ОК, так что после 16 часов царапин на голове я наконец-то прибил его!
Обзор решения:
В моем приложении есть форма Windows (не WPF), которая будет использоваться для создания пользователей электронной почты игруппы для уведомлений о событиях в программном обеспечении.Я создал комбинированный список, который извлекает элементы из двух разных источников таблиц данных (группы пользователей из одной и учетные записи пользователей из другой). Предполагается, что администратор может создавать пользователей и группы получателей электронной почты.
ЧастьЯ действительно боролся с тем, чтобы настроить комбинированный список, чтобы разрешить использование значков (импортированных изображений) и текста для отображения в списке комбинированного списка.Часть проблемы заключалась в том, чтобы обдумать владение свойством draw и создать макет исключительно с помощью кода в качестве пользовательской сущности.Я не смог найти полных примеров в Интернете, поэтому пришлось поискать в Интернете, и в конце я получил множество проб и ошибок.
Я добавил много примечаний в приведенном ниже коде в надеждечто другие извлекут выгоду из боли, которую я прошел сегодня!Возможно, моя среда была немного более индивидуальной, но потратьте немного времени на просмотр кода, и вскоре вы поймете, что я собрал.Надеюсь, это поможет:)
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
private void NotificationsForm_Load(object sender, EventArgs e)
{
PopulateUsersGroupsList(); // Used to create the list of User Groups & User Accounts when the form opens.
log.Info("NotificationsForm Opened");
}
// Create an image list that will be used for the combobox icons
readonly static ImageList imageListEmailRecipients = new ImageList();
// Create an List that will be used to store the user account and user group names from the two different data tables.
public static readonly List<KeyValuePair<string, string>> emailRecipientsUserList = new List<KeyValuePair<string, string>>();
/// <summary>
/// This method is used to create a list to hold the values pulled from two different data tables.
/// The information pulled provides the list with the names of the User Groups & User Accounts.
/// Note: When the Windows Form closes, the closing method runs the command 'emailRecipientsUserList.Clear()'
/// in order to ensure that the list is cleared and does not continue to build up with dulicate entries each
/// time the form is opened.
/// </summary>
private void PopulateUsersGroupsList()
{
// Add the two images to the image list, images are loaded from the properties resources folder.
// These images will be used as icons to display in the combobox.
imageListEmailRecipients.Images.Add((Image)(new Bitmap(Properties.Resources.UserGroup2)));
imageListEmailRecipients.Images.Add((Image)(new Bitmap(Properties.Resources.UserAccount)));
// Add a default string to the list for the combobox default value, prompting the user to make their selection
// before the open up the dropdown combobox.
emailRecipientsUserList.Add(new KeyValuePair<string, string>("", "--Select--"));
// Add each User Group from the data table to the list. KeyValuePairs are used so we can differentiate
// between the User Groups list and User Accounts list.
for (int i = 0; i < DB_UserGroups.userGroupsDataTable.Rows.Count; i++)
{
emailRecipientsUserList.Add(new KeyValuePair<string, string>("UserGroup", DB_UserGroups.userGroupsDataTable.Rows[i]["UserGroup"].ToString()));
}
// Add each User Account from the data table to the list. KeyValuePairs are used so we can differentiate
// between the User Groups list and User Accounts list.
for (int i = 0; i < DB_Users.userAccountsDataTable.Rows.Count; i++)
{
//emailRecipientsUserList.Add(DB_Users.userAccountsDataTable.Rows[i]["Username"].ToString());
emailRecipientsUserList.Add(new KeyValuePair<string, string>("Username", DB_Users.userAccountsDataTable.Rows[i]["Username"].ToString()));
}
// Run the method below that will populate the combobox with the User Groups & User Accounts from the list.
AddUsersGroupsComboboxPopulate();
}
/// <summary>
/// Method used to populate the combobox using the 'emailRecipientsUserList' created from the method above.
/// </summary>
private void AddUsersGroupsComboboxPopulate()
{
// Clear the comobox before re-populating.
AddUserGroupCombobox.Items.Clear();
// Map the combobox's data source to the 'emailRecipientsUserList' source.
this.AddUserGroupCombobox.DataSource = emailRecipientsUserList;
// Confirure the combobox to the show the 'Value' portion ONLY from the KeyValuePair
// value set found in the 'emailRecipientsUserList'.
this.AddUserGroupCombobox.DisplayMember = "Value";
// Configure the combobox to utilise the Key from the 'emailRecipientsUserList' as its member value.
this.AddUserGroupCombobox.ValueMember = "Key";
// Set the combobox to owner draw mode - otherwise you cannot change the output style to your own format.
AddUserGroupCombobox.DrawMode = DrawMode.OwnerDrawFixed;
// Instruct the combobox to draw itself using the 'AddUserGroupCombobox_DrawItem' method below.
AddUserGroupCombobox.DrawItem += AddUserGroupCombobox_DrawItem;
// Set the default height for each of the items displayed in the combobox.
AddUserGroupCombobox.ItemHeight = 20;
}
// Mouse index used to reference the position of the cursor when navigating up and down the combobox list.
private readonly int _MouseIndex = -1;
/// <summary>
/// This method is used to draw the items from the 'emailRecipientsUserList' into the combobox,
/// using an owner draw custom format so we can show the the User Group & User
/// Account icons adjacent their relevant names in the combobox list.
///
/// In the method above, we created the 'emailRecipientsUserList' that contains data columns
/// from two different data tables, the first datatable holds the names of the User Groups and the second
/// holds the User Accounts. We're utilizing the KeyValuePair in order to provide a
/// means of applying some logic to the population of our combobox in order to differentiate
/// between a User Group and a User Account. This allows us to dynamically
/// assign the relevant icon display, adjacent each of the items in the combobox list.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void AddUserGroupCombobox_DrawItem(object sender, DrawItemEventArgs e)
{
// Set the textBrush color to Windows Text.
Brush textBrush = SystemBrushes.WindowText;
if (e.Index > -1)
{
// Highlight the combobox item when the mouse cursor hovers over the item in the dropdown list.
if (e.Index == _MouseIndex)
{
e.Graphics.FillRectangle(SystemBrushes.HotTrack, e.Bounds);
textBrush = SystemBrushes.HighlightText;
}
else
{
// Highlight the combobox item when slected in the dropdown list.
if ((e.State & DrawItemState.Selected) == DrawItemState.Selected)
{
e.Graphics.FillRectangle(SystemBrushes.Highlight, e.Bounds);
textBrush = SystemBrushes.HighlightText;
}
else
{
// Restore background colour to deafult when the mouse leaves the item.
e.Graphics.FillRectangle(SystemBrushes.Window, e.Bounds);
}
}
// Draw the string i.e populate the combobox with the list of the text names
// for the User groups & User Accounts
e.Graphics.DrawString(emailRecipientsUserList[e.Index].Value.ToString(), e.Font, textBrush, e.Bounds.Left + 20, e.Bounds.Top);
// IF Statements below are used to determine which icon to display in the drop down list, depending on
// whether the comboxo item is a User Group or User Account name.
if (emailRecipientsUserList[e.Index].Key == "UserGroup")
{
// Image list index '0' represents the icon image for the User Group.
e.Graphics.DrawImage(imageListEmailRecipients.Images[0], e.Bounds.Left, e.Bounds.Top);
}
if (emailRecipientsUserList[e.Index].Key == "Username")
{
// Image list index '0' represents the icon image for the User Account.
e.Graphics.DrawImage(imageListEmailRecipients.Images[1], e.Bounds.Left, e.Bounds.Top);
}
}
}