DirectDraw 7 and 8-bit .BMPs
January 01, 2003 06:05 AM
Hi all,
I''m having some trouble loading .BMP files onto my DirectDraw surfaces.
I pretty much copied the example 8-bit .BMP code in Andre LaMothe''s TOTWGPG.
Basically the code reads in the BITMAPFILEHEADER, BITMAPINFOHEADER & palette, then allocates a memory buffer for the actual image and reads it in. I use the biWidth and biHeight attributes to determine the size of the image (using biSizeImage as in the example code causes the program to crash).
Next the program is supposed to copy the image data from the buffer to the DD7 primary surface using memcpy.
The code compiles OK, and executes without crashing, but instead of displaying the bitmap I just get a blank screen and the cursor.
I feel kind of stupid getting stuck on something this basic.. Any help would be muchly appreciated.
Thanks
100
January 03, 2003 03:21 AM
i haven''t read that tutorial, but i think it''s about writing your own bmp file loader. If so, who not use the LoadBitmap() supplied with GDI?
The past was unknown, the future was predicted.
The past was unknown, the future was predicted.
the future is just like the past, just later. - TANSTAAFL
134
January 03, 2003 03:36 AM
Look for other bitmap loading routines online. What I have found with all the books I have, WGPFD, TOTWGPG (Almost same book!), and Jim Adams'' PRPGWDX and Sams TYDX7 in 24, is that the code they contain is not always that good when simply copied. I either mix and match code from the books or I look thoroughly at the example code to see if I am missing something.
122
January 03, 2003 11:44 AM
are you back buffering? if so, you have to copy the bitmap to the backbuffer, then flip it.
post some code.
post some code.
Programmers of the world, UNTIE!
January 03, 2003 10:09 PM
quote: Original post by MattS423
are you back buffering? if so, you have to copy the bitmap to the backbuffer, then flip it.
OK, it works now. Thanks muchly!
Here's the code, if you're interested:
int fnLoadBitmap(BITMAP_FILE_PTR bitmap, char *fileName) { int hFile, // file handle index, // counter tempColor, // temp color entry offset, // file offset in bytes (where the actual image file starts) size; // file size OFSTRUCT fileData; // the file data information // open the file if it exists if ((hFile = OpenFile(fileName, &fileData, OF_READ)) == -1) return(0); // now load the bitmap file header _lread(hFile, &bitmap->BitmapFileHeader, sizeof(BITMAPFILEHEADER)); // test if this is a bitmap file if (bitmap->BitmapFileHeader.bfType != BITMAP_ID) { // close the file _lclose(hFile); // return error return(0); } // end if // now we know it's a bitmap, read in all the sections // read the bitmap info header _lread(hFile, &bitmap->BitmapInfoHeader, sizeof(BITMAPINFOHEADER)); // load the color palette if there is one if(bitmap->BitmapInfoHeader.biBitCount == 8) { _lread(hFile, &bitmap->palette, MAX_COLORS_PALETTE*sizeof(PALETTEENTRY)); // set all the flags in the palette correctly // and fix the reversed BGR RGBQUAD data format for(index=0; index < MAX_COLORS_PALETTE; index++) { // reverse the red and blue fields tempColor = bitmap->palette[index].peRed; bitmap->palette[index].peRed = bitmap->palette[index].peBlue; bitmap->palette[index].peBlue = tempColor; // always set the flags word to this bitmap->palette[index].peFlags = PC_NOCOLLAPSE; } // end for(index) } // end if // read the image data size = (int)(bitmap->BitmapInfoHeader.biWidth * bitmap->BitmapInfoHeader.biHeight); //size = (int)bitmap->BitmapInfoHeader.biSizeImage; _lseek(hFile, -(int)(size), SEEK_SET); // read the image if (bitmap->BitmapInfoHeader.biBitCount == 8 || bitmap->BitmapInfoHeader.biBitCount == 16 || bitmap->BitmapInfoHeader.biBitCount == 24) { // delete the last image if there was one if (bitmap->buffer) free(bitmap->buffer); // allocate memory for the image if (!(bitmap->buffer = (UCHAR *)malloc(size))) { // close the file _lclose(hFile); // return error return(0); } // end if // now read it in _lread(hFile, bitmap->buffer, size); } else { // close the file _lclose(hFile); // return error return(0); } // end if // close the file _lclose(hFile); // flip the bitmap fnFlipBitmap(bitmap->buffer, bitmap->BitmapInfoHeader.biWidth*(bitmap->BitmapInfoHeader.biBitCount/8), bitmap->BitmapInfoHeader.biHeight); // return success return(1);} // end fnLoadBitmap() and to copy it to the back buffer:
// lock the display surface if (FAILED(lpddSBack->Lock(NULL, &ddSD, DDLOCK_WAIT | DDLOCK_SURFACEMEMORYPTR, NULL))) return(0); // make copy of source and destination addresses UCHAR *ptrSrc = g_bitmap.buffer; UCHAR *ptrDest = (UCHAR *)ddSD.lpSurface;; // copy line by line for (int y = 0; y < SCREEN_HEIGHT; y++) { // copy line memcpy((void *)ptrDest, (const void *)ptrSrc, SCREEN_WIDTH); // advance pointers to next line ptrDest += ddSD.lPitch; ptrSrc += SCREEN_WIDTH; } // end for y // unlock surface if (FAILED(lpddSBack->Unlock(NULL))) return(0); [edited by - crunchlet on January 3, 2003 11:10:24 PM]
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