A snowy applet C ++ vc6.0

A small Win32 program. Use vc6.0.

1. # Include "stdafx. H"
2. # Include <windows. h>
3. # Include <math. h>
4. # Include <stdlib. h>
5. # Define id_timer 1
6. # Define snownum 500 // snowflake count
7. # Define contrast 50 // contrast
8. # Define ystart 5 // determines the Y coordinate at the beginning of the snowflake.
9. # Define snowcr RGB (0xff, 0xff, 0xff) // snowflake color-white
10. # Define snowgathercr RGB (0xdb, 0xdb, 0xff) // stacked snowflake color
12. Typedef struct tagsnow
13. {
14. Point ptsnowspos [snownum]; // used to save the coordinates of each snowflake
15. Colorref crorg [snownum]; // used to draw the original color of the screen before snowflake
16. Int ivx, Ivy, iallvx, iallvy;
17. } Snow;
19. Void initsnow (HDC, snow * sn, int isnow, int cxscreen );
20. Int getcontrast (HDC, snow * sn, int isnow );
21. Void drawsnow (HDC, snow * sn, int cxscreen );
23. Lresult callback wndproc (hwnd, uint, wparam, lparam );
25. Int winapi winmain (hinstance, hinstance hprevinstance,
26. Pstr szcmdline, int icmdshow)
27. {
28. Static tchar szappname [] = text ("cls1_snow ");
29. Hwnd;
30. MSG;
31. Wndclass;
33. Wndclass. Style = cs_hredraw | cs_vredraw;
34. Wndclass. lpfnwndproc = wndproc;
35. Wndclass. cbclsextra = 0;
36. Wndclass. cbwndextra = 0;
37. Wndclass. hinstance = hinstance;
38. Wndclass. hicon = loadicon (null, idi_application );
39. Wndclass. hcursor = loadcursor (null, idc_arrow );
40. Wndclass. hbrbackground = (hbrush) getstockobject (white_brush );
41. Wndclass. lpszmenuname = NULL;
42. Wndclass. lpszclassname = szappname;
44. If (! Registerclass (& wndclass ))
45. {
46. MessageBox (null, text ("this program requires Windows NT! "), Szappname, mb_iconerror );
47. Return 0;
48. }
50. Hwnd = createwindow (szappname, text ("desktop snow "),
51. Ws_minimizebox | ws_sysmenu,
52. Cw_usedefault, cw_usedefault,
53. 240,120,
54. Null, null, hinstance, null );
56. Showwindow (hwnd, icmdshow );
57. Updatewindow (hwnd );
59. While (getmessage (& MSG, null, 0, 0 ))
60. {
61. Translatemessage (& MSG );
62. Dispatchmessage (& MSG );
63. }
64. Return msg. wparam;
65. }
67. Lresult callback wndproc (hwnd, uint message, wparam, lparam)
68. {
69. HDC;
70. Paintstruct pS;
71. Rect;
72. Static int cxscreen, cyscreen; // screen width and height (unit: pixels)
73. Static int itimes, ilooptimes = 100;
74. Static snow snowdream;
75. Int I;
77. Switch (Message)
78. {
79. Case wm_create:
80. Cxscreen = getsystemmetrics (sm_cxscreen );
81. Cyscreen = getsystemmetrics (sm_cyscreen );
82. Srand (INT) getcurrenttime (); // initialize the random number generator
83. Snowdream. iallvx = (unsigned) rand () % 3-1; // snowflake overall horizontal floating speed (-, 1)
84. Snowdream. iallvy = (unsigned) rand () % 2 + 1; // The overall vertical falling speed of snowflake (1, 2)
85. HDC = getdc (null); // retrieves the context of the entire screen.
86. For (I = 0; I <snownum; I ++)
87. {
88. Snowdream. ptsnowspos [I]. x = rand () % cxscreen; // X coordinate of a snowflake that begins to fall
89. Snowdream. ptsnowspos [I]. Y = rand () % ystart; // y coordinate of a snowflake that begins to fall
90. Snowdream. crorg [I] = getpixel (HDC, snowdream. ptsnowspos [I]. X,
91. Snowdream. ptsnowspos [I]. Y); // obtain the original color value of the specified point.
92. }
93. Releasedc (null, HDC );
94. Settimer (hwnd, id_timer, 10, null); // timer, 10 ms
95. Return 0;
97. Case wm_displaychange: // when the resolution is changed
98. Cxscreen = getsystemmetrics (sm_cxscreen );
99. Cyscreen = getsystemmetrics (sm_cyscreen );
100. Return 0;
102. Case wm_timer:
103. HDC = getdc (null); // retrieves the context of the entire screen.
104. If (itimes> ilooptimes)
105. {
106. Itimes = 0;
107. Ilooptimes = 50 + (unsigned) rand () % 50;
108. If (snowdream. iallvx! = 0)
109. Snowdream. iallvx = 0;
110. Else
111. Snowdream. iallvx = (unsigned) rand () % 3-1; // snowflake overall horizontal floating speed (-, 1)
112. Snowdream. iallvy = (unsigned) rand () % 2 + 1; // The overall vertical falling speed of snowflake (1, 2)
113. }
114. Else
115. Itimes ++;
116. Drawsnow (HDC, & snowdream, cxscreen );
117. Releasedc (null, HDC );
118. Return 0;
120. Case wm_paint:
121. HDC = beginpaint (hwnd, & PS );
122. Getclientrect (hwnd, & rect );
123. Drawtext (HDC, text ("it's snowing on the desktop! "),-1, & rect,
124. Dt_singleline | dt_center | dt_vcenter );
125. Endpaint (hwnd, & PS );
126. Return 0;
128. Case wm_destroy:
129. Killtimer (hwnd, id_timer); // stop the timer
130. Invalidaterect (null, null, true); // refresh the Desktop
131. Postquitmessage (0 );
132. Return 0;
133. }
134. Return defwindowproc (hwnd, message, wparam, lparam );
135. }
137. Void initsnow (HDC, snow * sn, int isnow, int cxscreen) // initialize the isnow snowflake
138. {
139. Sn-> ptsnowspos [isnow]. x = (unsigned) rand () % cxscreen; // The Screen width in the X range
140. Sn-> ptsnowspos [isnow]. Y = (unsigned) rand () % ystart; // The value of Y is within the ystart pixel on the top of the screen.
141. Sn-> crorg [isnow] = getpixel (HDC, Sn-> ptsnowspos [isnow]. X,
142. Sn-> ptsnowspos [isnow]. Y); // obtain the original color value for the specified point
143. }
145. Int getcontrast (HDC, snow * sn, int isnow)
146. {
147. Int IR, Ig, IB;
148. Colorref crcmp;
150. If (0 = Sn-> ivx) // If the horizontal speed is 0, the point at the bottom of the pixel is greater than the value.
151. Crcmp = getpixel (HDC, Sn-> ptsnowspos [isnow]. X, Sn-> ptsnowspos [isnow]. Y + 1 );
152. Else // If the horizontal speed is greater than 0, take the point in the lower right. <0 indicates that the point in the lower left is used.
153. Crcmp = getpixel (HDC, Sn-> ptsnowspos [isnow]. x + (Sn-> ivx> 0? 1:-1), Sn-> ptsnowspos [isnow]. Y + 1 );
155. If (crcmp = snowcr) // if it is a snowflake color
156. Return 0;
158. // Obtain the difference between the blue, green, and red parts of the crcmp and the comparison point.
159. IB = ABS (crcmp> 16) & 0xff-(Sn-> crorg [isnow]> 16) & 0xff );
160. IG = ABS (crcmp> 8) & 0xff-(Sn-> crorg [isnow]> 8) & 0xff );
161. IR = ABS (crcmp) & 0xff-(Sn-> crorg [isnow]) & 0xff );
163. Return (IR + ig + IB)/3;
164. }
166. Void drawsnow (HDC, snow * sn, int cxscreen)
167. {
168. Int I;
169. For (I = 0; I <snownum; I ++)
170. {
171. // If the original color is not the snowflake color
172. If (Sn-> crorg [I]! = Snowcr)
173. Setpixel (HDC, Sn-> ptsnowspos [I]. X, Sn-> ptsnowspos [I]. y,
174. Sn-> crorg [I]); // restores the color of the previous position
176. Sn-> ivx = Sn-> iallvx * (I % 3 + 1); // X floating speed of snowflake
177. Sn-> Ivy = Sn-> iallvy * (I % 3 + 1); // y floating speed of snowflake
178. // Rand () % 5-2 jitter when the snowflake falls
179. Sn-> ptsnowspos [I]. x + = Sn-> ivx + rand () % 5-2; // The next X coordinate of snowflake
180. Sn-> ptsnowspos [I]. Y + = Sn-> Ivy + 1; // The next y coordinate of snowflake
182. // Obtain the original color value for the specified point
183. Sn-> crorg [I] = getpixel (HDC, Sn-> ptsnowspos [I]. X, Sn-> ptsnowspos [I]. y );
185. If (clr_invalid = Sn-> crorg [I]) // if the color fails to be obtained, the snowflake floats out of the screen.
186. {
187. Initsnow (HDC, Sn, I, cxscreen); // reinitialize snowflake
188. Continue;
189. }
190. If (Sn-> crorg [I]! = Snowcr) // if the color of the current vertex is not the color of snowflake
191. {
192. If (snowgathercr = Sn-> crorg [I]) // color of the current vertex = color of accumulated snow
193. {// Set to the snowflake color
194. Setpixel (HDC, Sn-> ptsnowspos [I]. X, Sn-> ptsnowspos [I]. Y, snowcr );
195. Sn-> crorg [I] = snowcr;
196. // Initsnow (HDC, Sn, I, cxscreen); // reinitialize snowflake
197. }
198. Else if (getcontrast (HDC, Sn, I)> 50) // If the contrast is greater than 50
199. {// Snow accumulation
200. Setpixel (HDC, Sn-> ptsnowspos [I]. X, Sn-> ptsnowspos [I]. Y, snowgathercr );
201. Setpixel (HDC, Sn-> ptsnowspos [I]. X-1, Sn-> ptsnowspos [I]. Y + 1, snowgathercr );
202. Setpixel (HDC, Sn-> ptsnowspos [I]. x + 1, Sn-> ptsnowspos [I]. Y + 1, snowgathercr );
203. Initsnow (HDC, Sn, I, cxscreen); // reinitialize snowflake
204. }
205. Else // contrast <50, do not accumulate, draw the snowflake frame, and then restore the original color of the point next time to produce the floating Effect
206. Setpixel (HDC, Sn-> ptsnowspos [I]. X, Sn-> ptsnowspos [I]. Y, snowcr );
207. }
208. }
209. }