WPF C#-用户按键上的DataGrid选择项
本文关键字：DataGrid 选择 C#- 用户 WPF | 更新日期: 2023-09-27 18:24:16
我使用此函数在用户按键时选择DataGrid上的项目。如果用户密钥是"A"，它将选择用户名以字母"A"开头的第一个项目。如果用户键再次为"A"，它将选择用户名以字母"A"开头的下一个项目，依此类推。该功能工作得很好，但我想要的是，当用户名以"A"开始的项目不再存在时（选择第一个项目），它目前仍保留在用户名以字母A开头的最后一个项目上。
private static Key lastKey;
private static int lastFoundIndex = 0;
public static void AccountsDataGrid_SearchByKey(object sender, KeyEventArgs e)
{
DataGrid dataGrid = sender as DataGrid;
if ((dataGrid.Items.Count == 0) && !(e.Key >= Key.A && e.Key <= Key.Z))
{
return;
}
if ((lastKey != e.Key) || (lastFoundIndex == dataGrid.Items.Count - 1))
{
lastFoundIndex = 0;
}
for (int i = lastFoundIndex; i < dataGrid.Items.Count; i++)
{
if (dataGrid.SelectedIndex == i)
{
continue;
}
Account account = dataGrid.Items[i] as Account;
if (account.Username.StartsWith(e.Key.ToString(), true, CultureInfo.CurrentCulture))
{
dataGrid.ScrollIntoView(account);
dataGrid.SelectedItem = account;
lastFoundIndex = i;
break;
}
}
lastKey = e.Key;
}
更新（带解决方案）：
受丹妮尔想法的启发，我修改了我的代码，如下所示，工作起来很有魅力。
private static Key lastKey;
private static int lastFoundIndex = 0;
public static void AccountsDataGrid_SearchByKey(object sender, KeyEventArgs e)
{
DataGrid dataGrid = sender as DataGrid;
if ((dataGrid.Items.Count == 0) && !(e.Key >= Key.A && e.Key <= Key.Z))
{
return;
}
if ((lastKey != e.Key) || (lastFoundIndex == dataGrid.Items.Count - 1))
{
lastFoundIndex = 0;
}
Func<object, bool> itemCompareMethod = (item) =>
{
Account account = item as Account;
if (account.Username.StartsWith(e.Key.ToString(), true, CultureInfo.CurrentCulture))
{
return true;
}
return false;
};
lastFoundIndex = FindDataGridRecordWithinRange(dataGrid, lastFoundIndex, dataGrid.Items.Count, itemCompareMethod);
if (lastFoundIndex == -1)
{
lastFoundIndex = FindDataGridRecordWithinRange(dataGrid, 0, dataGrid.Items.Count, itemCompareMethod);
}
if (lastFoundIndex != -1)
{
dataGrid.ScrollIntoView(dataGrid.Items[lastFoundIndex]);
dataGrid.SelectedIndex = lastFoundIndex;
}
if (lastFoundIndex == -1)
{
lastFoundIndex = 0;
dataGrid.SelectedItem = null;
}
lastKey = e.Key;
}
private static int FindDataGridRecordWithinRange(DataGrid dataGrid, int min, int max, Func<object, bool> itemCompareMethod)
{
for (int i = min; i < max; i++)
{
if (dataGrid.SelectedIndex == i)
{
continue;
}
if (itemCompareMethod(dataGrid.Items[i]))
{
return i;
}
}
return -1;
}
最终得到的解决方案不必要地复杂，并且会检查不需要检查的行。也不需要维护状态的两个静态变量。试试这个：
public void MainGrid_SearchByKey(object sender, KeyEventArgs e)
{
DataGrid dataGrid = sender as DataGrid;
if (dataGrid.Items.Count == 0 || e.Key < Key.A || e.Key > Key.Z)
{
return;
}
Func<object, bool> doesItemStartWithChar = (item) =>
{
Account account = item as Account;
return account.Username.StartsWith(e.Key.ToString(), true, CultureInfo.InvariantCulture);
};
int currentIndex = dataGrid.SelectedIndex;
int foundIndex = currentIndex;
// Search in following rows
foundIndex = FindMatchingItemInRange(dataGrid, currentIndex, dataGrid.Items.Count - 1, doesItemStartWithChar);
// If not found, search again in the previous rows
if (foundIndex == -1)
{
foundIndex = FindMatchingItemInRange(dataGrid, 0, currentIndex - 1, doesItemStartWithChar);
}
if (foundIndex > -1) // Found
{
dataGrid.ScrollIntoView(dataGrid.Items[foundIndex]);
dataGrid.SelectedIndex = foundIndex;
}
}
private static int FindMatchingItemInRange(DataGrid dataGrid, int min, int max, Func<object, bool> doesItemStartWithChar)
{
for (int i = min; i <= max; i++)
{
if (dataGrid.SelectedIndex == i) // Skip the current selection
{
continue;
}
if (doesItemStartWithChar(dataGrid.Items[i])) // If current item matches the string, return index
{
return i;
}
}
return -1;
}
关于您的评论，只需添加此复选框：
if (Keyboard.Modifiers.HasFlag(ModifierKeys.Control))
{
return;
}
您可以将for循环提取到一个单独的方法中，以确定是否找到了另一个项。
public int FindRecordWithinRange(DataGrid dataGrid, int min, int max)
{
for (int i = min; i < max; i++)
{
if (dataGrid.SelectedIndex == i)
continue;
Account account = dataGrid.Items[i] as Account;
if (account.Username.StartsWith(e.Key.ToString(), true, CultureInfo.CurrentCulture))
{
dataGrid.ScrollIntoView(account);
dataGrid.SelectedItem = account;
return i;
}
}
return -1;
}
然后用这样的东西调用它：
lastFoundIndex = FindRecordWithinRange(dataGrid, lastFoundIndex, dataGrid.Items.Count);
if (lastFoundIndex == -1)
lastFoundIndex = FindRecordWithinRange(dataGrid, 0, dataGrid.Items.Count);
if (lastFoundIndex == -1)
dataGrid.SelectedItem = null;
这基本上是从一开始就尝试搜索列表，也可以通过清除选择来处理没有找到项目的情况。在这种情况下，您可能还想滚动到开头，此时的处理取决于您想要做什么
你可能想在这里做的另一件事是提取你的ScrollIntoView和Selection逻辑，并在确定索引后处理它。
如果我像下面这样更改函数，它将在字母"A"的最后一个项目上停留2次，然后转到字母"A"的第一个项目（假设用户键仍然是"A"）。
private static Key lastKey;
private static int lastFoundIndex = 0;
public static void AccountsDataGrid_SearchByKey(object sender, KeyEventArgs e)
{
DataGrid dataGrid = sender as DataGrid;
if ((dataGrid.Items.Count == 0) && !(e.Key >= Key.A && e.Key <= Key.Z))
{
return;
}
if ((lastKey != e.Key) || (lastFoundIndex == dataGrid.Items.Count - 1))
{
lastFoundIndex = 0;
}
for (int i = lastFoundIndex; i < dataGrid.Items.Count; i++)
{
if ((lastFoundIndex > 0) && (lastFoundIndex == i))
{
lastFoundIndex = 0;
}
if (dataGrid.SelectedIndex == i)
{
continue;
}
Account account = dataGrid.Items[i] as Account;
if (account.Username.StartsWith(e.Key.ToString(), true, CultureInfo.CurrentCulture))
{
dataGrid.ScrollIntoView(account);
dataGrid.SelectedItem = account;
lastFoundIndex = i;
break;
}
}
lastKey = e.Key;
}
您的代码说，要从头开始重新搜索，lastFoundIndex应该等于dataGrid.Items.Count-1（假设再次按下相同的键）。但是您最后找到的Account可能不在Items集合的末尾，因此在按下上一个键时，lastFoundIndex没有设置为dataGrid.Items.Count-1。在这种情况下，你重新开始的条件没有得到满足。
尝试更改上次找到的检查和"for"循环，如下所示：
bool found = false;
bool lastFound = true;
if (lastKey != e.Key || lastFound)
{
lastFoundIndex = 0;
}
for (int i = lastFoundIndex; i < dataGrid.Items.Count; i++)
{
if (dataGrid.SelectedIndex == i)
{
continue;
}
Account account = dataGrid.Items[i] as Account;
if (account.Username.StartsWith(e.Key.ToString(), true, CultureInfo.CurrentCulture))
{
if (!found)
{
dataGrid.ScrollIntoView(account);
dataGrid.SelectedItem = account;
lastFoundIndex = i;
found = true;
}
else
{
lastFound = false;
break;
}
}
}
基本上，它会尝试再找到一个项目，看看这是否是最后一场比赛。