Skip to content

Use programatically check instead of assertion in method ComputeVisibleColumns of DataGridView.Methods to avoid null reference exception #13739

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: main
Choose a base branch
from
Open

Use programatically check instead of assertion in method ComputeVisibleColumns of DataGridView.Methods to avoid null reference exception #13739

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
dcb861d
Use logical judgment instead of assertion in method ComputeVisibleCol…
LeafShi1 Jul 25, 2025
2bd21b6
Update DataGridView.Methods.cs
LeafShi1 Jul 28, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
23 changes: 14 additions & 9 deletions src/System.Windows.Forms/System/Windows/Forms/Controls/DataGridView/DataGridView.Methods.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4699,15 +4699,20 @@ private void ComputeVisibleColumns()
(Columns[firstDisplayedScrollingCol]),
DataGridViewElementStates.Visible,
DataGridViewElementStates.Frozen);
ThrowInvalidOperationExceptionIfNull(dataGridViewColumn);
Debug.Assert(dataGridViewColumn.Thickness > displayWidth - cx);
firstDisplayedScrollingCol = dataGridViewColumn.Index;
FirstDisplayedScrollingColumnHiddenWidth = dataGridViewColumn.Thickness - displayWidth + cx;
_horizontalOffset -= displayWidth - cx;
visibleScrollingColumnsTmp++;
invalidate = true;
cx = displayWidth;
Debug.Assert(FirstDisplayedScrollingColumnHiddenWidth == GetNegOffsetFromHorizontalOffset(_horizontalOffset));

// If a valid previous column is found and its width exceeds the remaining displayable space,
// then perform a partial scroll.
if (dataGridViewColumn is not null)
{
Debug.Assert(dataGridViewColumn.Thickness > displayWidth - cx);
firstDisplayedScrollingCol = dataGridViewColumn.Index;
FirstDisplayedScrollingColumnHiddenWidth = dataGridViewColumn.Thickness - displayWidth + cx;
_horizontalOffset -= displayWidth - cx;
visibleScrollingColumnsTmp++;
invalidate = true;
cx = displayWidth;
Debug.Assert(FirstDisplayedScrollingColumnHiddenWidth == GetNegOffsetFromHorizontalOffset(_horizontalOffset));
}
}

// update the number of visible columns to the new reality
Expand Down