为啥会一直刷新WM_PAINT函数？求解啊

漠水

自制一个输出函数，调用后为啥会一直刷新

1. #include<windows.h>
   
2. #include "strsafe.h"
   
3. LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
   
4. 
   
5. int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
   
6. {
   
7. static TCHAR szAppName[] = TEXT("my windows");
   
8. HWND hwnd;
   
9. MSG msg;
   
10. WNDCLASS wndclass;
    
11. 
    
12. wndclass.style = CS_HREDRAW | CS_VREDRAW;
    
13. wndclass.lpfnWndProc = WndProc;
    
14. wndclass.cbClsExtra = 0;
    
15. wndclass.cbWndExtra = 0;
    
16. wndclass.hInstance = hInstance;
    
17. wndclass.hIcon = LoadIcon(NULL,IDI_APPLICATION);
    
18. wndclass.hCursor = LoadCursor(NULL,IDC_ARROW);
    
19. wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    
20. wndclass.lpszMenuName = NULL;
    
21. wndclass.lpszClassName = szAppName;
    
22. 
    
23. if(!RegisterClass(&wndclass))
    
24. {
    
25. MessageBox(NULL,TEXT(""),szAppName,MB_OK);
    
26. return 0;
    
27. 
    
28. }
    
29. 
    
30. hwnd = CreateWindow(szAppName,
    
31. TEXT("这才是正文"),
    
32. WS_OVERLAPPEDWINDOW,
    
33. CW_USEDEFAULT,
    
34. CW_USEDEFAULT,
    
35. CW_USEDEFAULT,
    
36. CW_USEDEFAULT,
    
37. NULL,
    
38. NULL,
    
39. hInstance,
    
40. NULL);
    
41. ShowWindow(hwnd, iCmdShow);
    
42. 
    
43. UpdateWindow(hwnd);
    
44. 
    
45. while(GetMessage(&msg,NULL,0,0))
    
46. {
    
47. TranslateMessage(&msg);
    
48. DispatchMessage(&msg);
    
49. 
    
50. }
    
51. 
    
52. return msg.wParam;
    
53. 
    
54. }
    
55. 
    
56. int print(HWND hwnd ,int ch,TCHAR cha[])
    
57. {
    
58. 
    
59. HDC hdc;
    
60. int x,y;
    
61. TCHAR szBuffer[128]; //字符数组
    
62. size_t TT; //字符数组长度
    
63. TEXTMETRIC tm; // 字符的尺寸 TEXTMETRIC 结构记录当前设备环境中有关字体的各种信息
    
64. 
    
65. hdc = GetDC(hwnd);
    
66. GetTextMetrics(hdc,&tm);
    
67. x = tm.tmAveCharWidth; //字符的尺寸宽度
    
68. y = tm.tmHeight +tm.tmExternalLeading; //字符的尺寸高度+字符的尺寸上下间距
    
69. 
    
70. StringCchPrintf(szBuffer,128,cha); //
    
71. StringCchLength(szBuffer,128,&TT); //
    
72. 
    
73. TextOut(hdc,0,ch*y,szBuffer,TT);
    
74. 
    
75. ReleaseDC(hwnd,hdc); //
    
76. 
    
77. ch = ch + 1;
    
78. return ch;
    
79. 
    
80. 
    
81. 
    
82. }
    
83. 
    
84. 
    
85. LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
    
86. {
    
87. 
    
88. int ch = 0;
    
89. 
    
90. 
    
91. TCHAR szBuffer[12] = TEXT("HELLO WORLD");
    
92. 
    
93. switch(message)
    
94. {
    
95. 
    
96. 
    
97. case WM_PAINT:
    
98. //s print(HWND hwnd ,s ch,TCHAR cha[])
    
99. ch = print(hwnd,ch,szBuffer);
    
100. ch = print(hwnd,ch,szBuffer);
     
101. 
     
102. return 0;
     
103. 
     
104. 
     
105. case WM_DESTROY:
     
106. PostQuitMessage(0);
     
107. return 0;
     
108. 
     
109. }
     
110. 
     
111. return DefWindowProc(hwnd,message,wParam,lParam);
     
112. 
     
113. 
     
114. }

复制代码

向往青莲

http://baike.baidu.com/link?url=DMiXg_-CIhKpcW3y74wwJIqHtdSZ4t2-ZAud-7zxXdw0cXegeuV6ceBIolp5NwhyDZEAP5omCLuN4ZHPU4xieq

漠水

向往青莲 发表于 2015-1-8 10:48
http://baike.baidu.com/link?url=DMiXg_-CIhKpcW3y74wwJIqHtdSZ4t2-ZAud-7zxXdw0cXegeuV6ceBIolp5NwhyDZEA ...

原来是因为WM_PAINT函数必须以hdc = BeginPaint(hwnd,&ps);这语句作为开始
以EndPaint(hwnd,&ps);作为结束
不能用GetDC(hwnd)和Release(hwnd,hdc)作为开始和结束啊

freeparty

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