在win32 窗口 绘制红色直线

在win32 窗口 绘制红色直线

测试环境: win7 64 位 vs2013

建立一个 win32 应用程序 ，空项目，名称是 HelloPaintRedLine,

在项目中添加源文件 HelloPaintRedLine.cpp :

内容如下:

#include <windows.h>
#include <stdlib.h>
#include <string.h>
#include <tchar.h>

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("HelloWin");
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 = szAppName;

if (!RegisterClass(&wndclass))
{
MessageBox(NULL, TEXT("This program requires Windows NT!"),
szAppName, MB_ICONERROR);
return 0;
}

hwnd = CreateWindow(szAppName,                  // window class name
TEXT("The Hello Program"), // window caption
WS_OVERLAPPEDWINDOW,        // window style
CW_USEDEFAULT,              // initial x position
CW_USEDEFAULT,              // initial y position
CW_USEDEFAULT,              // initial x size
CW_USEDEFAULT,              // initial y size
NULL,                       // parent window handle
NULL,                       // window menu handle
hInstance,                  // program instance handle
NULL);                     // creation parameters

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)
{
HDC         hdc;
PAINTSTRUCT ps;

switch (message)
{
case WM_CLOSE:
DestroyWindow(hwnd);
break;

case WM_DESTROY:
PostQuitMessage(0);
break;

case WM_PAINT:{                                       //1

hdc = BeginPaint(hwnd, &ps);                      //2

HPEN hPen = CreatePen(PS_SOLID,3,RGB(255,0,0));   //3

HPEN hOldPen = (HPEN)SelectObject(hdc,hPen);      //4

MoveToEx(hdc, 0, 50, NULL);                       //5

LineTo(hdc, 200, 50);                             //6

SelectObject(hdc, hOldPen);                       //7

DeleteObject(hPen);                               //8

EndPaint(hwnd, &ps);                              //9

break;                                            //10
}                                                     //11

default:
return DefWindowProc(hwnd, message, wParam, lParam);

}

return 0;
}

运行效果 如下 :