为什么我画线都是从原点开始啊，坐标我更新了啊（API）

Question

case WM_LBUTTONDOWN:
xPos=LOWORD(lParam);
yPos=HIWORD(lParam); break; case WM_MOUSEMOVE:

ptMouse.x=LOWORD(lParam);
ptMouse.y=HIWORD(lParam); MoveToEx(GetDC(hWnd),xPos,yPos,NULL);
LineTo(GetDC(hWnd),ptMouse.x,ptMouse.y);
wsprintf(szTitle,"Mouse Position: X=%d     ,Y=%d     ",ptMouse.x,ptMouse.y);
TextOut(GetDC(hWnd),500,200,szTitle,strlen(szTitle));
InvalidateRect(hWnd,NULL,FALSE);
xPos=ptMouse.x;
xPos=ptMouse.y; break;

Answer 1

xpos,ypos是静态的吧,初值为0，你只要一移鼠标，划线就开始了，你是不是想左键按一下后才开始画线？

Answer 2

你的xPos,yPos在哪儿定义的，是全局变量吗？

Answer 3

xpos,ypos是不是静态的，不是全局变量你在case WM_LBUTTONDOWN     xPos=LOWORD(lParam);
     yPos=HIWORD(lParam);WM_LBUTTONDOWN 消息结束后 xpos = ypos = 0;
 
正确的写法 static xpos,ypos;

Answer 4

;一开始把xpos=ypos=0;        case WM_MOUSEMOVE:
        
            ptMouse.x=LOWORD(lParam);
            ptMouse.y=HIWORD(lParam);if(xPos!=0 ||yPos!=0)
{
            MoveToEx(GetDC(hWnd),xPos,yPos,NULL);
            LineTo(GetDC(hWnd),ptMouse.x,ptMouse.y);
...
}
);
            xPos=ptMouse.x;
            xPos=ptMouse.y;            

Answer 5

to  qunta(旺财1860) "
不可以

Answer 6

你写错了吧
xPos=ptMouse.x;
xPos=ptMouse.y;//应该是yPos=ptMouse.y;吧

Answer 7

试试在
case WM_LBUTTONDOWN:
xPos=ptMouse.x=LOWORD(lParam);
yPos=ptMouse.y=HIWORD(lParam);

Answer 8

xPos/yPos老是变？有必要在MouseMove里改变这2个值吗？看你还4个▲

Answer 9

MoveToEx(GetDC(hWnd),xPos,yPos,NULL);
            LineTo(GetDC(hWnd),ptMouse.x,ptMouse.y);    HDC pDC = GetDC(hWbd);
          MoveToEx(pDC,xPos,yPos,NULL);
            LineTo(pDC,ptMouse.x,ptMouse.y);
绝对OK

Answer 10

http://www.csdn.net/expert/topic/653/653185.xml?temp=.9769861