UC知道WM_PAINT消息触发问题
来源：百度知道 编辑：UC知道 时间：2024/06/19 15:30:25
程序本来是想实现鼠标单击改变背景颜色。可是，程序运行时，为什么没有任何消息触发，背景颜色就一直不断的改变了？WM_PAINT怎么被触发的
#include <windows.h>
#include <stdlib.h>
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
void DrawRectangle (HWND) ;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("SetBackgroundColor") ;
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;
wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
#include <windows.h>
#include <stdlib.h>
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
void DrawRectangle (HWND) ;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("SetBackgroundColor") ;
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;
wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
这个基础，看一下《windows程序设计》第三章吧
wm_paint是有无效区域的时候 产生的消息，所以应首先恢复该区域，才不会一直循环下去
wm_paint中应该用beginpaint与endpaint这两个api，参数是PaintStruct类型，它们的功能正是使无效区域恢复
而不是getDC与releaseDC
invalidaterect也有使区域无效的功能，可用它手动触发wm_paint事件重绘