Thread: Load BMP from file func

Alright, I have a loadBMP function, but it doesn't actually load the BMP for some reason. the function and everything is contained in a header, which is included in Unit1.cpp

this is how I use it...

Code:

...
BITMAP_FILE bitmap;
....
//load background
if(!LoadBMP(&bitmap,"lvl2.bmp"))
   Application->MessageBoxA("Can't load BMP","ERORR",MB_OK); GameKill();

I trace through, and it returns the error at the line indicated

Code:

if(bitmap->bitmapinfoheader.biBitCount == 8 || bitmap->bitmapinfoheader.biBitCount == 16 ||
       bitmap->bitmapinfoheader.biBitCount == 24)
       {
               //delete the alst image if there was one
               if(bitmap->buffer)
                       delete bitmap->buffer;

               //allocate the memory for the image

               if(!(bitmap->buffer = (UCHAR *)malloc(bitmap->bitmapinfoheader.biSizeImage)))
               {
                       //close the file
                       _lclose(file_handle);

                       //return error
                        return(0);
               }

               //now read it in
               _lread(file_handle,bitmap->buffer, bitmap->bitmapinfoheader.biSizeImage);
       }
       else
       {
               //WOW! Serious error!  
               return(0);<<<-------------- THIS LINE <<----------
       }

I check the value of biSizeImage and its 24.....So why doesn't that fit the clause in the if statment?

All that happens is that I get the message saying It wasn't loaded(at the indicated line). Any ideas?

I've attached the header file below

Many thanks

DW

Code:

//this was taken from André LaMoth's "Tricks of the windows game programming gurus"
//p.346  2nd Revision

//NOTE:
//assumes your not stupid and arn't asking it to load a non-BMP file. the code is commented out for that

#include "Unit1.h"
#define BITMAP_ID            0x4D42 // universal id for a bitmap
#define MAX_COLORS_PALETTE   256

//////container structure for bitmap files///////////////////////////////////////
 typedef struct BITMAP_FILE_TAG
        {
        BITMAPFILEHEADER bitmapfileheader;  // this contains the bitmapfile header
        BITMAPINFOHEADER bitmapinfoheader;  // this is all the info including the palette
        PALETTEENTRY     palette[256];      // we will store the palette here
        UCHAR            *buffer;           // this is a pointer to the data

        } BITMAP_FILE, *BITMAP_FILE_PTR;


// PROTOTYPES  //////////////////////////////////////////////

int Flip_Bitmap(UCHAR *image, int bytes_per_line, int height);

int LoadBMP(BITMAP_FILE_PTR bitmap, char *filename);

int Unload_Bitmap_File(BITMAP_FILE_PTR bitmap);


//LOAD///////////////////////////////////////////////////////////////////////////
int LoadBMP(BITMAP_FILE_PTR bitmap, char *filename)
{
//this function opens a *.BMP file

        int file_handle; //the file handle
        int i; //looping var

        UCHAR *temp_buffer = NULL; //used to convert 24 bit images to 16bit
        OFSTRUCT file_data; // file data information

        //open file if it exists
        if((file_handle = OpenFile(filename,&file_data,OF_READ)) == -1)
                return(0); //Opening failed

        //load the bitmap header
        _lread(file_handle,&bitmap->bitmapfileheader,sizeof(BITMAPFILEHEADER));

    /*    //TEST IF THIS IS A BITMAP FILE
        if (bitmap->bitmapfileheader.bfType != BITMAP_ID)
        {
                //this definatly isn't a bitmap, so lets unload 'er
                _lclose(file_handle);

                //return error
                return(0);
        }   */


        //Now lets read in the infoheader
        _lread(file_handle, &bitmap->bitmapinfoheader,sizeof(BITMAPINFOHEADER));

        //NOW LOAD THE COLOR PALETTE IF THERE IS ONE
        if(bitmap->bitmapinfoheader.biBitCount == 8)
        {
                _lread(file_handle, &bitmap->palette,MAX_COLORS_PALETTE*sizeof(PALETTEENTRY));

                //Now set all the flags in the palette correctly and fix the reversed BGR RGBQUAD
                for(i = 0; i < MAX_COLORS_PALETTE; i++)
                {
                        int temp_color = bitmap->palette[i].peRed;
                        bitmap->palette[i].peRed = bitmap->palette[i].peBlue;
                        bitmap->palette[i].peBlue = temp_color;

                        bitmap->palette[i].peFlags = PC_NOCOLLAPSE;
                }
        }

        //image data
        _lseek(file_handle, -(int)(bitmap->bitmapinfoheader.biSizeImage),SEEK_END);

        // now read in the image, if the image is 8 or 16 bit then simply read it
        // but if its 24 bit then read it into a temporary area and then convert
        // it to a 16 bit image

        if(bitmap->bitmapinfoheader.biBitCount == 8 || bitmap->bitmapinfoheader.biBitCount == 16 ||
        bitmap->bitmapinfoheader.biBitCount == 24)
        {
                //delete the alst image if there was one
                if(bitmap->buffer)
                        delete bitmap->buffer;

                //allocate the memory for the image

                if(!(bitmap->buffer = (UCHAR *)malloc(bitmap->bitmapinfoheader.biSizeImage)))
                {
                        //close the file
                        _lclose(file_handle);

                        //return error
                         return(0);
                }

                //now read it in
                _lread(file_handle,bitmap->buffer, bitmap->bitmapinfoheader.biSizeImage);
        }
        else
        {
                //WOW! Serious error!
                return(0);
        }

        //close the file
        _lclose(file_handle);

        //flip the bitmap
        Flip_Bitmap(bitmap->buffer,
            bitmap->bitmapinfoheader.biWidth*(bitmap->bitmapinfoheader.biBitCount/8),
            bitmap->bitmapinfoheader.biHeight);

        // return success
        return(1);
}

/////UNLOAD//////////////////////////////////////////////////////////////////////
int Unload_Bitmap_File(BITMAP_FILE_PTR bitmap)
{
        // this function releases all memory associated with "bitmap"
        if (bitmap->buffer)
        {
                // release memory
                delete (bitmap->buffer);

                // reset pointer
                bitmap->buffer = NULL;

        } // end if

        // return success
        return(1);

}

//// FLIP ///////////////////////////////////////////////////////

int Flip_Bitmap(UCHAR *image, int bytes_per_line, int height)
{
// this function is used to flip bottom-up .BMP images

        UCHAR *buffer; // used to perform the image processing
        int index;     // looping index

        // allocate the temporary buffer
        if (!(buffer = (UCHAR *)malloc(bytes_per_line*height)))
                return(0);

        // copy image to work area
        memcpy(buffer,image,bytes_per_line*height);

        // flip vertically
        for (index=0; index < height; index++)
                memcpy(ℑ[((height-1) - index)*bytes_per_line], &buffer[index*bytes_per_line], bytes_per_line);

        // release the memory
        free(buffer);

        // return success
        return(1);

}

Originally Posted by Codeplug

I've only read the first 3 lines of code, but.....
>> I check the value of biSizeImage...
You're looking at biBitCount.

Heee. Typo. Sorry. I fixed that other line, but obviously that wasn't the issue, as when I trace through the load function, the highlighted line is the one that is hitm hence returning an error!

Could my BMP be the issue? I'll try a different image tonight, see if that helps!

Cheers

DW