[metacity] compositor: don't draw shadow under windows

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 5404d8f2c9d10f2dfcbb928978836256290c547a
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Mon Jan 19 04:49:56 2015 +0200

    compositor: don't draw shadow under windows

 src/compositor/compositor-xrender.c |   93 ++++++++++++++++++++++++++++------
 src/core/frame-private.h            |    3 -
 src/include/frame.h                 |    4 ++
 3 files changed, 80 insertions(+), 20 deletions(-)
---
diff --git a/src/compositor/compositor-xrender.c b/src/compositor/compositor-xrender.c
index 99e10b2..dd99329 100644
--- a/src/compositor/compositor-xrender.c
+++ b/src/compositor/compositor-xrender.c
@@ -592,16 +592,64 @@ make_shadow (MetaDisplay   *display,
   return ximage;
 }
 
+double shadow_offsets_x[LAST_SHADOW_TYPE] = {SHADOW_SMALL_OFFSET_X,
+                                             SHADOW_MEDIUM_OFFSET_X,
+                                             SHADOW_LARGE_OFFSET_X};
+double shadow_offsets_y[LAST_SHADOW_TYPE] = {SHADOW_SMALL_OFFSET_Y,
+                                             SHADOW_MEDIUM_OFFSET_Y,
+                                             SHADOW_LARGE_OFFSET_Y};
+
+static void
+shadow_clip (Display          *xdisplay,
+             Picture           shadow_picture,
+             XImage           *shadow_image,
+             MetaShadowType    shadow_type,
+             MetaFrameBorders  borders,
+             int               width,
+             int               height)
+{
+  int shadow_dx = -1 * shadow_offsets_x [shadow_type];
+  int shadow_dy = -1 * shadow_offsets_y [shadow_type];
+  XRectangle clip[4];
+
+  /* Top */
+  clip[0].x      = 0;
+  clip[0].y      = 0;
+  clip[0].width  = shadow_image->width;
+  clip[0].height = shadow_dy + borders.visible.top;
+
+  /* Bottom */
+  clip[1].x      = 0;
+  clip[1].y      = shadow_dy + (height - borders.visible.bottom);
+  clip[1].width  = shadow_image->width;
+  clip[1].height = shadow_image->height - (shadow_dy + (height - borders.visible.bottom));
+
+  /* Left */
+  clip[2].x      = 0;
+  clip[2].y      = shadow_dy + borders.visible.top;
+  clip[2].width  = shadow_dx + borders.visible.left;
+  clip[2].height = height - borders.visible.top - borders.visible.bottom;
+
+  /* Right */
+  clip[3].x      = width + shadow_dx;
+  clip[3].y      = shadow_dy + borders.visible.top;
+  clip[3].width  = shadow_image->width - (width + shadow_dx);
+  clip[3].height = height - borders.visible.top - borders.visible.bottom;
+
+  XRenderSetPictureClipRectangles (xdisplay, shadow_picture, 0, 0, clip, 4);
+}
+
 static Picture
-shadow_picture (MetaDisplay   *display,
-                MetaScreen    *screen,
-                MetaShadowType shadow_type,
-                double         opacity,
-                Picture        alpha_pict,
-                int            width,
-                int            height,
-                int           *wp,
-                int           *hp)
+shadow_picture (MetaDisplay      *display,
+                MetaScreen       *screen,
+                MetaShadowType    shadow_type,
+                double            opacity,
+                Picture           alpha_pict,
+                MetaFrameBorders  borders,
+                int               width,
+                int               height,
+                int              *wp,
+                int              *hp)
 {
   Display *xdisplay = meta_display_get_xdisplay (display);
   XImage *shadow_image;
@@ -624,8 +672,7 @@ shadow_picture (MetaDisplay   *display,
     }
 
   shadow_picture = XRenderCreatePicture (xdisplay, shadow_pixmap,
-                                         XRenderFindStandardFormat (xdisplay,
-PictStandardA8),
+                                         XRenderFindStandardFormat (xdisplay, PictStandardA8),
                                          0, 0);
   if (!shadow_picture)
     {
@@ -634,6 +681,11 @@ PictStandardA8),
       return None;
     }
 
+  shadow_clip (xdisplay,
+               shadow_picture, shadow_image, shadow_type,
+               borders,
+               width, height);
+
   gc = XCreateGC (xdisplay, shadow_pixmap, 0, 0);
   if (!gc)
     {
@@ -950,12 +1002,7 @@ window_has_shadow (MetaCompWindow *cw)
   return FALSE;
 }
 
-double shadow_offsets_x[LAST_SHADOW_TYPE] = {SHADOW_SMALL_OFFSET_X,
-                                             SHADOW_MEDIUM_OFFSET_X,
-                                             SHADOW_LARGE_OFFSET_X};
-double shadow_offsets_y[LAST_SHADOW_TYPE] = {SHADOW_SMALL_OFFSET_Y,
-                                             SHADOW_MEDIUM_OFFSET_Y,
-                                             SHADOW_LARGE_OFFSET_Y};
+
 static XserverRegion
 win_extents (MetaCompWindow *cw)
 {
@@ -971,8 +1018,19 @@ win_extents (MetaCompWindow *cw)
 
   if (cw->needs_shadow)
     {
+      MetaFrameBorders borders;
       XRectangle sr;
 
+      meta_frame_borders_clear (&borders);
+
+      if (cw->window)
+        {
+          MetaFrame *frame = meta_window_get_frame (cw->window);
+
+          if (frame)
+            meta_frame_calc_borders (frame, &borders);
+        }
+
       cw->shadow_dx = shadow_offsets_x [cw->shadow_type];
       cw->shadow_dy = shadow_offsets_y [cw->shadow_type];
 
@@ -984,6 +1042,7 @@ win_extents (MetaCompWindow *cw)
 
           cw->shadow = shadow_picture (display, screen, cw->shadow_type,
                                        opacity, cw->alpha_pict,
+                                       borders,
                                        cw->attrs.width + cw->attrs.border_width * 2,
                                        cw->attrs.height + cw->attrs.border_width * 2,
                                        &cw->shadow_width, &cw->shadow_height);
diff --git a/src/core/frame-private.h b/src/core/frame-private.h
index fe9cdb7..eafc324 100644
--- a/src/core/frame-private.h
+++ b/src/core/frame-private.h
@@ -57,9 +57,6 @@ void     meta_frame_queue_draw              (MetaFrame  *frame);
 
 MetaFrameFlags meta_frame_get_flags (MetaFrame *frame);
 
-/* These should ONLY be called from meta_window_move_resize_internal */
-void meta_frame_calc_borders       (MetaFrame         *frame,
-                                    MetaFrameBorders  *borders);
 void meta_frame_sync_to_window     (MetaFrame         *frame,
                                     int                gravity,
                                     gboolean           need_move,
diff --git a/src/include/frame.h b/src/include/frame.h
index 09b7457..5a0ae25 100644
--- a/src/include/frame.h
+++ b/src/include/frame.h
@@ -22,8 +22,12 @@
 
 #include <X11/Xlib.h>
 
+#include "common.h"
 #include "types.h"
 
 Window meta_frame_get_xwindow (MetaFrame *frame);
 
+void   meta_frame_calc_borders (MetaFrame        *frame,
+                                MetaFrameBorders *borders);
+
 #endif