Csharp 在DoubleClick上交换DataGridViewImageColumn的图像和工具提示

Note: Properties.Resources is a Factory, it returns a new object each time you ask for one. When you assign a new object from the Resource, the object it replaces is left to the GC. In case of Graphics objects, not a good thing. Better cache these objects and use the cached value.
Here I'm using a Dictionary<bool, Image> as storage facility:

private Dictionary<bool, Image> DataGridViewLockState = new Dictionary<bool, Image>() {
    [true]  = Resources.locked,
    [false] = Resources.unlocked
};

关于此处提供的代码:

• When you assign a reference to a local variable, don't declare it with a using statement. You need the referenced object alive, here, those are your Rows / Cells
  You're setting the ToolTip of a Cell that, as you have mentioned, belongs to a hidden CheckBox Column. I assume you want to set the ToolTip of the Image Column, so you can see it.

其他:

• 测试e.RowIndex和e.ColumIndex的负值，因为两者都可能是负值(您可能已经禁用了列排序，没关系，它是procedural)
• 最好还测试单元格的值是null还是DbNull.Value.如果数据不是从数据库中出来的，那也没关系，安全总比后悔好

When you have changed the current state of the affected Cells, call the [DataGridView].EndEdit() method. This commits the changes immediately.
It also raises the CellValueChanged event immediately, before the current event has completed. Keep this in mind if you have code in the CellValueChanged handler.
Better call EndEdit() last, to avoid some form of re-entrancy

private void dgvTest_CellContentDoubleClick(object sender, DataGridViewCellEventArgs e) {
    var dgv = sender as DataGridView;
    if (dgv is null || e.RowIndex < 0 || e.ColumnIndex < 0) return;
    if (dgv.Columns[e.ColumnIndex].Name != "ProjectLocked") return;

    var currentRow = dgv.Rows[e.RowIndex];
    var deleteCell = currentRow.Cells["DeleteLock"];

    if (deleteCell.Value is null || deleteCell.Value == DBNull.Value) {
        throw new InvalidOperationException("DeleteLock value cannot be null");
    }

    // Negate the current value, we want to change state
    bool value = !(bool)deleteCell.Value;

    currentRow.Cells["ProjectLocked"].Value = DataGridViewLockState[value];
    currentRow.Cells["ProjectLocked"].ToolTipText = value ? Resources.RowLocked : Resources.RowUnlocked;
    currentRow.DefaultCellStyle.BackColor = value ? dgv.DefaultCellStyle.BackColor : Color.LightGray;
    currentRow.DefaultCellStyle.ForeColor = value ? dgv.DefaultCellStyle.ForeColor : Color.DarkGray;
    deleteCell.Value = value;
    dgv.EndEdit();
}