diff options
Diffstat (limited to 'xnap.c')
| -rw-r--r-- | xnap.c | 56 |
1 files changed, 56 insertions, 0 deletions
@@ -18,8 +18,10 @@ struct pointer_t { int y1; }; +unsigned char channel(unsigned long px, Mask m); void compimg(void); void die(const char* s); +void mkppm(const char* path, XImage* img); void quit(Bool ex); void run(void); void setup(void); @@ -30,6 +32,34 @@ int scr = -1; struct pointer_t p = {0}; XImage* img = NULL; +unsigned char channel(unsigned long px, Mask m) +{ + if (m == 0) + return 0; + + int shift = 0; + /* shift down until we find channel */ + while ((m & 1UL) == 0) { + m >>= 1UL; + shift++; + } + + /* bits in channel */ + int bits = 0; + while (m & 1UL) { + m >>= 1UL; + bits++; + } + + /* raw channel value */ + unsigned long rv = (px >> shift) & ((1UL << bits) - 1UL); + + /* scale v from [0, 2^bits-1]->[0,255] to meet standard */ + if (bits == 8) + return rv; + return ((rv * 255UL) / ((1UL << bits) - 1UL)); +} + void compimg(void) { /* create selection rectangle */ @@ -45,6 +75,7 @@ void compimg(void) unsigned long p0 = XGetPixel(img, 0, 0); fprintf(stderr, "first pixe =#%lx depth=%d bpp=%d\n", p0, img->depth, img->bits_per_pixel); + mkppm("img.ppm", img); XDestroyImage(img); quit(True); } @@ -55,6 +86,31 @@ void die(const char* s) exit(EXIT_FAILURE); } +void mkppm(const char* path, XImage* img) +{ + FILE* f = fopen(path, "w"); + if (!f) + die("fopen failed"); + + /* write ppm metadata header */ + fprintf(f, "P6\n%d %d\n255\n", img->width, img->height); + + for (int y = 0; y < img->height; y++) { + for (int x = 0; x < img->width; x++) { + unsigned long px = XGetPixel(img, x, y); + unsigned char r = channel(px, img->red_mask); + unsigned char g = channel(px, img->green_mask); + unsigned char b = channel(px, img->blue_mask); + + fputc(r, f); + fputc(g, f); + fputc(b, f); + } + } + + fclose(f); +} + void quit(Bool ex) { XUngrabPointer(dpy, CurrentTime); |