Displaying a Bitmap

[flipsflops]

Suggestions please. I can display a bitmap file from a preloaded resouce (using LoadBitmap) onto a window, but unable to do so when using an externally loaded file (using CreateBitmap).

[external file format decompression is okay - PCX format]

[Jaeyeon Lee]

Check if the loaded file is a bitmap with palette(256 color image, for example).
In that case, you must realize the palette before you call BitBlt to display it correctly.

[flipsflops]

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Subject: Re: Displaying a Bitmap

I decode a PCX file, create & select the palette, but return a NULL when trying to realize it. I do not think this is the problem though.

The SelectObject function returns a NULL when tring to select the externally read in data, although the CreateBitmapIndirect & CreateCompatibleDC functions appear to work correctly and return handles.

The code below shows what I am doing, although what is wrong I cannot see ...


hpal = CreatePalette( &logpal );
oldhpal = SelectPalette( hdc, hpal, FALSE );
check = RealizePalette( hdc );
hbmpMyBitmap = CreateBitmapIndirect( &bm ); //hbmpMyBitmap = LoadBitmap(hInst, "MyBitmap"); //Using this internal resource, I display a bitmap in the window
//GetObject(hbmpMyBitmap, sizeof(BITMAP), &bm);
hdcMemory = CreateCompatibleDC(hdc);
hbmpOld = SelectObject(hdcMemory,
hbmpMyBitmap);i = BitBlt(hdc, 80, 80, bm.bmWidth, bm.bmHeight, hdcMemory, 0, 0, SRCCOPY);
SelectObject(hdcMemory, hbmpOld);
DeleteDC(hdcMemory);
ReleaseDC(hwnd, hdc);




any ideas please ?

[flipsflops]

It would seem that the hardware caperbility changes with different resolutions, and the RC_PALETTE funtionality disappeared on my system when I changed from colour 256 mode.

When in colour 256 mode I have RC_PALETTE functionality and hence I can display a decoded PCX file as a bitmap on a window.

I used GetDeviceCaps(phdc, RASTERCAPS) & RC_PALETTE

to check for the RC_PALETTE flag.

Thats it !