prog8/examples/cx16/imageviewer/bmp_module.p8
2020-12-21 23:45:26 +01:00

118 lines
3.8 KiB
Lua

%target cx16
%import graphics
%import diskio
bmp_module {
sub show_image(uword filenameptr) -> ubyte {
ubyte load_ok = false
ubyte[$36] header
uword size
uword width
uword height
ubyte bpp
uword offsetx
uword offsety
ubyte[256] palette0
ubyte[256] palette1
ubyte[256] palette2
ubyte[256] palette3
uword total_read = 0
palette0[0] = 0
palette1[0] = 0
palette2[0] = 0
palette3[0] = 0
if diskio.f_open(8, filenameptr) {
size = diskio.f_read(header, $36)
if size==$36 {
total_read = $36
if header[0]=='b' and header[1]=='m' {
uword bm_data_offset = mkword(header[11], header[10])
uword header_size = mkword(header[$f], header[$e])
width = mkword(header[$13], header[$12])
height = mkword(header[$17], header[$16])
bpp = header[$1c]
uword num_colors = header[$2e]
if num_colors == 0
num_colors = 2**bpp
uword skip_hdr = header_size - 40
repeat skip_hdr
void c64.CHRIN()
total_read += skip_hdr
size = diskio.f_read(&palette0, num_colors*4)
if size==num_colors*4 {
total_read += size
repeat bm_data_offset - total_read
void c64.CHRIN()
graphics.clear_screen(1, 0)
palette.set_bgra(&palette0, num_colors)
decode_bitmap()
load_ok = true
}
}
}
diskio.f_close()
}
return load_ok
sub start_plot() {
offsetx = 0
offsety = 0
if width < graphics.WIDTH
offsetx = (graphics.WIDTH - width - 1) / 2
if height < graphics.HEIGHT
offsety = (graphics.HEIGHT - height - 1) / 2
if width > graphics.WIDTH
width = graphics.WIDTH
if height > graphics.HEIGHT-1
height = graphics.HEIGHT-1
}
sub decode_bitmap() {
start_plot()
uword bits_width = width * bpp
ubyte pad_bytes = (((bits_width + 31) >> 5) << 2) - ((bits_width + 7) >> 3) as ubyte
uword x
uword y
ubyte b
for y in height-1 downto 0 {
cx16.FB_cursor_position(offsetx, offsety+y)
when bpp {
8 -> {
for x in 0 to width-1
cx16.FB_set_pixel(c64.CHRIN())
}
4 -> {
for x in 0 to width-1 step 2 {
b = c64.CHRIN()
cx16.FB_set_pixel(b>>4)
cx16.FB_set_pixel(b&15)
}
}
2 -> {
for x in 0 to width-1 step 4 {
b = c64.CHRIN()
cx16.FB_set_pixel(b>>6)
cx16.FB_set_pixel(b>>4 & 3)
cx16.FB_set_pixel(b>>2 & 3)
cx16.FB_set_pixel(b & 3)
}
}
1 -> {
for x in 0 to width-1 step 8
cx16.FB_set_8_pixels_opaque(255, 255, 0, c64.CHRIN())
}
}
repeat pad_bytes
void c64.CHRIN()
}
}
}
}