Painting a child window

[Eric Davis]

I'm trying to paint the background ofa child window but haven't been able to manage it. Does anybody know how this is accomplished?

include <windows.h>

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

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

HWND hwndButton3; //Window handle to button
void Horses(HWND);//Horse text function

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);

///////////////Create a button//////////////////////////
hwndButton3 = CreateWindow(
"BUTTON", // Predefined class; Unicode assumed.
"Test", // Button text.
WS_VISIBLE | WS_CHILD, // Styles.
10, // x position.
10, // y position.
95, // Button width.
85, // Button height.
hwnd, // Parent window.
NULL, // No menu.
(HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE),
NULL); // Pointer not needed.
////////////////////////////////////////////////////////

/* 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;

}

/ This function is called by the Windows function DispatchMessage() /
HWND aChildWindow;

LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message) / handle the messages /
{
case WM_CREATE:
/////////////////////Create a child window//////////////////////
int test;
if(test == 0)
{

     aChildWindow = CreateWindowEx (
       WS_EX_CLIENTEDGE,                   /* Extended possibilites for variation */
       szClassName,         /* Classname */
       NULL,       /* Title Text */
       WS_VISIBLE | WS_CHILD, /* default window */
       10,       /* Windows decides the position */
       100,       /* where the window ends up on the screen */
       200,                 /* The window width */
       200,                 /* and height in pixels */
      hwnd,        /* The window is a child-window to main window */
       NULL,                /* No menu */
       (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE),       /* Program Instance handler */
       NULL                 /* No Window Creation data */
       );
       test = 1;

       }
 break;

///////////////////////////////////////////////////////////////////

 case WM_COMMAND:   
    if ((HWND)lParam == hwndButton3 && HIWORD(wParam) == BN_CLICKED)
         {
         Horses(aChildWindow);
         return 0;
         }
         break;

    //case WM_ERASEBKGND:
    //break;

    case WM_DESTROY:
        PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
        break;
    default:                      /* for messages that we don't deal with */
        return DefWindowProc (hwnd, message, wParam, lParam);
}

return 0;

}

RECT ClientArea;
int x, y;
int count;
void Horses(HWND htowind)
{
HDC Hndltodc;
char str[] = "horses";
if( count==0)
{
x = 10;
y = 10;
}
Hndltodc = GetDC(htowind);

 TextOut(
 Hndltodc,           // handle to DC
 x,       // x-coordinate of starting position
 y,       // y-coordinate of starting position
 str,  // character string
 6       // number of characters
 );

 x=x+50;
 //y=y+50;
 count = count + 1;

 GetClientRect(
 htowind,
 &ClientArea
 );

 if(x > (int)ClientArea.right - 50)
 {
 y=y+20;
 x=10;
 }

 ReleaseDC(
 htowind,  // handle to window
 Hndltodc     // handle to DC
 );
    return;

}

[Eric Davis]

I have it! I had to move a few things to get it to work.... Having my child window under WM_CREATE was producing some very strange results when I tried to paint to it.

//////////////////////////////////////////////////////////////////////

include <windows.h>

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

/ Make the class name into a global variable /
char szClassName[ ] = "WindowsApp";
HWND aChildWindow;
HWND hwndButton3; //Window handle to button
void Horses(HWND);//Horse text function

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 | WS_CLIPCHILDREN, /* 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);

///////////////Create a button//////////////////////////
hwndButton3 = CreateWindow(
"BUTTON", // Predefined class; Unicode assumed.
"Test", // Button text.
WS_VISIBLE | WS_CHILD, // Styles.
10, // x position.
10, // y position.
95, // Button width.
85, // Button height.
hwnd, // Parent window.
NULL, // No menu.
(HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE),
NULL); // Pointer not needed.
////////////////////////////////////////////////////////

//////////Having my child window under WM_CREATE caused a lot of /////////problems

 aChildWindow = CreateWindowEx (
       WS_EX_CLIENTEDGE,                   /* Extended possibilites for variation */
       szClassName,         /* Classname */
       NULL,       /* Title Text */
       WS_VISIBLE | WS_CHILD, /* default window */
       10,       /* Place window on */
       100,       /* parent*/
       200,                 /* The window width */
       200,                 /* and height in pixels */
      hwnd,        /* The window is a child-window to main window */
       NULL,                /* No menu */
       (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE),       /* Program Instance handler */
       NULL                 /* No Window Creation data */
       );

////////////////////////////////////////////////////////////////////////////////////////

/* 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;

}

/ 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_CREATE:

        break;


 case WM_COMMAND:   
    if ((HWND)lParam == hwndButton3 && HIWORD(wParam) == BN_CLICKED)
         {
         Horses(aChildWindow);
         return 0;
         }
         break;

 case WM_PAINT:

 HBRUSH      hBrush ;
 HDC         hdc ;
 PAINTSTRUCT ps ;
 RECT        rc ;


      hdc = BeginPaint (aChildWindow, &ps) ;

      GetClientRect (aChildWindow, &rc) ;

      hBrush = CreateSolidBrush (RGB(255,255,255));


      FillRect (hdc, &rc, hBrush) ;

      EndPaint (aChildWindow, &ps) ;
      DeleteObject (hBrush) ;


      UpdateWindow(
      hwndButton3  // handle to window
      );
      break;



    case WM_DESTROY:
        PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
        break;
    default:                      /* for messages that we don't deal with */
        return DefWindowProc (hwnd, message, wParam, lParam);
}

return 0;

}

RECT ClientArea;
int x, y;
int count;
void Horses(HWND htowind)
{
HDC Hndltodc;
char str[] = "horses";
if( count==0)
{
x = 10;
y = 10;
}
Hndltodc = GetDC(htowind);

 TextOut(
 Hndltodc,           // handle to DC
 x,       // x-coordinate of starting position
 y,       // y-coordinate of starting position
 str,  // character string
 6       // number of characters
 );

 x=x+50;
 //y=y+50;
 count = count + 1;

 GetClientRect(
 htowind,
 &ClientArea
 );

 if(x > (int)ClientArea.right - 50)
 {
 y=y+20;
 x=10;
 }

 ReleaseDC(
 htowind,  // handle to window
 Hndltodc     // handle to DC
 );
    return;

}

[Eric Davis]

Now I can sleep tonight. Cool...

////////////////////////////////////////////////////////////////////////

 case WM_PAINT:

      PaintWindBckgnd(aChildWindow, 255, 255, 255);
      PaintWindBckgnd(hwnd, 0, 0, 0);

      UpdateWindow(
      hwndButton3  // handle to window
      );
      break;

[Musa]

Whats wrong with it, except it doesn't compile? After a simple fix it compiles and works.
what exactly do you want to achieve.
see
http://i150.photobucket.com/albums/s106/toatingbucket/untitled.jpg

[Eric Davis]

I want to paint the smaller child window in which the text appears. I am trying to make it white. I am learning the API and trying understand how it works.

[Eric Davis]

BTW: It compiles just fine on my machine. I'm using Dev.

[Musa]

Where are you trying to paint it white? I don't see it.
use fillrect http://msdn.microsoft.com/en-us/library/ms533283(VS.85).aspx
checkout http://msdn.microsoft.com/en-us/library/ms533223(VS.85).aspx for brush info

[Eric Davis]

Hmm... It gets even better. I've built a function that makes it even easier.

//////////////////////////////////////////////////////////

void PaintWindBckgnd(HWND hwnd, int r, int g, int b)
{
HBRUSH hBrush ;
HDC hdc ;
PAINTSTRUCT ps ;
RECT rc ;

      hdc = BeginPaint (hwnd, &ps) ;

      GetClientRect (hwnd, &rc) ;

      hBrush = CreateSolidBrush (RGB(r,g,b));


      FillRect (hdc, &rc, hBrush) ;

      EndPaint (hwnd, &ps) ;
      DeleteObject (hBrush) ;

      return;
      }