# Loading image files

- load_bitmap
- load_bmp
- load_lbm
- load_pcx
- load_tga
- register_bitmap_file_type
- save_bitmap
- save_bmp
- save_pcx
- save_tga
- set_color_conversion

Warning: when using truecolor images, you should always set the graphics mode before loading any bitmap data! Otherwise the pixel format (RGB or BGR) will not be known, so the file may be converted wrongly.

BITMAP *load_bitmap(const char *filename, RGB *pal);
Loads a bitmap from a file, returning a pointer to a bitmap and storing the palette data in the specified location, which should be an array of 256 RGB structures. You are responsible for destroying the bitmap when you are finished with it. Returns NULL on error. At present this function supports BMP, LBM, PCX, and TGA files, determining the type from the file extension. If the file contains a truecolor image, you must set the video mode or call set_color_conversion() before loading it.

> See also: load_bmp, load_lbm, load_pcx, load_tga, destroy_bitmap, save_bitmap, register_bitmap_file_type, set_color_depth, set_color_conversion.

BITMAP *load_bmp(const char *filename, RGB *pal);
Loads a 256 color or 24 bit truecolor Windows or OS/2 BMP file.

> See also: load_bitmap.

BITMAP *load_lbm(const char *filename, RGB *pal);
Loads a 256 color IFF ILBM/PBM file.

> See also: load_bitmap.

BITMAP *load_pcx(const char *filename, RGB *pal);
Loads a 256 color or 24 bit truecolor PCX file.

> See also: load_bitmap.

BITMAP *load_tga(const char *filename, RGB *pal);
Loads a 256 color, 15 bit hicolor, 24 bit truecolor, or 32 bit truecolor+alpha TGA file.

> See also: load_bitmap.

int save_bitmap(const char *filename, BITMAP *bmp, const RGB *pal);
Writes a bitmap into a file, using the specified palette, which should be an array of 256 RGB structures. Returns non-zero on error. The output format is determined from the filename extension: at present this function supports BMP, PCX and TGA formats.

Two things to watch out for: on some video cards it may be faster to copy the screen to a memory bitmap and save the latter, and if you use this to dump the screen into a file you may end up with an image much larger than you were expecting, because Allegro often creates virtual screens larger than the visible screen. You can get around this by using a sub-bitmap to specify which part of the screen to save, eg:

>           BITMAP *bmp;
>           PALETTE pal;

>           get_palette(pal);
>           bmp = create_sub_bitmap(screen, 0, 0, SCREEN_W, SCREEN_H);
>           save_bitmap("dump.pcx", bmp, pal);
>           destroy_bitmap(bmp);

> See also: save_bmp, save_pcx, save_tga, load_bitmap, register_bitmap_file_type.

int save_bmp(const char *filename, BITMAP *bmp, const RGB *pal);
Writes a bitmap into a 256 color or 24 bit truecolor BMP file.

> See also: save_bitmap.

int save_pcx(const char *filename, BITMAP *bmp, const RGB *pal);
Writes a bitmap into a 256 color or 24 bit truecolor PCX file.

> See also: save_bitmap.

int save_tga (const char *filename, BITMAP *bmp, const RGB *pal);
Writes a bitmap into a 256 color, 15 bit hicolor, 24 bit truecolor, or 32 bit truecolor+alpha TGA file.

> See also: save_bitmap.

void register_bitmap_file_type(const char *ext, BITMAP *(*load)(const char *filename, RGB *pal), int (*save)(const char *filename, BITMAP *bmp, const RGB *pal));
Informs the load_bitmap() and save_bitmap() functions of a new file type, providing routines to read and write images in this format (either function may be NULL).

> See also: load_bitmap, save_bitmap.

void set_color_conversion(int mode);
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 bits to 15 bits
>           COLORCONV_8_TO_16             // expand 8 bits to 16 bits
>           COLORCONV_8_TO_24             // expand 8 bits to 24 bits
>           COLORCONV_8_TO_32             // expand 8 bits to 32 bits
>           COLORCONV_15_TO_8             // reduce 15 bits to 8 bits
>           COLORCONV_15_TO_16            // expand 15 bits to 16 bits
>           COLORCONV_15_TO_24            // expand 15 bits to 24 bits
>           COLORCONV_15_TO_32            // expand 15 bits to 32 bits
>           COLORCONV_16_TO_8             // reduce 16 bits to 8 bits
>           COLORCONV_16_TO_15            // reduce 16 bits to 15 bits
>           COLORCONV_16_TO_24            // expand 16 bits to 24 bits
>           COLORCONV_16_TO_32            // expand 16 bits to 32 bits
>           COLORCONV_24_TO_8             // reduce 24 bits to 8 bits
>           COLORCONV_24_TO_15            // reduce 24 bits to 15 bits
>           COLORCONV_24_TO_16            // reduce 24 bits to 16 bits
>           COLORCONV_24_TO_32            // expand 24 bits to 32 bits
>           COLORCONV_32_TO_8             // reduce 32 bit RGB to 8 bits
>           COLORCONV_32_TO_15            // reduce 32 bit RGB to 15 bits
>           COLORCONV_32_TO_16            // reduce 32 bit RGB to 16 bits
>           COLORCONV_32_TO_24            // reduce 32 bit RGB to 24 bits
>           COLORCONV_32A_TO_8            // reduce 32 bit RGBA to 8 bits
>           COLORCONV_32A_TO_15           // reduce 32 bit RGBA to 15 bits
>           COLORCONV_32A_TO_16           // reduce 32 bit RGBA to 16 bits
>           COLORCONV_32A_TO_24           // reduce 32 bit RGBA to 24 bits
>           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 colors to
>                                         // hi/truecolor
>           COLORCONV_REDUCE_TO_256       // reduce hi/truecolor to 256
>                                         // colors
>           COLORCONV_EXPAND_15_TO_16     // expand 15 bit hicolor to
>                                         // 16 bits
>           COLORCONV_REDUCE_16_TO_15     // reduce 16 bit hicolor to
>                                         // 15 bits
>           COLORCONV_EXPAND_HI_TO_TRUE   // expand 15/16 bits to
>                                         // 24/32 bits
>           COLORCONV_REDUCE_TRUE_TO_HI   // reduce 24/32 bits to
>                                         // 15/16 bits
>           COLORCONV_24_EQUALS_32        // convert between 24 and
>                                         // 32 bits
>           COLORCONV_TOTAL               // everything to current format
>           COLORCONV_PARTIAL             // convert 15 <-> 16 and
>                                         // 24 <-> 32
>           COLORCONV_MOST                // all but hi/truecolor <-> 256
>           COLORCONV_DITHER              // dither during all color
>                                         // reductions

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, load_bitmap, load_datafile, fixup_datafile, makecol15_dither.

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