[freetype2-demos] upgray fbf5c76: [graph] Handle glyphs with 4 or 16 grays.

[Werner Lemberg]

branch: upgray
commit fbf5c760fca0709cde0e8f13ec8bd3d4de6e1dfb
Author: Alexei Podtelezhnikov <apodtele@gmail.com>
Commit: Alexei Podtelezhnikov <apodtele@gmail.com>

    [graph] Handle glyphs with 4 or 16 grays.
    
    * graph/gblblit.c (gblender_glyph_upgray): Convert to 256 grays.
    (gblender_blit_init): Call it if necessary.
---
 graph/gblblit.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/graph/gblblit.c b/graph/gblblit.c
index 0c5f756..f7b7fae 100644
--- a/graph/gblblit.c
+++ b/graph/gblblit.c
@@ -241,6 +241,27 @@
 
 /* */
 
+/* works best to convert from 4 or 16 grays to 256 grays,
+ * needs aligned buffers and clean padding
+ */
+static void
+gblender_glyph_upgray( grBitmap*  glyph )
+{
+  int        i, size = abs( glyph->pitch ) * glyph->rows;
+  uint32_t*  buf = (uint32_t*)glyph->buffer;
+  uint32_t   scale = 255U / ( glyph->grays - 1 );
+
+
+  for ( i = 4; i <= size; i += 4, buf++ )
+    *buf *= scale;
+
+  for ( i -= 4; i < size; i++ )
+    glyph->buffer[i] *= scale;
+
+  glyph->grays = 256;
+}
+
+
 static int
 gblender_blit_init( GBlenderBlit           blit,
                     int                    dst_x,
@@ -269,6 +290,8 @@ gblender_blit_init( GBlenderBlit           blit,
   {
   case gr_pixel_mode_gray:
     src_format = GBLENDER_SOURCE_GRAY8;
+    if ( glyph->grays != 256 )
+      gblender_glyph_upgray( glyph );
     if ( blender->channels )
       gblender_clear( blender );
     break;