Improvement: Support reading _NET_WM_OPACITY from client windows

- Some WMs don't respect Keith Packard's proposal of
  _NET_WM_WINDOW_OPACITY, and do not copy _NET_WM_OPACITY attribute of a
  client window to its frame windows, thus cause opacity set by
  non-override-redirect windows to have no effect. This commit adds
  support for reading _NET_WM_OPACITY from client windows if running
  with --detect-client-opacity. Thanks to pvanek for reporting.

- Change Makefile logic to determine options from 3 variables
  (NO_LIBCONFIG, NO_REGEX_PCRE, NO_REGEX_PCRE_JIT) instead of CFG to
  ensure compatibility when we add new options. CFG variable is no
  longer been respected.

1 files changed, 10 insertions, 1 deletions

diff --git a/compton.h b/compton.h
index 7a71fa808..dca11b68a 100644
--- a/compton.h
+++ b/compton.h
@@ -198,6 +198,10 @@ typedef struct _win {
   opacity_t opacity_cur;
   /// Cached value of opacity window attribute.
   opacity_t opacity_prop;
+  /// Cached value of opacity window attribute on client window. For
+  /// broken window managers not transferring client window's
+  /// _NET_WM_OPACITY value
+  opacity_t opacity_prop_client;
   /// Alpha mask Picture to render window with opacity.
   Picture alpha_pict;
 
@@ -302,7 +306,12 @@ typedef struct _options {
   /// Whether inactive_opacity overrides the opacity set by window
   /// attributes.
   Bool inactive_opacity_override;
+  /// Frame opacity. Relative to window opacity, also affects shadow
+  /// opacity.
   double frame_opacity;
+  /// Whether to detect _NET_WM_OPACITY on client windows. Used on window
+  /// managers that don't pass _NET_WM_OPACITY to frame windows.
+  Bool detect_client_opacity;
   /// How much to dim an inactive window. 0.0 - 1.0, 0 to disable.
   double inactive_dim;
 
@@ -780,7 +789,7 @@ static void
 unmap_win(Display *dpy, Window id, Bool fade);
 
 static opacity_t
-get_opacity_prop(Display *dpy, win *w, opacity_t def);
+wid_get_opacity_prop(Display *dpy, Window wid, opacity_t def);
 
 static double
 get_opacity_percent(Display *dpy, win *w);