Initial revision

git-svn-id: file:///fltk/svn/fltk/trunk@2 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

1 files changed, 76 insertions, 0 deletions

diff --git a/src/fl_overlay_visual.cxx b/src/fl_overlay_visual.cxx
new file mode 100644
index 000000000..a176bf69c
--- /dev/null
+++ b/src/fl_overlay_visual.cxx
@@ -0,0 +1,76 @@
+// Stupid X tricks
+
+// Return an overlay visual, if any.  Also allocate a colormap and
+// record the depth for fl_color() to use.
+// Another disgusting X interface, based on code extracted and
+// purified with great difficulty from XLayerUtil.C:
+
+#include <config.h>
+#if HAVE_OVERLAY
+#include <FL/Fl.H>
+#include <FL/x.H>
+
+// SERVER_OVERLAY_VISUALS property element:
+struct OverlayInfo {
+  long overlay_visual;
+  long transparent_type;
+  long value;
+  long layer;
+};
+
+extern Colormap fl_overlay_colormap;
+extern XVisualInfo* fl_overlay_visual;
+extern ulong fl_transparent_pixel;
+
+XVisualInfo *fl_find_overlay_visual() {
+  static char beenhere;
+  if (beenhere) return fl_overlay_visual;
+  beenhere = 1;
+
+  fl_open_display();
+  Atom overlayVisualsAtom =
+    XInternAtom(fl_display,"SERVER_OVERLAY_VISUALS",1);
+  if (!overlayVisualsAtom) return 0;
+  OverlayInfo *overlayInfo;
+  ulong sizeData, bytesLeft;
+  Atom actualType;
+  int actualFormat;
+  if (XGetWindowProperty(fl_display, RootWindow(fl_display, fl_screen),
+			 overlayVisualsAtom, 0L, 10000L, False,
+			 overlayVisualsAtom, &actualType, &actualFormat,
+			 &sizeData, &bytesLeft,
+			 (unsigned char **) &overlayInfo)) return 0;
+
+  if (actualType == overlayVisualsAtom && actualFormat == 32) {
+    int n = int(sizeData/4);
+    XVisualInfo* v = 0;
+    // find the greatest depth that has a transparent pixel:
+    for (int i = 0; i < n; i++) {
+      if (overlayInfo[i].transparent_type != 1) continue;
+      if (overlayInfo[i].layer <= 0) continue;
+      XVisualInfo templt;
+      templt.visualid = overlayInfo[i].overlay_visual;
+      int num;
+      XVisualInfo *v1=XGetVisualInfo(fl_display, VisualIDMask, &templt, &num);
+      if (v1->screen == fl_screen && 
+	  !v1->red_mask && (!v || v1->depth >= v->depth && v1->depth <= 8)) {
+	if (v) XFree((char*)v);
+	v = v1;
+	fl_transparent_pixel = overlayInfo[i].value;
+      } else {
+	XFree((char*)v1);
+      }
+    }
+    if (v) {
+      fl_overlay_visual = v;
+      fl_overlay_colormap = 
+	XCreateColormap(fl_display, RootWindow(fl_display, fl_screen),
+			v->visual, AllocNone);
+    }
+  }
+  XFree((char*)overlayInfo);
+  //  printf("overlay visual %d selected\n", fl_overlay_visual->visualid);
+  return fl_overlay_visual;
+}
+
+#endif