概述：
在公司，不能自己安裝軟件，也不能下載，但有時候需要截圖。用PrintScreen鍵只能截取全屏，感覺很麻煩。於是決定自己編寫一個截圖工具。
眾所周知，QQ截圖首先將截取全屏為一個圖片，然後用在這個圖片基礎上截取需要的部分。本程序實現方法類似。
程序運行截圖如下：
圖中心矩形為即將截取區域
程序很粗糙，希望大家提出寶貴意見。
1，自定義矩形類MyRectangle
在QQ截圖程序中，用戶用鼠標繪制出的截圖區域是可調整大小和位置的，在4個邊的中點和4個頂點各有一個小矩形標記。（如圖所示）
.NET Framework中本身沒有這樣的矩形，因此要自定義實現。
考慮到類的專用性，不必實現.Net Framework2.0中Rectangle的全部功能。
該MyRectangle類圖如下：
MyRectangle需包含如下屬性
int X記錄矩形左上角x坐標
int Y記錄矩形左上角y坐標
int DownPointX繪制矩形時鼠標落點x坐標
int DownPointY繪制矩形時鼠標落點y坐標
int Width矩形寬
int Height矩形高
int MinWidth 矩形最小寬度
int MinHeight 矩形最小高度
bool ChangeSizeMode 標識矩形當前繪制模式是否為“改變大小”
bool MoveMode 標識矩形當前繪制模式是否為“移動”
bool MouseOnLeftTop 標識鼠標當前位置是否在矩形左上角
bool MouseOnLeftMiddle 標識鼠標當前位置是否在矩形左邊中點
bool MouseOnLeftBottom 標識鼠標當前位置是否在矩形左下角
bool MouseOnRightTop 標識鼠標當前位置是否在矩形右上角
bool MouseOnRightMiddle 標識鼠標當前位置是否在矩形右邊中點
bool MouseOnRightBottom 標識鼠標當前位置是否在矩形右下角
bool MouseOnTopMiddle 標識鼠標當前位置是否在矩形頂邊中點
bool MouseOnBottomMiddle 標識鼠標當前位置是否在矩形底邊中點
bool MouseOnMiddle 標識鼠標當前位置是否在矩形中心
int LittleRectangleWidth 矩形周邊8個小矩形的寬度
int LittleRectangleHeight 矩形周邊8個小矩形的高度
Rectangle LeftTopRectangle 矩形左上角小矩形
Rectangle LeftMiddleRectangle 矩形左邊中點小矩形
Rectangle LeftBottomRectangle 矩形左下角小矩形
Rectangle RightTopRectangle 矩形右上角小矩形
Rectangle RightMiddleRectangle 矩形右邊中點小矩形
Rectangle RightBottomRectangle 矩形右下角小矩形
Rectangle TopMiddleRectangle 矩形頂邊中點小矩形
Rectangle BottomMiddleRectangle 矩形底邊中點小矩形
Rectangle Rect 主體矩形
Size Size 矩形大小
Image BackImage 背景圖片
Cursor MyCursor 光標樣式
矩形本身包含監測當前繪制模式和繪制方法，主要方法成員如下：
SetLittleRectangle() 設置8個小矩形
Draw(Color backColor) 繪制方法，+1重載
ChangeSize(MouseEventArgs e) 改變矩形大小
Move(int newX, int newY) 改變矩形位置
CheckMouseLocation(MouseEventArgs e) 判斷鼠標當前落點
setAllModeFalse() 將所有模式設定為false
public bool onChangingMode() 判斷當前繪制模式是否為“改變大小”或“移動”
Initialize(int x, int y, int width, int height) 根據給定參數初始化矩形
MyRectagle類代碼實現如下：
class MyRectangle
2 {
3 /**//// <summary>
4 /// The x-coordinate of the upper-left corner of the main rectangle
5 /// </summary>
6 private int x;
7
8 /**//// <summary>
9 /// The star x-coordinate when you draw the main rectangle
10 /// </summary>
11 private int downPointX;
12
13 /**//// <summary>
14 /// The y-coordinate of the upper-left corner of the main rectangle
15 /// </summary>
16 private int y;
17
18 /**//// <summary>
19 /// The star y-coordinate when you draw the main rectangle
20 /// </summary>
21 private int downPointY;
22
23 /**//// <summary>
24 /// The width of the main rectangle
25 /// </summary>
26 private int width;
27
28 /**//// <summary>
29 /// The height of the main rectangle
30 /// </summary>
31 private int height;
32
33 /**//// <summary>
34 /// The least width of the main rectangle
35 /// </summary>
36 private int minWidth;
37
38 /**//// <summary>
39 /// The least height of the main rectangle
40 /// </summary>
41 private int minHeight;
42
43 /**//// <summary>
44 /// Sign the main rectangle is on change size mode or not
45 /// </summary>
46 private bool changeSizeMode;
47
48 /**//// <summary>
49 /// Sign the main rectangle is on move mode or not
50 /// </summary>
51 private bool moveMode;
52
53 /**//// <summary>
54 /// Sign the current mouse position is on the upper-left corner of the main rectangle or not
55 /// </summary>
56 private bool mouseOnLeftTop;
57 /**//// <summary>
58 /// Sign the current mouse position is on the middle point of the left line of the main rectangle or not
59 /// </summary>
60 private bool mouseOnLeftMiddle;
61 /**//// <summary>
62 /// Sign the current mouse position is on the bottom-left corner of the main rectangle or not
63 /// </summary>
64 private bool mouseOnLeftBottom;
65
66 /**//// <summary>
67 /// Sign the current mouse position is on the upper-right corner of the mian rectangle or not
68 /// </summary>
69 private bool mouseOnRightTop;
70 /**//// <summary>
71 /// 鼠標落點在右中點標志
72 /// </summary>
73 private bool mouseOnRightMiddle;
74 /**//// <summary>
75 /// Sign the current mouse position is on the middle point of the right line of the main rectangle or not
76 /// </summary>
77 private bool mouseOnRightBottom;
78
79 /**//// <summary>
80 /// Sign the current mouse position is on the middle point of the top line of the main rectangle or not
81 /// </summary>
82 private bool mouseOnTopMiddle;
83 /**//// <summary>
84 /// Sign the current mouse position is on the middle point of the bottom line of the main rectangle or not
85 /// </summary>
86 private bool mouseOnBottomMiddle;
87
88 /**//// <summary>
89 /// Sign the current mouse position is in the main rectangle or not
90 /// </summary>
91 private bool mouseOnMiddle;
92 /**//// <summary>
93 /// The width of the 8 little rectangles that on the 4 corners and the 4 middle points that of the 4 lines of the main rectangle
94 /// </summary>
95 private int littleRectangleWidth;
96 /**//// <summary>
97 /// The height of the 8 little rectangles that on the 4 corners and the 4 middle points that of the 4 lines of the main rectangle
98 /// </summary>
99 private int littleRectangleHeight;
100
101 /**//// <summary>
102 /// The little rectangle on the upper-left corner of the main rectangle
103 /// </summary>
104 private Rectangle leftTopRectangle;
105 /**//// <summary>
106 /// The little rectangle on the middle point of the left line of the main rectangle
107 /// </summary>
108 private Rectangle leftMiddleRectangle;
109 /**//// <summary>
110 /// The little rectangle on the bottom-left corner of the main rectangle
111 /// </summary>
112 private Rectangle leftBottomRectangle;
113
114 /**//// <summary>
115 /// The little rectangle on the upper-right corner of the main rectangle
116 /// </summary>
117 private Rectangle rightTopRectangle;
118 /**//// <summary>
119 /// The little rectangle on the middle point of the right line of the main rectangle
120 /// </summary>
121 private Rectangle rightMiddleRectangle;
122 /**//// <summary>
123 /// The little rectangle on the bottom-right corner of the main rectangle
124 /// </summary>
125 private Rectangle rightBottomRectangle;
126
127 /**//// <summary>
128 /// The little rectangle on the middle point of the top line of the main rectangle
129 /// </summary>
130 private Rectangle topMiddleRectangle;
131 /**//// <summary>
132 /// The little rectangle on the middle point of the bottom line of the main rectangle
133 /// </summary>
134 private Rectangle bottomMiddleRectangle;
135
136 /**//// <summary>
137 /// The main rectangle
138 /// </summary>
139 private Rectangle rect;
140
141 /**//// <summary>
142 /// The size of the main rectangle
143 /// </summary>
144 private Size size;
145
146 /**//// <summary>
147 /// The background image of the screen
148 /// </summary>
149 private Image backImage;
150
151 /**//// <summary>
152 /// The cursor manner
153 /// </summary>
154 private Cursor myCursor;
155
156 /**//// <summary>
157 /// Gets of sets the x-coordinate of the upper-left corner of the main rectangle
158 /// </summary>
159 public int X
160 {
161 get { return x; }
162 set
163 {
164 x = value;
165 rect.X = value;
166 }
167 }
168 /**//// <summary>
169 /// Gets of sets the y-coordinate of the upper-left corner of the main rectangle
170 /// </summary>
171 public int Y
172 {
173 get { return y; }
174 set
175 {
176 y = value;
177 rect.Y = value;
178 }
179 }
180
181 /**//// <summary>
182 /// Gets of sets the star x-coordinate when you draw the main rectangle
183 /// </summary>
184 public int DownPointX
185 {
186 get { return downPointX; }
187 set { downPointX = value; }
188 }
189 /**//// <summary>
190 /// Gets of sets the star y-coordinate when you draw the main rectangle
191 /// </summary>
192 public int DownPointY
193 {
194 get { return downPointY; }
195 set { downPointY = value; }
196 }
197 /**//// <summary>
198 /// Gets of sets the width of the main rectangle
199 /// </summary>
200 public int Width
201 {
202 get { return width; }
203 set
204 {
205 width = value;
206 rect.Width = value;
207 }
208 }
209 /**//// <summary>
210 /// Gets or sets the height of the main rectangle
211 /// </summary>
212 public int Height
213 {
214 get { return height; }
215 set
216 {
217 height = value;
218 rect.Height = value;
219 }
220 }
221
222 /**//// <summary>
223 /// Gets or sets the least width of the main rectangle
224 /// </summary>
225 public int MinWidth
226 {
227 get { return minWidth; }
228 set { minWidth = value; }
229 }
230
231 /**//// <summary>
232 /// Gets or sets the least height of the main rectangle
233 /// </summary>
234 public int MinHeight
235 {
236 get { return minHeight; }
237 set { minHeight = value; }
238 }
239
240 /**//// <summary>
241 /// Gets or sets the sign of the change size mode of the main rectangle
242 /// </summary>
243 public bool ChangeSizeMode
244 {
245 get { return changeSizeMode; }
246 set
247 {
248 changeSizeMode = value;
249 moveMode = !value;
250 }
251 }
252
253 /**//// <summary>
254 /// Gets or sets the sign of the move mode of the main rectangle
255 /// </summary>
256 public bool MoveMode
257 {
258 get { return moveMode; }
259 set
260 {
261 moveMode = value;
262 changeSizeMode = !value;
263 }
264 }
265
266 /**//// <summary>
267 /// Gets or sets the sign of current mouse position
268 /// (is on the upper-left corner of the main rectangle or not)
269 /// </summary>
270 public bool MouseOnLeftTop
271 {
272 get { return mouseOnLeftTop; }
273 set
274 {
275 mouseOnLeftTop = value;
276 if (value)
277 {
278 mouseOnLeftMiddle = false;
279 mouseOnLeftBottom = false;
280
281 mouseOnRightTop = false;
282 mouseOnRightMiddle = false;
283 mouseOnRightBottom = false;
284
285 mouseOnTopMiddle = false;
286 mouseOnBottomMiddle = false;
287
288 mouseOnMiddle = false;
289 }
290 }
291 }
292 /**//// <summary>
293 /// Gets or sets the sign of current mouse position
294 /// (is on the middle point of the left line of the main rectangle or not)
295 /// </summary>
296 public bool MouseOnLeftMiddle
297 {
298 get { return mouseOnLeftMiddle; }
299 set
300 {
301 mouseOnLeftMiddle = value;
302 if (value)
303 {
304 mouseOnLeftTop = false;
305 mouseOnLeftBottom = false;
306
307 mouseOnRightTop = false;
308 mouseOnRightMiddle = false;
309 mouseOnRightBottom = false;
310
311 mouseOnTopMiddle = false;
312 mouseOnBottomMiddle = false;
313
314 mouseOnMiddle = false;
315 }
316 }
317 }
318 /**//// <summary>
319 /// Gets or sets the sign of current mouse position
320 /// (is on the bottom-left corner of the main rectangle or not)
321 /// </summary>
322 public bool MouseOnLeftBottom
323 {
324 get { return mouseOnLeftBottom; }
325 set
326 {
327 mouseOnLeftBottom = value;
328 if (value)
329 {
330 mouseOnLeftTop = false;
331 mouseOnLeftMiddle = false;
332
333 mouseOnRightTop = false;
334 mouseOnRightMiddle = false;
335 mouseOnRightBottom = false;
336
337 mouseOnTopMiddle = false;
338 mouseOnBottomMiddle = false;
339
340 mouseOnMiddle = false;
341 }
342 }
343 }
344
345 /**//// <summary>
346 /// Gets or sets the sign of current mouse position
347 /// (is on the upper-right corner of the main rectangle or not)
348 /// </summary>
349 public bool MouseOnRightTop
350 {
351 get { return mouseOnRightTop; }
352 set
353 {
354 mouseOnRightTop = value;
355 if (value)
356 {
357 mouseOnLeftTop = false;
358 MouseOnLeftMiddle = false;
359 mouseOnLeftBottom = false;
360
361 mouseOnRightMiddle = false;
362 mouseOnRightBottom = false;
363
364 mouseOnTopMiddle = false;
365 mouseOnBottomMiddle = false;
366
367 mouseOnMiddle = false;
368 }
369 }
370 }
371 /**//// <summary>
372 /// Gets or sets the sign of current mouse position
373 /// (is on the middle point of the right line of the main rectangle or not)
374 /// </summary>
375 public bool MouseOnRightMiddle
376 {
377 get { return mouseOnRightMiddle; }
378 set
379 {
380 mouseOnRightMiddle = value;
381 if (value)
382 {
383 mouseOnLeftTop = false;
384 mouseOnLeftBottom = false;
385 mouseOnLeftMiddle = false;
386
387 mouseOnRightTop = false;
388 mouseOnRightBottom = false;
389
390 mouseOnTopMiddle = false;
391 mouseOnBottomMiddle = false;
392
393 mouseOnMiddle = false;
394 }
395 }
396 }
397 /**//// <summary>
398 /// Gets or sets the sign of current mouse position
399 /// (is on the bottom-right corner of the main rectangle or not)
400 /// </summary>
401 public bool MouseOnRightBottom
402 {
403 get { return mouseOnRightBottom; }
404 set
405 {
406 mouseOnRightBottom = value;
407 if (value)
408 {
409 mouseOnLeftTop = false;
410 mouseOnLeftBottom = false;
411 mouseOnLeftMiddle = false;
412
413 mouseOnRightTop = false;
414 mouseOnRightMiddle = false;
415
416 mouseOnTopMiddle = false;
417 mouseOnBottomMiddle = false;
418
419 mouseOnMiddle = false;
420 }
421 }
422 }
423
424 /**//// <summary>
425 /// Gets or sets the sign of current mouse position
426 /// (is on the middle point of the top line of the main rectangle or not)
427 /// </summary>
428 public bool MouseOnTopMiddle
429 {
430 get { return mouseOnTopMiddle; }
431 set
432 {
433 mouseOnTopMiddle = value;
434 if (value)
435 {
436 mouseOnLeftTop = false;
437 mouseOnLeftBottom = false;
438 mouseOnLeftMiddle = false;
439
440 mouseOnRightTop = false;
441 mouseOnRightBottom = false;
442 mouseOnRightMiddle = false;
443
444 mouseOnBottomMiddle = false;
445
446 mouseOnMiddle = false;
447 }
448 }
449 }
450 /**//// <summary>
451 /// Gets or sets the sign of current mouse position
452 /// (is on the middle point of the middle line of the main rectangle or not)
453 /// </summary>
454 public bool MouseOnBottomMiddle
455 {
456 get { return mouseOnBottomMiddle; }
457 set
458 {
459 mouseOnBottomMiddle = value;
460 if (value)
461 {
462 mouseOnLeftTop = false;
463 mouseOnLeftBottom = false;
464 mouseOnLeftMiddle = false;
465
466 mouseOnRightTop = false;
467 mouseOnRightBottom = false;
468 mouseOnRightMiddle = false;
469
470 mouseOnTopMiddle = false;
471
472 mouseOnMiddle = false;
473 }
474 }
475 }
476
477 /**//// <summary>
478 /// Gets or sets the sign of current mouse position
479 /// (is in the main rectangle or not)
480 /// </summary>
481 public bool MouseOnMiddle
482 {
483 get { return mouseOnMiddle; }
484 set
485 {
486 mouseOnMiddle = value;
487 if (value)
488 {
489 mouseOnLeftTop = false;
490 mouseOnLeftBottom = false;
491 mouseOnLeftMiddle = false;
492
493 mouseOnRightTop = false;
494 mouseOnRightBottom = false;
495 mouseOnRightMiddle = false;
496
497 mouseOnTopMiddle = false;
498 MouseOnBottomMiddle = false;
499 }
500 }
501 }
502 /**//// <summary>
