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box-drawing: LIGHT ARC: fix alignment of arcs when thickness is > 1px

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Daniel Eklöf 2021-01-02 02:26:12 +01:00
parent 87dcdc2b3b
commit d8e40cf5d4
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1 changed files with 58 additions and 29 deletions
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87
box-drawing.c
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@ -1214,16 +1214,9 @@ static void
draw_box_drawings_light_arc(wchar_t wc, struct buf *buf)
{
int thick = thickness(LIGHT);
int delta = thick / 2;
int extra = thick % 2;
/* x^2 / a^2 + y^2 / b^2 == 1 */
int hw = (buf->width - thick) / 2;
int hh = (buf->height - thick) / 2;
double a = hw;
double b = hh;
double a = (buf->width - thick) / 2;
double b = (buf->height - thick) / 2;
double a2 = a * a;
double b2 = b * b;
@ -1232,32 +1225,61 @@ draw_box_drawings_light_arc(wchar_t wc, struct buf *buf)
for (int i = 0; i < num_samples; i++) {
double y = i / 16.;
double x = sqrt(a2 * (1. - y * y / b2));
int row = round(y);
int col = round(x);
const int row = round(y);
const int col = round(x);
if (col < 0)
continue;
int row_start = 0;
int row_end = 0;
int col_start = 0;
int col_end = 0;
/*
* At this point, row/col is only correct for ╯. For the other
* arcs, we need to mirror the arc around either the x-, y- or
* both axis.
*/
switch (wc) {
case L'╭':
row = buf->height - row - 1 - (1 - buf->height % 2);
col = buf->width - col - 1 - (1 - buf->width % 2);
row_end = buf->height - row - (thick % 2 ? 1 - buf->height % 2 : buf->height % 2);
row_start = row_end - thick;
col_end = buf->width - col - (thick % 2 ? 1 - buf->width % 2 : buf->width % 2);
col_start = col_end - thick;
break;
case L'╮':
row = buf->height - row - 1 - (1 - buf->height % 2);
row_end = buf->height - row - (thick % 2 ? 1 - buf->height % 2 : buf->height % 2);
row_start = row_end - thick;
col_start = col;
col_end = col_start + thick;
break;
case L'╰':
col = buf->width - col - 1 - (1 - buf->width % 2);
row_start = row;
row_end = row_start + thick;
col_end = buf->width - col - (thick % 2 ? 1 - buf->width % 2 : buf->width % 2);
col_start = col_end - thick;
break;
case L'╯':
row_start = row;
row_end = row_start + thick;
col_start = col;
col_end = col_start + thick;
break;
}
for (int r = row - delta; r < row + delta + extra; r++) {
assert(row_end > row_start);
assert(col_end > col_start);
for (int r = row_start; r < row_end; r++) {
if (r < 0 || r >= buf->height)
continue;
for (int c = col - delta; c < col + delta + extra; c++) {
for (int c = col_start; c < col_end; c++) {
if (c >= 0 && c < buf->width) {
size_t idx = c / 8;
size_t bit_no = c % 8;
@ -1267,23 +1289,30 @@ draw_box_drawings_light_arc(wchar_t wc, struct buf *buf)
}
}
/*
* Since a cell may not be completely symmetrical around its y-
* and x-axis, the mirroring done above may result in the last
* col/row of the arc not being filled in. This code ensures they
* are.
*/
if (wc == L'╭' || wc == L'╰') {
for (int x = 2 * hw; x < buf->width; x++) {
for (int y = max(hh - delta, 0); y < min(hh + delta + extra, buf->height); y++) {
size_t ofs = x / 8;
size_t bit_no = x % 8;
buf->data[y * buf->stride + ofs] |= 1 << bit_no;
}
for (int y = 0; y < thick; y++) {
int row = (buf->height - thick) / 2 + y;
int col = buf->width - 1;
size_t ofs = col / 8;
size_t bit_no = col % 8;
buf->data[row * buf->stride + ofs] |= 1 << bit_no;
}
}
if (wc == L'╭' || wc == L'╮') {
for (int y = 2 * hh; y < buf->height; y++) {
for (int x = max(hw - delta, 0); x < min(hw + delta + extra, buf->width); x++) {
size_t ofs = x / 8;
size_t bit_no = x % 8;
buf->data[y * buf->stride + ofs] |= 1 << bit_no;
}
for (int x = 0; x < thick; x++) {
int row = buf->height - 1;
int col = (buf->width - thick) / 2 + x;
size_t ofs = col / 8;
size_t bit_no = col % 8;
buf->data[row * buf->stride + ofs] |= 1 << bit_no;
}
}
}