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Annotation of 42BSD/usr.lib/lib2648/update.c, revision 1.1.1.1

1.1       root        1: /*     update.c        4.1     83/03/09        */
                      2: /*
                      3:  * update: the key output optimization routine of the whole editor.
                      4:  * The input consists of two bit matrices (mold is what's on the screen,
                      5:  * mnew is what we want to be on the screen) and the coordinates of
                      6:  * the lower left corner on the screen where this matrix is.
                      7:  * This routine does whatever is necessary to get the screen to look
                      8:  * like mnew, assuming that it currently looks like mold.
                      9:  *
                     10:  * (If I could patent this process for bread and other food I
                     11:  * would be a rich man.)
                     12:  */
                     13: 
                     14: #include "bit.h"
                     15: 
                     16: update(mold, mnew, rows, cols, baser, basec)
                     17: bitmat mold, mnew;
                     18: int rows, cols, baser, basec;
                     19: {
                     20:        int irow;
                     21:        register int i, j, k;
                     22:        int r1, r2, c1, c2, nr1, nr2, nc1, nc2;
                     23:        extern int QUIET;
                     24: 
                     25: #ifdef TRACE
                     26:        if (trace)
                     27:                fprintf(trace, "update(mold=%x, mnew=%x, rows=%d, cols=%d, baser=%d, basec=%d)\n", mold, mnew, rows, cols, baser, basec);
                     28: #endif
                     29: 
                     30:        if (QUIET)
                     31:                return;
                     32:        aminmax(mold, rows, cols, &r1, &c1, &r2, &c2);
                     33:        aminmax(mnew, rows, cols, &nr1, &nc1, &nr2, &nc2);
                     34:        r1 = min(r1, nr1); r2 = max(r2, nr2);
                     35:        c1 = min(c1, nc1); c2 = max(c2, nc2);
                     36: 
                     37:        dumpmat("mold:", mold, rows, cols);
                     38:        dumpmat("mnew:", mnew, rows, cols);
                     39: 
                     40:        for (i=r1; i<=r2; i++) {
                     41:                irow = baser + rows - i - 1;
                     42:                if (emptyrow(mnew, rows, cols, i)) {
                     43:                        if (emptyrow(mold, rows, cols, i)) {
                     44:                                continue;       /* identically blank. skip. */
                     45:                        }
                     46:                        /*
                     47:                         * Row i is to be cleared.  Look for some more
                     48:                         * rows to clear and do it all at once.
                     49:                         */
                     50:                        for (j=i+1; j<rows && emptyrow(mnew,rows,cols,j); j++)
                     51:                                ;
                     52:                        areaclear(baser+rows-j, basec, irow, basec+cols-1);
                     53:                        i = j-1;        /* skip the others */
                     54:                } else for (j=c1; j<=c2; j++) {
                     55:                        /*
                     56:                         * Result row is not all blank.  We look for stretches
                     57:                         * of bits that have to be changed (in either
                     58:                         * direction) and draw an exclusive or line over all
                     59:                         * the bits in each stretch.
                     60:                         */
                     61:                        if (mat(mold,rows,cols,i,j,1)!=mat(mnew,rows,cols,i,j,2)){
                     62:                                for (k=j+1; k<cols && mat(mold,rows,cols,i,k,3)!=
                     63:                                        mat(mnew,rows,cols,i,k,4); k++)
                     64:                                        ;
                     65:                                k--;
                     66:                                setxor();
                     67:                                line(basec+j, irow, basec+k, irow);
                     68:                                j = k;  /* skip the others */
                     69:                        }
                     70:                }
                     71:        }
                     72: }

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