[英]TableLayoutPanel is only able to find Controls by Point that were in the visible area on startup
我有一個帶有滾動條的TableLayoutPanel
(因為Controls的總高度大於TableLayoutPanel
的高度)。 我嘗試使用PageUp-和PageDown-Keys以編程方式滾動到下一行/上一行。
滾動有效,但僅在我想滾動到程序啟動時已經在可見區域中的Control范圍內。 當我嘗試使控件進一步下降(同時進入可見區域)時, tlp.GetChildAtPoint(new Point(1, tlp.AutoScrollPosition.Y * -1 + 2))
返回null
。
有人可以幫我解決這個問題嗎?
注意:我找到了一種解決方法(請參閱我的答案),但是我當然可以接受其他解決方案。
重現該問題的代碼:
public class FormTLPTest : Form
{
TableLayoutPanel tlp;
public FormTLPTest()
{
Height = 200;
Width = 200;
KeyPreview = true;
tlp = new TableLayoutPanel();
tlp.Dock = DockStyle.Fill;
tlp.CellBorderStyle = TableLayoutPanelCellBorderStyle.Single;
tlp.AutoScroll = false;
tlp.VerticalScroll.Visible = true;
tlp.HorizontalScroll.Visible = false;
tlp.ColumnStyles.Add(new ColumnStyle(SizeType.Absolute, 40));
Controls.Add(tlp);
tlp.SuspendLayout();
for (int i = 0; i < 20; i++)
{
Label lb2 = new Label();
lb2.Margin = new Padding(0);
lb2.Dock = DockStyle.Fill;
lb2.BackColor = Color.White;
lb2.Text = "Line " + i;
tlp.Controls.Add(lb2, 0, i);
tlp.RowStyles.Add(new RowStyle(SizeType.Absolute, 18));
tlp.RowCount++;
}
tlp.ResumeLayout();
tlp.AutoScroll = true;
KeyDown += FormTLPTest_KeyDown;
}
private void FormTLPTest_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.PageUp || e.KeyCode == Keys.PageDown || e.KeyCode == Keys.Next)
{
Control currentTopControl = tlp.GetChildAtPoint(new Point(1, tlp.AutoScrollPosition.Y * -1 + 2));
int currentRow = 0;
if (currentTopControl != null)
currentRow = tlp.GetPositionFromControl(currentTopControl).Row;
int nextRow = -1;
if (e.KeyCode == Keys.PageUp)
nextRow = currentRow - 1;
else
nextRow = currentRow + 1;
if (nextRow < 0 || nextRow > tlp.RowCount - 1)
return;
Control nextTopControl = tlp.GetControlFromPosition(0, nextRow);
tlp.AutoScrollPosition = nextTopControl.Location;
}
}
}
我找到了避免GetChildAtPoint
方法的解決方案。 它檢查第一列的每個控件的位置,以獲取第一個可見列。
我還必須將.AutoScrollPosition = ...
替換為滾動到最后一個控件,然后再滾動到所需的控件(我希望該控件位於可見區域的頂部)。
更改了KeyDown
-listener:
private void FormTLPTest_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.PageUp || e.KeyCode == Keys.PageDown || e.KeyCode == Keys.Next)
{
int currentRow = 0;
for (int y=0;y<tlp.RowCount;y++)
{
Control c = tlp.GetControlFromPosition(0, y);
if (c.Location.Y >= 0)
{
currentRow = y;
break;
}
}
int nextRow = -1;
if (e.KeyCode == Keys.PageUp)
nextRow = currentRow - 1;
else
nextRow = currentRow + 1;
if (nextRow < 0 || nextRow > tlp.RowCount - 1)
return;
Control nextTopControl = tlp.GetControlFromPosition(0, nextRow);
tlp.ScrollControlIntoView(tlp.GetControlFromPosition(0, tlp.RowCount - 1));
tlp.ScrollControlIntoView(nextTopControl);
}
}
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