Winform组合ComboBox和TreeView实现ComboTreeView

最近做winform项目需要用到类似combobox的treeview控件。

虽然各种第三方控件很多，但是存在各种版本不兼容问题。所以自己写了个简单的combotreeview控件。

下图是实现效果：

目前实现的比较简单，能满足我项目中的需求。

此处是项目中的代码简化后的版本，供大家参考。

  1 using system;
  2 using system.collections.generic;
  3 using system.windows.forms;
  4 
  5 namespace customcontrol.tree
  6 {
  7     public abstract class combotreeview<t> : combobox where t : class
  8     {
  9         protected const int wm_lbuttondown = 0x0201, wm_lbuttondblclk = 0x0203;
 10 
 11         protected treeview treeview;
 12         protected toolstripcontrolhost treeviewhost;
 13         protected toolstripdropdown dropdown;
 14         protected bool dropdownopen = false;
 15         protected treenode selectednode;
 16         protected t selectednodedata;
 17         protected t tobeselected;
 18 
 19         public combotreeview(treeview internaltreeview)
 20         {
 21             if (null == internaltreeview)
 22             {
 23                 throw new argumentnullexception("internaltreeview");
 24             }
 25             this.initializecontrols(internaltreeview);
 26         }
 27 
 28         public event treenodechangedeventhandler treenodechanged;
 29 
 30         protected virtual void initializecontrols(treeview internaltreeview)
 31         {
 32             this.treeview = internaltreeview;
 33             this.treeview.borderstyle = borderstyle.fixedsingle;
 34             this.treeview.margin = new padding(0);
 35             this.treeview.padding = new padding(0);
 36             this.treeview.afterexpand += new treevieweventhandler(this.whenafterexpand);
 37 
 38             this.treeviewhost = new toolstripcontrolhost(this.treeview);
 39             this.treeviewhost.margin = new padding(0);
 40             this.treeviewhost.padding = new padding(0);
 41             this.treeviewhost.autosize = false;
 42 
 43             this.dropdown = new toolstripdropdown();
 44             this.dropdown.margin = new padding(0);
 45             this.dropdown.padding = new padding(0);
 46             this.dropdown.autosize = false;
 47             this.dropdown.dropshadowenabled = true;
 48             this.dropdown.items.add(this.treeviewhost);
 49             this.dropdown.closed += new toolstripdropdownclosedeventhandler(this.ondropdownclosed);
 50 
 51             this.dropdownwidth = this.width;
 52             base.dropdownstyle = comboboxstyle.dropdownlist;
 53             base.sizechanged += new eventhandler(this.whencomboboxsizechanged);
 54         }
 55 
 56         public new comboboxstyle dropdownstyle
 57         {
 58             get { return base.dropdownstyle; }
 59             set { base.dropdownstyle = comboboxstyle.dropdownlist; }
 60         }
 61 
 62         public virtual treenode selectednode
 63         {
 64             get { return this.selectednode; }
 65             private set { this.treeview.selectednode = value; }
 66         }
 67 
 68         public virtual t selectednodedata
 69         {
 70             get { return this.selectednodedata; }
 71             set
 72             {
 73                 this.selectednodedata = value;
 74                 this.tobeselected = value;
 75                 this.updatecombobox(value);
 76             }
 77         }
 78 
 79         protected new int selectedindex
 80         {
 81             get { return base.selectedindex; }
 82             set { base.selectedindex = value; }
 83         }
 84 
 85         protected new object selecteditem
 86         {
 87             get { return base.selecteditem; }
 88             set { base.selecteditem = value; }
 89         }
 90 
 91         public virtual string displaymember { get; set; } = "name";
 92 
 93         /// <summary>gets the internal treeview control.</summary>
 94         public virtual treeview treeview => this.treeview;
 95 
 96         /// <summary>gets the collection of tree nodes that are assigned to the tree view control.</summary>
 97         /// <returns>a <see cref="t:system.windows.forms.treenodecollection" /> that represents the tree nodes assigned to the tree view control.</returns>
 98         public virtual treenodecollection nodes => this.treeview.nodes;
 99 
100         public new int dropdownheight { get; set; } = 100;
101 
102         public new int dropdownwidth { get; set; } = 100;
103 
104         protected virtual void showdropdown()
105         {
106             this.dropdown.width = this.width;
107             this.dropdown.height = this.dropdownheight;
108             this.treeviewhost.width = this.width;
109             this.treeviewhost.height = this.dropdownheight;
110             this.treeview.font = this.font;
111             this.dropdown.focus();
112             this.dropdownopen = true;
113             this.dropdown.show(this, 0, base.height);
114         }
115 
116         protected virtual void hidedropdown()
117         {
118             this.dropdown.hide();
119             this.dropdownopen = false;
120         }
121 
122         protected virtual void toggledropdown()
123         {
124             if (!this.dropdownopen)
125             {
126                 this.showdropdown();
127             }
128             else
129             {
130                 this.hidedropdown();
131             }
132         }
133 
134         protected override void wndproc(ref message m)
135         {
136             if ((wm_lbuttondown == m.msg) || (wm_lbuttondblclk == m.msg))
137             {
138                 if (!this.focused)
139                 {
140                     this.focus();
141                 }
142                 this.toggledropdown();
143             }
144             else
145             {
146                 base.wndproc(ref m);
147             }
148         }
149 
150         protected override void dispose(bool disposing)
151         {
152             if (disposing)
153             {
154                 if (this.dropdown != null)
155                 {
156                     this.dropdown.dispose();
157                     this.dropdown = null;
158                 }
159             }
160             base.dispose(disposing);
161         }
162 
163         protected virtual void whentreenodechanged(treenode newvalue)
164         {
165             if ((null != this.selectednode) || (null != newvalue))
166             {
167                 bool changed;
168                 if ((null != this.selectednode) && (null != newvalue))
169                 {
170                     changed = (this.selectednode.gethashcode() != newvalue.gethashcode());
171                 }
172                 else
173                 {
174                     changed = true;
175                 }
176 
177                 if (changed && (null != this.treenodechanged))
178                 {
179                     try
180                     {
181                         this.treenodechanged.invoke(this, new treenodechangedeventargs(this.selectednode, newvalue));
182                     }
183                     catch (exception)
184                     {
185                         // do nothing
186                     }
187                 }
188 
189                 this.selectednode = newvalue;
190             }
191         }
192 
193         protected virtual void ondropdownclosed(object sender, toolstripdropdownclosedeventargs e)
194         {
195             if (null == this.tobeselected)
196             {
197                 var selectednode = this.treeview.selectednode;
198                 var selecteddata = this.gettreenodedata(selectednode);
199                 this.updatecombobox(selecteddata);
200                 this.whentreenodechanged(selectednode);
201             }
202         }
203 
204         protected virtual void updatecombobox(t data)
205         {
206             base.displaymember = this.displaymember; // update displaymember
207             if (null != data)
208             {
209                 this.datasource = new list<t>() { data };
210                 this.selectedindex = 0;
211             }
212             else
213             {
214                 this.datasource = null;
215             }
216         }
217 
218         protected virtual void whenafterexpand(object sender, treevieweventargs e)
219         {
220             if (null != this.tobeselected)
221             {
222                 if (this.selectchildnode(e.node.nodes, this.tobeselected))
223                 {
224                     this.tobeselected = null;
225                 }
226             }
227         }
228 
229         protected virtual void whencomboboxsizechanged(object sender, eventargs e)
230         {
231             this.dropdownwidth = base.width;
232         }
233 
234         public virtual bool selectchildnode(treenodecollection nodes, t data)
235         {
236             var node = this.findchildnode(nodes, data);
237             if (null != node)
238             {
239                 this.doselecttreenode(node);
240                 return true;
241             }
242             else
243             {
244                 return false;
245             }
246         }
247 
248         protected abstract bool identical(t x, t y);
249 
250         protected virtual void doselecttreenode(treenode node)
251         {
252             this.selectednode = node;
253             this.expandtreenode(node.parent);
254         }
255 
256         public virtual treenode findchildnode(treenodecollection nodes, t data)
257         {
258             foreach (treenode node in nodes)
259             {
260                 var nodedata = this.gettreenodedata(node);
261                 if (this.identical(nodedata, data))
262                 {
263                     return node;
264                 }
265             }
266 
267             return null;
268         }
269 
270         public virtual void expandtreenode(treenode node)
271         {
272             if (null != node)
273             {
274                 node.expand();
275                 this.expandtreenode(node.parent);
276             }
277         }
278 
279         public abstract t gettreenodedata(treenode node);
280     }
281 }

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