[gtk/glyphy2: 29/32] Update to boldness api changes in glyphy

[Matthias Clasen <matthiasc src gnome org>]

commit 312d7b26606bd64bc7c6466ff2447a7084421c03
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Apr 4 20:38:04 2022 -0400

    Update to boldness api changes in glyphy
    
    With this, synthetic bold fonts work as well
    as the do with freetype.

 gsk/gl/gskglglyphylibrary.c     | 32 ++++++++++++++++++++------------
 gsk/gl/gskglrenderjob.c         |  6 +++++-
 gsk/gl/resources/glyphy.fs.glsl |  4 ++--
 3 files changed, 27 insertions(+), 15 deletions(-)
---
diff --git a/gsk/gl/gskglglyphylibrary.c b/gsk/gl/gskglglyphylibrary.c
index fd5d1d503a..3a0ec8b3a1 100644
--- a/gsk/gl/gskglglyphylibrary.c
+++ b/gsk/gl/gskglglyphylibrary.c
@@ -54,7 +54,10 @@
 #include <glyphy.h>
 
 #define TOLERANCE (1/2048.)
-#define MIN_FONT_SIZE 10
+#define MIN_FONT_SIZE 14
+#define GRID_SIZE 20 /* Per EM */
+#define ENLIGHTEN_MAX .01 /* Per EM */
+#define EMBOLDEN_MAX .024 /* Per EM */
 #define ITEM_W 64
 #define ITEM_H_QUANTUM 8
 
@@ -349,6 +352,9 @@ encode_glyph (GskGLGlyphyLibrary *self,
   guint upem = hb_face_get_upem (face);
   double tolerance = upem * tolerance_per_em;
   double faraway = (double)upem / (MIN_FONT_SIZE * M_SQRT2);
+  double unit_size = (double) upem / GRID_SIZE;
+  double enlighten_max = (double) upem * ENLIGHTEN_MAX;
+  double embolden_max = (double) upem * EMBOLDEN_MAX;
   double avg_fetch_achieved;
   GskPathBuilder *builder;
   GskPath *path, *simplified;
@@ -380,17 +386,19 @@ encode_glyph (GskGLGlyphyLibrary *self,
                                           self->acc_endpoints->len,
                                           FALSE);
 
-  if (!glyphy_arc_list_encode_blob ((gpointer)self->acc_endpoints->data,
-                                    self->acc_endpoints->len,
-                                    buffer,
-                                    buffer_len,
-                                    faraway,
-                                    4, /* UNUSED */
-                                    &avg_fetch_achieved,
-                                    output_len,
-                                    nominal_width,
-                                    nominal_height,
-                                    extents))
+  if (!glyphy_arc_list_encode_blob2 ((gpointer)self->acc_endpoints->data,
+                                     self->acc_endpoints->len,
+                                     buffer,
+                                     buffer_len,
+                                     faraway,
+                                     unit_size,
+                                     enlighten_max,
+                                     embolden_max,
+                                     &avg_fetch_achieved,
+                                     output_len,
+                                     nominal_width,
+                                     nominal_height,
+                                     extents))
     return FALSE;
 
   glyphy_extents_scale (extents, 1./upem, 1./upem);
diff --git a/gsk/gl/gskglrenderjob.c b/gsk/gl/gskglrenderjob.c
index 6f6f45772e..4fe13b2791 100644
--- a/gsk/gl/gskglrenderjob.c
+++ b/gsk/gl/gskglrenderjob.c
@@ -3164,6 +3164,8 @@ gsk_gl_render_job_visit_text_node_glyphy (GskGLRenderJob      *job,
   float font_scale;
   gboolean synthetic_bold;
 
+#define GRID_SIZE 20
+
   g_assert (!gsk_text_node_has_color_glyphs (node));
 
   if (!(num_glyphs = gsk_text_node_get_num_glyphs (node)))
@@ -3237,9 +3239,11 @@ gsk_gl_render_job_visit_text_node_glyphy (GskGLRenderJob      *job,
           gsk_gl_program_set_uniform1f (job->current_program,
                                         UNIFORM_GLYPHY_CONTRAST, 0,
                                         1.0);
+
+          /* 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 ? 0.1 : 0.0);
+                                        synthetic_bold ? 0.0208 * GRID_SIZE : 0.0);
 
 #if 0
           gsk_gl_program_set_uniform1f (job->current_program,
diff --git a/gsk/gl/resources/glyphy.fs.glsl b/gsk/gl/resources/glyphy.fs.glsl
index 66860734df..a42aa9df54 100644
--- a/gsk/gl/resources/glyphy.fs.glsl
+++ b/gsk/gl/resources/glyphy.fs.glsl
@@ -47,6 +47,7 @@ main()
   float m = length (vec2 (length (dpdx), length (dpdy))) * SQRT2_2;
 
   float gsdist = glyphy_sdf (p, gi.nominal_size GLYPHY_DEMO_EXTRA_ARGS);
+  gsdist -= u_boldness;
   float sdist = gsdist / m * u_contrast;
 
 #if 0
@@ -70,14 +71,13 @@ main()
 
     glyphy_arc_list_t arc_list = glyphy_arc_list (p, gi.nominal_size GLYPHY_DEMO_EXTRA_ARGS);
     // Color the number of endpoints per cell blue
-    color += vec4 (0,0,1,.1) * float(arc_list.num_endpoints) * 32./255.;
+    color += vec4 (0,0,1,.4) * float(arc_list.num_endpoints) * 32./255.;
 
     gskSetOutputColor(color);
   }
   else
 #endif
   {
-    sdist -= u_boldness * 10.;
     if (u_outline)
       sdist = abs (sdist) - u_outline_thickness * .5;
     if (sdist > 1.)