belahcene wrote:
> Hi,
> I use fltk (C++ graphical interface) to create an electronics design package.
> I created a list of objects and placed them on a window. My problem is how to
> save the file, I think to create a list in memory for the objects placed on
> the sheet and store them in a file.
> I think (not sure of course) that xfig for example uses this procedure ?
Sure sounds like a simple matter of making your class(s) that
handle the components have Save() and Load() methods.
This general technique has always worked for me:
// A/C TRANSFORMER CLASS
class Transformer {
int x, y; // position on board
int num_pins; // number of pins
// ..
// SAVE TO FILE
int Save(FILE *fp) {
if ( fprintf(fp, "xfmr %d %d %d\n", x, y, num_pins) < 0 ) return(-1);
return(0);
}
// LOAD FROM FILE
int Load(const char *s, string& errmsg) {
if ( sscanf(s, "xfmr %d %d %d", &x, &y, &num_pins) == 3 ) return(0);
errmsg = "bad command or argument: ";
errmsg += s;
return(-1);
}
};
..and your 'save' and 'load' functions might look like:
// SAVE ALL COMPONTENTS
int Save(const char* filename) {
int err = 0;
// OPEN FILE
FILE *fp = fopen(filename, "w");
if ( fp == NULL ) {
Fail(filename, 0, strerror(errno));
return(-1);
}
// SAVE TRANSFORMERS
fprintf(fp, "# TRANSFORMERS\n");
for ( int t=0; t<transformers.size(); t++ ) {
if ( transformers[t].Save(fp) < 0 ) {
err = Fail(filename, 0, strerror(errno));
goto save_fail;
}
}
// SAVE RESISTORS
fprintf(fp, "# RESISTORS\n");
// ..ETC..
save_fail:
if ( fclose(fp) < 0 )
Fail(filename, 0, strerror(errno));
return(err);
}
// LOAD ALL COMPONTENTS
#define ISIT(x) if ( strncmp(s, x, strlen(x)) == 0 )
int Load(const char* filename) {
// OPEN FILE
FILE *fp = fopen(filename, "r");
if ( fp == NULL ) {
Fail(filename, 0, strerror(errno));
return(-1);
}
// LOAD COMPONENTS
int err = 0;
int line = 0;
char s[1024];
string errmsg;
while ( fgets(s, sizeof(s), fp) ) {
++line;
if ( s[0] == '#' ) continue; // skip comments
ISIT("xfmr") {
Transformer *x = new Transformer();
if ( x->Load(s, errmsg) < 0 ) {
err = Fail(filename, line, errmsg);
break;
}
// ..Add to transformers array..
continue;
}
ISIT("res") {
// ..ETC..
}
errmsg = "Unknown command: ";
errmsg += s;
Fail(filename, line, s);
break;
}
fclose(fp);
return(err);
}
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