Move Window w/Mouse

[qhimq]

To download source and executable:
https://netfiles.uiuc.edu/qmitche2/www/mouse/

#include <windows.h>
//#include <stdio.h>
 
// Variables
HWND hwndMain; // Main window HWND
// Functions
LRESULT CALLBACK MainWndProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam);
 
int WINAPI 
WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, 
        int nCmdShow)
{
    MSG msg;
    WNDCLASSEX wcx;
    {
    // Fill in the WNDCLASS Struct
    wcx.cbSize = sizeof(WNDCLASSEX);
    wcx.style = CS_DBLCLKS;
    wcx.lpfnWndProc = MainWndProc;
    wcx.cbClsExtra = 0;
    wcx.cbWndExtra = 0;
    wcx.hInstance = hInstance;
    wcx.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wcx.hCursor = LoadCursor (NULL, IDC_ARROW);
    wcx.hbrBackground = (HBRUSH) COLOR_BACKGROUND;
    wcx.lpszMenuName = NULL;
    wcx.lpszClassName = "Draw";
    wcx.hIconSm = NULL;
    }
    if(!RegisterClassEx(&wcx))
        return 0;
 
    hwndMain = CreateWindowEx(0,
                            "Draw",
                            "Draw Example Application",
                            WS_OVERLAPPEDWINDOW,
                            CW_USEDEFAULT,
                            CW_USEDEFAULT,
                            400,
                            300,
                            NULL,
                            NULL,
                            hInstance,
                            NULL);
 
    ShowWindow(hwndMain,nCmdShow);
 
    while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}
 
LRESULT CALLBACK MainWndProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam)
{
    POINT thisPoint; // Stores the current point
    static bool drawing = false;
 
 
    switch(msg)
    {
    case WM_PAINT:
    {
        PAINTSTRUCT Ps;
        HDC hDC=BeginPaint(hwnd, &Ps);
 
        Rectangle(hDC, 0, 0, 100, 100);
 
        EndPaint(hwnd, &Ps);
    }
    break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    case WM_LBUTTONDOWN:
        // Says, We've begun drawing
        drawing = true;
 
        // Capture mouse
        //SetCapture(hwnd);
        break;
    case WM_LBUTTONUP:
        drawing = false;
        //ReleaseCapture();
        break;
    case WM_MOUSEMOVE:
        if (drawing)
        {
            thisPoint.x = LOWORD(lParam);
            thisPoint.y = HIWORD(lParam);
            //printf("x:%d ",thisPoint.x);
            //printf("y:%d\n",thisPoint.y);
 
            SetWindowPos(hwnd,NULL,
                thisPoint.x,
                thisPoint.y,
                0,
                0,
                SWP_NOSIZE);
            UpdateWindow(hwnd);
        }
        break;
    default:
        return DefWindowProc(hwnd,msg,wParam,lParam);
    }
    return 0;
}
 

Why does it move the window in two different spots at (almost) the same time?

I want the window to move with my mouse when I hold on the left mouse button.

Any ideas would be nice.

I tried the setcapture function, and i didn't see it affect anything.
(compile with gdi32 )

[qhimq]

I figured it out:

#include <windows.h>
#include <stdio.h>
 
// Variables
HWND hwndMain; // Main window HWND
// Functions
LRESULT CALLBACK MainWndProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam);
 
int WINAPI 
WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, 
        int nCmdShow)
{
    MSG msg;
    WNDCLASSEX wcx;
    {
    // Fill in the WNDCLASS Struct
    wcx.cbSize = sizeof(WNDCLASSEX);
    wcx.style = CS_DBLCLKS;
    wcx.lpfnWndProc = MainWndProc;
    wcx.cbClsExtra = 0;
    wcx.cbWndExtra = 0;
    wcx.hInstance = hInstance;
    wcx.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wcx.hCursor = LoadCursor (NULL, IDC_ARROW);
    wcx.hbrBackground = (HBRUSH) COLOR_BACKGROUND;
    wcx.lpszMenuName = NULL;
    wcx.lpszClassName = "Draw";
    wcx.hIconSm = NULL;
    }
    if(!RegisterClassEx(&wcx))
        return 0;
 
    hwndMain = CreateWindowEx(0,
                            "Draw",
                            "Draw Example Application",
                            WS_OVERLAPPEDWINDOW,
                            CW_USEDEFAULT,
                            CW_USEDEFAULT,
                            400,
                            300,
                            NULL,
                            NULL,
                            hInstance,
                            NULL);
 
    ShowWindow(hwndMain,nCmdShow);
 
    while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}
 
LRESULT CALLBACK MainWndProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam)
{
    POINT thisPoint; // Stores the current point
    POINT oldPoint;
    static bool drawing = false;
 
 
    switch(msg)
    {
    case WM_PAINT:
    {
        PAINTSTRUCT Ps;
        HDC hDC=BeginPaint(hwnd, &Ps);
 
        Rectangle(hDC, 0, 0, 100, 100);
 
        EndPaint(hwnd, &Ps);
    }
    break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    case WM_LBUTTONDOWN:
        // Says, We've begun drawing
        drawing = true;
        oldPoint = thisPoint;
        // Capture mouse
        //SetCapture(hwnd);
        break;
    case WM_LBUTTONUP:
        drawing = false;
        //ReleaseCapture();
        break;
    case WM_MOUSEMOVE:
        if (drawing && ((MK_LBUTTON & wParam) == MK_LBUTTON))
        {
            thisPoint.x = LOWORD(lParam);
            thisPoint.y = HIWORD(lParam);
 
            printf("x:%d ",thisPoint.x);
            printf("y:%d\n",thisPoint.y);
 
            RECT rc;
            GetClientRect(hwnd,&rc);
 
            POINT pt;
            pt.x=rc.left-4+(thisPoint.x-oldPoint.x);
            pt.y=rc.top-23+(thisPoint.y-oldPoint.y);
            ClientToScreen(hwnd, &pt);
 
            POINT half;
            half.x=(rc.right-rc.left)/2;
            half.y=(rc.bottom-rc.top)/2;
            SetWindowPos(hwnd,NULL,
                pt.x-half.x,
                pt.y-half.y,
                0,
                0,
                SWP_NOSIZE);
            UpdateWindow(hwnd);
 
        }
        break;
    default:
        return DefWindowProc(hwnd,msg,wParam,lParam);
    }
    return 0;
}
 
 

[niskin]

Well done, it's always great to figure out things ourselves, for both the learning experience and the sense of achievement.