1 files changed, 74 insertions, 0 deletions
diff --git a/src/x.c b/src/x.c
new file mode 100644
index 0000000..4289c06
--- /dev/null
+++ b/src/x.c
@@ -0,0 +1,74 @@
+/**
+ * get-luminosity — Determine how bright it is in your room
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program 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.
+ * 
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "linearise.h"
+
+#include <stddef.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+#include <pthread.h>
+
+
+static Display* restrict display;
+
+
+static double get_brightness(int screen)
+{
+  auto Window root = XRootWindow(display, screen);
+  auto long width  = (long)XDisplayWidth(display, screen);
+  auto long height = (long)XDisplayHeight(display, screen);
+  auto XImage* restrict image = XGetImage(display, root, 0, 0, width, height, AllPlanes, ZPixmap);
+  register double sum = 0;
+  register unsigned char* restrict pixels;
+  register unsigned char* restrict end;
+  
+  if (image == NULL)
+    return -1;
+  
+  pixels = (unsigned char*)(image->data);
+  end = pixels + width * height * 4;
+  
+  while (pixels != end)
+    {
+      sum += LINEAR_MAP[*pixels++];
+      sum += LINEAR_MAP[*pixels++];
+      sum += LINEAR_MAP[*pixels++];
+      pixels++;
+    }
+  
+  XDestroyImage(image);
+  return sum / (double)(height * width * 3);
+}
+
+
+int main(void)
+{
+  int screen, screens;
+  
+  if (display = XOpenDisplay(NULL), display == NULL)
+    return 1;
+  
+  screens = (size_t)ScreenCount(display);
+  for (screen = 0; screen < screens; screen++)
+    fprintf(stderr, "%lf\n", get_brightness(screen));
+  
+  XCloseDisplay(display);
+  return 0;
+}
+