wpf - WPF 固定文档溢出

Question

我编写了以下代码来创建固定文档。

在页面上，我添加了一个堆栈面板。堆栈面板包含一些文本块和网格。网格应该有三列：10%、45% 和 45%。

然而，网格离开了页面，但我不知道为什么。有什么建议么？

FixedDocument fd = new FixedDocument();

Grid grd = new Grid();
grd.ShowGridLines = true;
grd.HorizontalAlignment = HorizontalAlignment.Stretch;

RowDefinition row_def;
ColumnDefinition col_def;

col_def = new ColumnDefinition();
col_def.Width = new GridLength(0.1, GridUnitType.Star);
grd.ColumnDefinitions.Add(col_def);
col_def = new ColumnDefinition();
col_def.Width = new GridLength(0.45, GridUnitType.Star);
grd.ColumnDefinitions.Add(col_def);
col_def = new ColumnDefinition();
col_def.Width = new GridLength(0.45, GridUnitType.Star);
grd.ColumnDefinitions.Add(col_def);
...
StackPanel sp = new StackPanel();
sp.Margin = new Thickness(32, 20, 20, 20);
sp.Children.Add(grd);
...
Size pgSize = new Size(96 * 8.27, 96 * 11.69);
FixedPage fp = new FixedPage();
fp.Width = pgSize.Width;
fp.Height = pgSize.Height;
fp.Children.Add(sp);

PageContent pc = new PageContent();
pc.Child = fp;
fd.Pages.Add(pc);

我尝试仅将网格添加到堆栈面板，仅将网格本身添加到没有堆栈面板，并且我还尝试将这些值用于 GridLenth，但没有任何区别：

col_def = new ColumnDefinition();
col_def.Width = new GridLength(10, GridUnitType.Star);
grd.ColumnDefinitions.Add(col_def);
col_def = new ColumnDefinition();
col_def.Width = new GridLength(45, GridUnitType.Star);
grd.ColumnDefinitions.Add(col_def);
col_def = new ColumnDefinition();
col_def.Width = new GridLength(45, GridUnitType.Star);
grd.ColumnDefinitions.Add(col_def);