Index: ftstring.c
===================================================================
RCS file: /cvs/freetype/ft2demos/src/ftstring.c,v
retrieving revision 1.10
diff -c -r1.10 ftstring.c
*** ftstring.c	2002/04/28 02:48:45	1.10
--- ftstring.c	2002/06/08 06:53:46
***************
*** 55,60 ****
--- 55,61 ----
    static int  antialias = 1;        /* is anti-aliasing active ?    */
    static int  use_sbits = 0;        /* do we use embedded bitmaps ? */
    static int  kerning   = 1;
+   static int  use_gamma = 1;
  
    static int  res = 72;             /* default resolution in dpi */
  
***************
*** 162,167 ****
--- 163,213 ----
    static TGlyph  glyphs[ MAX_GLYPHS ];
    static int     num_glyphs;
  
+   /*************************************************************************/
+   /*                                                                       */
+   /* Gamma correction.                                                     */
+   /*                                                                       */
+   /*                                                                       */
+   static double  gamma_value = 2.0f;
+   static FT_Byte gamma_ramp[256];
+ 
+   static void
+   init_gamma( void )
+   {
+     int i;
+     double gamma_inv = 1.0f / gamma_value;
+ 
+     for (i = 0; i < 256; i++)
+       gamma_ramp[i] = (FT_Byte)( pow((double)i / 256.0f, gamma_inv) * 256.0f );
+   }
+ 
+   static void
+   apply_gamma( grBitmap* bmp )
+   {
+     int i, j;
+     char* buffer = bmp->buffer;
+ 
+     for (i = 0; i < bmp->rows; i++)
+     {
+       for (j = 0; j < bmp->width; j++)
+         /* bitmap color is the inverse of coverage values, hence the '255-x' */
+         buffer[j] = 255 - gamma_ramp[255 - (FT_Byte)buffer[j]];
+ 
+       buffer += bmp->pitch;
+     }
+   }
+ 
+   static void
+   draw_gamma_ramp( void )
+   {
+     int i, x, y;
+     
+     x = (bit.width - 256) / 2;
+     y = (bit.rows + 256) / 2;
+     for (i = 0; i < 256; i++, x++)
+       bit.buffer[bit.pitch*(y - gamma_ramp[i]) + x] = 80;
+   }
+ 
  
    /*************************************************************************/
    /*                                                                       */
***************
*** 384,389 ****
--- 430,437 ----
              case ft_pixel_mode_grays:
                bit3.mode  = gr_pixel_mode_gray;
                bit3.grays = source->num_grays;
+               if (use_gamma)
+                 apply_gamma(&bit3);
                break;
  
              default:
***************
*** 484,489 ****
--- 532,538 ----
      grWriteln("  a         : toggle anti-aliasing" );
      grWriteln("  h         : toggle outline hinting" );
      grWriteln("  k         : toggle kerning" );
+     grWriteln("  g         : toggle gamma correction" );
      grLn();
      grWriteln("  Up        : increase pointsize by 1 unit" );
      grWriteln("  Down      : decrease pointsize by 1 unit" );
***************
*** 495,500 ****
--- 544,552 ----
      grWriteln("  F7        : big rotate counter-clockwise");
      grWriteln("  F8        : big rotate clockwise");
      grLn();
+     grWriteln("  F9        : decrease gamma by 0.1" );
+     grWriteln("  F10       : increase gamma by 0.1" );
+     grLn();
      grWriteln("press any key to exit this help screen");
  
      grRefreshSurface( surface );
***************
*** 550,555 ****
--- 602,614 ----
                       : (char *)"glyph hinting is now ignored";
        break;
  
+     case grKEY( 'g' ):
+       use_gamma = !use_gamma;
+       new_header = use_gamma
+                      ? (char *)"gamma correction is now on"
+                      : (char *)"gamma correction is now off";
+       return 1;
+ 
      case grKeyF1:
      case grKEY( '?' ):
        Help();
***************
*** 571,576 ****
--- 630,638 ----
      case grKeyRight: i =   1; goto Do_Rotate;
      case grKeyF7:    i = -10; goto Do_Rotate;
      case grKeyF8:    i =  10; goto Do_Rotate;
+ 
+     case grKeyF9 : if (gamma_value > 0.1f) gamma_value -= 0.1f; goto Do_Gamma_Set;
+     case grKeyF10:                         gamma_value += 0.1f; goto Do_Gamma_Set;
      default:
        ;
      }
***************
*** 580,585 ****
--- 642,657 ----
      Rotation = ( Rotation + i ) & 127;
      return 1;
  
+   Do_Gamma_Set:
+   {
+     static char header_buffer[64];
+ 
+     sprintf(header_buffer, "gamma is %.1f", gamma_value);
+     new_header = header_buffer;
+     init_gamma();
+     return 1;
+   }
+ 
    Do_Scale:
      ptsize += i;
      if ( ptsize < 1 )         ptsize = 1;
***************
*** 731,736 ****
--- 803,810 ----
        goto Display_Font;
  
    Success:
+     init_gamma();
+ 
      /* prepare the text to be rendered */
      prepare_text( (unsigned char*)Text );
  
***************
*** 773,778 ****
--- 847,854 ----
          {
            reset_transform();
            layout_glyphs();
+           if (use_gamma)
+             draw_gamma_ramp();
            render_string( bit.width/2, bit.rows/2 );
          }