Displaying a bmp in Windows
Author
I'm having an awful time trying to get this .bmp to show up in a window that I made. The following is the .rc file...
//MyBp.rc
MyBp BITMAP MyBp.bmp
Correct me if I'm wrong, but the above is the correct way to make a bitmap .rc file, right? Anyhow, the following is the WinProc which handles WM_PAINT, WM_CREATE and WM_DESTROY which all relate to the bitmap I'm working with.
LRESULT CALLBACK WinProc(HWND hwnd, UINT message,
WPARAM wParam, LPARAM lParam)
{
HDC hdc, memdc; // handles to the device context
PAINTSTRUCT ps;
switch(message){
case WM_CREATE:
// hbit becomes the handle to MyBp
hbit = LoadBitmap(hInst, "MyBp");
break;
case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);
memdc = CreateCompatibleDC(hdc);
SelectObject(memdc, hbit); // select the bitmap to be drawn
BitBlt(hdc, 0, 0, 256, 128,
memdc, 0, 0, SRCCOPY); // display the image
BitBlt(hdc, 300, 100, 256, 128,
memdc, 0, 0, SRCCOPY); // display a 2nd bitmap
EndPaint(hwnd, &ps); // realse the DC
DeleteDC(memdc); // free the memory context
break;
case WM_DESTROY: // terminate the program
DeleteObject(hbit);
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd, message, wParam, lParam);
}
return 0;
}
What the heck am I doing wrong? The application compiles without any errors, but when the window pops up, all I can see are two very small dots in the coordinates where the images should be. Can anyone help?
GO LEAFS GO!
Edit: Oh yah, hbit and hInst were declared with the following:
HBITMAP hbit;
HINSTANCE hInst;
Edited by - Fredric on 4/26/00 8:17:19 PM
I can´t find any bugs in the code you show me:
But try to set a breakpoint after the load of the bitmap,
and check if the image gets loaded correct (hbit != NULL)
Is hbit declared gloabal or inside WinProc? If it´s inside make sure to make it static.
Also the use of LoadBitmap is bad, because LoadBitmap() has problem with big images (and a lot of other things).
Instead use LoadImage(); it gives you much more control.
But try to set a breakpoint after the load of the bitmap,
and check if the image gets loaded correct (hbit != NULL)
Is hbit declared gloabal or inside WinProc? If it´s inside make sure to make it static.
Also the use of LoadBitmap is bad, because LoadBitmap() has problem with big images (and a lot of other things).
Instead use LoadImage(); it gives you much more control.
hey! i had the exact same problem, but i figured it out! here''s what you could be doing wrong:
The MyBp file has to be created and ACTUALLY ATTACHED to the EXE. It can''t just contain a filename and expect windows to load it for you, no, it wont do that
. You have to use VC++''s little image editor for this. It would be greatly easier to load the file externally with LoadImage, since you also have the full power of any editor you chose, and not just the crappy VC++ image editor. You simply go to (on the menu), Insert->Resource->Custom... and enter BITMAP when it asks for the name of the resourse. Of course, things get only more confusing from there, so just load the file externally. Heres the code:
This is how you would load it, and Bitmap now contains the bitmap. you then can use bitblt to blit it to the screen.
The MyBp file has to be created and ACTUALLY ATTACHED to the EXE. It can''t just contain a filename and expect windows to load it for you, no, it wont do that
. You have to use VC++''s little image editor for this. It would be greatly easier to load the file externally with LoadImage, since you also have the full power of any editor you chose, and not just the crappy VC++ image editor. You simply go to (on the menu), Insert->Resource->Custom... and enter BITMAP when it asks for the name of the resourse. Of course, things get only more confusing from there, so just load the file externally. Heres the code:CBitmap Bitmap; // this is what holds the bitmap.HBITMAP hBitmap; // handle used to load bitmap.hBitmap = LoadImage(/*Forgot what parameters go here, one is filename, one is some flags, look it up */);Bitmap.DeleteObject(); //DING DING DING, if you don''t want an assert error on the second load, do thisBitmap.Attach (hBitmap); // attaches bitmap to object This is how you would load it, and Bitmap now contains the bitmap. you then can use bitblt to blit it to the screen.
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