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Implement hb-shape --verify unsafe-to-concat flag 

15 tests failing. Those look like legit places that unsafe-to-concat
needs more implementation.
This commit is contained in:
Behdad Esfahbod 2021-11-19 14:10:34 -07:00
parent 3122c2cdc4
commit 36b1561715
1 changed files with 189 additions and 9 deletions
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198
util/shape-options.hh
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@ -129,7 +129,9 @@ struct shape_options_t
{
if (!verify_buffer_monotone (buffer, error))
return false;
if (!verify_buffer_safe_to_break (buffer, text_buffer, font, error))
if (!verify_buffer_unsafe_to_break (buffer, text_buffer, font, error))
return false;
if (!verify_buffer_unsafe_to_concat (buffer, text_buffer, font, error))
return false;
return true;
}
@ -158,17 +160,15 @@ struct shape_options_t
return true;
}
bool verify_buffer_safe_to_break (hb_buffer_t *buffer,
hb_buffer_t *text_buffer,
hb_font_t *font,
const char **error=nullptr)
bool verify_buffer_unsafe_to_break (hb_buffer_t *buffer,
hb_buffer_t *text_buffer,
hb_font_t *font,
const char **error=nullptr)
{
if (cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES &&
cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)
{
/* Cannot perform this check without monotone clusters.
* Then again, unsafe-to-break flag is much harder to use without
* monotone clusters. */
/* Cannot perform this check without monotone clusters. */
return true;
}
@ -255,7 +255,7 @@ struct shape_options_t
if (diff)
{
if (error)
*error = "Safe-to-break test failed.";
*error = "unsafe-to-break test failed.";
ret = false;
/* Return the reconstructed result instead so it can be inspected. */
@ -269,6 +269,186 @@ struct shape_options_t
return ret;
}
bool verify_buffer_unsafe_to_concat (hb_buffer_t *buffer,
hb_buffer_t *text_buffer,
hb_font_t *font,
const char **error=nullptr)
{
if (cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES &&
cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)
{
/* Cannot perform this check without monotone clusters. */
return true;
}
/* Check that shuffling up text before shaping at safe-to-concat points
* is indeed safe. */
/* This is what we do:
*
* 1. We shape text once. Then segment the text at all the safe-to-concat
* points;
*
* 2. Then we create two buffers, one containing all the even segments and
* one all the odd segments.
*
* 3. Because all these segments were safe-to-concat at both ends, we
* expect that concatenating them and shaping should NOT change the
* shaping results of each segment. As such, we expect that after
* shaping the two buffers, we still get cluster boundaries at the
* segment boundaries, and that those all are safe-to-concat points.
* Moreover, that there are NOT any safe-to-concat points within the
* segments.
*
* 4. Finally, we reconstruct the shaping results of the original text by
* simply interleaving the shaping results of the segments from the two
* buffers, and assert that the total shaping results is the same as
* the one from original buffer in step 1.
*/
hb_buffer_t *fragments[2] {hb_buffer_create_similar (buffer),
hb_buffer_create_similar (buffer)};
hb_buffer_t *reconstruction = hb_buffer_create_similar (buffer);
hb_segment_properties_t props;
hb_buffer_get_segment_properties (buffer, &props);
hb_buffer_set_segment_properties (fragments[0], &props);
hb_buffer_set_segment_properties (fragments[1], &props);
hb_buffer_set_segment_properties (reconstruction, &props);
unsigned num_glyphs;
hb_glyph_info_t *info = hb_buffer_get_glyph_infos (buffer, &num_glyphs);
unsigned num_chars;
hb_glyph_info_t *text = hb_buffer_get_glyph_infos (text_buffer, &num_chars);
bool forward = HB_DIRECTION_IS_FORWARD (hb_buffer_get_direction (buffer));
if (!forward)
hb_buffer_reverse (buffer);
/*
* Split text into segments and collect into to fragment streams.
*/
{
unsigned fragment_idx = 0;
unsigned start = 0;
unsigned text_start = 0;
unsigned text_end = 0;
for (unsigned end = 1; end < num_glyphs + 1; end++)
{
if (end < num_glyphs &&
(info[end].cluster == info[end-1].cluster ||
info[end].mask & HB_GLYPH_FLAG_UNSAFE_TO_CONCAT))
continue;
/* Accumulate segment corresponding to glyphs start..end. */
if (end == num_glyphs)
text_end = num_chars;
else
{
unsigned cluster = info[end].cluster;
while (text_end < num_chars && text[text_end].cluster < cluster)
text_end++;
}
assert (text_start < text_end);
if (0)
printf("start %d end %d text start %d end %d\n", start, end, text_start, text_end);
#if 0
hb_buffer_flags_t flags = hb_buffer_get_flags (fragment);
if (0 < text_start)
flags = (hb_buffer_flags_t) (flags & ~HB_BUFFER_FLAG_BOT);
if (text_end < num_chars)
flags = (hb_buffer_flags_t) (flags & ~HB_BUFFER_FLAG_EOT);
hb_buffer_set_flags (fragment, flags);
#endif
hb_buffer_append (fragments[fragment_idx], text_buffer, text_start, text_end);
start = end;
text_start = text_end;
fragment_idx = 1 - fragment_idx;
}
}
bool ret = true;
hb_buffer_diff_flags_t diff;
/*
* Shape the two fragment streams.
*/
if (!hb_shape_full (font, fragments[0], features, num_features, shapers) ||
!hb_shape_full (font, fragments[1], features, num_features, shapers))
{
if (error)
*error = "All shapers failed while shaping fragments.";
ret = false;
goto out;
}
if (!forward)
{
hb_buffer_reverse (fragments[0]);
hb_buffer_reverse (fragments[1]);
}
/*
* Reconstruct results.
*/
{
unsigned fragment_idx = 0;
unsigned fragment_start[2] {0, 0};
unsigned fragment_num_glyphs[2];
hb_glyph_info_t *fragment_info[2];
for (unsigned i = 0; i < 2; i++)
fragment_info[i] = hb_buffer_get_glyph_infos (fragments[i], &fragment_num_glyphs[i]);
while (fragment_start[0] < fragment_num_glyphs[0] ||
fragment_start[1] < fragment_num_glyphs[1])
{
unsigned fragment_end = fragment_start[fragment_idx] + 1;
while (fragment_end < fragment_num_glyphs[fragment_idx] &&
(fragment_info[fragment_idx][fragment_end].cluster == fragment_info[fragment_idx][fragment_end - 1].cluster ||
fragment_info[fragment_idx][fragment_end].mask & HB_GLYPH_FLAG_UNSAFE_TO_CONCAT))
fragment_end++;
hb_buffer_append (reconstruction, fragments[fragment_idx], fragment_start[fragment_idx], fragment_end);
fragment_start[fragment_idx] = fragment_end;
fragment_idx = 1 - fragment_idx;
}
}
if (!forward)
{
hb_buffer_reverse (buffer);
hb_buffer_reverse (reconstruction);
}
/*
* Diff results.
*/
diff = hb_buffer_diff (reconstruction, buffer, (hb_codepoint_t) -1, 0);
if (diff)
{
if (error)
*error = "unsafe-to-concat test failed.";
ret = false;
/* Return the reconstructed result instead so it can be inspected. */
hb_buffer_set_length (buffer, 0);
hb_buffer_append (buffer, reconstruction, 0, -1);
}
out:
hb_buffer_destroy (reconstruction);
hb_buffer_destroy (fragments[0]);
hb_buffer_destroy (fragments[1]);
return ret;
}
void shape_closure (const char *text, int text_len,
hb_font_t *font, hb_buffer_t *buffer,
hb_set_t *glyphs)