/// <summary>
/// 测量所有已经生成的单元格。
/// </summary>
/// <param name="columns"></param>
/// <param name="availableSize"></param>
/// <returns></returns>
private Size MeasureChild(TreeGridColumnCollection columns, Size availableSize)
{
double maxWidth = availableSize.Width;
double maxHeight = availableSize.Height;
double rowDesiredHeight = 0.0; //行最终需要的高度
double rowDesiredWidth = 0.0; //行最终需要的宽度
bool firstTime = true; //是否在 Init 状态下还没有初始化过 DesiredWidthList。
var cells = this.InternalChildren;
for (int i = this._from, j = 0; i <= this._to; i++, j++)
{
var column = columns[i];
//当前行还可用的宽度
double rowAvaiableWidth = Math.Max(0, maxWidth - rowDesiredWidth);
//第一列额外元素需要的宽度
double headersDesiredWidth = 0;
#region 测量第一列额外元素需要的宽度
if (i == 0)
{
//测量 RowHeader
if (this.ShowRowHeader)
{
headersDesiredWidth += this.RowHeaderWidth;
rowAvaiableWidth -= this.RowHeaderWidth;
//this._rowHeaderContainer.Measure(new Size(columnWidth, maxHeight));
//x += this._rowHeaderContainer.DesiredSize.Width;
//columnWidth -= this._rowHeaderContainer.DesiredSize.Width;
}
//留下 FirstColumnIndent
var firstColumnIndent = Math.Min(this.FirstColumnIndent, rowAvaiableWidth);
headersDesiredWidth += firstColumnIndent;
rowAvaiableWidth -= firstColumnIndent;
//测量 Expander
if (this.ShowExpander)
{
var expander = this.Expander;
expander.Measure(new Size(rowAvaiableWidth, maxHeight));
headersDesiredWidth += expander.DesiredSize.Width;
rowAvaiableWidth -= expander.DesiredSize.Width;
}
}
#endregion
var cell = cells[j];
//测量单元格
var state = column.State;
if (state == ColumnMeasureState.Init || state == ColumnMeasureState.Headered)
{
if (firstTime)
{
TreeGridHelper.EnsureDesiredWidthList(ref this._desiredWidthList, this._treeGrid.Columns);
this.LayoutUpdated += this.OnMeasureLayoutUpdated;
firstTime = false;
}
cell.Measure(new Size(rowAvaiableWidth, maxHeight));
//只有在虚拟化后的当前页面时，才影响动态宽度。
if (this._cellsPresenter.IsOnCurrentPage)
{
//当前列需要的宽度应该是列的宽度加额外元素的宽度。
column.EnsureDataWidth(cell.DesiredSize.Width + headersDesiredWidth);
}
this._desiredWidthList[column.StableIndex] = column.DesiredDataWidth;
rowDesiredWidth += column.DesiredDataWidth;
}
else
{
var actualWidth = column.CalculateActualWidth();
rowAvaiableWidth = Math.Min(rowAvaiableWidth, actualWidth - headersDesiredWidth);
cell.Measure(new Size(rowAvaiableWidth, maxHeight));
rowDesiredWidth += actualWidth;
}
rowDesiredHeight = Math.Max(rowDesiredHeight, cell.DesiredSize.Height);
}
rowDesiredWidth += TreeGridHeaderRowPresenter.c_EndPadding;
this._cellsPresenter.IsOnCurrentPageValid = false;
return(new Size(rowDesiredWidth, rowDesiredHeight));
}
/// <summary>
/// 保证 _desiredWidthList 与 columns 长度一致。
/// </summary>
internal void EnsureDesiredWidthList()
{
TreeGridHelper.EnsureDesiredWidthList(ref this._desiredWidthList, this.Columns);
}