xspeed1989
commented
3 years ago @smohantty
/*************************************************************************/
/* */
/* Render a straight line across multiple cells in any direction. */
/* */
static void gray_render_line(RAS_ARG_ TPos to_x, TPos to_y)
{
TPos dx, dy, fx1, fy1, fx2, fy2;
TCoord ex1, ex2, ey1, ey2;
ex1 = TRUNC(ras.x);
ex2 = TRUNC(to_x);
ey1 = TRUNC(ras.y);
ey2 = TRUNC(to_y);
/* perform vertical clipping */
if ((ey1 >= ras.max_ey && ey2 >= ras.max_ey) ||
(ey1 < ras.min_ey && ey2 < ras.min_ey))
goto End;
dx = to_x - ras.x;
dy = to_y - ras.y;
fx1 = ras.x - SUBPIXELS(ex1);
fy1 = ras.y - SUBPIXELS(ey1);
if (ex1 == ex2 && ey1 == ey2) /* inside one cell */
;
else if (dy == 0) /* ex1 != ex2 */ /* any horizontal line */
{
ex1 = ex2;
gray_set_cell(RAS_VAR_ ex1, ey1);
} else if (dx == 0) {
if (dy > 0) /* vertical line up */
do {
fy2 = ONE_PIXEL;
ras.cover += (fy2 - fy1);
ras.area += (fy2 - fy1) * fx1 * 2;
fy1 = 0;
ey1++;
gray_set_cell(RAS_VAR_ ex1, ey1);
} while (ey1 != ey2);
else /* vertical line down */
do {
fy2 = 0;
ras.cover += (fy2 - fy1);
ras.area += (fy2 - fy1) * fx1 * 2;
fy1 = ONE_PIXEL;
ey1--;
gray_set_cell(RAS_VAR_ ex1, ey1);
} while (ey1 != ey2);
} else /* any other line */
{
TArea prod = dx * fy1 - dy * fx1;
SW_FT_UDIVPREP(dx);
SW_FT_UDIVPREP(dy);
/* The fundamental value `prod' determines which side and the */
/* exact coordinate where the line exits current cell. It is */
/* also easily updated when moving from one cell to the next. */
do {
if (prod <= 0 && prod - dx * ONE_PIXEL > 0) /* left */
{
fx2 = 0;
fy2 = (TPos)SW_FT_UDIV(-prod, -dx);
prod -= dy * ONE_PIXEL;
ras.cover += (fy2 - fy1);
ras.area += (fy2 - fy1) * (fx1 + fx2);
fx1 = ONE_PIXEL;
fy1 = fy2;
ex1--;
} else if (prod - dx * ONE_PIXEL <= 0 &&
prod - dx * ONE_PIXEL + dy * ONE_PIXEL > 0) /* up */
{
prod -= dx * ONE_PIXEL;
fx2 = (TPos)SW_FT_UDIV(-prod, dy);
fy2 = ONE_PIXEL;
ras.cover += (fy2 - fy1);
ras.area += (fy2 - fy1) * (fx1 + fx2);
fx1 = fx2;
fy1 = 0;
ey1++;
} else if (prod - dx * ONE_PIXEL + dy * ONE_PIXEL <= 0 &&
prod + dy * ONE_PIXEL >= 0) /* right */
{
prod += dy * ONE_PIXEL;
fx2 = ONE_PIXEL;
fy2 = (TPos)SW_FT_UDIV(prod, dx);
ras.cover += (fy2 - fy1);
ras.area += (fy2 - fy1) * (fx1 + fx2);
fx1 = 0;
fy1 = fy2;
ex1++;
} else /* ( prod + dy * ONE_PIXEL < 0 &&
prod > 0 ) down */
{
fx2 = (TPos)SW_FT_UDIV(prod, -dy);
fy2 = 0;
prod += dx * ONE_PIXEL;
ras.cover += (fy2 - fy1);
ras.area += (fy2 - fy1) * (fx1 + fx2);
fx1 = fx2;
fy1 = ONE_PIXEL;
ey1--;
}
gray_set_cell(RAS_VAR_ ex1, ey1);
// the while never break out.
} while (ex1 != ex2 || ey1 != ey2);
}
fx2 = to_x - SUBPIXELS(ex2);
fy2 = to_y - SUBPIXELS(ey2);
ras.cover += (fy2 - fy1);
ras.area += (fy2 - fy1) * (fx1 + fx2);
End:
ras.x = to_x;
ras.y = to_y;
}
@smohantty Loading the json file in the attachment by rlottie will cause this function to enter an infinite loop
frame index:58
43721-keywords.zip