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[justify] Document API

This commit is contained in:
Behdad Esfahbod 2023-03-01 14:08:16 -07:00
parent d29d7b7a3d
commit 96d4ed0931
3 changed files with 56 additions and 29 deletions
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1
docs/harfbuzz-sections.txt
View File

@ -780,6 +780,7 @@ hb_set_t
<FILE>hb-shape</FILE>
hb_shape
hb_shape_full
hb_shape_justify
hb_shape_list_shapers
</SECTION>

78
src/hb-shape.cc
View File

@ -199,18 +199,18 @@ hb_shape (hb_font_t *font,
static float
buffer_width (hb_buffer_t *buffer)
buffer_advance (hb_buffer_t *buffer)
{
float w = 0;
float a = 0;
auto *pos = buffer->pos;
unsigned count = buffer->len;
if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction))
for (unsigned i = 0; i < count; i++)
w += pos[i].x_advance;
a += pos[i].x_advance;
else
for (unsigned i = 0; i < count; i++)
w += pos[i].y_advance;
return w;
a += pos[i].y_advance;
return a;
}
static void
@ -224,21 +224,47 @@ reset_buffer (hb_buffer_t *buffer,
hb_buffer_set_content_type (buffer, HB_BUFFER_CONTENT_TYPE_UNICODE);
}
/**
* hb_shape_justify:
* @font: a mutable #hb_font_t to use for shaping
* @buffer: an #hb_buffer_t to shape
* @features: (array length=num_features) (nullable): an array of user
* specified #hb_feature_t or `NULL`
* @num_features: the length of @features array
* @shaper_list: (array zero-terminated=1) (nullable): a `NULL`-terminated
* array of shapers to use or `NULL`
* @min_target_advance: Minimum advance width/height to aim for.
* @max_target_advance: Maximum advance width/height to aim for.
* @advance: (inout): Input/output advance width/height of the buffer.
* @var_tag: (out): Variation-axis tag used for justification.
* @var_value: (out): Variation-axis value used to reach target justification.
*
* See hb_shape_full() for basic details. If @shaper_list is not `NULL`, the specified
* shapers will be used in the given order, otherwise the default shapers list
* will be used.
*
* In addition, justify the shaping results such that the shaping results reach
* the target advance width/height, depending on the buffer direction.
*
* Return value: false if all shapers failed, true otherwise
*
* XSince: REPLACEME
**/
hb_bool_t
hb_shape_justify (hb_font_t *font,
hb_buffer_t *buffer,
const hb_feature_t *features,
unsigned int num_features,
const char * const *shaper_list,
float min_target_width,
float max_target_width,
float *width, /* IN/OUT */
float min_target_advance,
float max_target_advance,
float *advance, /* IN/OUT */
hb_tag_t *var_tag, /* OUT */
float *var_value /* OUT */)
{
// TODO Negative font scales?
if (min_target_width <= *width && *width <= max_target_width)
if (min_target_advance <= *advance && *advance <= max_target_advance)
return hb_shape_full (font, buffer,
features, num_features,
shaper_list);
@ -266,7 +292,7 @@ hb_shape_justify (hb_font_t *font,
features, num_features,
shaper_list))
{
*width = buffer_width (buffer);
*advance = buffer_advance (buffer);
return true;
}
else
@ -280,23 +306,23 @@ hb_shape_justify (hb_font_t *font,
hb_memcpy (text_info, buffer->info, text_len * sizeof (buffer->info[0]));
auto text = hb_array<const hb_glyph_info_t> (text_info, text_len);
if (!*width)
if (!*advance)
{
hb_font_set_variation (font, tag, axis_info.default_value);
if (!hb_shape_full (font, buffer,
features, num_features,
shaper_list))
return false;
*width = buffer_width (buffer);
*advance = buffer_advance (buffer);
}
if (min_target_width <= *width && *width <= max_target_width)
if (min_target_advance <= *advance && *advance <= max_target_advance)
return true;
double a, b, ya, yb;
if (*width < min_target_width)
if (*advance < min_target_advance)
{
ya = *width;
ya = *advance;
a = axis_info.default_value;
b = axis_info.max_value;
@ -306,16 +332,16 @@ hb_shape_justify (hb_font_t *font,
features, num_features,
shaper_list))
return false;
yb = buffer_width (buffer);
yb = buffer_advance (buffer);
if (yb <= 0)
{
*width = (float) yb;
*advance = (float) yb;
return true;
}
}
else
{
yb = *width;
yb = *advance;
a = axis_info.min_value;
b = axis_info.default_value;
@ -325,10 +351,10 @@ hb_shape_justify (hb_font_t *font,
features, num_features,
shaper_list))
return false;
ya = buffer_width (buffer);
ya = buffer_advance (buffer);
if (ya >= 0)
{
*width = (float) ya;
*advance = (float) ya;
return true;
}
}
@ -345,13 +371,13 @@ hb_shape_justify (hb_font_t *font,
shaper_list)))
{
failed = true;
return (double) min_target_width;
return (double) min_target_advance;
}
double w = buffer_width (buffer);
DEBUG_MSG (JUSTIFY, nullptr, "Trying '%c%c%c%c' axis parameter %f. Width %g. Target: min %g max %g",
double w = buffer_advance (buffer);
DEBUG_MSG (JUSTIFY, nullptr, "Trying '%c%c%c%c' axis parameter %f. Advance %g. Target: min %g max %g",
HB_UNTAG (tag), x, w,
(double) min_target_width, (double) max_target_width);
(double) min_target_advance, (double) max_target_advance);
return w;
};
@ -359,7 +385,7 @@ hb_shape_justify (hb_font_t *font,
double itp = solve_itp (f,
a, b,
epsilon,
min_target_width, max_target_width,
min_target_advance, max_target_advance,
ya, yb, y);
hb_free (text_info);
@ -368,7 +394,7 @@ hb_shape_justify (hb_font_t *font,
return false;
*var_value = (float) itp;
*width = (float) y;
*advance = (float) y;
return true;
}

6
src/hb-shape.h
View File

@ -59,9 +59,9 @@ hb_shape_justify (hb_font_t *font,
const hb_feature_t *features,
unsigned int num_features,
const char * const *shaper_list,
float min_target_width,
float max_target_width,
float *width, /* IN/OUT */
float min_target_advance,
float max_target_advance,
float *advance, /* IN/OUT */
hb_tag_t *var_tag, /* OUT */
float *var_value /* OUT */);