Hi, I'm reading Programming Windows Fifth Edition by Charles Petzold. In the part I'm
reading, it talks about GDI functions. I'm trying to get the pixels that are 1 to 100 + the
mouse x coordinate and the y coorinate, then draw them on my window. It's hard to explain. I want it to make a complete copy of the 100x100 box from the mouse position. Look at my drawing:

100px
*----------
|----------|
|----------| 100px
|----------|
------------

The * is the cursor. I want to get all of the pixels, then draw them on my window. It's like a copy of what's around the mouse. I tried it, but the box just goes black then white.

#include <windows.h>
#include <stdio.h>
#define ID_TIMER 1

/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

/*  Make the class name into a global variable  */
char szClassName[ ] = "WindowsApp";

int WINAPI WinMain (HINSTANCE hThisInstance,
                    HINSTANCE hPrevInstance,
                    LPSTR lpszArgument,
                    int nFunsterStil)

{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default color as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
           0,                   /* Extended possibilites for variation */
           szClassName,         /* Classname */
           "Windows App",       /* Title Text */
           WS_OVERLAPPEDWINDOW, /* default window */
           CW_USEDEFAULT,       /* Windows decides the position */
           CW_USEDEFAULT,       /* where the window ends up on the screen */
           544,                 /* The programs width */
           375,                 /* and height in pixels */
           HWND_DESKTOP,        /* The window is a child-window to desktop */
           NULL,                /* No menu */
           hThisInstance,       /* Program Instance handler */
           NULL                 /* No Window Creation data */
           );

    /* Make the window visible on the screen */
    ShowWindow (hwnd, nFunsterStil);

    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }

    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}

void PaintRoutine (HDC hdc, COLORREF crColor, int cxClient, int cyClient, int sx, int sy)
{
     HBRUSH   hBrush ;
     RECT     rect ;
     
     hBrush = CreateSolidBrush (crColor) ;
     SetRect (&rect, sx, sy, cxClient, cyClient) ;
     FillRect (hdc, &rect, hBrush) ;
     DeleteObject (SelectObject (hdc, GetStockObject (WHITE_BRUSH))) ;
     
     return;
}

/*  This function is called by the Windows function DispatchMessage()  */

LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)                  /* handle the messages */
    {
        case WM_DESTROY:
            PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
            break;
        case WM_CREATE:
             SetTimer (hwnd, ID_TIMER, 100, NULL) ;
             break;
        case WM_TIMER:
             HDC hDC, hwnddc;
             hDC = CreateDC(TEXT("DISPLAY"), NULL, NULL, NULL);
             hwnddc = GetDC(hwnd);
             POINT pt;
             GetCursorPos(&pt);
             for (int x = 0; x < 100; x++)
             {
             for (int y = 0; y < 100; y++)
             {
             PaintRoutine(hwnddc, GetPixel(hDC, pt.x + x, pt.y + y), 1, 1, 1 + x, 1 + y);
             }
             }
             DeleteDC(hDC);
             ReleaseDC(hwnd, hwnddc);
             InvalidateRect(hwnd, NULL, false);
             break;
        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }

    return 0;
}

Recommended Answers

All 3 Replies

Try replacing the line PaintRoutine(hwnddc, GetPixel(hDC, pt.x + x, pt.y + y), 1, 1, 1 + x, 1 + y); with SetPixel(hwnddc, x, y, GetPixel(hDC, pt.x + x, pt.y + y));

Try replacing the line PaintRoutine(hwnddc, GetPixel(hDC, pt.x + x, pt.y + y), 1, 1, 1 + x, 1 + y); with SetPixel(hwnddc, x, y, GetPixel(hDC, pt.x + x, pt.y + y));

Nonsense.
Just blit with BitBlt() (!!!)

commented: Nonsense. -1

Thanks mitrmkar. That worked perfectly!

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.