asking for bitmap info

hi guys .. I am a beginner programmer using c and Im looking for info on how to create a bitmap file .. draw to it .. close it ..and save it.

any help appreciated .. Im in an info gathering phase right now so anything considered..

thanks al.

A good start is to read up on the bmp file format: BMP file format - Wikipedia, the free encyclopedia

If you're writing a game it might pay off to use a library like the SDL (Simple DirectMedia Layer), which provides support for loading BMPs, displaying them, drawing pixels and handing keyboard and mouse input. If you're just wanting to use the Windows API (not what I'd suggest but you can if you wish) I believe LoadImage() is a good place to start.

See also:
http://cboard.cprogramming.com/cplus...aying-bmp.html
Lazy Foo' Productions
C++: graphics, memory device context, loadimage function

thanks for the help so far ..

I want to draw huge mandelbrot set pictures ..

currently I can draw pictures up too 12,000 x 8,000 pixels using sdl .. I want to increase that to at least 60,000 x 40,000 which I cannot do at the moment if it is even possible so I am looking at creating a bitmap file and dawing to the file.

any hints suggestions or downright critisims appreciated .. al.

There are several significant problems with images that size.

1. An image that size, even if only 8 bits per pixel, will take 2.4 gigabytes of memory.
2. 2.4 gigabytes is more than a userspace process can allocate on some operating systems.
3. 2.4 billion is exceeds the range of a signed 32-bit integer.
4. 60000 and 40000 both exceed the range of a signed 16-bit integer.
5. A lot of image file formats represent the width and height of images as 16-bit integers.
6. A lot of image file manipulation programs have bugs in them (such as using signed values instead of unsigned for certain things... ahem.)

You might create an image that large, but have fun finding a viewer that can open it. I speak, sadly, from experience.

:p thanks for the heads up .. appreciate it .. could have spent a lot of time and effort only to be frustrated ..

I am trying to write some code to draw the 2x2 bitmap on BMP file format - Wikipedia, the free encyclopedia.

I don't know how to fill in the array of colors .. so far as my thinking is going I think I need a structure with red green and brown elements and an array to hold copies of the structure.

how to access this or write out the results is still outside my skills .. I have been looking for a while on this issue .. so any help again very much appreciated ..

heres my code so far .. its a work in progress but you can see what I have done so far .. thanks al.

Code:

//objective write bimap from // http://en.wikipedia.org/wiki/BMP_file_format#Bitmap_file_header #include<stdio.h> #include<stdlib.h> #include<inttypes.h> #include<errno.h> struct bmpfile{ unsigned char magic[2]; }; struct fileheader{ uint32_t filesize; uint16_t creator1; uint16_t creator2; uint32_t bmpoffset; }; struct bmpinfoheader{ uint32_t headersize; int32_t width; int32_t height; uint16_t nplanes; uint16_t bitsperpixel; uint32_t compressiontype; uint32_t bitmapbytesize; int32_t hres; int32_t vres; uint32_t ncolors; uint32_t nimpcolors; }; struct rgb{ unsigned char rgbBlue; unsigned char rgbGreen; unsigned char rgbRed; unsigned char rgbReserved; }; void create( struct bmpfile* bfp, struct fileheader* fhp, struct bmpinfoheader* bhp ); void *write( struct bmpfile* bfp, struct fileheader* fhp, struct bmpinfoheader* bhp, FILE *fp, struct rgb* p ); FILE *open( FILE *fp ); int close( FILE *fp ); void create( struct bmpfile* bfp, struct fileheader* fhp, struct bmpinfoheader* bhp ){ int bpl; bfp->magic[0] = 'B'; bfp->magic[1] = 'M'; fhp->filesize = 70; fhp->bmpoffset = 54; bhp->width = 2; bhp->height = 2; bhp->nplanes = 1; bhp->bitsperpixel = 24; bhp->compressiontype = 0; bhp->bitmapbytesize = 16; bhp->hres = 2835; bhp->vres = 2835; bhp->ncolors = 0; bhp->nimpcolors = 0; bhp->headersize = bhp->bitsperpixel + bhp->bitmapbytesize; } /* the total number of bytes necessary to store one row of pixels can be calculated as (( width * bitsperpixel ) / 32 ) * 4; in this case it is (( 2 * 24 ) / 8 ) = 6 rounded up to 8 bpl = p->width * 3; if( bpl & 0x0003 ){ bpl != 0x0003; ++bpl; the total number of bytes necessary to store an array of pixels can be calculated by accounting for the effect of rounding up the size of each row to a multiple of 4 bytes .. pixelarraysize = rowsize * | height | 8 * 2 = 16 the total bitmap image filesize can be approximated as filesize = 54 + pixelarraysize = 70 offset is always 54 fhp->filesize = fhp->bmpoffset + bmp->hieght * bpl fhp->bmpoffset = 54 headersize is for bytes after bm ie the 24 + 16 = 40 */ void *write( struct bmpfile* bfp, struct fileheader* fhp, struct bmpinfoheader* bhp, FILE *fp, struct rgb* p ){ fwrite(&bfp,sizeof(fp),1,fp); fwrite(&fhp,sizeof(fp),1,fp); fwrite(&bhp,sizeof(fp),1,fp); /* write out color array here */ } struct rgb *colors( struct rgb* p ){ int c; for( c = 0; c < 4; c++ ){ p-> } // 2nd trouble spot return( p ); } FILE *open( FILE *fp ){ errno = 0; //function may choke on null filename .. fp = fopen("foo.bmp","wb"); if( fp == NULL ){ fprintf( stderr,"open fail %s\n",strerror(errno)); } return( fp ); } int close( FILE *fp ){ int s; if( fp == NULL ){ return 0; } errno = 0; fclose( fp ); if( s == EOF ){ perror("close fail"); } return s; } int main(){ struct bmpfile bf; struct bmpfile *bfp; bfp = & bf; struct fileheader fh; struct fileheader *fhp; fhp = &fh; struct bmpinfoheader bh; struct bmpinfoheader *bhp; bhp = &bh; struct rgb color[ 4 ]; struct rgb *p; p = &color; FILE *fp; colors( p ); create( bfp,fhp,bhp );//bitmap open( fp ); write( bfp, fhp, bhp, fp, p ); close( fp ); return( 0 ); }