
fixedElement.ColumnStart = Math.Max(fixedElement.ColumnStart, currentCol);
}
else
{
// Set the start column to the specified column, which we have already done.
}
fixedElement.RowStart = Math.Max(fixedElement.RowStart, currentRow);
// advance the reservation grid
int j;
for (j = 0; j < fixedElement.RowStart - currentRow; j++)
{
reservationGrid.AdvanceRow();
}
// try to layout the absolutely positioned element as if it were non-absolutely positioned.
// In this way we can tell whether this element overlaps with others or fits on the table.
AdvanceUntilFits(maxColumns, reservationGrid, fixedElement, out _);
// we have exceeded the row limit. just return
if (fixedElement.RowStart >= maxRows)
{
return false;
}
for (; j < fixedElement.RowStart - currentRow; j++)
{
// advance the reservation grid if the fixedElement's row position has changed during layout
reservationGrid.AdvanceRow();
}
currentRow = fixedElement.RowStart;
// make sure that we truncate the element's column span if it is too big
colStop = Math.Min(fixedElement.ColumnStart + fixedElement.ColumnSpan, maxColumns);
rowStop = Math.Min(fixedElement.RowStart + fixedElement.RowSpan, maxRows);
// reserve space in the reservation grid
reservationGrid.ReserveAll(fixedElement, rowStop, colStop);
fixedElement = GetNextLayoutInfo(fixedChildrenInfo, ref fixedElementIndex, absolutelyPositioned: true);
}
currentCol = colStop;
numRows = (numRows == int.MaxValue) ? rowStop : Math.Max(numRows, rowStop);
numColumns = (numColumns == int.MaxValue) ? colStop : Math.Max(numColumns, colStop);
}
Debug.Assert(numRows <= maxRows, "number of rows allocated shouldn't exceed max number of rows");
Debug.Assert(numColumns <= maxColumns, "number of columns allocated shouldn't exceed max number of columns");
// we should respect column count and row count as according to GrowStyle.
if (growStyle == TableLayoutPanelGrowStyle.FixedSize)
{
// now that we've calculated the assignments - use the "max" as the actual number of rows.
numColumns = maxColumns;
numRows = maxRows;
}
else if (growStyle == TableLayoutPanelGrowStyle.AddRows)
{
numColumns = maxColumns;
numRows = Math.Max(containerInfo.MaxRows, numRows);
}
else
{ // add columns
numRows = (maxRows == int.MaxValue) ? numRows : maxRows;
numColumns = Math.Max(containerInfo.MaxColumns, numColumns);
}
// PERF: prevent overallocation of Strip[] arrays. We're going to null these guys out
// anyways... so only allocate when the number of rows and columns is different.
if (containerInfo.Rows is null || containerInfo.Rows.Length != numRows)
{
containerInfo.Rows = new Strip[numRows];
}
if (containerInfo.Columns is null || containerInfo.Columns.Length != numColumns)
{
containerInfo.Columns = new Strip[numColumns];
}
containerInfo.Valid = true;
return true;
}
/// <summary>
/// GetNextLayoutInfo: part of xAssignRowsAndColumns.
/// helper function that walks through the collection picking out the next flow element or fixed element.
/// </summary>
private static LayoutInfo? GetNextLayoutInfo(LayoutInfo[] layoutInfo, ref int index, bool absolutelyPositioned)
{
for (int i = ++index; i < layoutInfo.Length; i++)
{
if (absolutelyPositioned == layoutInfo[i].IsAbsolutelyPositioned)
{
index = i;
return layoutInfo[i];
}
}
index = layoutInfo.Length;
return null;
}
/// <summary>
/// IsCursorPastInsertionPoint: part of xAssignRowsAndColumns.
/// check to see if the user specified location for fixedLayoutInfo has passed the insertion point specified by the cursor
/// </summary>
private static bool IsCursorPastInsertionPoint(LayoutInfo fixedLayoutInfo, int insertionRow, int insertionCol)
{
Debug.Assert(fixedLayoutInfo.IsAbsolutelyPositioned, "should only check for those elements which are absolutely positioned");
// if the element is bumped to a row below its specified row position, it means that the element overlaps with previous controls
if (fixedLayoutInfo.RowPosition < insertionRow)
{
return true;
}
// if the element is bumped to a column after its specified column position, it also means that the element
// overlaps with previous controls
if (fixedLayoutInfo.RowPosition == insertionRow && fixedLayoutInfo.ColumnPosition < insertionCol)
{
return true;
}
return false;
}
/// <summary>
/// IsOverlappingWithReservationGrid: part of xAssignRowsAndColumns.
/// check to see if the absolutely positioned layoutInfo fits in the reservation grid
/// </summary>
private static bool IsOverlappingWithReservationGrid(LayoutInfo fixedLayoutInfo, ReservationGrid reservationGrid, int currentRow)
{
// since we shall not put anything above our current row, this means that the fixedLayoutInfo overlaps
// with something already placed on the table
if (fixedLayoutInfo.RowPosition < currentRow)
{
return true;
}
for (int rowOffset = fixedLayoutInfo.RowPosition - currentRow; rowOffset < fixedLayoutInfo.RowPosition - currentRow + fixedLayoutInfo.RowSpan; rowOffset++)
{
for (int colOffset = fixedLayoutInfo.ColumnPosition; colOffset < fixedLayoutInfo.ColumnPosition + fixedLayoutInfo.ColumnSpan; colOffset++)
{
if (reservationGrid.IsReserved(colOffset, rowOffset))
{
return true;
}
}
}
return false;
}
/// <summary>
/// AdvanceUntilFits: part of xAssignRowsAndColumns.
/// Advances the position of layoutInfo until we have enough space and do not
/// collide with a rowSpanned element. ColStop will be the column on which the
/// element ends (exclusive).
/// </summary>
private static void AdvanceUntilFits(int maxColumns, ReservationGrid reservationGrid, LayoutInfo layoutInfo, out int colStop)
{
int prevRow = layoutInfo.RowStart;
do
{
GetColStartAndStop(maxColumns, layoutInfo, out colStop);
}
while (ScanRowForOverlap(maxColumns, reservationGrid, layoutInfo, colStop, layoutInfo.RowStart - prevRow));
}
/// <summary>
/// GetColStartAndStop: part of xAssignRowsAndColumns.
/// </summary>
private static void GetColStartAndStop(int maxColumns, LayoutInfo layoutInfo, out int colStop)
{
// Compute the column our element ends on
colStop = layoutInfo.ColumnStart + layoutInfo.ColumnSpan;
if (colStop > maxColumns)
{
if (layoutInfo.ColumnStart != 0)
{
// If we are not already at the beginning or a row, move down
// to the next row.
layoutInfo.ColumnStart = 0;
layoutInfo.RowStart++;
}
// Cap colStop in case we have a element too large to fit on any row.
colStop = Math.Min(layoutInfo.ColumnSpan, maxColumns);
}
}
private static bool ScanRowForOverlap(int maxColumns, ReservationGrid reservationGrid, LayoutInfo layoutInfo, int stopCol, int rowOffset)
{
for (int i = layoutInfo.ColumnStart; i < stopCol; i++)
{
if (reservationGrid.IsReserved(i, rowOffset))
{
// If we hit reserved space, advance startCol past it. If we hit the end of the row,
// just stop. AdvanceUntilFits will move to the next row and call us again.
for (layoutInfo.ColumnStart = i + 1;
layoutInfo.ColumnStart < maxColumns && reservationGrid.IsReserved(layoutInfo.ColumnStart, rowOffset);
layoutInfo.ColumnStart++)
{
;
}
return true;
}
}
return false;
}
private static Size ApplyStyles(ContainerInfo containerInfo, Size proposedConstraints, bool measureOnly)
{
Size preferredSize = Size.Empty;
// allocate space for all absolutely sized strips. Set the size of the rest of the strips to 0.
InitializeStrips(containerInfo.Columns, containerInfo.ColumnStyles);
InitializeStrips(containerInfo.Rows, containerInfo.RowStyles);
// perf optimization - detect if we should worry about column spans
containerInfo.ChildHasColumnSpan = false;
containerInfo.ChildHasRowSpan = false;
// detect all rows/columns which have control starting from it
foreach (LayoutInfo layoutInfo in containerInfo.ChildrenInfo)
{
containerInfo.Columns[layoutInfo.ColumnStart].IsStart = true;
containerInfo.Rows[layoutInfo.RowStart].IsStart = true;
if (layoutInfo.ColumnSpan > 1)
{
containerInfo.ChildHasColumnSpan = true;
}
if (layoutInfo.RowSpan > 1)
{
containerInfo.ChildHasRowSpan = true;
}
}
preferredSize.Width = InflateColumns(containerInfo, proposedConstraints, measureOnly);
int expandLastElementWidth = Math.Max(0, proposedConstraints.Width - preferredSize.Width);
preferredSize.Height = InflateRows(containerInfo, proposedConstraints, expandLastElementWidth, measureOnly);
return preferredSize;
}
// allocate space for all absolutely sized strips. Set the size of the rest of the strips to 0.
private static void InitializeStrips(Strip[] strips, TableLayoutStyleCollection styles)
{
Strip strip;
for (int i = 0; i < strips.Length; i++)
{
TableLayoutStyle? style = i < styles.Count ? styles[i] : null;
strip = strips[i];
if (style is not null && style.SizeType == SizeType.Absolute)
{
strip.MinSize = (int)Math.Round((double)styles[i].Size);
strip.MaxSize = strip.MinSize;
}
else
{
strip.MinSize = 0;
strip.MaxSize = 0;
}
strip.IsStart = false;
strips[i] = strip;
}
}
private static int InflateColumns(ContainerInfo containerInfo, Size proposedConstraints, bool measureOnly)
{
bool dontHonorConstraint = measureOnly;
LayoutInfo[] sortedChildren = containerInfo.ChildrenInfo;
if (containerInfo.ChildHasColumnSpan)
{
Sort(sortedChildren, ColumnSpanComparer.GetInstance);
}
// Normally when we are called from GetPreferredSize (measureOnly is true), we want to treat ourselves
// as being unbounded. But in some scenarios, we actually do want to honor the constraints. When
// we are docked or anchored in the right combination, and our parent's layout engine supports
// dock and anchoring, and we are actually constrained in at least one direction,
// then we should honor the constraint.
// The Int16.MaxValue check will tell us whether we are actually constrained or not. This is not ideal.
if (dontHonorConstraint && (proposedConstraints.Width < short.MaxValue))
{
if (containerInfo.Container is TableLayoutPanel tlp && tlp.ParentInternal is not null && tlp.ParentInternal.LayoutEngine == DefaultLayout.Instance)
{
if (tlp.Dock is DockStyle.Top or DockStyle.Bottom or DockStyle.Fill)
{
dontHonorConstraint = false; // we want to honor constraints
}
if ((tlp.Anchor & (AnchorStyles.Left | AnchorStyles.Right)) == (AnchorStyles.Left | AnchorStyles.Right))
{
dontHonorConstraint = false; // we want to honor constraints
}
}
}
foreach (LayoutInfo layoutInfo in sortedChildren)
{
IArrangedElement element = layoutInfo.Element;
int columnSpan = layoutInfo.ColumnSpan;
// since InitializeStrips already allocated absolutely sized columns, we can skip over them
if (columnSpan > 1 || !IsAbsolutelySized(layoutInfo.ColumnStart, containerInfo.ColumnStyles))
{
int minWidth;
int maxWidth;
// optimize for the case where one of the parameters is known.
if ((columnSpan == 1 && layoutInfo.RowSpan == 1) &&
(IsAbsolutelySized(layoutInfo.RowStart, containerInfo.RowStyles)))
{
int constrainingHeight = (int)containerInfo.RowStyles[layoutInfo.RowStart].Size;
minWidth = GetElementSize(element, new Size(0, constrainingHeight)).Width;
maxWidth = minWidth;
}
else
{
minWidth = GetElementSize(element, new Size(1, 0)).Width;
maxWidth = GetElementSize(element, Size.Empty).Width;
}
// tack on margins
Padding margin = CommonProperties.GetMargin(element);
minWidth += margin.Horizontal;
maxWidth += margin.Horizontal;
// distribute the minimum size, then maximum size over the columns
int colStop = Math.Min(layoutInfo.ColumnStart + layoutInfo.ColumnSpan, containerInfo.Columns.Length);
DistributeSize(containerInfo.ColumnStyles, containerInfo.Columns, layoutInfo.ColumnStart, colStop, minWidth, maxWidth, containerInfo.CellBorderWidth);
}
}
int width = DistributeStyles(containerInfo.CellBorderWidth, containerInfo.ColumnStyles, containerInfo.Columns, proposedConstraints.Width, dontHonorConstraint);
// TLP doesn't honor proposedConstraints
if (dontHonorConstraint && width > proposedConstraints.Width && proposedConstraints.Width > 1)
{
// Step 1: iterate through the rows or columns,
// - calculate the amount of space allocated
// - for percent size columns
// - sum up the total "%"s being used
// - eg totalPercent = 22 + 22 + 22 = 66%. each column should take up 1/3 of the remaining space.
Strip[] strips = containerInfo.Columns;
float totalPercent = 0;
int totalPercentAllocatedSpace = 0;
TableLayoutStyleCollection styles = containerInfo.ColumnStyles;
for (int i = 0; i < strips.Length; i++)
{
Strip strip = strips[i];
if (i < styles.Count)
{
TableLayoutStyle style = styles[i];
if (style.SizeType == SizeType.Percent)
{
totalPercent += style.Size;
totalPercentAllocatedSpace += strip.MinSize;
}
}
}
// We will attempt to steal from percentage size columns in order to
// meet the proposed constraints as closely as possible
int currentOverflow = width - proposedConstraints.Width;
int stealAmount = Math.Min(currentOverflow, totalPercentAllocatedSpace);
for (int i = 0; i < strips.Length; i++)
{
if (i < styles.Count)
{
TableLayoutStyle style = styles[i];
if (style.SizeType == SizeType.Percent)
{
float percentageOfTotal = style.Size / (float)totalPercent;
strips[i].MinSize -= (int)(percentageOfTotal * stealAmount);
}
}
}
return width - stealAmount;
}
return width;
}
private static int InflateRows(ContainerInfo containerInfo, Size proposedConstraints, int expandLastElementWidth, bool measureOnly)
{
bool dontHonorConstraint = measureOnly;
LayoutInfo[] sortedChildren = containerInfo.ChildrenInfo;
if (containerInfo.ChildHasRowSpan)
{
Sort(sortedChildren, RowSpanComparer.GetInstance);
}
bool multiplePercent = containerInfo.HasMultiplePercentColumns;
// Normally when we are called from GetPreferredSize (measureOnly is true), we want to treat ourselves
// as being unbounded. But in some scenarios, we actually do want to honor the constraints. When
// we are docked or anchored in the right combination, and our parent's layout engine supports
// dock and anchoring, and we are actually constrained in at least one direction,
// then we should honor the constraint.
// The Int16.MaxValue check will tell us whether we are actually constrained or not. This is not ideal.
if (dontHonorConstraint && (proposedConstraints.Height < short.MaxValue))
{
if (containerInfo.Container is TableLayoutPanel tlp && tlp.ParentInternal is not null && tlp.ParentInternal.LayoutEngine == DefaultLayout.Instance)
{
if (tlp.Dock is DockStyle.Left or DockStyle.Right or DockStyle.Fill)
{
dontHonorConstraint = false; // we want to honor constraints
}
if ((tlp.Anchor & (AnchorStyles.Top | AnchorStyles.Bottom)) == (AnchorStyles.Top | AnchorStyles.Bottom))
{
dontHonorConstraint = false; // we want to honor constraints
}
}
}
foreach (LayoutInfo layoutInfo in sortedChildren)
{
IArrangedElement element = layoutInfo.Element;
int rowSpan = layoutInfo.RowSpan;
// we can skip over absolute row styles, as they've been preallocated
if (rowSpan > 1 || !IsAbsolutelySized(layoutInfo.RowStart, containerInfo.RowStyles))
{
int currentWidth = SumStrips(containerInfo.Columns, layoutInfo.ColumnStart, layoutInfo.ColumnSpan);
// make sure that the total width is the actual final width to avoid
// inconsistency of width between the ApplyStyles and SetElementBounds
// Only apply when there is one multiple percentage column
if (!dontHonorConstraint && layoutInfo.ColumnStart + layoutInfo.ColumnSpan >= containerInfo.MaxColumns && !multiplePercent)
{
currentWidth += expandLastElementWidth;
}
// since we know the width at this point, use that as the constraining width.
Padding margin = CommonProperties.GetMargin(element);
int minHeight = GetElementSize(element, new Size(currentWidth - margin.Horizontal, 0)).Height + margin.Vertical;
int maxHeight = minHeight;
int rowStop = Math.Min(layoutInfo.RowStart + layoutInfo.RowSpan, containerInfo.Rows.Length);
DistributeSize(containerInfo.RowStyles, containerInfo.Rows, layoutInfo.RowStart, rowStop, minHeight, maxHeight, containerInfo.CellBorderWidth);
}
}
return DistributeStyles(containerInfo.CellBorderWidth, containerInfo.RowStyles, containerInfo.Rows, proposedConstraints.Height, dontHonorConstraint);
}
private static Size GetElementSize(IArrangedElement element, Size proposedConstraints) =>
CommonProperties.GetAutoSize(element)
? element.GetPreferredSize(proposedConstraints)
: CommonProperties.GetSpecifiedBounds(element).Size;
internal static int SumStrips(Strip[] strips, int start, int span)
{
int size = 0;
for (int i = start; i < Math.Min(start + span, strips.Length); i++)
{
Strip strip = strips[i];
size += strip.MinSize;
}
return size;
}
/// <summary>
/// Sets the minimum size for each element
/// </summary>
private static void DistributeSize(TableLayoutStyleCollection styles, Strip[] strips, int start, int stop, int min, int max, int cellBorderWidth)
{
xDistributeSize(styles, strips, start, stop, min, MinSizeProxy.GetInstance, cellBorderWidth);
xDistributeSize(styles, strips, start, stop, max, MaxSizeProxy.GetInstance, cellBorderWidth);
}
private static void xDistributeSize(TableLayoutStyleCollection styles, Strip[] strips, int start, int stop, int desiredLength, SizeProxy sizeProxy, int cellBorderWidth)
{
int currentLength = 0; // total length allocated so far
int numUninitializedStrips = 0; // number of strips whose Size is 0 and is not absolutely positioned
// subtract the space for cell borders. Notice if a control spans two columns its
// proposed size is 10 and the border width is 3, we actually only need to distribute
// 7 pixels among the two cells it spans
desiredLength -= cellBorderWidth * (stop - start - 1);
desiredLength = Math.Max(0, desiredLength);
for (int i = start; i < stop; i++)
{
sizeProxy.Strip = strips[i];
if (!IsAbsolutelySized(i, styles) && sizeProxy.Size == 0)
{
// the strip is not absolutely sized and it hasn't been initialized
numUninitializedStrips++;
}
currentLength += sizeProxy.Size;
}
int missingLength = desiredLength - currentLength;
if (missingLength <= 0)
{
// no extra space left. Simply return.
return;
}
if (numUninitializedStrips == 0)
{
// look for any strip whose style is percent. If there is one, dump all space in it
int lastPercent;
for (lastPercent = stop - 1; lastPercent >= start; lastPercent--)
{
if (lastPercent < styles.Count && styles[lastPercent].SizeType == SizeType.Percent)
{
break;
}
}
// we have found one strip whose style is percent.
// make sure that the for loop below only looks at this strip
if (lastPercent != start - 1)
{
stop = lastPercent + 1;
}
// every strip has absolute width or all of them have already been allocated space
// walk backwards
for (int i = stop - 1; i >= start; i--)
{
if (!IsAbsolutelySized(i, styles))
{
// dump the extra space to this strip
sizeProxy.Strip = strips[i];
if (!(i == strips.Length - 1) // this is not the last strip
&& !strips[i + 1].IsStart // and there is no control starting from the strip next to it
&& !IsAbsolutelySized(i + 1, styles))
{ // and the strip next to it is not absolutely sized
// try to "borrow" space from the strip next to it
sizeProxy.Strip = strips[i + 1];
int offset = Math.Min(sizeProxy.Size, missingLength);
sizeProxy.Size -= offset;
strips[i + 1] = sizeProxy.Strip;
sizeProxy.Strip = strips[i];
}
// put whatever left into this strip
sizeProxy.Size += missingLength;
strips[i] = sizeProxy.Strip;
break;
}
}
// if we fall through here, everything is absolutely positioned. discard the extra space
}
// there are some uninitialized strips
else
{
// average space to be distributed
int average = missingLength / numUninitializedStrips;
// total number of uninitialized strips encountered so far
int uninitializedStripIndex = 0;
for (int i = start; i < stop; i++)
{
sizeProxy.Strip = strips[i];
// this is an uninitialized strip
if (!IsAbsolutelySized(i, styles) && sizeProxy.Size == 0)
{
uninitializedStripIndex++;
if (uninitializedStripIndex == numUninitializedStrips)
{
// we are at the last strip. place round off error here
average = missingLength - average * (numUninitializedStrips - 1);
}
sizeProxy.Size += average;
strips[i] = sizeProxy.Strip;
}
}
}
}
// determines whether strip[index]'s style is absolutely sized
private static bool IsAbsolutelySized(int index, TableLayoutStyleCollection styles) =>
(index < styles.Count) && styles[index].SizeType == SizeType.Absolute;
/// <summary>
/// Now that we've allocated minimum and maximum sizes to everyone (the strips), distribute the extra space
/// as according to the Row/Column styles.
/// </summary>
private static int DistributeStyles(int cellBorderWidth, TableLayoutStyleCollection styles, Strip[] strips, int maxSize, bool dontHonorConstraint)
{
int usedSpace = 0;
// first, allocate the minimum space required for each element
float totalPercent = 0;
float totalPercentAllocatedSpace = 0;
float totalAbsoluteAndAutoSizeAllocatedSpace = 0;
bool hasAutoSizeColumn = false;
// Step 1: iterate through the rows or columns,
// - calculate the amount of space allocated
// - for autosize and fixed size columns
// - for percent size columns
// - sum up the total "%"s being used
// - eg totalPercent = 22 + 22 + 22 = 66%. each column should take up 1/3 of the remaining space.
for (int i = 0; i < strips.Length; i++)
{
Strip strip = strips[i];
if (i < styles.Count)
{
TableLayoutStyle style = styles[i];
switch (style.SizeType)
{
case SizeType.Absolute:
totalAbsoluteAndAutoSizeAllocatedSpace += strip.MinSize;
// We guarantee a strip will be exactly abs pixels
Debug.Assert((strip.MinSize == style.Size), "absolutely sized strip's size should be set before we call ApplyStyles");
break;
case SizeType.Percent:
totalPercent += style.Size;
totalPercentAllocatedSpace += strip.MinSize;
break;
default:
totalAbsoluteAndAutoSizeAllocatedSpace += strip.MinSize;
hasAutoSizeColumn = true;
break;
}
}
else
{
hasAutoSizeColumn = true;
}
strip.MaxSize += cellBorderWidth;
strip.MinSize += cellBorderWidth; // add the padding for the cell border
strips[i] = strip;
usedSpace += strip.MinSize;
}
int remainingSpace = maxSize - usedSpace;
// Step 2: (ONLY if we have % style column)
// - distribute unused space for absolute/autosize columns to percentage columns
// - determine the extra space that is not being used for autosize and fixed columns
// - divide space amongst % style columns using ratio of %/total % * total extra space
if (totalPercent > 0)
{
if (!dontHonorConstraint)
{
if (totalPercentAllocatedSpace > maxSize - totalAbsoluteAndAutoSizeAllocatedSpace)
{
// fixup for the case where we've actually allocated more space than we have.
// this can happen when the sum of the widths/heights of the controls are larger than the size of the
// table (aka maxSize)
// Don't want negative size...
totalPercentAllocatedSpace = Math.Max(0, maxSize - totalAbsoluteAndAutoSizeAllocatedSpace);
}
if (remainingSpace > 0)
{
// If there's space left over, then give it to the percentage columns/rows
totalPercentAllocatedSpace += remainingSpace;
}
else if (remainingSpace < 0)
{
// If there's not enough space, then remove space from the percentage columns.
// We do this by recalculating the space available.
totalPercentAllocatedSpace = maxSize - totalAbsoluteAndAutoSizeAllocatedSpace - (strips.Length * cellBorderWidth);
}
// in this case the strips fill up the remaining space.
for (int i = 0; i < strips.Length; i++)
{
Strip strip = strips[i];
SizeType sizeType = i < styles.Count ? styles[i].SizeType : SizeType.AutoSize;
if (sizeType == SizeType.Percent)
{
TableLayoutStyle style = styles[i];
// cast to int / (take the floor) so we know we don't accidentally go over our limit.
// the rest will be distributed later.
int stripSize = (int)(style.Size * totalPercentAllocatedSpace / totalPercent);
usedSpace -= strip.MinSize; // back out the size we thought we were allocating before.
usedSpace += stripSize + cellBorderWidth; // add in the new size we think we're going to use.
strip.MinSize = stripSize + cellBorderWidth;
strips[i] = strip;
}
}
}
else
{
// the size of the item defines the size allocated to the percentage style columns.
// this supports [Ok][Cancel] in a 50% 50% column arrangement. When one grows it pushes the whole table
// larger.
int maxPercentWidth = 0;
for (int i = 0; i < strips.Length; i++)
{
Strip strip = strips[i];
SizeType sizeType = i < styles.Count ? styles[i].SizeType : SizeType.AutoSize;
// Performing the inverse calculation for GetPreferredSize:
//
// stylePercent * totalWidth colWidth * totalPercent
// colWidth = ------------------------- ---> totalWidth = -----------------------
// totalPercent stylePercent
//
// we'll take the max of the total widths as the one for our preferred size.
if (sizeType == SizeType.Percent)
{
TableLayoutStyle style = styles[i];
int totalWidth = (int)Math.Round(((strip.MinSize * totalPercent) / style.Size));
maxPercentWidth = Math.Max(maxPercentWidth, totalWidth);
usedSpace -= strip.MinSize;
}
}
usedSpace += maxPercentWidth;
}
}
remainingSpace = maxSize - usedSpace;
// Step 3: add remaining space to autosize columns
// - usually we only do this if we're not in preferred size (remainingSpace would be < 0)
// - and there are no % style columns
if (hasAutoSizeColumn && remainingSpace > 0)
{
for (int i = 0; i < strips.Length; i++)
{
Strip strip = strips[i];
SizeType sizeType = i < styles.Count ? styles[i].SizeType : SizeType.AutoSize;
if (sizeType == SizeType.AutoSize)
{
int delta = Math.Min(strip.MaxSize - strip.MinSize, remainingSpace);
if (delta > 0)
{
usedSpace += delta;
remainingSpace -= delta;
strip.MinSize += delta;
strips[i] = strip;
}
}
}
}
Debug.Assert((dontHonorConstraint || (usedSpace == SumStrips(strips, 0, strips.Length))), "Error computing usedSpace.");
return usedSpace;
}
private static void SetElementBounds(ContainerInfo containerInfo, RectangleF displayRectF)
{
int cellBorderWidth = containerInfo.CellBorderWidth;
float top = displayRectF.Y;
int currentCol = 0;
int currentRow = 0;
bool isContainerRTL = false;
if (containerInfo.Container is Control containerAsControl)
{
isContainerRTL = containerAsControl.RightToLeft == RightToLeft.Yes;
}
LayoutInfo[] childrenInfo = containerInfo.ChildrenInfo;
float startX = isContainerRTL ? displayRectF.Right : displayRectF.X;
// sort everything according to row major, column minor order
// so that we can ensure that as we walk through all elements
// the cursor always goes from left to right and from top to bottom.
Sort(childrenInfo, PostAssignedPositionComparer.GetInstance);
for (int i = 0; i < childrenInfo.Length; i++)
{
LayoutInfo layoutInfo = childrenInfo[i];
IArrangedElement element = layoutInfo.Element;
// Advance top to the beginning of this elements row.
Debug.Assert(currentRow <= layoutInfo.RowStart, "RowStart should increase in forward Z-order.");
if (currentRow != layoutInfo.RowStart)
{
for (; currentRow < layoutInfo.RowStart; currentRow++)
{
top += containerInfo.Rows[currentRow].MinSize;
}
startX = isContainerRTL ? displayRectF.Right : displayRectF.X;
currentCol = 0;
}
// Advance left to the beginning of this elements column.
Debug.Assert(currentCol <= layoutInfo.ColumnStart, "ColumnStart should increase in forward Z-order.");
for (; currentCol < layoutInfo.ColumnStart; currentCol++)
{
if (isContainerRTL)
{
startX -= containerInfo.Columns[currentCol].MinSize;
}
else
{
startX += containerInfo.Columns[currentCol].MinSize;
}
}
// Sum the total width of the span. We increment currentCol as we
// do this.
int colStop = currentCol + layoutInfo.ColumnSpan;
int width = 0;
for (; currentCol < colStop && currentCol < containerInfo.Columns.Length; currentCol++)
{
width += containerInfo.Columns[currentCol].MinSize;
}
if (isContainerRTL)
{
startX -= width;
}
// Sum the total height of the span. We do not increment RowSpan
// as we do this because there may be more elements on this row.
int rowStop = currentRow + layoutInfo.RowSpan;
int height = 0;
for (int rowIndex = currentRow; rowIndex < rowStop && rowIndex < containerInfo.Rows.Length; rowIndex++)
{
height += containerInfo.Rows[rowIndex].MinSize;
}
Rectangle cellBounds = new((int)(startX + cellBorderWidth / 2.0f), (int)(top + cellBorderWidth / 2.0f), width - cellBorderWidth, height - cellBorderWidth);
// We laid out the rows and columns with the element's margins included.
// We now deflate the rect to get the actual element bounds.
Padding elementMargin = CommonProperties.GetMargin(element);
if (isContainerRTL)
{
(elementMargin.Left, elementMargin.Right) = (elementMargin.Right, elementMargin.Left);
}
cellBounds = LayoutUtils.DeflateRect(cellBounds, elementMargin);
// make sure our sizes are non-negative
cellBounds.Width = Math.Max(cellBounds.Width, 1);
cellBounds.Height = Math.Max(cellBounds.Height, 1);
AnchorStyles anchorStyles = LayoutUtils.GetUnifiedAnchor(element);
Rectangle elementBounds = LayoutUtils.AlignAndStretch(GetElementSize(element, cellBounds.Size), cellBounds, anchorStyles);
// If the element was not BoxStretch.Both, AlignAndStretch does not guarantee
// that the element has been clipped to the cell bounds.
elementBounds.Width = Math.Min(cellBounds.Width, elementBounds.Width);
elementBounds.Height = Math.Min(cellBounds.Height, elementBounds.Height);
if (isContainerRTL)
{
elementBounds.X = cellBounds.X + (cellBounds.Right - elementBounds.Right);
}
element.SetBounds(elementBounds, BoundsSpecified.None);
if (!isContainerRTL)
{
startX += width;
}
}
Debug_VerifyNoOverlapping(containerInfo.Container);
}
internal static IArrangedElement? GetControlFromPosition(IArrangedElement container, int column, int row)
{
ArgumentOutOfRangeException.ThrowIfNegative(row);
ArgumentOutOfRangeException.ThrowIfNegative(column);
ArrangedElementCollection children = container.Children;
ContainerInfo containerInfo = GetContainerInfo(container);
if (children is null || children.Count == 0)
{
// nothing in the container. returns null.
return null;
}
if (!containerInfo.Valid)
{
// hasn't performed layout yet. assign rows and columns first
EnsureRowAndColumnAssignments(container, containerInfo, doNotCache: true);
}
for (int i = 0; i < children.Count; i++)
{
LayoutInfo layoutInfo = GetLayoutInfo(children[i]);
// the row and column specified is within the region enclosed by the element.
if (layoutInfo.ColumnStart <= column && (layoutInfo.ColumnStart + layoutInfo.ColumnSpan - 1) >= column &&
layoutInfo.RowStart <= row && (layoutInfo.RowStart + layoutInfo.RowSpan - 1) >= row)
{
return layoutInfo.Element;
}
}
return null;
}
internal static TableLayoutPanelCellPosition GetPositionFromControl(IArrangedElement? container, IArrangedElement? child)
{
if (container is null || child is null)
{
return new TableLayoutPanelCellPosition(-1, -1);
}
ArrangedElementCollection children = container.Children;
ContainerInfo containerInfo = GetContainerInfo(container);
if (children is null || children.Count == 0)
{
// nothing in the container. returns null.
return new TableLayoutPanelCellPosition(-1, -1);
}
if (!containerInfo.Valid)
{
// hasn't performed layout yet. assign rows and columns first
EnsureRowAndColumnAssignments(container, containerInfo, doNotCache: true);
}
LayoutInfo layoutInfo = GetLayoutInfo(child);
return new TableLayoutPanelCellPosition(layoutInfo.ColumnStart, layoutInfo.RowStart);
}
internal static LayoutInfo GetLayoutInfo(IArrangedElement element)
{
if (!element.Properties.TryGetValue(s_layoutInfoProperty, out LayoutInfo? layoutInfo))
{
layoutInfo = new LayoutInfo(element);
SetLayoutInfo(element, layoutInfo);
}
return layoutInfo;
}
internal static void SetLayoutInfo(IArrangedElement element, LayoutInfo value)
{
element.Properties.AddOrRemoveValue(s_layoutInfoProperty, value);
Debug.Assert(GetLayoutInfo(element) == value, "GetLayoutInfo should return the same value as we set it to");
}
#region ContainerInfo
internal static bool HasCachedAssignments(ContainerInfo containerInfo) => containerInfo.Valid;
internal static void ClearCachedAssignments(ContainerInfo containerInfo) => containerInfo.Valid = false;
// we make sure that our containerInfo never returns null. If there is no
// existing containerInfo, instantiate a new one and store it in the property
// store.
internal static ContainerInfo GetContainerInfo(IArrangedElement container)
{
if (!container.Properties.TryGetValue(s_containerInfoProperty, out ContainerInfo? containerInfo))
{
containerInfo = container.Properties.AddValue(s_containerInfoProperty, new ContainerInfo(container));
}
return containerInfo;
}
#endregion
#region DEBUG
// Verify that the Row/Column assignments on the control are current.
[Conditional("DEBUG_LAYOUT")]
private static void Debug_VerifyAssignmentsAreCurrent(IArrangedElement container, ContainerInfo containerInfo)
{
#if DEBUG
Dictionary<IArrangedElement, LayoutInfo> oldLayoutInfo = [];
ArrangedElementCollection children = container.Children;
List<LayoutInfo> childrenInfo = new(children.Count);
int minSpace = 0;
int minColumn = 0;
for (int i = 0; i < children.Count; i++)
{
IArrangedElement element = children[i];
if (!element.ParticipatesInLayout)
{
// If the element does not participate in layout (i.e., Visible = false), we
// exclude it from the childrenInfos list and it is ignored by the engine.
continue;
}
LayoutInfo layoutInfo = GetLayoutInfo(element);
childrenInfo.Add(layoutInfo);
minSpace += layoutInfo.RowSpan * layoutInfo.ColumnSpan;
if (layoutInfo.IsAbsolutelyPositioned)
{
minColumn = Math.Max(minColumn, layoutInfo.ColumnPosition + layoutInfo.ColumnSpan);
}
}
// Create a copy of the layoutInfos so we can restore to our original state
foreach (LayoutInfo layoutInfo in childrenInfo)
{
oldLayoutInfo[layoutInfo.Element] = layoutInfo.Clone();
}
Strip[] rows = containerInfo.Rows;
Strip[] cols = containerInfo.Columns;
AssignRowsAndColumns(containerInfo);
Debug.Assert((containerInfo.Columns is null && cols is null) || containerInfo.Columns!.Length == cols.Length,
"Cached assignment info is invalid: Number of required columns has changed.");
Debug.Assert((containerInfo.Rows is null && rows is null) || containerInfo.Rows!.Length == rows.Length,
"Cached assignment info is invalid: Number of required rows has changed.");
foreach (LayoutInfo layoutInfo in childrenInfo)
{
Debug.Assert(layoutInfo.Equals(oldLayoutInfo[layoutInfo.Element]),
$"Cached assignment info is invalid: LayoutInfo has changed. old layoutinfo: {oldLayoutInfo[layoutInfo.Element].RowStart} {oldLayoutInfo[layoutInfo.Element].ColumnStart} new layoutinfo: {layoutInfo.RowStart} {layoutInfo.ColumnStart} and the element is {layoutInfo.Element}");
SetLayoutInfo(layoutInfo.Element, oldLayoutInfo[layoutInfo.Element]);
}
// Restore the information in row and column strips. Note that whenever we do a AssignRowAndColumns()
// we instantiate new row and column strip collections, we have to restore the value back later.
containerInfo.Rows = rows!;
containerInfo.Columns = cols!;
#endif // DEBUG
}
// Verifies that there is no overlapping of controls on the table (unless forced to do so via abs. positioning)
[Conditional("DEBUG_LAYOUT")]
private static void Debug_VerifyNoOverlapping(IArrangedElement container)
{
// this code may be useful for debugging, but doesn't work well with
// row styles
List<LayoutInfo> layoutInfos = new(container.Children.Count);
ContainerInfo containerInfo = GetContainerInfo(container);
foreach (IArrangedElement element in container.Children)
{
if (!element.ParticipatesInLayout)
{
// If the element does not participate in layout (i.e., Visible = false), we
// exclude it from the layoutInfos list and it is ignored by the engine.
continue;
}
layoutInfos.Add(GetLayoutInfo(element));
}
for (int i = 0; i < layoutInfos.Count; i++)
{
LayoutInfo layoutInfo1 = layoutInfos[i];
Rectangle elementBounds1 = layoutInfo1.Element.Bounds;
Rectangle cellsOccupied1 = new(layoutInfo1.ColumnStart, layoutInfo1.RowStart, layoutInfo1.ColumnSpan, layoutInfo1.RowSpan);
for (int j = i + 1; j < layoutInfos.Count; j++)
{
LayoutInfo layoutInfo2 = layoutInfos[j];
Rectangle elementBounds2 = layoutInfo2.Element.Bounds;
Rectangle cellsOccupied2 = new(layoutInfo2.ColumnStart, layoutInfo2.RowStart, layoutInfo2.ColumnSpan, layoutInfo2.RowSpan);
Debug.Assert(!cellsOccupied1.IntersectsWith(cellsOccupied2), "controls overlap in the same cell");
// The actual control overlaps horizontally. this can only happen if all columns are absolutely sized
if (LayoutUtils.IsIntersectHorizontally(elementBounds1, elementBounds2))
{
int k;
Debug.Assert(containerInfo.ColumnStyles.Count >= layoutInfo1.ColumnStart + layoutInfo1.ColumnSpan, "length of column style too short");
Debug.Assert(containerInfo.ColumnStyles.Count >= layoutInfo1.ColumnStart + layoutInfo2.ColumnSpan, "length of column style too short");
for (k = layoutInfo1.ColumnStart; k < layoutInfo1.ColumnStart + layoutInfo1.ColumnSpan; k++)
{
Debug.Assert(containerInfo.ColumnStyles[k].SizeType == SizeType.Absolute, $"column {k} is not absolutely sized");
}
for (k = layoutInfo2.ColumnStart; k < layoutInfo2.ColumnStart + layoutInfo2.ColumnSpan; k++)
{
Debug.Assert(containerInfo.ColumnStyles[k].SizeType == SizeType.Absolute, $"column {k} is not absolutely sized");
}
}
// The actual control overlaps vertically.
if (LayoutUtils.IsIntersectVertically(elementBounds1, elementBounds2))
{
int k;
Debug.Assert(containerInfo.RowStyles.Count >= layoutInfo1.RowStart + layoutInfo1.RowSpan, "length of row style too short");
Debug.Assert(containerInfo.RowStyles.Count >= layoutInfo2.RowStart + layoutInfo2.RowSpan, "length of row style too short");
for (k = layoutInfo1.RowStart; k < layoutInfo1.RowStart + layoutInfo1.RowSpan; k++)
{
Debug.Assert(containerInfo.RowStyles[k].SizeType == SizeType.Absolute, $"column {k} is not absolutely sized");
}
for (k = layoutInfo2.RowStart; k < layoutInfo2.RowStart + layoutInfo2.RowSpan; k++)
{
Debug.Assert(containerInfo.RowStyles[k].SizeType == SizeType.Absolute, $"column {k} is not absolutely sized");
}
}
}
}
}
#endregion
}
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