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How do I get a hexadecimal string representation of a GdkRGBA struct in C?
I have a program that reads a hexadecimal string representation from a configuration file, turns it into a GdkRGBA struct from Gdk, uses gtk_color_dialog_button_set_rgba () to set it as the default colour of a GtkColorDialogButton, and then listens to user changes to the aforementioned button.
On user change, I want to write back the chosen value to the configuration file so that it is persistent across program launches, and I need it to be a hexadecimal string representation for legacy compatibility reasons (the configuration file is ~/.Xresources, so it needs to be compatible with many existing programs). However, while Gdk provides a gdk_rgba_parse () function to parse a hexadecimal string representation of a colour into a GdkRGBA struct, I can't find anything to do the inverse, i.e., turn a GdkRGBA struct into a hexadecimal string representation. There is gdk_rgba_to_string (), but it only returns strings of the form rgb(r,g,b) or rgba(r,g,b,a), whereas I want #rrggbb.
How can I get the hexadecimal string representation of a GdkRGBA struct's value in C?
1 answer
The following users marked this post as Works for me:
| User | Comment | Date |
|---|---|---|
| Newbyte | (no comment) | Jan 4, 2025 at 15:59 |
I ended up implementing it like this:
#define RGB_HEX_STRING_LENGTH 8
gchar *
gdkrgba_to_rgb_hex_string (const GdkRGBA *const from)
{
guchar red = roundf (from->red * 255.0f);
guchar green = roundf (from->green * 255.0f);
guchar blue = roundf (from->blue * 255.0f);
gchar *to = malloc (RGB_HEX_STRING_LENGTH);
snprintf (to, RGB_HEX_STRING_LENGTH, "#%02hhx%02hhx%02hhx", red, green, blue);
return to;
}
This works since the properties of the GdkRGBA struct are public, so we can access them directly.
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