I am trying to draw pattern linear gradient with color rgba(248, 205, 205, 1). I’ve seen a linear gradient in GtkColorChooserWidget with color rgb(248, 205, 205). But when i tried to draw it with Cairo in Gtk3 drawing area, it is not showing (black color showing). How to show linear gradient with color rgb(248, 205, 205, 1)?

Photo from GtkColorChooserWidget :

#include <cairo.h>
#include <gtk/gtk.h>

void draw_gradient2(cairo_t *);
static gboolean on_draw_event(GtkWidget *widget, cairo_t *cr, gpointer user_data){         
  draw_gradient2(cr);
  return FALSE;
}

void draw_gradient2(cairo_t *cr){
    int width = 400;
    int height = 50;

    cairo_pattern_t *gradient;
    gradient =cairo_pattern_create_linear(0.0, 0.0,  width, 0.0);
    cairo_pattern_add_color_stop_rgba (gradient, 0.0, 248/256, 205/256, 205/256, 0.3);
    cairo_pattern_add_color_stop_rgba (gradient, 1.0, 248/256, 205/256, 205/256, 1);

    cairo_set_source (cr, gradient);
    cairo_paint (cr);
    cairo_pattern_destroy (gradient);
}

int main(int argc, char *argv[]){
  GtkWidget *window;
  GtkWidget *darea;  

  gtk_init(&argc, &argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);

  darea = gtk_drawing_area_new();
  gtk_container_add(GTK_CONTAINER (window), darea);

  g_signal_connect(G_OBJECT(darea), "draw", G_CALLBACK(on_draw_event), NULL);  
  g_signal_connect(G_OBJECT(window), "destroy",G_CALLBACK(gtk_main_quit), NULL);

  gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
  gtk_window_set_default_size(GTK_WINDOW(window), 400, 50); 
  gtk_window_set_title(GTK_WINDOW(window), "Linear gradients");

  gtk_widget_set_app_paintable(window, TRUE);
  gtk_widget_show_all(window);

  gtk_main();
  return 0;
}