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V_SCROLL.C
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C/C++ Source or Header
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1991-05-03
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3KB
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90 lines
/* v_scroll.c */
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <tools/viewport.h>
int v_scroll_region( viewport *v, int up, int to_left,
int left, int top, int right, int bottom )
{
/* Move the text in the viewport "to_left" lines to the left and up
* "up" lines. Go right if "to_left" is negative, down if "up" is
* negative. Cursor position is not changed. Newly opened space
* is filled with blanks. This function may not be used to clear
* the viewport--false is returned (and no movement occurs along
* that axis) if the requested movement is >= the viewpoint
* dimension. Use v_clear() to clear a viewport.
*
* The scrolled region is bounded by by the window-relative left and right
* columms, and top and bottom rows. You can use 0,0,100,100 for these
* last four arguments if you want to scroll the whole window because
* v_scroll_region truncates the box size down to the viewport size
* if necessary.
*/
int this_many, from, to, ncols, nrows;
int value = 1; /* return value */
if( v->magic != VMAGIC )
return 0;
if( v->inactive )
v_open( v );
left = v->col + left; /* figure out the cooridinates */
top = v->row + top; /* of the upper left corner, */
ncols = right-left +1; /* and the size of the affected */
nrows = bottom-top +1; /* region. */
if( (left >= v->ncols) || (top >= v->nrows) ) /* bounding box is outside */
return 0; /* window entirely. */
if( left + ncols > v->ncols ) /* if the bounding box is outside */
{ /* of the window, truncate it down */
ncols = v->ncols - left ; /* to fit. */
value = 0;
}
if( top + nrows > v->nrows )
{
nrows = v->nrows - top ;
value = 0;
}
/* Do horizontal motion first, then vertical. */
if( to_left )
{
this_many = ncols - abs(to_left) ;
from = (to_left > 0) ? (left + to_left):(left );
to = (to_left > 0) ? (left ):(left - to_left);
if( this_many < 0 )
value = 0;
else if( this_many > 0 )
movetext( from+1, top+1, from+this_many, top+nrows,
to +1, top +1 );
_v_fill_scr( VINIT_CHAR | (v->bcolor << 4 | v->fcolor) << 8,
top, to_left > 0 ? left + this_many : left,
nrows, ncols - this_many );
}
if( up )
{
this_many = nrows - abs( up ) ;
from = (up > 0) ? (top + up) : (top );
to = (up > 0) ? (top ) : (top - up);
if( this_many < 0 )
value = 0;
else if( this_many > 0 )
movetext( left+1, from+1, left+ncols, from+this_many,
left+1, to+1 );
_v_fill_scr( VINIT_CHAR | (v->bcolor << 4 | v->fcolor) << 8,
up > 0 ? top + this_many : top , left,
nrows - this_many, ncols );
}
return value;
}