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glyphy: Implement synthetic italic

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Use the font matrix found in the FcPattern to
transform the quads we use to render the glyphs.

This makes Cantarell Italic come out just like
it does with freetype.
This commit is contained in:
Matthias Clasen
2022-04-04 21:52:04 -04:00
parent 922daf2ed7
commit 370c47e595
1 changed files with 29 additions and 12 deletions
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41
gsk/gl/gskglrenderjob.c
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@@ -3153,21 +3153,35 @@ add_encoded_glyph (GskGLDrawVertex *vertices,
*vertices = (GskGLDrawVertex) { .position = { eg->x, eg->y}, .uv = { eg->g16hi, eg->g16lo}, .color = { c[0], c[1], c[2], c[3] } };
}
static gboolean
font_is_synthetic_bold (PangoFont *font)
static void
get_synthetic_font_params (PangoFont *font,
gboolean *embolden,
PangoMatrix *matrix)
{
*embolden = FALSE;
*matrix = (PangoMatrix) PANGO_MATRIX_INIT;
#ifdef HAVE_PANGOFT
if (PANGO_IS_FC_FONT (font))
{
FcPattern *pattern = pango_fc_font_get_pattern (PANGO_FC_FONT (font));
gboolean ret;
FcBool b;
FcMatrix mat;
FcMatrix *m;
if (FcPatternGetBool (pattern, FC_EMBOLDEN, 0, &ret) == FcResultMatch)
return ret;
if (FcPatternGetBool (pattern, FC_EMBOLDEN, 0, &b) == FcResultMatch)
*embolden = b;
FcMatrixInit (&mat);
for (int i = 0; FcPatternGetMatrix (pattern, FC_MATRIX, i, &m) == FcResultMatch; i++)
FcMatrixMultiply (&mat, &mat, m);
matrix->xx = mat.xx;
matrix->xy = mat.xy;
matrix->yx = mat.yx;
matrix->yy = mat.yy;
}
#endif
return FALSE;
}
static inline void
@@ -3193,7 +3207,8 @@ gsk_gl_render_job_visit_text_node_glyphy (GskGLRenderJob *job,
guint i;
int x_position = 0;
float font_scale;
gboolean synthetic_bold;
gboolean embolden;
PangoMatrix matrix = PANGO_MATRIX_INIT;
#define GRID_SIZE 20
@@ -3206,7 +3221,7 @@ gsk_gl_render_job_visit_text_node_glyphy (GskGLRenderJob *job,
return;
font = (PangoFont *)gsk_text_node_get_font (node);
synthetic_bold = font_is_synthetic_bold (font);
get_synthetic_font_params (font, &embolden, &matrix);
glyphs = gsk_text_node_get_glyphs (node, NULL);
library = job->driver->glyphy_library;
@@ -3274,7 +3289,7 @@ gsk_gl_render_job_visit_text_node_glyphy (GskGLRenderJob *job,
/* 0.0208 is the value used by freetype for synthetic emboldening */
gsk_gl_program_set_uniform1f (job->current_program,
UNIFORM_GLYPHY_BOLDNESS, 0,
synthetic_bold ? 0.0208 * GRID_SIZE : 0.0);
embolden ? 0.0208 * GRID_SIZE : 0.0);
#if 0
gsk_gl_program_set_uniform1f (job->current_program,
@@ -3297,8 +3312,10 @@ gsk_gl_render_job_visit_text_node_glyphy (GskGLRenderJob *job,
EncodedGlyph encoded[4];
#define ENCODE_CORNER(_cx, _cy) \
G_STMT_START { \
float _vx = x + cx + font_scale * ((1-_cx) * glyph->extents.min_x + _cx * glyph->extents.max_x); \
float _vy = y + cy - font_scale * ((1-_cy) * glyph->extents.min_y + _cy * glyph->extents.max_y); \
float _dx = _cx * (glyph->extents.max_x - glyph->extents.min_x); \
float _dy = _cy * (glyph->extents.max_y - glyph->extents.min_y); \
float _vx = x + cx + font_scale * (glyph->extents.min_x + matrix.xx * _dx + matrix.xy * _dy); \
float _vy = y + cy - font_scale * (glyph->extents.min_y + matrix.yx * _dx + matrix.yy * _dy); \
encoded_glyph_init (&encoded[_cx * 2 + _cy], _vx, _vy, _cx, _cy, glyph); \
} G_STMT_END
ENCODE_CORNER (0, 0);