bionic (3) set_color_conversion.3alleg4.gz

NAME

       set_color_conversion - Tells Allegro how to convert images during loading time.

SYNOPSIS

       #include <allegro.h>

       void set_color_conversion(int mode);

DESCRIPTION

       Specifies  how  to  convert  images  between the various color depths when reading graphics from external
       bitmap files or datafiles. The mode is a bitmask specifying which types of conversion are allowed. If the
       appropriate  bit  is  set,  data will be converted into the current pixel format (selected by calling the
       set_color_depth() function), otherwise it will be left in the same format as the disk file,  leaving  you
       to convert it manually before the graphic can be displayed. The default mode is total conversion, so that
       all images will be loaded in the appropriate format for the current video mode. Valid bit flags are:

          COLORCONV_NONE                // disable all format
                                        // conversions
          COLORCONV_8_TO_15             // expand 8-bit to 15-bit
          COLORCONV_8_TO_16             // expand 8-bit to 16-bit
          COLORCONV_8_TO_24             // expand 8-bit to 24-bit
          COLORCONV_8_TO_32             // expand 8-bit to 32-bit
          COLORCONV_15_TO_8             // reduce 15-bit to 8-bit
          COLORCONV_15_TO_16            // expand 15-bit to 16-bit
          COLORCONV_15_TO_24            // expand 15-bit to 24-bit
          COLORCONV_15_TO_32            // expand 15-bit to 32-bit
          COLORCONV_16_TO_8             // reduce 16-bit to 8-bit
          COLORCONV_16_TO_15            // reduce 16-bit to 15-bit
          COLORCONV_16_TO_24            // expand 16-bit to 24-bit
          COLORCONV_16_TO_32            // expand 16-bit to 32-bit
          COLORCONV_24_TO_8             // reduce 24-bit to 8-bit
          COLORCONV_24_TO_15            // reduce 24-bit to 15-bit
          COLORCONV_24_TO_16            // reduce 24-bit to 16-bit
          COLORCONV_24_TO_32            // expand 24-bit to 32-bit
          COLORCONV_32_TO_8             // reduce 32-bit RGB to 8-bit
          COLORCONV_32_TO_15            // reduce 32-bit RGB to 15-bit
          COLORCONV_32_TO_16            // reduce 32-bit RGB to 16-bit
          COLORCONV_32_TO_24            // reduce 32-bit RGB to 24-bit
          COLORCONV_32A_TO_8            // reduce 32-bit RGBA to 8-bit
          COLORCONV_32A_TO_15           // reduce 32-bit RGBA to 15-bit
          COLORCONV_32A_TO_16           // reduce 32-bit RGBA to 16-bit
          COLORCONV_32A_TO_24           // reduce 32-bit RGBA to 24-bit
          COLORCONV_DITHER_PAL          // dither when reducing to 8-bit
          COLORCONV_DITHER_HI           // dither when reducing to
                                        // hicolor
          COLORCONV_KEEP_TRANS          // keep original transparency

       For convenience, the following macros can be used to select common combinations of these flags:

          COLORCONV_EXPAND_256          // expand 256-color to hi/truecolor
          COLORCONV_REDUCE_TO_256       // reduce hi/truecolor to 256-color
          COLORCONV_EXPAND_15_TO_16     // expand 15-bit hicolor to 16-bit
          COLORCONV_REDUCE_16_TO_15     // reduce 16-bit hicolor to 15-bit
          COLORCONV_EXPAND_HI_TO_TRUE   // expand 15/16-bit to 24/32-bit
          COLORCONV_REDUCE_TRUE_TO_HI   // reduce 24/32-bit to 15/16-bit
          COLORCONV_24_EQUALS_32        // convert between 24- and 32-bit
          COLORCONV_TOTAL               // everything to current format
          COLORCONV_PARTIAL             // convert 15 <-> 16-bit and
                                        // 24 <-> 32-bit
          COLORCONV_MOST                // all but hi/truecolor <-> 256
          COLORCONV_DITHER              // dither during all color reductions
          COLORCONV_KEEP_ALPHA          // convert everything to current format
                                        // unless it would lose alpha information

       If you enable the COLORCONV_DITHER flag, dithering will be  performed  whenever  truecolor  graphics  are
       converted  into  a  hicolor  or  paletted  format,  including  by  the blit() function, and any automatic
       conversions that take place while reading graphics from  disk.  This  can  produce  much  better  looking
       results, but is obviously slower than a direct conversion.

       If  you  intend  using  converted  bitmaps with functions like masked_blit() or draw_sprite(), you should
       specify the COLORCONV_KEEP_TRANS flag. It will ensure that the masked areas  in  the  bitmap  before  and
       after  the  conversion  stay  exactly the same, by mapping transparent colors to each other and adjusting
       colors which would be converted to the transparent color otherwise. It  affects  every  blit()  operation
       between distinct pixel formats and every automatic conversion.

SEE ALSO

       set_color_depth(3alleg4),    load_bitmap(3alleg4),    load_datafile(3alleg4),    fixup_datafile(3alleg4),
       makecol15_dither(3alleg4),     get_color_conversion(3alleg4),     exalpha(3alleg4),     exblend(3alleg4),
       exdata(3alleg4), exexedat(3alleg4), exlights(3alleg4), exrotscl(3alleg4), exxfade(3alleg4)