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write TGAs with RLE compression

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This commit is contained in:
fahickman 2015-05-11 21:38:55 -07:00
parent 947bdcd027
commit e0e4bd4d86
1 changed files with 104 additions and 30 deletions
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134
stb_image_write.h
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@ -149,6 +149,14 @@ static void writefv(FILE *f, const char *fmt, va_list v)
}
}
static void writef(FILE *f, const char *fmt, ...)
{
va_list v;
va_start(v, fmt);
writefv(f, fmt, v);
va_end(v);
}
static void write3(FILE *f, unsigned char a, unsigned char b, unsigned char c)
{
unsigned char arr[3];
@ -156,11 +164,42 @@ static void write3(FILE *f, unsigned char a, unsigned char b, unsigned char c)
fwrite(arr, 3, 1, f);
}
static void write_pixels(FILE *f, int rgb_dir, int vdir, int x, int y, int comp, void *data, int write_alpha, int scanline_pad, int expand_mono)
static void write_pixel(FILE *f, int rgb_dir, int comp, int write_alpha, int expand_mono, const unsigned char *d)
{
unsigned char bg[3] = { 255, 0, 255}, px[3];
int k;
if (write_alpha < 0)
fwrite(&d[comp - 1], 1, 1, f);
switch (comp) {
case 1: fwrite(d, 1, 1, f);
break;
case 2: if (expand_mono)
write3(f, d[0], d[0], d[0]); // monochrome bmp
else
fwrite(d, 1, 1, f); // monochrome TGA
break;
case 4:
if (!write_alpha) {
// composite against pink background
for (k = 0; k < 3; ++k)
px[k] = bg[k] + ((d[k] - bg[k]) * d[3]) / 255;
write3(f, px[1 - rgb_dir], px[1], px[1 + rgb_dir]);
break;
}
/* FALLTHROUGH */
case 3:
write3(f, d[1 - rgb_dir], d[1], d[1 + rgb_dir]);
break;
}
if (write_alpha > 0)
fwrite(&d[comp - 1], 1, 1, f);
}
static void write_pixels(FILE *f, int rgb_dir, int vdir, int x, int y, int comp, void *data, int write_alpha, int scanline_pad, int expand_mono)
{
stbiw_uint32 zero = 0;
int i,j,k, j_end;
int i,j, j_end;
if (y <= 0)
return;
@ -173,31 +212,7 @@ static void write_pixels(FILE *f, int rgb_dir, int vdir, int x, int y, int comp,
for (; j != j_end; j += vdir) {
for (i=0; i < x; ++i) {
unsigned char *d = (unsigned char *) data + (j*x+i)*comp;
if (write_alpha < 0)
fwrite(&d[comp-1], 1, 1, f);
switch (comp) {
case 1: fwrite(d, 1, 1, f);
break;
case 2: if (expand_mono)
write3(f, d[0],d[0],d[0]); // monochrome bmp
else
fwrite(d, 1, 1, f); // monochrome TGA
break;
case 4:
if (!write_alpha) {
// composite against pink background
for (k=0; k < 3; ++k)
px[k] = bg[k] + ((d[k] - bg[k]) * d[3])/255;
write3(f, px[1-rgb_dir],px[1],px[1+rgb_dir]);
break;
}
/* FALLTHROUGH */
case 3:
write3(f, d[1-rgb_dir],d[1],d[1+rgb_dir]);
break;
}
if (write_alpha > 0)
fwrite(&d[comp-1], 1, 1, f);
write_pixel(f, rgb_dir, comp, write_alpha, expand_mono, d);
}
fwrite(&zero,scanline_pad,1,f);
}
@ -232,9 +247,68 @@ int stbi_write_tga(char const *filename, int x, int y, int comp, const void *dat
{
int has_alpha = (comp == 2 || comp == 4);
int colorbytes = has_alpha ? comp-1 : comp;
int format = colorbytes < 2 ? 3 : 2; // 3 color channels (RGB/RGBA) = 2, 1 color channel (Y/YA) = 3
return outfile(filename, -1,-1, x, y, comp, 0, (void *) data, has_alpha, 0,
"111 221 2222 11", 0,0,format, 0,0,0, 0,0,x,y, (colorbytes+has_alpha)*8, has_alpha*8);
int format = colorbytes < 2 ? 11 : 10; // 3 color channels (RGB/RGBA) = 10, 1 color channel (Y/YA) = 11
FILE *f;
if (y < 0 || x < 0) return 0;
f = fopen(filename, "wb");
if (f) {
int i,j,k;
writef(f, "111 221 2222 11", 0,0,format, 0,0,0, 0,0,x,y, 24+8*has_alpha, 8*has_alpha);
for (j = y - 1; j >= 0; --j) {
unsigned char *line = (unsigned char *) data + j * x * comp;
int run;
for (i = 0; i < x; i += run) {
unsigned char *first = line + i * comp;
int diff = 1;
run = 1;
if (i < x - 1) {
++run;
diff = memcmp(first, line + (i + 1) * comp, comp);
if (diff) {
unsigned char *next = first;
for (k = i + 2; k < x && run < 128; ++k) {
if (memcmp(next, line + k * comp, comp)) {
next += comp;
++run;
} else {
--run;
break;
}
}
} else {
for (k = i + 2; k < x && run < 128; ++k) {
if (!memcmp(first, line + k * comp, comp)) {
++run;
} else {
break;
}
}
}
}
if (diff) {
unsigned char header = (unsigned char) (run - 1);
fwrite(&header, 1, 1, f);
for (k = 0; k < run; ++k) {
write_pixel(f, -1, comp, has_alpha, 0, first + k * comp);
}
} else {
unsigned char header = (unsigned char) (run - 1) | 0x80;
fwrite(&header, 1, 1, f);
write_pixel(f, -1, comp, has_alpha, 0, first);
}
}
}
fclose(f);
}
return f != NULL;
}
// *************************************************************************************************