[HarfBuzz] Some experiments with harfbuzz/OpenGL

[Behdad Esfahbod]

On 13-04-12 01:44 PM, Nicolas Rougier wrote:
> 
> 
> Hi,
> 
> Thanks to the great example available at https://github.com/lxnt/ex-sdl-freetype-harfbuzz, I did some experiments to render
> some Arabic text using OpenGL/Freetype/Harfbuzz.
> 
> You can find a screenshot here: http://freetype-gl.googlecode.com/svn/wiki/images/arabic.png
> 
> Sources are available in http://code.google.com/p/freetype-gl/source/browse/trunk/harfbuzz.
> It's quite experimental though...
> 
> I hope the text is ok since I don't read Arabic (google helped me on this).

First, you were ignoring the glyph offsets:

Index: demo-harfbuzz.c
===================================================================
--- demo-harfbuzz.c	(revision 216)
+++ demo-harfbuzz.c	(working copy)
@@ -182,14 +182,16 @@
             int codepoint = glyph_info[j].codepoint;
             float x_advance = glyph_pos[j].x_advance/(64.*64.); // because of
vhinting trick
             float y_advance = glyph_pos[j].y_advance/(64.);
+            float x_offset = glyph_pos[j].x_offset/(64.*64.); // because of
vhinting trick
+            float y_offset = glyph_pos[j].y_offset/(64.);
             texture_glyph_t *glyph = texture_font_get_glyph(fonts[i], codepoint);

             float r = 0.0;
             float g = 0.0;
             float b = 0.0;
             float a = 1.0;
-            float x0 = x + glyph->offset_x;
-            float y0 = y + glyph->offset_y;
+            float x0 = x + x_offset + glyph->offset_x;
+            float y0 = y + y_offset + glyph->offset_y;
             float x1 = x0 + glyph->width;
             float y1 = y0 - glyph->height;
             float s0 = glyph->s0;


Next, you should create the hb-ft font after setting size on the FT face:

Index: texture-font.c
===================================================================
--- texture-font.c	(revision 216)
+++ texture-font.c	(working copy)
@@ -170,7 +170,6 @@
             }
         }
     }
-    self->hb_ft_font = hb_ft_font_create( self->ft_face, NULL );

     /* Set char size */
     error = FT_Set_Char_Size( self->ft_face, (int)(size*64), 0, hdpi*hres,
vdpi );
@@ -184,6 +183,8 @@
     /* Set transform matrix */
     FT_Set_Transform( self->ft_face, &matrix, NULL );

+    self->hb_ft_font = hb_ft_font_create( self->ft_face, NULL );
+
     return self;
  }



Looks correct after adding these.  Though, I was under the impression that
Amiri has much better mark positioning.  Khaled, am I missing anything here?

b

-- 
behdad
http://behdad.org/