public IEnumerable <OrderFormPage> PaginateCore(Size size)
{
// ページネーションを行うために、実際に DataGrid を生成する。
var preview = new OrderFormPage(Header, Items);
var presenter =
new ContentPresenter()
{
Content = preview,
Width = size.Width,
Height = size.Height,
};
presenter.Measure(size);
presenter.Arrange(new Rect(new Point(0, 0), size));
presenter.UpdateLayout();
var headeredGrid =
presenter.VisualDescendantsBreadthFirstOrder().OfType <HeaderedGrid>().First();
var scrollViewer = headeredGrid.ScrollViewer;
var grid = headeredGrid.Grid;
var items = preview.Items;
var index = 0;
while (index < items.Count)
{
// 表示されている行数を計算する。
var totalRowHeight =
grid.RowDefinitions[0].ActualHeight;
var count = 0;
while (index + count < items.Count)
{
totalRowHeight += grid.RowDefinitions[1 + index + count].ActualHeight;
if (totalRowHeight > scrollViewer.ViewportHeight)
{
break;
}
count++;
}
if (count == 0)
{
// ヘッダー行が大きすぎてコンテンツを表示できていない。
throw new Exception();
}
var pageItems =
Enumerable.Range(index, count).Select(i => items[i]).ToArray();
// 1画面に表示できた行からなるページを追加する。
yield return(new OrderFormPage(Header, pageItems));
if (index + count < items.Count)
{
// いまのページに追加された分の行を非表示 (高さ 0) にする。
foreach (var i in Enumerable.Range(index, count))
{
grid.RowDefinitions[1 + i].MaxHeight = 0.0;
}
// scrollViewer.ViewportHeight を更新する。
presenter.UpdateLayout();
}
index += count;
}
}
Paginate <X>(this ISingleHeaderedGridPage <X> @this, Size pageSize)
{
var presenter =
new ContentPresenter()
{
Content = @this,
Width = pageSize.Width,
Height = pageSize.Height,
};
presenter.Measure(pageSize);
presenter.Arrange(new Rect(new Point(0, 0), pageSize));
presenter.UpdateLayout();
var headeredGrid =
presenter.VisualDescendantsBreadthFirstOrder().OfType <HeaderedGrid>().First();
var scrollViewer = headeredGrid.ScrollViewer;
var grid = headeredGrid.Grid;
var items = @this.Items;
var index = 0;
while (index < items.Count)
{
// Count the visible rows.
var totalRowHeight =
grid.RowDefinitions[0].ActualHeight;
var count = 0;
while (index + count < items.Count)
{
totalRowHeight += grid.RowDefinitions[1 + index + count].ActualHeight;
if (totalRowHeight > scrollViewer.ViewportHeight)
{
break;
}
count++;
}
if (count == 0)
{
throw new Exception("Because of too large header row or too small height, the page can't show any rows.");
}
yield return
(Enumerable.Range(index, count).Select(i => items[i]).ToArray());
if (index + count < items.Count)
{
// Hide visible rows.
foreach (var i in Enumerable.Range(index, count))
{
grid.RowDefinitions[1 + i].MaxHeight = 0.0;
}
// Update UI properties, including scrollViewer.ViewportHeight.
presenter.UpdateLayout();
}
index += count;
}
}
