WM_PAINT 问题
请问为什么下面的程序会出现一些区域 没有重绘 的现象（灰色的区域）？
重现步骤：
运行下面程序， 最大化
运行另外一个程序，比如计算器， 移动计算器窗口
就会出现 灰色区域 （最好快速拖动计算器窗口，比较容易重现）
// vcwin32.cpp : Defines the entry point for the application.//#include "stdafx.h"#include "vcwin32.h"//---------------------------------------#include <windows.h>#include <winuser.h>#include <commctrl.h>#include <tchar.h>#include <assert.h>HINSTANCE ghInstance;// Global Instance// Prototyp WindowFunctionLRESULT CALLBACK WndProcedure (HWND hwnd, UINT msg,WPARAM w, LPARAM l);//****************************************************************************************HWND mainWin;int WINAPI _tWinMain(HINSTANCE hInstance, HINSTANCE /*hPrevInstance*/, LPTSTR /*lpCmdLine*/, int nCmdShow){ //InitCommonControls(); static TCHAR szAppName[]= __TEXT("Test_WmPaint"); static TCHAR szTitleBar[]= __TEXT("Title Bar"); WNDCLASSEX wndclass; MSG msg; // Register Class ghInstance = hInstance; wndclass.cbSize = sizeof(WNDCLASSEX); wndclass.style = CS_HREDRAW | CS_VREDRAW | CS_DBLCLKS ; wndclass.lpfnWndProc = WndProcedure; wndclass.cbClsExtra = 0; wndclass.cbWndExtra = 0; wndclass.hInstance = hInstance; wndclass.hIcon = NULL;//LoadIcon (ghInstance, IDI_APPLICATION); wndclass.hCursor = LoadCursor (NULL, IDC_ARROW); //wndclass.hbrBackground = Null; //wndclass.hbrBackground = CreateSolidBrush(RGB(200,0,0)); wndclass.hbrBackground = (HBRUSH)(COLOR_GRAYTEXT+1);//GetStockObject (WHITE_BRUSH); wndclass.lpszMenuName = NULL; wndclass.lpszClassName = szAppName; wndclass.hIconSm = NULL;//LoadIcon(NULL, IDI_APPLICATION); if (!RegisterClassEx (&wndclass)) { MessageBox(NULL, __TEXT("Window Registration Failed!"), __TEXT("Error!"), MB_ICONEXCLAMATION | MB_OK); return -1; } // Create Window and show Window mainWin = CreateWindow (szAppName, szTitleBar, WS_OVERLAPPEDWINDOW, //WS_POPUP, //!WS_CAPTION , 200, // x position for this window 200, // y position for this window 300, // window width 300, // window height NULL, // parent NULL, // menu hInstance, NULL); // user data if (mainWin == NULL) { MessageBox(NULL, __TEXT("Window Creation Failed!"), __TEXT("Error!"),MB_ICONEXCLAMATION | MB_OK); return 0; } ShowWindow (mainWin, nCmdShow); UpdateWindow (mainWin); // Dispatch Message or exit program while (GetMessage (&msg, NULL, 0, 0)) { //if(!IsDialogMessage(hwnd, &msg)){ TranslateMessage (&msg); DispatchMessage (&msg); //} } return (msg.wParam);}//**************************************************************************HBRUSH brushes[] = { CreateSolidBrush(RGB(100,0,0)), CreateSolidBrush(RGB(0,160,0)), CreateSolidBrush(RGB(0,0,255)),};LRESULT CALLBACK WndProcedure (HWND hWnd, UINT wMsg, WPARAM wParam, LPARAM lParam){ static int x=0; assert(hWnd!=NULL); int ret=0; HDC hdc=NULL; //HPEN pen=NULL; PAINTSTRUCT ps; RECT rt; SetRect(&rt,0,0,0,0); // init switch (wMsg) { case WM_CREATE: break; case WM_LBUTTONDOWN: return 0; /* hdc = GetDC(hWnd); GetClientRect(hWnd, &rt); FillRect(hdc, &rt, brushes[0]); ReleaseDC(hWnd, hdc); break; */ case WM_PAINT:{ x++; hdc = BeginPaint(hWnd, &ps); rt = ps.rcPaint; SetRect(&rt, 0,0,2000,2000); //use this line can easy see which region is painted. ret=FillRect(hdc, &rt/*&ps.rcPaint*/, brushes[x%2]); //ret=FillRect(hdc, &ps.rcPaint, brushes[0]); if(ret==0) { MessageBox(mainWin, __TEXT("fill rect Error "), __TEXT("Error"), MB_OK); } //RedrawWindow(hWnd, &ps.rcPaint, NULL, RDW_NOERASE); EndPaint(hWnd, &ps); //GdiFlush (); return 0; } case WM_ERASEBKGND: hdc = (HDC)wParam; rt.left = 0 ; rt.top = 0; rt.right = 300; rt.bottom = 300; ret=FillRect(hdc, &rt, brushes[2] ); return 1; case WM_DESTROY: PostQuitMessage (0); return (0); } return DefWindowProc (hWnd, wMsg, wParam, lParam);}
case WM_ERASEBKGND: hdc = (HDC)wParam; GetClientRect(hWnd, &rt); //rt.left = 0 ; rt.top = 0; //rt.right = 300; rt.bottom = 300; ret=FillRect(hdc, &rt, brushes[2] ); return 1;
[解决办法]
你选择一片区域重绘试试，就知道哪出问题了。
[解决办法]