Winform中如何实现下拉树效果
简介:Winform中如何实现下拉树效果(类似于ComboBox下拉时显示的是树状结构),
如果是BS的WebForm就有很多解决方案了,Devexpress就更方便,利用DropdownList和TreeView去组合控件实现
但是CS中的Winform的传统窗体控件和Devexpress里面去实现此功能就比较麻烦了
而此文,我们要讲解的就是如何利用Winform的传统用户控件去实现下拉树的效果
主要利用TextBox,TreeView,Button等控件事件组合而成类似于ComboBox下拉出现树状结构
下面就看看我们要实现的下拉树的效果图:
说明:上图所示的就是我们要实现的效果当点击下拉控件时,出现一个树状结构,
当我们选择树节点时(双击),把相应的节点值,放入上面的文本框中
好了,下面我们就马上去看看,这样的功能是如何实现的呢?
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首先我们需要建立一个用户控件,如图:
说明:不需要再进行任何操作
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接下来,我们需要放一张图片文件,这张图片文件是为了模拟下拉框右边的三角下拉按钮用的,如图:
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接下来就是完全的代码模块了,就这样的界面操作,是如何让我们做到下拉树效果的呢?
在用户控件窗体CS文件中,我们需要添加如下代码:
一.自定义成员变量
二.内部辅助方法
三.对TextBox的事件处理
四.对TreeView的事件处理
五.对Button的事件处理
六.对自身的事件处理
七.外部属性封装
八.构造函数
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别看上面说的步骤很多,其实加起来也就几百行代码,也没有什么难点,接下来我们就依次展示我们八大步骤模块的代码:
一.自定义成员变量
#region 自定义成员变量
private TextBox m_TextBox;
private TreeView m_TreeView;
private Button m_DropdownButton;
private int m_MaxDropDownItems = 8;
//是否正在显示下拉列表
private bool b_Dropdown = false;
//使能
private bool b_Enabled = true;
//事件
public event EventHandler DropDown;
public event EventHandler DropDownClosed;
public event EventHandler EnableChanged;
public event TreeViewCancelEventHandler BeforeExpand;
public event TreeViewCancelEventHandler BeforeCollapse;
public event TreeViewEventHandler AfterExpand;
public event TreeViewEventHandler AfterCollapse;
#endregion
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二.内部辅助方法
#region 内部辅助方法
/// <summary>
/// 创建并初始化所有控件，包括添加事件处理函数
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
private void InitControls()
{
//TextBox
this.m_TextBox = new TextBox();
this.m_TextBox.KeyDown += new KeyEventHandler(m_TextBox_KeyDown);
this.m_TextBox.Parent = this;
//Button
this.m_DropdownButton = new Button();
//Assembly asm = Assembly.GetExecutingAssembly();
//System.IO.Stream stream = asm.GetManifestResourceStream(asm.GetName().Name + ".BM_dropdown.bmp");
Bitmap bm = new Bitmap(this.GetType(), "BM_dropdown.bmp");
this.m_DropdownButton.Image = bm;
this.m_DropdownButton.Width = 16;
this.m_DropdownButton.Height = this.m_TextBox.Height - 2;
this.m_DropdownButton.Location = new Point(this.m_TextBox.Right - 18, 1);
this.m_DropdownButton.Click += new EventHandler(m_DropdownButton_Click);
this.m_DropdownButton.FlatStyle = FlatStyle.Flat;
this.m_DropdownButton.Parent = this;
this.m_DropdownButton.BringToFront();
//TreeView
this.m_TreeView = new TreeView();
this.m_TreeView.Visible = false;
this.m_TreeView.DoubleClick += new EventHandler(m_TreeView_DoubleClick);
this.m_TreeView.KeyDown += new KeyEventHandler(m_TreeView_KeyDown);
this.m_TreeView.LostFocus += new EventHandler(m_TreeView_LostFocus);
this.m_TreeView.BeforeExpand += new TreeViewCancelEventHandler(m_TreeView_BeforeExpand);
this.m_TreeView.BeforeCollapse += new TreeViewCancelEventHandler(TreeComboBox_BeforeCollapse);
this.m_TreeView.AfterExpand += new TreeViewEventHandler(m_TreeView_AfterExpand);
this.m_TreeView.AfterCollapse += new TreeViewEventHandler(TreeComboBox_AfterCollapse);
this.m_TreeView.Location = new Point(0, 0);
this.m_TreeView.Parent = null;
this.LostFocus += new EventHandler(TreeComboBox_LostFocus);
}
/// <summary>
/// 布局所有控件，让TextBox尺寸适应容器尺寸
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
private void LayoutControls()
{
this.m_TextBox.Width = this.Width;
this.Height = this.m_TextBox.Height;
this.m_DropdownButton.Left = this.m_TextBox.Right - 18;
this.m_DropdownButton.Height = this.m_TextBox.Height - 2;
this.m_TreeView.Width = this.Width;
this.m_TreeView.Height = (int) ((this.Font.Height + 3)*this.m_MaxDropDownItems);
}
/// <summary>
/// 显示下拉列表
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
private void ShowDropDown()
{
if (this.Parent == null)
return;
// 智能计算显示的位置，尝试在下方显示，如果没有足够空间，则在上方显示
// 尝试在下方的位置（现在只是相对父窗口的相对位置）
Point pos = new Point(this.Left, this.Bottom - 1);
// 把位置映射到顶层窗口,获取父窗口的屏幕坐标
Point parentPos = this.Parent.PointToScreen(this.Parent.Location);
// 获取顶层窗口的屏幕坐标
Point topParentPos = this.TopLevelControl.PointToScreen(this.Parent.Location);
// 把相对父窗口的位置变换为相对顶级窗口的位置，因为popup的父是顶级窗口
pos.Offset(parentPos.X - topParentPos.X, parentPos.Y - topParentPos.Y);
// 检查是否有足够空间用于在label下方显示day picker
if ((pos.Y + this.m_TreeView.Height) > this.TopLevelControl.ClientRectangle.Height)
{
// 没有足够的空间（超出了顶级窗口客户区），尝试在上方显示将Y方向，向上平移
pos.Y -= (this.Height + this.m_TreeView.Height);
if (pos.Y < 0)
{
// 如果上方仍然没有空间显示，则显示在顶级窗口的底部
pos.Y = (this.TopLevelControl.ClientRectangle.Height - this.m_TreeView.Height);
}
}
// 尝试停靠,如果右边超过顶级窗口的客户区，则将控件向左移动，并紧靠在顶级窗口右侧
if ((pos.X + this.m_TreeView.Width) > this.TopLevelControl.ClientRectangle.Width)
pos.X = (this.TopLevelControl.ClientRectangle.Width - this.m_TreeView.Width);
this.m_TreeView.Location = pos; // this.Parent.PointToScreen(pt);
this.m_TreeView.Visible = true;
this.m_TreeView.Parent = this.TopLevelControl;
this.m_TreeView.BringToFront();
this.b_Dropdown = true;
//raise event
if (this.DropDown != null)
this.DropDown(this, EventArgs.Empty);
this.m_TreeView.Focus();
}
/// <summary>
/// 隐藏下拉列表
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
private void HideDropDown()
{
if (this.DropDownClosed != null)
this.DropDownClosed(this, EventArgs.Empty);
this.m_TreeView.Parent = null;
this.m_TreeView.Visible = false;
this.b_Dropdown = false;
}
#endregion-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
三.对TextBox的事件处理
#region 事件处理 - TextBox
/// <summary>
/// 在编辑框中按下按键
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void m_TextBox_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
if (this.b_Dropdown)
this.HideDropDown();
else
this.ShowDropDown();
}
else if (e.KeyCode == Keys.Down)
{
this.ShowDropDown();
this.m_TreeView.Focus();
}
}
#endregion-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
四.对TreeView的事件处理
#region 事件处理 - TreeView
/// <summary>
/// 在下拉列表中选择了一个节点的事件处理！
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void m_TreeView_KeyDown(object sender, KeyEventArgs e)
{
//如果按下回车表示要选中当前节点
if (e.KeyCode == Keys.Enter)
{
this.m_TreeView_DoubleClick(sender, EventArgs.Empty);
}
}
/// <summary>
/// 失去焦点时，如果不是被下拉按钮夺取的焦点，则隐藏它！
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void m_TreeView_LostFocus(object sender, EventArgs e)
{
if (!this.m_DropdownButton.Focused)
this.HideDropDown();
}
/// <summary>
/// 在下拉列表中双击
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void m_TreeView_DoubleClick(object sender, EventArgs e)
{
TreeNode node = this.m_TreeView.SelectedNode;
if (node != null)
this.m_TextBox.Text = node.Text;
if (this.b_Dropdown)
{
this.HideDropDown();
}
}
/// <summary>
/// 折叠后事件
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void TreeComboBox_AfterCollapse(object sender, TreeViewEventArgs e)
{
if (this.AfterCollapse != null)
this.AfterCollapse(this, e);
}
/// <summary>
/// 折叠前事件
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void TreeComboBox_BeforeCollapse(object sender, TreeViewCancelEventArgs e)
{
if (this.BeforeCollapse != null)
this.BeforeCollapse(this, e);
}
/// <summary>
/// 展开后事件
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void m_TreeView_AfterExpand(object sender, TreeViewEventArgs e)
{
if (this.AfterExpand != null)
this.AfterExpand(this, e);
}
/// <summary>
/// 展开前事件
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void m_TreeView_BeforeExpand(object sender, TreeViewCancelEventArgs e)
{
if (this.BeforeExpand != null)
this.BeforeExpand(this, e);
}
#endregion-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
五.对Button的事件处理
#region 事件处理 - Button
/// <summary>
/// 下拉按钮点击事件
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void m_DropdownButton_Click(object sender, EventArgs e)
{
//throw new Exception("The method or operation is not implemented.");
if (this.b_Dropdown)
this.HideDropDown();
else
this.ShowDropDown();
}
#endregion-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
六.对自身的事件处理
#region 事件处理 - 自身
/// <summary>
/// 失去焦点
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void TreeComboBox_LostFocus(object sender, EventArgs e)
{
if (this.b_Dropdown)
this.HideDropDown();
}
/// <summary>
/// 重设尺寸
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="e"></param>
protected override void OnResize(EventArgs e)
{
base.OnResize(e);
this.LayoutControls();
}
/// <summary>
/// 尺寸改变
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
/// <param name="e"></param>
protected override void OnSizeChanged(EventArgs e)
{
base.OnSizeChanged(e);
this.LayoutControls();
}
#endregion-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
七.外部属性封装
#region 外部属性封装
/// <summary>
/// 获取节点集合
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
public TreeNodeCollection Nodes
{
get { return this.m_TreeView.Nodes; }
}
/// <summary>
/// 设置或者获取节点的图片列表
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
public ImageList ImageList
{
get { return this.m_TreeView.ImageList; }
set { this.m_TreeView.ImageList = value; }
}
/// <summary>
/// 重写enabled属性
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
public new bool Enabled
{
get { return this.b_Enabled; }
set
{
if (this.b_Enabled != value)
{
this.b_Enabled = value;
this.m_DropdownButton.Enabled = value;
this.b_Enabled = value;
//当灰掉时，隐藏下拉列表
if (!this.b_Enabled && this.b_Dropdown)
this.HideDropDown();
if (this.EnableChanged != null)
this.EnableChanged(this, EventArgs.Empty);
}
}
}
/// <summary>
/// 字体
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
public override Font Font
{
get { return base.Font; }
set
{
base.Font = value;
this.m_TextBox.Font = value;
this.m_TreeView.Font = value;
//调整布局
this.LayoutControls();
}
}
/// <summary>
/// 重写Text
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
public override string Text
{
get { return this.m_TextBox.Text; }
set
{
if (this.Text != value)
{
this.m_TextBox.Text = value;
}
}
}
/// <summary>
/// 是否显示lines
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
public bool ShowLines
{
get { return this.m_TreeView.ShowLines; }
set { this.m_TreeView.ShowLines = value; }
}
/// <summary>
/// 是否显示+ -按钮
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
public bool ShowPlusMinus
{
get { return this.m_TreeView.ShowPlusMinus; }
set { this.m_TreeView.ShowPlusMinus = value; }
}
/// <summary>
/// 是否显示root lines
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
public bool ShowRootLines
{
get { return this.m_TreeView.ShowRootLines; }
set { this.m_TreeView.ShowRootLines = value; }
}
/// <summary>
/// 是否显示root lines
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
public bool ShowNodeToolTips
{
get { return this.m_TreeView.ShowNodeToolTips; }
set { this.m_TreeView.ShowNodeToolTips = value; }
}
/// <summary>
/// 获取或者设置选中的节点！
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
public TreeNode SelectedNode
{
get { return this.m_TreeView.SelectedNode; }
set
{
this.m_TreeView.SelectedNode = value;
if (value != null)
this.Text = value.Text;
}
}
/// <summary>
/// 设置下拉最多项
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 13:29:37</time>
public int MaxDropDownItems
{
get { return this.m_MaxDropDownItems; }
set
{
if (this.m_MaxDropDownItems != value)
{
this.m_MaxDropDownItems = value;
this.m_TreeView.Height = this.m_TextBox.Height*value;
}
}
}
#endregion-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
八.构造函数
/// <summary>
/// 构造函数
/// </summary>
public TreeComboBox()
{
this.InitControls();
this.LayoutControls();
}-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
OK,经过上面八个步骤,我们的下拉树自定义控件就完成了,接下来,就看下我们是如何使用它的
首先我们需要生成一下项目,成功后我们将在我们的工具栏中,看到如下控件:
说明:做到此处出现错误时,请参照文章尾部提出的解决方案...
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接下来我们就需要把该控件拖到我们的窗体中
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这些完成的之后,接下来我们就是我们真正的代码调用模块了,我们需要在调用下拉树控件窗体中添加如下代码:
首先是绑定数据:
/// <summary>
/// 数据分类数据绑定
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 14:22:35</time>
private void BindDataType()
{
for (int i = 0; i < 4; i++)
{
tcbDataType.Nodes.Add("key" + i, "Depart" + i, 0, 0);
for (int j = 0; j < i + 1; j++)
{
tcbDataType.Nodes[i].Nodes.Add("key_child" + i + j, "User" + i + j, 2, 2);
}
}
}说明:此处的for循环代表树的级数,在此我们可以看出,此代码将会生成一个两级树,如果我们想出现多级,只需要加入多个循环,就可以了
如果您嫌麻烦,可以封装一下通用方法
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其次是添加事件:
1.添加折叠事件
/// <summary>
/// 下拉树折叠后事件
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 14:18:29</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void tcbDataType_AfterCollapse(object sender, TreeViewEventArgs e)
{
if (e.Node.ImageIndex == 1)
e.Node.ImageIndex = e.Node.SelectedImageIndex = 0;
}2.添加展开事件
/// <summary>
/// 下拉树展开后事件
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-11-1 14:18:29</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void tcbDataType_AfterExpand(object sender, TreeViewEventArgs e)
{
if (e.Node.ImageIndex == 0)
e.Node.ImageIndex = e.Node.SelectedImageIndex = 1; }-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
最后,我们需要注册事件:
可以在调用窗体的构造函数中加入如下代码:
this.tcbDataType.AfterExpand += new TreeViewEventHandler(tcbDataType_AfterExpand);
this.tcbDataType.AfterCollapse += new TreeViewEventHandler(tcbDataType_AfterCollapse);
或者查看下拉树控件的属性,在相应的事件中,选择我们编写的事件即可,如下图:
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好了,到此,我们的下拉树就完成了,让我们看下效果,如图:
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细心的人一定会发现,不对啊,这个数结构和文章的第一张图里面不一样啊,是的,因为少了节点图片,
我们做的这么久还没有给节点加图片的操作呢,好了,接下来,就是我最后的操作了
给树节点加图片操作,分三步
1.拖一个ImageList控件到窗体中
2.给ImageList添加图片列表,如图
3.将我们的下拉树控件中的属性ImageList设置成我们刚拖进来的ImageList控件,就可以了
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好的,做到这,我们的下拉树控件的一个完整效果就完成了,运行之后,我们就会看见文章刚出现的效果图的画面了
不过,做到这,我们还要最后一个收尾操作,那就是获取下拉树中用户选择的节点键和值
代码如下:
/// <summary>
/// 查询
/// </summary>
/// <author>PengZhen</author>
/// <time>2013-10-30 11:08:03</time>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btSelect_Click(object sender, EventArgs e)
{
string value = tcbDataType.SelectedNode.Name;
MessageBox.Show(value);
string text = tcbDataType.Text.Trim();
MessageBox.Show(text);
}-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
OK,OK,终于,整个下拉树的完整操作就全部实现了,有木有发现很简单呢,嘿嘿
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备注:此控件请放在窗体中使用,别放在用户控件中使用,至于为什么,您可以试试,就会出现意想不到的效果噢,
而出现此问题,就留给你们自己去思考,解决吧,多去试试,变通思想,会出现更奇妙的事噢,
好了,就写到这,让你们自己去见证奇迹的时刻把,嘿嘿...
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写点题外话,当你们去完成以上操作时,可能会出现以下错误,去看看下面的链接,就知道怎么去解决了
System.ArgumentException无法在类中找到资源