[gtk/glyph-cache-fixes] gl: Glyph cache fixes

[Matthias Clasen <matthiasc src gnome org>]

commit d276d2629acdefb54a67f7a8760feffa09c7e033
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Jul 30 22:21:52 2019 -0400

    gl: Glyph cache fixes
    
    Pass the full location to the glyph cache lookup,
    and use the same rounding as cairo does. This makes
    the output much closer to the cairo renderer.

 gsk/gl/gskglglyphcache.c        | 19 +++++++++----------
 gsk/gl/gskglglyphcacheprivate.h |  4 ++--
 gsk/gl/gskglrenderer.c          | 14 +++++++-------
 3 files changed, 18 insertions(+), 19 deletions(-)
---
diff --git a/gsk/gl/gskglglyphcache.c b/gsk/gl/gskglglyphcache.c
index a33a1357aa..ff87229b56 100644
--- a/gsk/gl/gskglglyphcache.c
+++ b/gsk/gl/gskglglyphcache.c
@@ -237,7 +237,7 @@ add_to_cache (GskGLGlyphCache  *self,
       value->texture_id = gsk_gl_driver_create_texture (driver, width, height);
 
       gsk_gl_driver_bind_source_texture (driver, value->texture_id);
-      gsk_gl_driver_init_texture_empty (driver, value->texture_id, GL_NEAREST, GL_NEAREST);
+      gsk_gl_driver_init_texture_empty (driver, value->texture_id, GL_LINEAR, GL_LINEAR);
 
       value->tx = 0.0f;
       value->ty = 0.0f;
@@ -245,18 +245,17 @@ add_to_cache (GskGLGlyphCache  *self,
       value->th = 1.0f;
     }
 
-
   upload_glyph (key, value);
 }
 
-#define PHASE(x) ((x % PANGO_SCALE) * 4 / PANGO_SCALE)
+#define PHASE(x) ((int)(floor (4 * (x + 0.125)) - 4 * floor (x + 0.125)))
 
 gboolean
 gsk_gl_glyph_cache_lookup (GskGLGlyphCache  *cache,
                            PangoFont        *font,
                            PangoGlyph        glyph,
-                           int               x,
-                           int               y,
+                           float             x,
+                           float             y,
                            float             scale,
                            GskGLDriver      *driver,
                            GskGLCachedGlyph *cached_glyph_out)
@@ -264,6 +263,7 @@ gsk_gl_glyph_cache_lookup (GskGLGlyphCache  *cache,
   GskGLCachedGlyph *value;
   guint xshift = PHASE (x);
   guint yshift = PHASE (y);
+  const guint key_scale = (guint)(scale * 1024);
 
   value = g_hash_table_lookup (cache->hash_table,
                                &(GlyphCacheKey) {
@@ -271,7 +271,7 @@ gsk_gl_glyph_cache_lookup (GskGLGlyphCache  *cache,
                                  .glyph = glyph,
                                  .xshift = xshift,
                                  .yshift = yshift,
-                                 .scale = (guint)(scale * 1024)
+                                 .scale = key_scale
                                });
 
   if (value)
@@ -298,7 +298,6 @@ gsk_gl_glyph_cache_lookup (GskGLGlyphCache  *cache,
     {
       GlyphCacheKey *key;
       PangoRectangle ink_rect;
-      const guint key_scale = (guint)(scale * 1024);
 
       pango_font_get_glyph_extents (font, glyph, &ink_rect, NULL);
       pango_extents_to_pixels (&ink_rect, NULL);
@@ -322,11 +321,11 @@ gsk_gl_glyph_cache_lookup (GskGLGlyphCache  *cache,
       key->glyph = glyph;
       key->xshift = xshift;
       key->yshift = yshift;
-      key->scale =  key_scale;
+      key->scale = key_scale;
 
       if (key->scale > 0 &&
-          ink_rect.width * key->scale > 0 &&
-          ink_rect.height * key->scale > 0)
+          value->draw_width * key->scale / 1024 > 0 &&
+          value->draw_height * key->scale / 1024 > 0)
         add_to_cache (cache, key, driver, value);
 
       *cached_glyph_out = *value;
diff --git a/gsk/gl/gskglglyphcacheprivate.h b/gsk/gl/gskglglyphcacheprivate.h
index 0859798907..ee1912c3a6 100644
--- a/gsk/gl/gskglglyphcacheprivate.h
+++ b/gsk/gl/gskglglyphcacheprivate.h
@@ -57,8 +57,8 @@ void                     gsk_gl_glyph_cache_begin_frame     (GskGLGlyphCache
 gboolean                 gsk_gl_glyph_cache_lookup          (GskGLGlyphCache        *self,
                                                              PangoFont              *font,
                                                              PangoGlyph              glyph,
-                                                             int                     x,
-                                                             int                     y,
+                                                             float                   x,
+                                                             float                   y,
                                                              float                   scale,
                                                              GskGLDriver            *driver,
                                                              GskGLCachedGlyph       *cached_glyph_out);
diff --git a/gsk/gl/gskglrenderer.c b/gsk/gl/gskglrenderer.c
index b2fee7872f..cced23aa9b 100644
--- a/gsk/gl/gskglrenderer.c
+++ b/gsk/gl/gskglrenderer.c
@@ -592,11 +592,14 @@ render_text_node (GskGLRenderer   *self,
       if (gi->glyph == PANGO_GLYPH_EMPTY)
         continue;
 
+      cx = (double)(x_position + gi->geometry.x_offset) / PANGO_SCALE;
+      cy = (double)(gi->geometry.y_offset) / PANGO_SCALE;
+
       gsk_gl_glyph_cache_lookup (self->glyph_cache,
                                  (PangoFont *)font,
                                  gi->glyph,
-                                 x * PANGO_SCALE + x_position + gi->geometry.x_offset,
-+                                y * PANGO_SCALE + gi->geometry.y_offset,
+                                 x + cx,
++                                y + cy,
                                  text_scale,
                                  self->gl_driver,
                                  &glyph);
@@ -608,9 +611,6 @@ render_text_node (GskGLRenderer   *self,
       if (glyph.texture_id == 0)
         goto next;
 
-      cx = (x_position + gi->geometry.x_offset) / PANGO_SCALE;
-      cy = gi->geometry.y_offset / PANGO_SCALE;
-
       ops_set_texture (builder, glyph.texture_id);
 
       tx  = glyph.tx;
@@ -618,8 +618,8 @@ render_text_node (GskGLRenderer   *self,
       tx2 = tx + glyph.tw;
       ty2 = ty + glyph.th;
 
-      glyph_x = x + cx + glyph.draw_x;
-      glyph_y = y + cy + glyph.draw_y;
+      glyph_x = floor (x + cx + 0.125) + glyph.draw_x;
+      glyph_y = floor (y + cy + 0.125) + glyph.draw_y;
       glyph_w = glyph.draw_width;
       glyph_h = glyph.draw_height;