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From: Jimbo on 1 Jan 2010 03:42
Hello

I am trying to make an Win32 application where whenever the left
button is clicked, a bitmap is created at the mouse coordinates.

Problem: the bitmap is not created when I left click(nothing happens),
left click is being received. I believe its the way I am trying to
make the bitmap which is the problem. Is there is a better way to do
what I am trying to do?

Loose "Algorithm":
- Left mouse button is pressed anywhere on client window.
- Windows proceedure function receives WM_LBUTTONDOWN message; mouse
x,y coords are stored in variables int x,y & sends custom message
IDB_DRAW which triggers bitmap creation.
- Win Proceedure receives WM_COMMAND (wParam)IDB_DRAW message. A
static window is created to display a bitmap at the x,y coords.
(problem occurs here).

Code: (code under "case IDB_DRAW" does not work & I dont know why?)

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM
lParam)
{
HBITMAP pic = NULL;
int x,y;

switch(msg)
{
case WM_CREATE:
{
//pic = LoadImage(GetModuleHandle(NULL),
pic = (HBITMAP)LoadImage(NULL,"ball.bmp",IMAGE_BITMAP,
0,0,
LR_CREATEDIBSECTION | LR_DEFAULTSIZE |
LR_LOADFROMFILE);

if (pic==NULL) {
MessageBox(hwnd,"Failed to load bitmap","Error",MB_OK
| MB_ICONERROR);
}
}
break;
case WM_LBUTTONDOWN:
{
// get mouse x,y coords
x = LOWORD(lParam);
y = HIWORD(lParam);
// send message to create bitmap
SendMessage(hwnd,IDB_DRAW,0,0);
MessageBox(hwnd,"wdw ","kj",MB_OK);
}
break;
case WM_COMMAND:
{
switch(LOWORD(wParam))
{
case IDB_DRAW:
{
HWND bmDot = CreateWindowEx(
0,"Static","",WS_BORDER | WS_CHILD
| WS_VISIBLE | SS_BITMAP,
x,y,CW_USEDEFAULT,
CW_USEDEFAULT,hwnd,NULL,gInstance,NULL);

SendMessage(bmDot,STM_SETIMAGE,(WPARAM)
IMAGE_BITMAP,(LPARAM)pic);
}
break;
default:
break;
}
}
break;
case WM_CLOSE:
DestroyWindow(hwnd);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd, msg, wParam, lParam);
}
return 0;
}

From: Paul N on 1 Jan 2010 11:07
On 1 Jan, 08:42, Jimbo <nill...(a)yahoo.com> wrote:
> Hello
>
> I am trying to make an Win32 application where whenever the left
> button is clicked, a bitmap is created at the mouse coordinates.
>
> Problem: the bitmap is not created when I left click(nothing happens),
> left click is being received. I believe its the way I am trying to
> make the bitmap which is the problem. Is there is a better way to do
> what I am trying to do?
>
> Loose "Algorithm":
> - Left mouse button is pressed anywhere on client window.
> - Windows proceedure function receives WM_LBUTTONDOWN message; mouse
> x,y coords are stored in variables int x,y & sends custom message
> IDB_DRAW which triggers bitmap creation.
> - Win Proceedure receives WM_COMMAND (wParam)IDB_DRAW message. A
> static window is created to display a bitmap at the x,y coords.
> (problem occurs here).
>
> Code: (code under "case IDB_DRAW" does not work & I dont know why?)

I'm not at all an expert, but I think I can see the problem here, so
in case the experts are all on holiday, here are my thoughts:

> LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM
> lParam)
> {
>     HBITMAP pic = NULL;
>     int x,y;
>
>     switch(msg)
>     {
>         case WM_CREATE:
>         {
>              //pic = LoadImage(GetModuleHandle(NULL),
>              pic = (HBITMAP)LoadImage(NULL,"ball.bmp",IMAGE_BITMAP,
> 0,0,
>                              LR_CREATEDIBSECTION | LR_DEFAULTSIZE |
> LR_LOADFROMFILE);
>
>              if (pic==NULL) {
>                  MessageBox(hwnd,"Failed to load bitmap","Error",MB_OK
> | MB_ICONERROR);
>              }
>         }
>         break;
>         case WM_LBUTTONDOWN:
>         {
>              // get mouse x,y coords
>              x = LOWORD(lParam);
>              y = HIWORD(lParam);
>              // send message to create bitmap
>              SendMessage(hwnd,IDB_DRAW,0,0);

This looks wrong. You are sending a message of type "IDB_DRAW", when
what you want (see a couple of lines further down) is a message of
type WM_COMMAND whose wParam is IDB_DRAW.

>              MessageBox(hwnd,"wdw ","kj",MB_OK);
>         }
>         break;
>         case WM_COMMAND:
>         {
>              switch(LOWORD(wParam))
>              {
>                  case IDB_DRAW:
>                  {
>                       HWND bmDot = CreateWindowEx(
>                                    0,"Static","",WS_BORDER | WS_CHILD
> | WS_VISIBLE | SS_BITMAP,
>                                    x,y,CW_USEDEFAULT,
> CW_USEDEFAULT,hwnd,NULL,gInstance,NULL);
>
>                       SendMessage(bmDot,STM_SETIMAGE,(WPARAM)
> IMAGE_BITMAP,(LPARAM)pic);
>                  }
>                  break;
>                  default:
>                  break;
>              }
>         }
>         break;
>         case WM_CLOSE:
>             DestroyWindow(hwnd);
>         break;
>         case WM_DESTROY:
>             PostQuitMessage(0);
>         break;
>         default:
>             return DefWindowProc(hwnd, msg, wParam, lParam);
>     }
>     return 0;
>
>
>
> }

Hope that helps.
Paul.

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