sixel: empty pixels in the last sixel row doesn’t contribute to the image height

All-empty pixels rows in the last sixel row should not be included in
the final sixel image.

This allows applications to emit sixels whose height is not a multiple
of 6, and is how XTerm works.

This is done by tracking the largest row number that contains
non-empty pixels.

In unhook, when emitting the image, the image height is adjusted based
on this value.
This commit is contained in:
Daniel Eklöf 2021-03-07 14:44:16 +01:00
parent d35963f584
commit c181eb2bf6
No known key found for this signature in database
GPG key ID: 5BBD4992C116573F
2 changed files with 18 additions and 1 deletions

18
sixel.c
View file

@ -37,6 +37,7 @@ sixel_init(struct terminal *term)
term->sixel.state = SIXEL_DECSIXEL;
term->sixel.pos = (struct coord){0, 0};
term->sixel.max_non_empty_row_no = 0;
term->sixel.row_byte_ofs = 0;
term->sixel.color_idx = 0;
term->sixel.param = 0;
@ -695,6 +696,13 @@ sixel_reflow(struct terminal *term)
void
sixel_unhook(struct terminal *term)
{
if (term->sixel.image.height > term->sixel.max_non_empty_row_no + 1) {
LOG_DBG(
"last row only partially filled, reducing image height: %d -> %d",
term->sixel.image.height, term->sixel.max_non_empty_row_no + 1);
term->sixel.image.height = term->sixel.max_non_empty_row_no + 1;
}
int pixel_row_idx = 0;
int pixel_rows_left = term->sixel.image.height;
const int stride = term->sixel.image.width * sizeof(uint32_t);
@ -846,6 +854,7 @@ resize(struct terminal *term, int new_width, int new_height)
if (new_width > term->sixel.max_width ||
new_height > term->sixel.max_height)
{
LOG_WARN("maximum image dimensions reached");
return false;
}
@ -921,13 +930,20 @@ sixel_add(struct terminal *term, uint32_t color, uint8_t sixel)
size_t ofs = term->sixel.row_byte_ofs + term->sixel.pos.col;
uint32_t *data = term->sixel.image.data;
int max_non_empty_row = 0;
for (int i = 0; i < 6; i++, sixel >>= 1, ofs += width) {
if (sixel & 1)
if (sixel & 1) {
data[ofs] = color;
max_non_empty_row = i;
}
}
xassert(sixel == 0);
term->sixel.pos.col++;
term->sixel.max_non_empty_row_no = max(
term->sixel.max_non_empty_row_no,
term->sixel.pos.row + max_non_empty_row);
}
static void

View file

@ -521,6 +521,7 @@ struct terminal {
} state;
struct coord pos; /* Current sixel coordinate */
int max_non_empty_row_no;
size_t row_byte_ofs; /* Byte position into image, for current row */
int color_idx; /* Current palette index */
uint32_t *private_palette; /* Private palette, used when private mode 1070 is enabled */