I've been building a basic interface for dealing with graphic surfaces lately. I already had most of the routines for 16bpp and 8bpp bitmaps in older Toncs, but but their use was still somewhat awkward because you had to provide some details of the destination manually; most notably a base pointer and the pitch. This got more than a little annoying, especially when trying to make blitters as well. So I made some changes.
{
u8 *data; //!< Surface data pointer.
u32 pitch; //!< Scanline pitch in bytes (PONDER: alignment?).
u16 width; //!< Image width in pixels.
u16 height; //!< Image width in pixels.
u8 bpp; //!< Bits per pixel.
u8 type; //!< Surface type (not used that much).
u16 palSize; //!< Number of colors.
u16 *palData; //!< Pointer to palette.
} TSurface;
I've rebuilt the routines around a surface description struct called
TSurface
(see above). This way, I can just initialize the
surface somewhere and just pass the pointer to that surface around.
There are a number of different kinds of surfaces. The most important
ones are these three:
- bmp16. 16bpp bitmap surfaces.
- bmp8. 8bpp bitmap surfaces.
- chr4c. 4bpp tiled surfaces, in column-major order (i.e., tile 1 is
under tile 0 instead of to the right). Column-major order may seem
strange, but it actually simplifies the code considerably. There is also a
chr4r
mode for normal, row-major tiling, but that's unfinished and will probably remain so.

Demonstrating surface routines for 4bpp tiles.
For each of these three, I have the most important rendering functions:
plotting pixels, lines, rectangles and blits. Yes, blits too. Even for
chr4c
-mode. There are routines for frames (empty
rectangles) and floodfill as well. The functions have a uniform interface
with respect to surface-type, so switching between them should be
easy were it necessary. There are also tables with function pointers
to these routines, so by using those you need not really care about
the details of the surface after its creation. I'll probably add a
pointer to such a table in TSurface
in the future.
Linkies
- Demo project: surface.zip.
- Tonclib: tonclib.
- Tonclib manual, TSurface module.
The image on the right is the result of the following routine. Turret pic semi-knowingly provided by Kawa.
const TSurfaceProcTab *procs, u16 colors[])
{
// Init object text
tte_init_obj(&oam_mem[127], ATTR0_TALL, ATTR1_SIZE_8, 512,
CLR_YELLOW, 0, &vwf_default, NULL);
tte_init_con();
tte_set_margins(8, 140, 160, 152);
// And go!
tte_printf("#{es;P}%s surface primitives#{w:60}", procs->name);
tte_printf("#{es;P}Rect#{w:20}");
procs->rect(dst, 20, 20, 100, 100, colors[0]);
tte_printf("#{w:30;es;P}Frame#{w:20}");
procs->frame(dst, 21, 21, 99, 99, colors[1]);
tte_printf("#{w:30;es;P}Hlines#{w:20}");
procs->hline(dst, 23, 23, 96, colors[2]);
procs->hline(dst, 23, 96, 96, colors[2]);
tte_printf("#{w:30;es;P}Vlines#{w:20}");
procs->vline(dst, 23, 25, 94, colors[3]);
procs->vline(dst, 96, 25, 94, colors[3]);
tte_printf("#{w:30;es;P}Lines#{w:20}");
procs->line(dst, 25, 25, 94, 40, colors[4]);
procs->line(dst, 94, 25, 79, 94, colors[4]);
procs->line(dst, 94, 94, 25, 79, colors[4]);
procs->line(dst, 25, 94, 40, 25, colors[4]);
tte_printf("#{w:30;es;P}Full blit#{w:20}");
procs->blit(dst, 120, 16, src->width, src->height, src, 0, 0);
tte_printf("#{w:30;es;P}Partial blit#{w:20}");
procs->blit(dst, 40, 40, 40, 40, src, 12, 8);
tte_printf("#{w:30;es;P}Floodfill#{w:20}");
procs->flood(dst, 40, 32, colors[5]);
tte_printf("#{w:30;es;P}Again !#{w:20}");
procs->flood(dst, 40, 32, colors[6]);
tte_printf("#{w:30;es;P;w:30}Ta-dah!!!#{w:20}");
key_wait_till_hit(KEY_ANY);
}
// Test 4bpp tiled, column-major surfaces
void test_chr4c_procs()
{
TSurface turret, dst;
// Init turret for blitting.
srf_init(&turret, SRF_CHR4C, turretChr4cTiles, 128, 128, 4, NULL);
// Init destination surface
srf_init(&dst, SRF_CHR4C, tile_mem[0], 240, 160, 4, pal_bg_mem);
schr4c_prep_map(&dst, se_mem[31], 0);
GRIT_CPY(pal_bg_mem, turretChr4cPal);
// Set video stuff
REG_DISPCNT= DCNT_MODE0 | DCNT_BG2 | DCNT_OBJ | DCNT_OBJ_1D;
REG_BG2CNT= BG_CBB(0)|BG_SBB(31);
u16 colors[8]= { 6, 13, 1, 14, 15, 0, 14, 0 };
// Run internal tester
test_surface_procs(&turret, &dst, &chr4c_tab, colors);
}