如何让鼠标所画的东西不消失 - C++ Builder / Windows SDK/API
不知道是不是在这个论坛提问的，最近在学习《WINDOWS程序设计》第7章的时候，有这么一个程序，用鼠标的例子，不过我运行后停留一段时候或重新按下鼠标，之前所画的就木有了，我想把之前的保留下来，顺便请教下，我鼠标点击的换种颜色，求高手修改下，谢谢啦
#include "stdafx.h"
#include "打老鼠.h"
#define MAXPOINTS 1000
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance,
HINSTANCE hPrevstance,
PSTR szCmdLine,
int iCmdShow)
{
static TCHAR name[] = TEXT("打老鼠");
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);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = name;
if(!RegisterClass(&wndclass))
{
MessageBox(NULL, TEXT("这个程序需要在WINDOWS NT下运行"),
name, MB_ICONERROR | MB_YESNOCANCEL | MB_DEFBUTTON3 | MB_HELP);
return 0;
}
hwnd = CreateWindow(name, TEXT("打老鼠"),
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
hInstance,
NULL);
ShowWindow(hwnd, iCmdShow);
UpdateWindow(hwnd);
while(GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static POINT pt[MAXPOINTS];
static int iCount;
HDC hdc;
int i, j;
PAINTSTRUCT ps;
switch(message)
{
case WM_LBUTTONDOWN:
iCount = 0;
InvalidateRect(hwnd, NULL, TRUE); //向指定的窗体添加一个矩形，然后窗口客户区域的这一部分将被重新绘制
return 0;
case WM_MOUSEMOVE:
if(wParam &MK_LBUTTON && iCount < 1000)
{
pt[iCount ].x = LOWORD(lParam);
pt[iCount++].y = HIWORD(lParam);
hdc = GetDC(hwnd);
SetPixel(hdc, LOWORD(lParam), HIWORD(lParam), 0);
ReleaseDC(hwnd, hdc);
}
return 0;
case WM_LBUTTONUP:
InvalidateRect(hwnd, NULL, FALSE);
return 0;
case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);
SetCursor(LoadCursor(NULL, IDC_WAIT));
ShowCursor(TRUE);
for(i = 0; i < iCount - 1; i++)
for(j = i + 1; j < iCount; j++)
{
MoveToEx(hdc, pt[i].x, pt[i].y, NULL);
LineTo(hdc, pt[i].x, pt[i].y);
}
ShowCursor(FALSE);
SetCursor(LoadCursor(NULL, IDC_ARROW));
EndPaint(hwnd, &ps);
return 0;
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);
}
