Get image of window with alpha channel, if available

Use xcb_composite_name_pixmap() to name the off-screen pixmap for the window,
replacing it with a new one when the window is mapped or resized.  Also name the
composite pixmap for adopted windows.

(We need to be more careful than currently in MAP_NOTIFY.  Always update the
name of the off-fscreen pixmap in MAP_NOTIFY, but only generate a
XCWM_EVENT_WINDOW_CREATE for override-redirect windows (since one was already
generated in MAP_REQUEST for non-override-redirect windows)

Ensure border width is zero, as border is included in composite pixmap image of
the window.

4 files changed, 57 insertions, 13 deletions

diff --git a/include/xcwm/window.h b/include/xcwm/window.h
index ad28790..6f1b98c 100644
--- a/include/xcwm/window.h
+++ b/include/xcwm/window.h
@@ -105,6 +105,7 @@ struct xcwm_window_t {
     int initial_damage;         /* Set to 1 for override-redirect windows */
     void *local_data;   /* Area for data client cares about */
     unsigned int opacity;
+    xcb_pixmap_t composite_pixmap_id;
 };
 
 /**
diff --git a/src/libxcwm/event_loop.c b/src/libxcwm/event_loop.c
index 3c0d50b..75be677 100644
--- a/src/libxcwm/event_loop.c
+++ b/src/libxcwm/event_loop.c
@@ -30,6 +30,7 @@
 
 #include <pthread.h>
 #include <xcwm/xcwm.h>
+#include <xcb/composite.h>
 #include "xcwm_internal.h"
 
 /* Definition of abstract data type for event */
@@ -102,6 +103,24 @@ _xcwm_event_stop_loop(void)
     return 1;
 }
 
+static void
+_xcwm_window_composite_pixmap_release(xcwm_window_t *window)
+{
+  if (window->composite_pixmap_id)
+    {
+      xcb_free_pixmap(window->context->conn, window->composite_pixmap_id);
+      window->composite_pixmap_id = 0;
+    }
+}
+
+static void
+_xcwm_window_composite_pixmap_update(xcwm_window_t *window)
+{
+  _xcwm_window_composite_pixmap_release(window);
+  window->composite_pixmap_id = xcb_generate_id(window->context->conn);
+  xcb_composite_name_window_pixmap(window->context->conn, window->window_id, window->composite_pixmap_id);
+}
+
 /*
   Generate a XCWM_EVENT_WINDOW_CREATE event for all
   existing mapped top-level windows when we start
@@ -136,6 +155,8 @@ _xcwm_windows_adopt(xcwm_context_t *context, xcwm_event_cb_t callback_ptr)
                 continue;
             }
 
+            _xcwm_window_composite_pixmap_update(window);
+
             xcwm_event_t *return_evt = malloc(sizeof(xcwm_event_t));
             if (!return_evt) {
                 continue;
@@ -366,15 +387,28 @@ run_event_loop(void *thread_arg_struct)
                     (xcb_map_notify_event_t *)evt;
                 return_evt = malloc(sizeof(xcwm_event_t));
                 /* notify->event holds parent of the window */
-                return_evt->window =
-                    _xcwm_window_create(context, notify->window,
-                                        notify->event);
-                if (!return_evt->window) {
-                    free(return_evt);
-                    break;
+
+                xcwm_window_t *window =
+                    _xcwm_get_window_node_by_window_id(notify->window);
+                if (!window)
+                {
+                    /*
+                      No MAP_REQUEST for override-redirect windows, so
+                      need to create the xcwm_window_t for it now
+                    */
+                    printf("MAP_NOTIFY without MAP_REQUEST\n");
+                    window =
+                        _xcwm_window_create(context, notify->window,
+                                            notify->event);
+
+                    _xcwm_window_composite_pixmap_update(window);
+
+                    return_evt->window = window;
+                    return_evt->event_type = XCWM_EVENT_WINDOW_CREATE;
+                    callback_ptr(return_evt);
                 }
-                return_evt->event_type = XCWM_EVENT_WINDOW_CREATE;
-                callback_ptr(return_evt);
+
+                _xcwm_window_composite_pixmap_update(window);
                 break;
             }
 
@@ -415,6 +449,8 @@ run_event_loop(void *thread_arg_struct)
 
                 callback_ptr(return_evt);
 
+                _xcwm_window_composite_pixmap_release(window);
+
                 // Release memory for the window
                 _xcwm_window_release(window);
                 break;
@@ -422,6 +458,12 @@ run_event_loop(void *thread_arg_struct)
 
             case XCB_CONFIGURE_NOTIFY:
             {
+                xcb_configure_notify_event_t *request =
+                    (xcb_configure_notify_event_t *)evt;
+                xcwm_window_t *window =
+                    _xcwm_get_window_node_by_window_id(request->window);
+                if (window)
+                    _xcwm_window_composite_pixmap_update(window);
                 break;
             }
 
diff --git a/src/libxcwm/image.c b/src/libxcwm/image.c
index 7b476fa..8389720 100644
--- a/src/libxcwm/image.c
+++ b/src/libxcwm/image.c
@@ -47,7 +47,7 @@ xcwm_image_copy_full(xcwm_window_t *window)
     xcb_flush(window->context->conn);
     /* Get the full image of the window */
     image = xcb_image_get(window->context->conn,
-                          window->window_id,
+                          window->composite_pixmap_id,
                           0,
                           0,
                           geom_reply->width,
@@ -75,7 +75,6 @@ xcwm_image_copy_full(xcwm_window_t *window)
 xcwm_image_t *
 xcwm_image_copy_damaged(xcwm_window_t *window)
 {
-
     xcb_image_t *image;
 
     xcb_flush(window->context->conn);
@@ -87,7 +86,7 @@ xcwm_image_copy_damaged(xcwm_window_t *window)
 
     /* Get the image of the damaged area of the window */
     image = xcb_image_get(window->context->conn,
-                          window->window_id,
+                          window->composite_pixmap_id,
                           window->dmg_bounds->x,
                           window->dmg_bounds->y,
                           window->dmg_bounds->width,
diff --git a/src/libxcwm/window.c b/src/libxcwm/window.c
index eaa38ce..201584f 100644
--- a/src/libxcwm/window.c
+++ b/src/libxcwm/window.c
@@ -128,6 +128,7 @@ _xcwm_window_create(xcwm_context_t *context, xcb_window_t new_window,
     window->bounds->width = geom->width;
     window->bounds->height = geom->height;
     window->opacity = ~0;
+    window->composite_pixmap_id = 0;
 
     /* Find an set the parent */
     window->parent = _xcwm_get_window_node_by_window_id(parent);
@@ -545,14 +546,15 @@ _xcwm_resize_window(xcb_connection_t *conn, xcb_window_t window,
                     int x, int y, int width, int height)
 {
 
-    uint32_t values[] = { x, y, width, height };
+    uint32_t values[] = { x, y, width, height, 0 };
 
     xcb_configure_window(conn,
                          window,
                          XCB_CONFIG_WINDOW_X |
                          XCB_CONFIG_WINDOW_Y |
                          XCB_CONFIG_WINDOW_WIDTH |
-                         XCB_CONFIG_WINDOW_HEIGHT,
+                         XCB_CONFIG_WINDOW_HEIGHT |
+                         XCB_CONFIG_WINDOW_BORDER_WIDTH,
                          values);
     xcb_flush(conn);
 }