Re: [Dev-C++] Drawing Lines (Let's put an end to this thread)...

[Christiaan S. <ck...@ia...>]

Yes I am a newbie but dont hold it against me! The code is there to draw =
a pixel not a line. I just drew it multiple times so you could see it. =
And yes it doesnt clear up and stuff but this is just a small part of =
the code specifically designed to test plotting a pixel, not to promote =
good programming practice.
    -----Original Message-----
    From: David Nebinger <dne...@mi...>
    To: dev...@li... =
<dev...@li...>
    Date: Monday, November 05, 2001 10:59 PM
    Subject: [Dev-C++] Drawing Lines (Let's put an end to this =
thread)...
   =20
   =20
    OK, it's obvious that the person that coded:
    =20
    > case WM_PAINT:
    >         SetPixel(GetDC(hwnd),100,100,0x00FF0000);
    >         SetPixel(GetDC(hwnd),101,100,0x00FF0000);
    >         SetPixel(GetDC(hwnd),102,100,0x00FF0000);
    >         SetPixel(GetDC(hwnd),103,100,0x00FF0000);
    >         SetPixel(GetDC(hwnd),104,100,0x00FF0000);
    >         break;
   =20
    is really a newbie.  Multiple calls to GetDC() with no handle reuse, =
no ReleaseDC() calls, and trying to plot pixels rather than the =
MoveToEx()/LineTo() calls.
    =20
    In case he's wondering, here's the code to do what he wanted:
    =20
    case WM_PAINT:
        {
            HDC hdc;
            PAINTSTRUCT ps;
            HBRUSH hbr,oldBrush;
    =20
            hdc=3DBeginPaint(hwnd,&ps); // get the device context during =
a WM_PAINT message
            hbr =3D CreateSolidBrush(RGB(0,0,0xff)); // create a brush =
for drawing
            oldBrush =3D (HBRUSH) SelectObject(hdc,hbr); // select the =
brush into the DC
            MoveToEx(hdc,100,100,NULL); // Move to the specified =
position
            LineTo(hdc,104,100); // draw the line
            SelectObject(hdc,oldBrush); // select the old brush back to =
the dc
            DeleteObject(hbr); // delete our temporary brush
            EndPaint(hwnd,&ps); // end the paint session
        }
        break;
    =20
    Now all of these functions are documented either in the Win32 SDK =
help file previously mentioned at =
ftp://ftp.cs.virginia.edu/pub/lcc-win32/win32hlp.exe site.
    =20
    Of course there's always the definitive source at Microsoft's MSDN =
site: http://msdn.microsoft.com/library/ where you'll find all of the =
info from the Win32 help file and then some.
    =20
    I would suggest that the person trying to figure out how to plot =
pixels should pick up an introductory book to programming Win32 in C/C++ =
(Charles Petzold did a marvelous job in Programming Windows 95; it's C & =
C++ (but avoids MFC), explains all about how to use the Windows API for =
drawing), and then come back when he runs into a problem...
    =20
    Dave