Cannot render image as wallpaper when compositor is running - c

Question

I've been trying to learn both Imlib & X11, as I've been working on a project that includes both of them, and I've came across a weird issue with it. Basically, whenever I try to render my wallpaper, it will just do it "in the background," and will only show when I kill off my compositor (feh.) When I use programs like feh or xsetroot, they are both able to draw over picom, but my code cannot for some reason. I have a wrapper over it written in haskell, but I will omit that for simplicity. Here is the code I've been working with:
#include <X11/Xlib.h>
#include <Imlib2.h>
#include <stdio.h>
#include <stdlib.h>
static void
die(int err, char *msg)
{
fprintf(stderr, "%s: %s\n", "qzbg", msg);
exit(err);
}
struct dSize {
uint32_t w;
uint32_t h;
};
struct System {
Display *dpy;
Screen *screen;
Window root;
uint32_t screen_count;
};
static inline struct dSize
get_display_size()
{
struct dSize x;
Display *dpy = XOpenDisplay(NULL);
if (!dpy) {
die (-1, "Failed to open display.");
}
Screen *screen = DefaultScreenOfDisplay(dpy);
if (!screen) {
die (-1, "Failed to obtain the default screen.");
}
x.w = screen->width;
x.h = screen->height;
return x;
}
static void
set_wallpaper(int h, int w, struct System sys)
{
Pixmap pix;
sys.dpy = XOpenDisplay(NULL);
sys.screen_count = DefaultScreen(sys.dpy);
sys.root = RootWindow(sys.dpy, sys.screen_count);
pix = XCreatePixmap(sys.dpy, sys.root,
h, w,
DefaultDepth(sys.dpy, sys.screen_count));
imlib_context_set_display(sys.dpy);
imlib_context_set_visual(DefaultVisual(sys.dpy, sys.screen_count));
imlib_context_set_colormap(DefaultColormap(sys.dpy, sys.screen_count));
imlib_context_set_drawable(pix);
imlib_render_image_on_drawable(0, 0);
XSetWindowBackgroundPixmap(sys.dpy, sys.root, pix);
XClearWindow(sys.dpy, sys.root);
while (XPending(sys.dpy)) {
XEvent ev;
XNextEvent(sys.dpy, &ev);
}
XFreePixmap(sys.dpy, pix);
imlib_free_image_and_decache();
XCloseDisplay(sys.dpy);
}
void
set_background(char *filename, struct System sys)
{
Imlib_Image image;
int img_w, img_h;
image = imlib_load_image(filename);
if (!image)
die(-1, "Could not load image.");
imlib_context_set_image(image);
img_w = imlib_image_get_width();
img_h = imlib_image_get_height();
set_wallpaper(img_w, img_h, sys);
}
int
render(char *prog)
{
struct dSize size = get_display_size();
struct System sys;
set_background(prog, sys);
}
The structs are just for convenience. I am able to render the image properly as my wallpaper whenever I don't have picom active, but I cannot seem to figure out why it does not work with the compositor active.
When I run my program to set the wallpaper (with picom active,) it returns 0 (shown below)
~ via λ 9.4.2
❯ qzbg -t ~/.wallpaper/sub/haskell_gray.jpg
Set wallpaper: 0
I am assuming that picom adds a layer to the desktop, though I'm not sure exactly how that works for overwriting it.