Get the current background on GTK 2 Gnome Linux

.gitmodules

@@ -4,3 +4,6 @@
 [submodule "Dependencies/gamelib"]
 	path = Dependencies/gamelib
 	url = https://macoy.me/code/macoy/gamelib.git
+[submodule "Dependencies/stb"]
+	path = Dependencies/stb
+	url = https://github.com/nothings/stb

Dependencies/gamelib

@@ -1 +1 @@
-Subproject commit f3537168a01904f6049a615d8a890e7d02d42e91
+Subproject commit d75b3f7aa95cd86b0b07ed26da3e3a17299b5a24

Dependencies/stb

@@ -0,0 +1 @@
+Subproject commit af1a5bc352164740c1cc1354942b1c6b72eacb8a

src/AutoColor.cake

@@ -1 +1,69 @@
-(defun auto-color-pick-from-current-background ())
+(import "Image.cake"
+ &comptime-only "CHelpers.cake")
+(c-import "stdio.h") ;; fprintf
+
+(comptime-cond
+ ('Unix
+  ;; Gnome GTK
+  (add-c-search-directory-module "/usr/include/glib-2.0")
+  (add-c-search-directory-module "/usr/include/glib-2.0")
+  (add-c-search-directory-module "/usr/lib/x86_64-linux-gnu/glib-2.0/include")
+  (c-import "gio/gio.h")
+  (add-library-dependency "glib-2.0" "gio-2.0")
+
+  (defun-local auto-color-get-current-background-filename (error-string (* (* (const char)))
+                                                           &return (* (const char)))
+    (var g-settings (* GSettings) (g_settings_new "org.gnome.desktop.background"))
+    (unless g-settings
+      (set (deref error-string) "Unable to get GTK settings for org.gnome.desktop.background")
+      (return null))
+    (var background (* gchar) (g_settings_get_string g-settings "picture-uri"))
+    (unless background
+      (set (deref error-string) "Unable to get picture-uri from org.gnome.desktop.background")
+      (return null))
+
+    (var file-uri (* (const char)) "file://")
+    (var file-uri-prefix-length size_t (strlen file-uri))
+    (unless (= 0 (strncmp file-uri background file-uri-prefix-length))
+      (set (deref error-string) "Unable to process picture-uri: uri type not supported")
+      (return null))
+
+    (set background (+ background file-uri-prefix-length))
+    (return background))))
+
+(defun auto-color-pick-from-file (image-to-load (* (const char)) &return bool)
+  (var width int 0)
+  (var height int 0)
+  (var num-pixel-components int 0)
+  (var num-desired-channels int 3)
+  (var pixel-data (* (unsigned char))
+    (stbi_load image-to-load (addr width) (addr height) (addr num-pixel-components)
+               num-desired-channels))
+  (unless pixel-data
+    (fprintf stderr "error: failed to load %s with message: %s\n" image-to-load
+             (stbi_failure_reason))
+    (return false))
+
+  (fprintf stderr "size of %s: %dx%d\n" image-to-load width height)
+    (fprintf stderr "num components in %s: %d\n" image-to-load num-pixel-components)
+    (fprintf stderr "first three pixels:\n")
+    (each-in-range 3 i
+      (var rgb-components (* (unsigned char)) (addr (at (* i 3) pixel-data)))
+      (fprintf stderr "[%d] %d %d %d\n"
+               i
+               (at 0 rgb-components)
+               (at 1 rgb-components)
+               (at 2 rgb-components)))
+
+  (return true))
+
+(defun auto-color-pick-from-current-background (&return bool)
+  (var error-string (* (const char)) null)
+  (var background-filename (* (const char))
+    (auto-color-get-current-background-filename (addr error-string)))
+  (unless background-filename
+    (fprintf stderr "error: %s" error-string)
+    (return false))
+  (fprintf stderr "\nPicking colors from '%s'\n" background-filename)
+
+  (return (auto-color-pick-from-file background-filename)))

src/AutoColorCLI.cake

@@ -1,7 +1,34 @@
 (import "AutoColor.cake")
 (c-import "<stdio.h>")
 
+(var g-copyright-string (* (const char))
+  #"#Auto Color
+Created by Macoy Madson <macoy@macoy.me>.
+https://macoy.me/code/macoy/file-helper
+Copyright (c) 2021 Macoy Madson.
+
+Auto Color is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+Auto Color is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with Auto Color.  If not, see <https://www.gnu.org/licenses/>.#"#)
+
+;; (defun-local print-help ()
+;;   (fprintf stderr "Expected filename\n"))
+
 (defun main (num-arguments int arguments ([] (* char)) &return int)
-  (fprintf stderr "Hello, world!\n")
+  ;; (unless (> 1 num-arguments)
+  ;;   (print-help)
+  ;;   (return 1))
+  (fprintf stderr "%s\n" g-copyright-string)
   (auto-color-pick-from-current-background)
   (return 0))
+
+(set-cakelisp-option executable-output "auto-color")