Default X screen / screen selection

[mkoskar]

Now there is an option -screens that translates into variable screen_mask and is used like this:

  unsigned long screen_mask = ~0;
  for (/* global */ screen = 0; screen < ScreenCount(display); screen++) {
    if ((screen_mask & (1 << screen)) == 0)
      continue;

So if I would like to operate on a single screen say 0, I would have to pass -screens 1, for 1 it would be -screens 2, for 2 it would be -screens 4 etc.

Moreover (and this is my use case), it's impossible to operate on default (preferred in XCB lingo) screen, i.e., if DISPLAY=:1.1 I would like hsetroot just to manipulate root window of X screen 1.

I have hardcoded following quick & dirty solution to do so:

diff --git a/hsetroot.c b/hsetroot.c
index 79e5c7b..4c23393 100644
--- a/hsetroot.c
+++ b/hsetroot.c
@@ -284,9 +284,15 @@ main(int argc, char **argv)
     outputs = XineramaQueryScreens(display, &noutputs);
   }
 
+  int screen_def = DefaultScreen(display);
+  printf("screen_def = %d\n", screen_def);
+
   for (/* global */ screen = 0; screen < ScreenCount(display); screen++) {
-    if ((screen_mask & (1 << screen)) == 0)
-      continue;
+    //if ((screen_mask & (1 << screen)) == 0)
+    //  continue;
+
+    if (screen != screen_def)
+        continue;
 
     Imlib_Context *context = imlib_context_new();
     imlib_context_push(context);

Because I feel like operating on multiple X screens might be useful for somebody I would suggest leaving -screens be and creating new option e.g., -screen <int>, which would take a preference before -screens and specify single X screen to work on, or -1 for the DefaultScreen(display).