大家好
我正在尝试创建一个自定义组合框。我创建了一个自定义下拉按钮并使用 is 作为下拉按钮。用户按下此按钮后，将打开一个面板，其中包含可以选择的项目列表（按钮格式）。用户选择一个项目后，下拉按钮的文本需要更改为所选项目的文本。我知道这是普通 Windows 窗体组合框的基本功能，但我将向此自定义组合框添加一些功能，这些功能对于普通 Windows 窗体组合框不可用。我遇到的问题是，自定义下拉按钮文本的更新仅在打开包含可用项目的面板、关闭它并再次打开它之后发生。我确信我只是简单的事情。一些帮助将不胜感激。
请参阅下面的自定义下拉按钮代码：
namespace Example.CustomControls
{
public class DropdownCheckBox : CheckBox
{
private int initialWidth;
private string dropdownText;
private Icon dropdownIcon = Properties.Resources.DropDownArrow;
public string DropDownText
{
get { return dropdownText; }
set
{
dropdownText = value;
this.Text = value;
}
}
public DropdownCheckBox()
{
TextAlign = ContentAlignment.MiddleLeft;
Margin = new Padding(0);
Padding = new Padding(0);
FlatAppearance.BorderSize = 1;
FlatStyle = FlatStyle.Flat;
BackColor = SystemColors.Window;
Appearance = Appearance.Button;
FlatAppearance.MouseOverBackColor = SystemColors.Window;
FlatAppearance.MouseDownBackColor = SystemColors.Window;
initialWidth = this.Width;
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
Text = dropdownText;
this.AutoSize = false;
this.Height = 21;
Rectangle dropDownIconRectangle = new Rectangle(this.Width - this.Height + 2, 2, this.Height - 4, this.Height - 4);
e.Graphics.FillRectangle(new SolidBrush(SystemColors.Control), dropDownIconRectangle);
e.Graphics.DrawIcon(dropdownIcon, dropDownIconRectangle);
}
}
}
我继承自复选框控件，因为我使用按钮的状态来打开和关闭包含可用项目列表（按钮格式）的面板。
请参阅下面为项目创建按钮的面板代码：
namespace Example.CustomControls
{
public class ButtonsPanel : Panel
{
public bool createState = false;
public string selectedItemButtonText;
public string[] itemsList = new string[0];
public string[] ItemsList
{
get { return itemsList; }
set
{
this.Controls.Clear();
itemsList = value;
createState = true;
Refresh();
}
}
public ButtonsPanel()
{
Dock = DockStyle.Top;
Margin = new Padding(0);
Padding = new Padding(0);
BorderStyle = BorderStyle.FixedSingle;
BackColor = SystemColors.Window;
AutoScroll = true;
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
this.Height = 5 * 21;
if (createState == true)
{
foreach (string item in itemsList.Reverse())
{
Button itemButton = new Button
{
Text = item,
Height = 21,
Dock = DockStyle.Top,
TextAlign = ContentAlignment.MiddleLeft,
Margin = new Padding(0),
Padding = new Padding(0),
FlatStyle = FlatStyle.Flat,
BackColor = SystemColors.Window,
};
itemButton.FlatAppearance.BorderSize = 0;
itemButton.FlatAppearance.MouseOverBackColor = SystemColors.Highlight;
itemButton.FlatAppearance.MouseDownBackColor = SystemColors.Highlight;
this.Controls.Add(itemButton);
}
foreach (Control itemButton in this.Controls)
{
itemButton.Click += ItemButton_Click;
}
createState = false;
}
}
private void ItemButton_Click(object sender, EventArgs e)
{
Button itemButton = (Button)sender;
selectedItemButtonText = itemButton.Text;
}
}
}
请参阅下面的自定义组合框代码：
namespace Example.CustomControls
{
public class CustomComboBox : UserControl
{
private string dropdownCheckBoxText = "Select Items";
private string[] dropDownitemsList = new string[0];
private DropdownCheckBox dropdownCheckBox;
private ButtonsPanel dropdownPanel;
public string DropDownButtonText
{
get { return dropdownCheckBoxText; }
set
{
dropdownCheckBoxText = value;
dropdownCheckBox.DropDownText = value;
}
}
public string[] DropDownItemsArray
{
get { return dropDownitemsList; }
set
{
dropdownPanel.Controls.Clear();
dropDownitemsList = value;
dropdownPanel.itemsList = value;
dropdownPanel.createState = true;
Refresh();
}
}
public CustomComboBox()
{
dropdownCheckBox = new DropdownCheckBox()
{
DropDownText = dropdownCheckBoxText,
Dock = DockStyle.Top
};
dropdownPanel = new ButtonsPanel();
this.Controls.Add(dropdownCheckBox);
this.Controls.Add(dropdownPanel);
dropdownPanel.Visible = false;
dropdownCheckBox.CheckedChanged += DropDownCheckBox_CheckedChanged;
}
private void DropDownCheckBox_CheckedChanged(object sender, EventArgs e)
{
if (dropdownCheckBox.Checked == true)
{
Console.WriteLine("Eina");
this.Height = dropdownCheckBox.Height + dropdownPanel.Height;
dropdownPanel.Visible = true;
dropdownPanel.BringToFront();
foreach (Button itemButton in dropdownPanel.Controls)
{
itemButton.MouseClick += CustomComboBox_MouseClick;
}
}
else
{
this.Height = dropdownCheckBox.Height;
dropdownPanel.Visible = false;
dropdownPanel.SendToBack();
foreach (Button itemButton in dropdownPanel.Controls)
{
itemButton.MouseClick -= CustomComboBox_MouseClick;
}
}
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
if (dropdownCheckBox.Checked == true)
{
this.Height = dropdownCheckBox.Height + dropdownPanel.Height;
}
else
{
this.Height = dropdownCheckBox.Height;
}
}
private void CustomComboBox_MouseClick(object sender, MouseEventArgs e)
{
dropdownCheckBoxText = dropdownPanel.selectedItemButtonText; ;
dropdownCheckBox.DropDownText = dropdownPanel.selectedItemButtonText;
}
}
}
据我所知，当我创建“CustomComboBox_MouseClick”事件时，最初报告了 0 个控件，但我不确定为什么。
namespace WindowsFormsApp2
{
public class CustomComboBox : FlowLayoutPanel
{
private CheckBox dropDownButton;
private FlowLayoutPanel dropDownFlowLayoutPanel;
private Button itemButton;
private Icon dropdownIcon = Properties.Resources.DropDownArrow;
public CustomComboBox(string initialDropDownButtonText, string[] itemsList)
{
dropDownButton = new CheckBox
{
Text = initialDropDownButtonText,
Height = 23,
Margin = new Padding(1, 1, 1, 0),
Appearance = Appearance.Button,
FlatStyle = FlatStyle.Flat,
TextAlign = System.Drawing.ContentAlignment.MiddleLeft,
BackColor = SystemColors.Window
};
dropDownButton.FlatAppearance.MouseOverBackColor = SystemColors.Window;
dropDownButton.FlatAppearance.MouseDownBackColor = SystemColors.Window;
dropDownButton.FlatAppearance.CheckedBackColor = SystemColors.Window;
dropDownButton.Paint += DropDownButton_Paint;
dropDownFlowLayoutPanel = new FlowLayoutPanel
{
Height = 10 * dropDownButton.Height,
BorderStyle = BorderStyle.FixedSingle,
Margin = new Padding(1, 0, 1, 1),
BackColor = SystemColors.Window,
AutoScroll = true
};
foreach (string item in itemsList)
{
itemButton = new Button
{
Text = item,
Height = 23,
Width = dropDownFlowLayoutPanel.Width,
Margin = new Padding(0),
FlatStyle = FlatStyle.Flat,
TextAlign = System.Drawing.ContentAlignment.MiddleLeft,
BackColor = SystemColors.Window
};
itemButton.FlatAppearance.BorderSize = 0;
itemButton.FlatAppearance.MouseOverBackColor = SystemColors.Highlight;
itemButton.FlatAppearance.MouseDownBackColor = SystemColors.Highlight;
dropDownFlowLayoutPanel.Controls.Add(itemButton);
}
foreach (Button button in dropDownFlowLayoutPanel.Controls)
{
button.Click += Button_Click;
}
this.Controls.Add(dropDownButton);
this.Controls.Add(dropDownFlowLayoutPanel);
dropDownButton.CheckedChanged += DropDownButton_CheckedChanged;
}
private void DropDownButton_CheckedChanged(object sender, EventArgs e)
{
if (dropDownButton.Checked)
{
this.Height = dropDownButton.Height + dropDownFlowLayoutPanel.Height + 2;
}
else
{
this.Height = dropDownButton.Height + 1;
}
}
private void Button_Click(object sender, EventArgs e)
{
Button clickedItem = (Button)sender;
dropDownButton.Text = clickedItem.Text;
}
private void DropDownButton_Paint(object sender, PaintEventArgs e)
{
Rectangle dropDownButtonIconRectangle = new Rectangle(dropDownButton.Width - dropDownButton.Height + 2, 2, dropDownButton.Height - 4, dropDownButton.Height - 4);
e.Graphics.FillRectangle(new SolidBrush(SystemColors.Control), dropDownButtonIconRectangle);
e.Graphics.DrawIcon(dropdownIcon, dropDownButtonIconRectangle);
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
dropDownButton.Width = this.Width - 2;
dropDownFlowLayoutPanel.Width = this.Width - 2;
if (dropDownButton.Checked)
{
this.Height = dropDownButton.Height + dropDownFlowLayoutPanel.Height + 1;
}
else
{
this.Height = dropDownButton.Height + 1;
}
}
}
}