Non-Opaque (semi-transparent) specially-shaped windows painted incorrectly.

[richardgv]

This is the second bug I indicated in the "by the way" part of a reply to the Maximized Chromium window issue, just lifted out here to make the issue easier to see: #36 (comment)

The problem:
When a specially shaped (non-rectangular) window becomes transparent, compton renders the part out of its shape incorrectly. Just run compton, run oclock, then set oclock window's opacity to like 50%, and you see the issue. Try moving the oclock window around if it's not obvious where the problem is.

The patch:

Should I repeat my usual words that I know nothing and this patch can be very unreliable? :-) It's taken from xcompmgr:

diff --git a/src/compton.c b/src/compton.c
index b72dc59..57f9926 100644
--- a/src/compton.c
+++ b/src/compton.c
@@ -1122,6 +1122,10 @@ paint_all(Display *dpy, XserverRegion region) {
     if (w->mode != WINDOW_SOLID || HAS_FRAME_OPACITY(w)) {
       int x, y, wid, hei;

+      // Necessary to make sure specially-shaped windows are
+      // painted correctly
+      XFixesIntersectRegion(dpy, w->border_clip, w->border_clip, w->border_size);
+      XFixesSetPictureClipRegion (dpy, root_buffer, 0, 0, w->border_clip);
 #if HAS_NAME_WINDOW_PIXMAP
       x = w->a.x;
       y = w->a.y;

By the way:

To make sure you don't get puzzled, here's a list of the patches I posted that needs review so far:

• "Ultimate" patch for the two Chromium window issues, using ShapeNotify: Maximized Chromium window sometimes gets partially hidden (& another Chromium issue & research results & fixes) #36 (comment)

  (I don't know a way to get around these two issues by simply changing painting sequence, without relying on the bounding region, which can be unreliable. Probably there's a way if we change how the Picture of a window is retrieved, but I suspect that painting in this way would result in huge performance loss. I guess listening to ShapeNotify is the best option right now.)

• Patch for the opacity bugs: 5 opacity-related bugs (& patch) #37

• Colored shadow patch, of course you may have a better way to implement it: [FeatureRequest] Colored shadows. #35 (comment)

• The patch above.