2 files changed, 42 insertions, 0 deletions
diff --git a/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.cxx b/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.cxx
index 0385413f1..cdcfd4548 100644
--- a/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.cxx
+++ b/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.cxx
@@ -21,6 +21,10 @@
 #include "../../config_lib.h"
 #include "Fl_Xlib_Graphics_Driver.h"
 
+#if HAVE_XRENDER
+#include <X11/extensions/Xrender.h>
+#endif
+
 
 const char *Fl_Xlib_Graphics_Driver::class_id = "Fl_Xlib_Graphics_Driver";
 
@@ -34,6 +38,43 @@ Fl_Graphics_Driver *Fl_Graphics_Driver::newMainGraphicsDriver()
   return new Fl_Xlib_Graphics_Driver();
 }
 
+char Fl_Xlib_Graphics_Driver::can_do_alpha_blending() {
+  return Fl_X::xrender_supported();
+}
+
+
+void Fl_Xlib_Graphics_Driver::copy_offscreen(int x, int y, int w, int h, Fl_Offscreen pixmap, int srcx, int srcy) {
+  XCopyArea(fl_display, pixmap, fl_window, fl_gc, srcx, srcy, w, h, x, y);
+}
+
+void Fl_Xlib_Graphics_Driver::copy_offscreen_with_alpha(int x, int y, int w, int h,
+                                                        Fl_Offscreen pixmap, int srcx, int srcy) {
+#if HAVE_XRENDER
+  XRenderPictureAttributes srcattr;
+  memset(&srcattr, 0, sizeof(XRenderPictureAttributes));
+  static XRenderPictFormat *srcfmt = XRenderFindStandardFormat(fl_display, PictStandardARGB32);
+  static XRenderPictFormat *dstfmt = XRenderFindStandardFormat(fl_display, PictStandardRGB24);
+
+  Picture src = XRenderCreatePicture(fl_display, pixmap, srcfmt, 0, &srcattr);
+  Picture dst = XRenderCreatePicture(fl_display, fl_window, dstfmt, 0, &srcattr);
+
+  if (!src || !dst) {
+    fprintf(stderr, "Failed to create Render pictures (%lu %lu)\n", src, dst);
+    return;
+  }
+
+  const Fl_Region clipr = fl_clip_region();
+  if (clipr)
+    XRenderSetPictureClipRegion(fl_display, dst, clipr);
+
+  XRenderComposite(fl_display, PictOpOver, src, None, dst, srcx, srcy, 0, 0,
+                   x, y, w, h);
+
+  XRenderFreePicture(fl_display, src);
+  XRenderFreePicture(fl_display, dst);
+#endif
+}
+
 //
 // End of "$Id$".
 //
diff --git a/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.h b/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.h
index 577f5f573..8cd086a2a 100644
--- a/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.h
+++ b/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.h
@@ -37,6 +37,7 @@ public:
   static const char *class_id;
   const char *class_name() {return class_id;};
   virtual int has_feature(driver_feature mask) { return mask & NATIVE; }
+  char can_do_alpha_blending();
   
   // --- bitmap stuff
   Fl_Bitmask create_bitmask(int w, int h, const uchar *array);