get_colorpixel.c

/*
 * vim:ts=4:sw=4:expandtab
 *
 * i3 - an improved dynamic tiling window manager
 * © 2009 Michael Stapelberg and contributors (see also: LICENSE)
 *
 */
#include "libi3.h"
#include "queue.h"

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
struct Colorpixel {
    char hex[8];
    uint32_t pixel;

    SLIST_ENTRY(Colorpixel) colorpixels;
};

SLIST_HEAD(colorpixel_head, Colorpixel) colorpixels;

/*
 * Returns the colorpixel to use for the given hex color (think of HTML).
 *
 * The hex_color has to start with #, for example #FF00FF.
 *
 * NOTE that get_colorpixel() does _NOT_ check the given color code for validity.
 * This has to be done by the caller.
 *
 */
uint32_t get_colorpixel(const char *hex) {
    char strgroups[3][3] = {
        {hex[1], hex[2], '\0'},
        {hex[3], hex[4], '\0'},
        {hex[5], hex[6], '\0'}};
    uint8_t r = strtol(strgroups[0], NULL, 16);
    uint8_t g = strtol(strgroups[1], NULL, 16);
    uint8_t b = strtol(strgroups[2], NULL, 16);

    /* Shortcut: if our screen is true color, no need to do a roundtrip to X11 */
    if (root_screen == NULL || root_screen->root_depth == 24 || root_screen->root_depth == 32) {
        return (0xFFUL << 24) | (r << 16 | g << 8 | b);
    }

    /* Lookup this colorpixel in the cache */
    struct Colorpixel *colorpixel;
    SLIST_FOREACH (colorpixel, &(colorpixels), colorpixels) {
        if (strcmp(colorpixel->hex, hex) == 0)
            return colorpixel->pixel;
    }

#define RGB_8_TO_16(i) (65535 * ((i)&0xFF) / 255)
    int r16 = RGB_8_TO_16(r);
    int g16 = RGB_8_TO_16(g);
    int b16 = RGB_8_TO_16(b);

    xcb_alloc_color_reply_t *reply;

    reply = xcb_alloc_color_reply(conn, xcb_alloc_color(conn, root_screen->default_colormap, r16, g16, b16),
                                  NULL);

    if (!reply) {
        LOG("Could not allocate color\n");
        exit(1);
    }

    uint32_t pixel = reply->pixel;
    free(reply);

    /* Store the result in the cache */
    struct Colorpixel *cache_pixel = scalloc(1, sizeof(struct Colorpixel));

    strncpy(cache_pixel->hex, hex, 7);
    cache_pixel->hex[7] = '\0';

    cache_pixel->pixel = pixel;

    SLIST_INSERT_HEAD(&(colorpixels), cache_pixel, colorpixels);

    return pixel;
}