（九）c#Winform自定义控件-树
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2023-04-04 20:14:49
前提 入行已经7,8年了，一直想做一套漂亮点的自定义控件，于是就有了本系列文章。 开源地址：https://gitee.com/kwwwvagaa/net_winform_custom_control 如果觉得写的还行，请点个 star 支持一下吧 欢迎前来交流探讨： 企鹅群568015492 目录 ......
前提
入行已经7,8年了，一直想做一套漂亮点的自定义控件，于是就有了本系列文章。
开源地址：
如果觉得写的还行，请点个 star 支持一下吧
欢迎前来交流探讨： 企鹅群568015492
目录
准备工作
对原始树控件treeview进行扩展以更改样式
先了解一下我们需要哪些功能，控件ain可以更改整好颜色，行高，选中效果，分割线等
开始
添加组件，命名treeviewex 继承treeview
先看下属性
1 private const int ws_vscroll = 2097152;
2
3 private const int gwl_style = -16;
4
5 private dictionary<string, string> _lsttips = new dictionary<string, string>();
6
7 private font _tipfont = new font("arial unicode ms", 12f);
8
9 private image _tipimage = resources.tips;
10
11 private bool _isshowtip = false;
12
13 private bool _isshowbycustommodel = true;
14
15 private int _nodeheight = 50;
16
17 private image _nodedownpic = resources.list_add;
18
19 private image _nodeuppic = resources.list_subtract;
20
21 private color _nodebackgroundcolor = color.fromargb(61, 60, 66);
22
23 private color _nodeforecolor = color.white;
24
25 private bool _nodeisshowsplitline = false;
26
27 private color _nodesplitlinecolor = color.fromargb(54, 53, 58);
28
29 private color m_nodeselectedcolor = color.fromargb(255, 121, 74);
30
31 private color m_nodeselectedforecolor = color.white;
32
33 private bool _parentnodecanselect = true;
34
35 private sizef treefontsize = sizef.empty;
36
37 private bool blnhasvbar = false;
38
39 public dictionary<string, string> lsttips
40 {
41 get
42 {
43 return this._lsttips;
44 }
45 set
46 {
47 this._lsttips = value;
48 }
49 }
50
51 [category("自定义属性"), description("角标文字字体")]
52 public font tipfont
53 {
54 get
55 {
56 return this._tipfont;
57 }
58 set
59 {
60 this._tipfont = value;
61 }
62 }
63
64 [category("自定义属性"), description("是否显示角标")]
65 public image tipimage
66 {
67 get
68 {
69 return this._tipimage;
70 }
71 set
72 {
73 this._tipimage = value;
74 }
75 }
76
77 [category("自定义属性"), description("是否显示角标")]
78 public bool isshowtip
79 {
80 get
81 {
82 return this._isshowtip;
83 }
84 set
85 {
86 this._isshowtip = value;
87 }
88 }
89
90 [category("自定义属性"), description("使用自定义模式")]
91 public bool isshowbycustommodel
92 {
93 get
94 {
95 return this._isshowbycustommodel;
96 }
97 set
98 {
99 this._isshowbycustommodel = value;
100 }
101 }
102
103 [category("自定义属性"), description("节点高度（isshowbycustommodel=true时生效）")]
104 public int nodeheight
105 {
106 get
107 {
108 return this._nodeheight;
109 }
110 set
111 {
112 this._nodeheight = value;
113 base.itemheight = value;
114 }
115 }
116
117 [category("自定义属性"), description("下翻图标（isshowbycustommodel=true时生效）")]
118 public image nodedownpic
119 {
120 get
121 {
122 return this._nodedownpic;
123 }
124 set
125 {
126 this._nodedownpic = value;
127 }
128 }
129
130 [category("自定义属性"), description("上翻图标（isshowbycustommodel=true时生效）")]
131 public image nodeuppic
132 {
133 get
134 {
135 return this._nodeuppic;
136 }
137 set
138 {
139 this._nodeuppic = value;
140 }
141 }
142
143 [category("自定义属性"), description("节点背景颜色（isshowbycustommodel=true时生效）")]
144 public color nodebackgroundcolor
145 {
146 get
147 {
148 return this._nodebackgroundcolor;
149 }
150 set
151 {
152 this._nodebackgroundcolor = value;
153 }
154 }
155
156 [category("自定义属性"), description("节点字体颜色（isshowbycustommodel=true时生效）")]
157 public color nodeforecolor
158 {
159 get
160 {
161 return this._nodeforecolor;
162 }
163 set
164 {
165 this._nodeforecolor = value;
166 }
167 }
168
169 [category("自定义属性"), description("节点是否显示分割线（isshowbycustommodel=true时生效）")]
170 public bool nodeisshowsplitline
171 {
172 get
173 {
174 return this._nodeisshowsplitline;
175 }
176 set
177 {
178 this._nodeisshowsplitline = value;
179 }
180 }
181
182 [category("自定义属性"), description("节点分割线颜色（isshowbycustommodel=true时生效）")]
183 public color nodesplitlinecolor
184 {
185 get
186 {
187 return this._nodesplitlinecolor;
188 }
189 set
190 {
191 this._nodesplitlinecolor = value;
192 }
193 }
194
195 [category("自定义属性"), description("选中节点背景颜色（isshowbycustommodel=true时生效）")]
196 public color nodeselectedcolor
197 {
198 get
199 {
200 return this.m_nodeselectedcolor;
201 }
202 set
203 {
204 this.m_nodeselectedcolor = value;
205 }
206 }
207
208 [category("自定义属性"), description("选中节点字体颜色（isshowbycustommodel=true时生效）")]
209 public color nodeselectedforecolor
210 {
211 get
212 {
213 return this.m_nodeselectedforecolor;
214 }
215 set
216 {
217 this.m_nodeselectedforecolor = value;
218 }
219 }
220
221 [category("自定义属性"), description("父节点是否可选中")]
222 public bool parentnodecanselect
223 {
224 get
225 {
226 return this._parentnodecanselect;
227 }
228 set
229 {
230 this._parentnodecanselect = value;
231 }
232 }
样式的更改主要通过节点的重绘，我们使用drawnode事件来完成
1 base.drawnode += new drawtreenodeeventhandler(this.treeview_drawnode);
2
3 private void treeview_drawnode(object sender, drawtreenodeeventargs e)
4 {
5 try
6 {
7 if (e.node == null || !this._isshowbycustommodel || (e.node.bounds.width <= 0 && e.node.bounds.height <= 0 && e.node.bounds.x <= 0 && e.node.bounds.y <= 0))
8 {
9 e.drawdefault = true;
10 }
11 else
12 {
13 if (base.nodes.indexof(e.node) == 0)
14 {
15 this.blnhasvbar = this.isverticalscrollbarvisible();
16 }
17 font font = e.node.nodefont;
18 if (font == null)
19 {
20 font = ((treeview)sender).font;
21 }
22 if (this.treefontsize == sizef.empty)
23 {
24 this.treefontsize = this.getfontsize(font, e.graphics);
25 }
26 bool flag = false;
27 int num = 0;
28 if (base.imagelist != null && base.imagelist.images.count > 0 && e.node.imageindex >= 0 && e.node.imageindex < base.imagelist.images.count)
29 {
30 flag = true;
31 num = (e.bounds.height - base.imagelist.imagesize.height) / 2;
32 }
33 if ((e.state == treenodestates.selected || e.state == treenodestates.focused || e.state == (treenodestates.focused | treenodestates.selected)) && (this._parentnodecanselect || e.node.nodes.count <= 0))
34 {
35 e.graphics.fillrectangle(new solidbrush(this.m_nodeselectedcolor), new rectangle(new point(0, e.node.bounds.y), new size(base.width, e.node.bounds.height)));
36 e.graphics.drawstring(e.node.text, font, new solidbrush(this.m_nodeselectedforecolor), (float)e.bounds.x, (float)e.bounds.y + ((float)this._nodeheight - this.treefontsize.height) / 2f);
37 }
38 else
39 {
40 e.graphics.fillrectangle(new solidbrush(this._nodebackgroundcolor), new rectangle(new point(0, e.node.bounds.y), new size(base.width, e.node.bounds.height)));
41 e.graphics.drawstring(e.node.text, font, new solidbrush(this._nodeforecolor), (float)e.bounds.x, (float)e.bounds.y + ((float)this._nodeheight - this.treefontsize.height) / 2f);
42 }
43 if (flag)
44 {
45 int num2 = e.bounds.x - num - base.imagelist.imagesize.width;
46 if (num2 < 0)
47 {
48 num2 = 3;
49 }
50 e.graphics.drawimage(base.imagelist.images[e.node.imageindex], new rectangle(new point(num2, e.bounds.y + num), base.imagelist.imagesize));
51 }
52 if (this._nodeisshowsplitline)
53 {
54 e.graphics.drawline(new pen(this._nodesplitlinecolor, 1f), new point(0, e.bounds.y + this._nodeheight - 1), new point(base.width, e.bounds.y + this._nodeheight - 1));
55 }
56 bool flag2 = false;
57 if (e.node.nodes.count > 0)
58 {
59 if (e.node.isexpanded && this._nodeuppic != null)
60 {
61 e.graphics.drawimage(this._nodeuppic, new rectangle(base.width - (this.blnhasvbar ? 50 : 30), e.bounds.y + (this._nodeheight - 20) / 2, 20, 20));
62 }
63 else if (this._nodedownpic != null)
64 {
65 e.graphics.drawimage(this._nodedownpic, new rectangle(base.width - (this.blnhasvbar ? 50 : 30), e.bounds.y + (this._nodeheight - 20) / 2, 20, 20));
66 }
67 flag2 = true;
68 }
69 if (this._isshowtip && this._lsttips.containskey(e.node.name) && !string.isnullorwhitespace(this._lsttips[e.node.name]))
70 {
71 int num3 = base.width - (this.blnhasvbar ? 50 : 30) - (flag2 ? 20 : 0);
72 int num4 = e.bounds.y + (this._nodeheight - 20) / 2;
73 e.graphics.drawimage(this._tipimage, new rectangle(num3, num4, 20, 20));
74 sizef sizef = e.graphics.measurestring(this._lsttips[e.node.name], this._tipfont, 100, stringformat.generictypographic);
75 e.graphics.drawstring(this._lsttips[e.node.name], this._tipfont, new solidbrush(color.white), (float)(num3 + 10) - sizef.width / 2f - 3f, (float)(num4 + 10) - sizef.height / 2f);
76 }
77 }
78 }
79 catch (exception ex)
80 {
81 throw ex;
82 }
83 }
84
85 private sizef getfontsize(font font, graphics g = null)
86 {
87 sizef result;
88 try
89 {
90 bool flag = false;
91 if (g == null)
92 {
93 g = base.creategraphics();
94 flag = true;
95 }
96 sizef sizef = g.measurestring("a", font, 100, stringformat.generictypographic);
97 if (flag)
98 {
99 g.dispose();
100 }
101 result = sizef;
102 }
103 catch (exception ex)
104 {
105 throw ex;
106 }
107 return result;
108 }
109
110 [dllimport("user32", charset = charset.auto)]
111 private static extern int getwindowlong(intptr hwnd, int nindex);
112
113 private bool isverticalscrollbarvisible()
114 {
115 return base.ishandlecreated && (treeviewex.getwindowlong(base.handle, -16) & 2097152) != 0;
116 }
我们还需要对选中节点时做一些处理
1 private void treeviewex_nodemouseclick(object sender, treenodemouseclickeventargs e)
2 {
3 try
4 {
5 if (e.node != null)
6 {
7 if (e.node.nodes.count > 0)
8 {
9 if (e.node.isexpanded)
10 {
11 e.node.collapse();
12 }
13 else
14 {
15 e.node.expand();
16 }
17 }
18 if (base.selectednode != null)
19 {
20 if (base.selectednode == e.node && e.node.isexpanded)
21 {
22 if (!this._parentnodecanselect)
23 {
24 if (e.node.nodes.count > 0)
25 {
26 base.selectednode = e.node.nodes[0];
27 }
28 }
29 }
30 }
31 }
32 }
33 catch (exception ex)
34 {
35 throw ex;
36 }
37 }
选中后也需要根据属性做相应的操作
1 private void treeviewex_afterselect(object sender, treevieweventargs e)
2 {
3 try
4 {
5 if (e.node != null)
6 {
7 if (!this._parentnodecanselect)
8 {
9 if (e.node.nodes.count > 0)
10 {
11 e.node.expand();
12 base.selectednode = e.node.nodes[0];
13 }
14 }
15 }
16 }
17 catch (exception ex)
18 {
19 throw ex;
20 }
21 }
主要的东西就这些了，我们看下完成的代码吧
1 // 版权所有 黄正辉 交流群：568015492 qq：623128629
2 // 文件名称：treeviewex.cs
3 // 创建日期：2019-08-15 16:00:55
4 // 功能描述：treeview
5 // 项目地址：https://gitee.com/kwwwvagaa/net_winform_custom_control
6
7 using system;
8 using system.collections.generic;
9 using system.componentmodel;
10 using system.diagnostics;
11 using system.drawing;
12 using system.linq;
13 using system.runtime.interopservices;
14 using system.text;
15 using system.windows.forms;
16 using hzh_controls.properties;
17
18 namespace hzh_controls.controls
19 {
20 public partial class treeviewex : treeview
21 {
22
23 private const int ws_vscroll = 2097152;
24
25 private const int gwl_style = -16;
26
27 private dictionary<string, string> _lsttips = new dictionary<string, string>();
28
29 private font _tipfont = new font("arial unicode ms", 12f);
30
31 private image _tipimage = resources.tips;
32
33 private bool _isshowtip = false;
34
35 private bool _isshowbycustommodel = true;
36
37 private int _nodeheight = 50;
38
39 private image _nodedownpic = resources.list_add;
40
41 private image _nodeuppic = resources.list_subtract;
42
43 private color _nodebackgroundcolor = color.fromargb(61, 60, 66);
44
45 private color _nodeforecolor = color.white;
46
47 private bool _nodeisshowsplitline = false;
48
49 private color _nodesplitlinecolor = color.fromargb(54, 53, 58);
50
51 private color m_nodeselectedcolor = color.fromargb(255, 121, 74);
52
53 private color m_nodeselectedforecolor = color.white;
54
55 private bool _parentnodecanselect = true;
56
57 private sizef treefontsize = sizef.empty;
58
59 private bool blnhasvbar = false;
60
61 public dictionary<string, string> lsttips
62 {
63 get
64 {
65 return this._lsttips;
66 }
67 set
68 {
69 this._lsttips = value;
70 }
71 }
72
73 [category("自定义属性"), description("角标文字字体")]
74 public font tipfont
75 {
76 get
77 {
78 return this._tipfont;
79 }
80 set
81 {
82 this._tipfont = value;
83 }
84 }
85
86 [category("自定义属性"), description("是否显示角标")]
87 public image tipimage
88 {
89 get
90 {
91 return this._tipimage;
92 }
93 set
94 {
95 this._tipimage = value;
96 }
97 }
98
99 [category("自定义属性"), description("是否显示角标")]
100 public bool isshowtip
101 {
102 get
103 {
104 return this._isshowtip;
105 }
106 set
107 {
108 this._isshowtip = value;
109 }
110 }
111
112 [category("自定义属性"), description("使用自定义模式")]
113 public bool isshowbycustommodel
114 {
115 get
116 {
117 return this._isshowbycustommodel;
118 }
119 set
120 {
121 this._isshowbycustommodel = value;
122 }
123 }
124
125 [category("自定义属性"), description("节点高度（isshowbycustommodel=true时生效）")]
126 public int nodeheight
127 {
128 get
129 {
130 return this._nodeheight;
131 }
132 set
133 {
134 this._nodeheight = value;
135 base.itemheight = value;
136 }
137 }
138
139 [category("自定义属性"), description("下翻图标（isshowbycustommodel=true时生效）")]
140 public image nodedownpic
141 {
142 get
143 {
144 return this._nodedownpic;
145 }
146 set
147 {
148 this._nodedownpic = value;
149 }
150 }
151
152 [category("自定义属性"), description("上翻图标（isshowbycustommodel=true时生效）")]
153 public image nodeuppic
154 {
155 get
156 {
157 return this._nodeuppic;
158 }
159 set
160 {
161 this._nodeuppic = value;
162 }
163 }
164
165 [category("自定义属性"), description("节点背景颜色（isshowbycustommodel=true时生效）")]
166 public color nodebackgroundcolor
167 {
168 get
169 {
170 return this._nodebackgroundcolor;
171 }
172 set
173 {
174 this._nodebackgroundcolor = value;
175 }
176 }
177
178 [category("自定义属性"), description("节点字体颜色（isshowbycustommodel=true时生效）")]
179 public color nodeforecolor
180 {
181 get
182 {
183 return this._nodeforecolor;
184 }
185 set
186 {
187 this._nodeforecolor = value;
188 }
189 }
190
191 [category("自定义属性"), description("节点是否显示分割线（isshowbycustommodel=true时生效）")]
192 public bool nodeisshowsplitline
193 {
194 get
195 {
196 return this._nodeisshowsplitline;
197 }
198 set
199 {
200 this._nodeisshowsplitline = value;
201 }
202 }
203
204 [category("自定义属性"), description("节点分割线颜色（isshowbycustommodel=true时生效）")]
205 public color nodesplitlinecolor
206 {
207 get
208 {
209 return this._nodesplitlinecolor;
210 }
211 set
212 {
213 this._nodesplitlinecolor = value;
214 }
215 }
216
217 [category("自定义属性"), description("选中节点背景颜色（isshowbycustommodel=true时生效）")]
218 public color nodeselectedcolor
219 {
220 get
221 {
222 return this.m_nodeselectedcolor;
223 }
224 set
225 {
226 this.m_nodeselectedcolor = value;
227 }
228 }
229
230 [category("自定义属性"), description("选中节点字体颜色（isshowbycustommodel=true时生效）")]
231 public color nodeselectedforecolor
232 {
233 get
234 {
235 return this.m_nodeselectedforecolor;
236 }
237 set
238 {
239 this.m_nodeselectedforecolor = value;
240 }
241 }
242
243 [category("自定义属性"), description("父节点是否可选中")]
244 public bool parentnodecanselect
245 {
246 get
247 {
248 return this._parentnodecanselect;
249 }
250 set
251 {
252 this._parentnodecanselect = value;
253 }
254 }
255 public treeviewex()
256 {
257 base.hideselection = false;
258 base.drawmode = treeviewdrawmode.ownerdrawall;
259 base.drawnode += new drawtreenodeeventhandler(this.treeview_drawnode);
260 base.nodemouseclick += new treenodemouseclickeventhandler(this.treeviewex_nodemouseclick);
261 base.sizechanged += new eventhandler(this.treeviewex_sizechanged);
262 base.afterselect += new treevieweventhandler(this.treeviewex_afterselect);
263 base.fullrowselect = true;
264 base.showlines = false;
265 base.showplusminus = false;
266 base.showrootlines = false;
267 this.backcolor = color.fromargb(61, 60, 66);
268 doublebuffered = true;
269 }
270 protected override void wndproc(ref message m)
271 {
272
273 if (m.msg == 0x0014) // 禁掉清除背景消息wm_erasebkgnd
274
275 return;
276
277 base.wndproc(ref m);
278
279 }
280 private void treeviewex_afterselect(object sender, treevieweventargs e)
281 {
282 try
283 {
284 if (e.node != null)
285 {
286 if (!this._parentnodecanselect)
287 {
288 if (e.node.nodes.count > 0)
289 {
290 e.node.expand();
291 base.selectednode = e.node.nodes[0];
292 }
293 }
294 }
295 }
296 catch (exception ex)
297 {
298 throw ex;
299 }
300 }
301
302 private void treeviewex_sizechanged(object sender, eventargs e)
303 {
304 this.refresh();
305 }
306
307 private void treeviewex_nodemouseclick(object sender, treenodemouseclickeventargs e)
308 {
309 try
310 {
311 if (e.node != null)
312 {
313 if (e.node.nodes.count > 0)
314 {
315 if (e.node.isexpanded)
316 {
317 e.node.collapse();
318 }
319 else
320 {
321 e.node.expand();
322 }
323 }
324 if (base.selectednode != null)
325 {
326 if (base.selectednode == e.node && e.node.isexpanded)
327 {
328 if (!this._parentnodecanselect)
329 {
330 if (e.node.nodes.count > 0)
331 {
332 base.selectednode = e.node.nodes[0];
333 }
334 }
335 }
336 }
337 }
338 }
339 catch (exception ex)
340 {
341 throw ex;
342 }
343 }
344
345 private void treeview_drawnode(object sender, drawtreenodeeventargs e)
346 {
347 try
348 {
349 if (e.node == null || !this._isshowbycustommodel || (e.node.bounds.width <= 0 && e.node.bounds.height <= 0 && e.node.bounds.x <= 0 && e.node.bounds.y <= 0))
350 {
351 e.drawdefault = true;
352 }
353 else
354 {
355 if (base.nodes.indexof(e.node) == 0)
356 {
357 this.blnhasvbar = this.isverticalscrollbarvisible();
358 }
359 font font = e.node.nodefont;
360 if (font == null)
361 {
362 font = ((treeview)sender).font;
363 }
364 if (this.treefontsize == sizef.empty)
365 {
366 this.treefontsize = this.getfontsize(font, e.graphics);
367 }
368 bool flag = false;
369 int num = 0;
370 if (base.imagelist != null && base.imagelist.images.count > 0 && e.node.imageindex >= 0 && e.node.imageindex < base.imagelist.images.count)
371 {
372 flag = true;
373 num = (e.bounds.height - base.imagelist.imagesize.height) / 2;
374 }
375 if ((e.state == treenodestates.selected || e.state == treenodestates.focused || e.state == (treenodestates.focused | treenodestates.selected)) && (this._parentnodecanselect || e.node.nodes.count <= 0))
376 {
377 e.graphics.fillrectangle(new solidbrush(this.m_nodeselectedcolor), new rectangle(new point(0, e.node.bounds.y), new size(base.width, e.node.bounds.height)));
378 e.graphics.drawstring(e.node.text, font, new solidbrush(this.m_nodeselectedforecolor), (float)e.bounds.x, (float)e.bounds.y + ((float)this._nodeheight - this.treefontsize.height) / 2f);
379 }
380 else
381 {
382 e.graphics.fillrectangle(new solidbrush(this._nodebackgroundcolor), new rectangle(new point(0, e.node.bounds.y), new size(base.width, e.node.bounds.height)));
383 e.graphics.drawstring(e.node.text, font, new solidbrush(this._nodeforecolor), (float)e.bounds.x, (float)e.bounds.y + ((float)this._nodeheight - this.treefontsize.height) / 2f);
384 }
385 if (flag)
386 {
387 int num2 = e.bounds.x - num - base.imagelist.imagesize.width;
388 if (num2 < 0)
389 {
390 num2 = 3;
391 }
392 e.graphics.drawimage(base.imagelist.images[e.node.imageindex], new rectangle(new point(num2, e.bounds.y + num), base.imagelist.imagesize));
393 }
394 if (this._nodeisshowsplitline)
395 {
396 e.graphics.drawline(new pen(this._nodesplitlinecolor, 1f), new point(0, e.bounds.y + this._nodeheight - 1), new point(base.width, e.bounds.y + this._nodeheight - 1));
397 }
398 bool flag2 = false;
399 if (e.node.nodes.count > 0)
400 {
401 if (e.node.isexpanded && this._nodeuppic != null)
402 {
403 e.graphics.drawimage(this._nodeuppic, new rectangle(base.width - (this.blnhasvbar ? 50 : 30), e.bounds.y + (this._nodeheight - 20) / 2, 20, 20));
404 }
405 else if (this._nodedownpic != null)
406 {
407 e.graphics.drawimage(this._nodedownpic, new rectangle(base.width - (this.blnhasvbar ? 50 : 30), e.bounds.y + (this._nodeheight - 20) / 2, 20, 20));
408 }
409 flag2 = true;
410 }
411 if (this._isshowtip && this._lsttips.containskey(e.node.name) && !string.isnullorwhitespace(this._lsttips[e.node.name]))
412 {
413 int num3 = base.width - (this.blnhasvbar ? 50 : 30) - (flag2 ? 20 : 0);
414 int num4 = e.bounds.y + (this._nodeheight - 20) / 2;
415 e.graphics.drawimage(this._tipimage, new rectangle(num3, num4, 20, 20));
416 sizef sizef = e.graphics.measurestring(this._lsttips[e.node.name], this._tipfont, 100, stringformat.generictypographic);
417 e.graphics.drawstring(this._lsttips[e.node.name], this._tipfont, new solidbrush(color.white), (float)(num3 + 10) - sizef.width / 2f - 3f, (float)(num4 + 10) - sizef.height / 2f);
418 }
419 }
420 }
421 catch (exception ex)
422 {
423 throw ex;
424 }
425 }
426
427 private sizef getfontsize(font font, graphics g = null)
428 {
429 sizef result;
430 try
431 {
432 bool flag = false;
433 if (g == null)
434 {
435 g = base.creategraphics();
436 flag = true;
437 }
438 sizef sizef = g.measurestring("a", font, 100, stringformat.generictypographic);
439 if (flag)
440 {
441 g.dispose();
442 }
443 result = sizef;
444 }
445 catch (exception ex)
446 {
447 throw ex;
448 }
449 return result;
450 }
451
452 [dllimport("user32", charset = charset.auto)]
453 private static extern int getwindowlong(intptr hwnd, int nindex);
454
455 private bool isverticalscrollbarvisible()
456 {
457 return base.ishandlecreated && (treeviewex.getwindowlong(base.handle, -16) & 2097152) != 0;
458 }
459 }
460 }
用处及效果
用处：觉得原始的treeview太难看了，想换一种好看点的风格
效果：
调用示例
for (int i = 0; i < 3; i++)
{
treenode tn = new treenode(" 父节点" + i);
for (int j = 0; j < 3; j++)
{
tn.nodes.add(" 子节点" + j);
}
this.treeviewex1.nodes.add(tn);
}
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