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