XDnD: support large images retrieval.devs/jackdanielz/dnd

Large images require a special process during pasting, as the data
is sent in chunks and not in only one part. The INCR mechanism
(ICCCM 2.7.2) is needed for this.

@feature

2 files changed, 90 insertions, 5 deletions

diff --git a/src/lib/ecore_x/xlib/ecore_x_events.c b/src/lib/ecore_x/xlib/ecore_x_events.c
index 8ab79a4582..28df7fc0d5 100644
--- a/src/lib/ecore_x/xlib/ecore_x_events.c
+++ b/src/lib/ecore_x/xlib/ecore_x_events.c
@@ -22,6 +22,11 @@
 #define CODESET "INVALID"
 #endif /* ifndef CODESET */
 
+static unsigned long _clipboard_incr_data_length = 0; /* Current received data length */
+static char *_clipboard_incr_data = NULL; /* Current received data */
+static Ecore_X_Event_Selection_Notify *_clipboard_incr_event = NULL; /* Event to send once the data is ready */
+Eina_Bool clipboard_incr_start = EINA_FALSE;
+
 typedef struct _Ecore_X_Mouse_Down_Info
 {
    EINA_INLIST;
@@ -1328,6 +1333,56 @@ _ecore_x_event_handle_circulate_request(XEvent *xevent)
 void
 _ecore_x_event_handle_property_notify(XEvent *xevent)
 {
+   /* ICCCM 2.7.2: incremental data sending
+    * The process has been initiated during selection_notify
+    * event (specifically in ecore_x_window_prop_property_get).
+    * This code retrieves the data from the owner and appends
+    * it to a buffer.
+    * A property returning a size equal to zero indicates the end
+    * of the sending and results in sending the event to the upper
+    * layer with all the data.
+    */
+   if (xevent->xproperty.state == PropertyNewValue && clipboard_incr_start)
+     {
+        Atom type_ret = 0;
+        int size_ret = 0;
+        unsigned long num_ret = 0, bytes = 0, dummy;
+        unsigned char *prop_ret = NULL;
+        XGetWindowProperty(_ecore_x_disp, xevent->xproperty.window,
+              xevent->xproperty.atom, 0, 0, False, AnyPropertyType,
+              &type_ret, &size_ret, &num_ret, &bytes, &prop_ret);
+        XFree(prop_ret);
+        if (bytes <= 0)
+          {
+             if (_clipboard_incr_data_length)
+               {
+                  /* The transaction is now finished. Th selection notify event can be sent
+                   * with all the retrieved data. */
+                  _clipboard_incr_event->data = _ecore_x_selection_parse(_clipboard_incr_event->target,
+                        _clipboard_incr_data, _clipboard_incr_data_length, size_ret);
+                  _clipboard_incr_data = NULL;
+                  _clipboard_incr_data_length = 0;
+                  clipboard_incr_start = EINA_FALSE;
+
+                  ecore_event_add(ECORE_X_EVENT_SELECTION_NOTIFY, _clipboard_incr_event,
+                        _ecore_x_event_free_selection_notify, NULL);
+                  ecore_x_window_prop_property_del(xevent->xproperty.window, xevent->xproperty.atom);
+               }
+             return;
+          }
+        /* Retrieval of the chunk */
+        XGetWindowProperty(_ecore_x_disp, xevent->xproperty.window,
+              xevent->xproperty.atom, 0, bytes, False, AnyPropertyType,
+              &type_ret, &size_ret, &num_ret, &dummy, &prop_ret);
+        bytes = num_ret * size_ret / 8;
+        _clipboard_incr_data = realloc(_clipboard_incr_data, _clipboard_incr_data_length + bytes);
+        memcpy(_clipboard_incr_data + _clipboard_incr_data_length, prop_ret, bytes);
+        XFree(prop_ret);
+        _clipboard_incr_data_length += bytes;
+        /* We delete the property to indicate the owner to send the next chunk */
+        ecore_x_window_prop_property_del(xevent->xproperty.window, xevent->xproperty.atom);
+        return;
+     }
    _ecore_x_last_event_mouse_move = 0;
    {
       Ecore_X_Event_Window_Property *e;
@@ -1465,7 +1520,10 @@ _ecore_x_event_handle_selection_notify(XEvent *xevent)
         format = ecore_x_window_prop_property_get(xevent->xselection.requestor,
                                                   xevent->xselection.property,
                                                   XA_ATOM, 32, &data, &num_ret);
-        if (!format)
+        /* clipboard_incr_start is checked here because INCR requests are
+         * handled asynchronously. Most of the handling is in the property
+         * notify event handler. */
+        if (!clipboard_incr_start && !format)
           {
              /* fallback if targets handling is not working and try get the
               * selection directly */
@@ -1484,7 +1542,7 @@ _ecore_x_event_handle_selection_notify(XEvent *xevent)
                                                   xevent->xselection.property,
                                                   AnyPropertyType, 8, &data,
                                                   &num_ret);
-        if (!format) return;
+        if (!clipboard_incr_start && !format) return;
      }
 
    e = calloc(1, sizeof(Ecore_X_Event_Selection_Notify));
@@ -1510,10 +1568,18 @@ _ecore_x_event_handle_selection_notify(XEvent *xevent)
    else
      e->selection = ECORE_X_SELECTION_OTHER;
 
-   e->data = _ecore_x_selection_parse(e->target, data, num_ret, format);
+   if (!clipboard_incr_start)
+     {
+        e->data = _ecore_x_selection_parse(e->target, data, num_ret, format);
 
-   ecore_event_add(ECORE_X_EVENT_SELECTION_NOTIFY, e,
-                   _ecore_x_event_free_selection_notify, NULL);
+        ecore_event_add(ECORE_X_EVENT_SELECTION_NOTIFY, e,
+              _ecore_x_event_free_selection_notify, NULL);
+     }
+   else
+     {
+        /* In case of INCR, the event is stored until the data is ready */
+        _clipboard_incr_event = e;
+     }
 }
 
 void
diff --git a/src/lib/ecore_x/xlib/ecore_x_window_prop.c b/src/lib/ecore_x/xlib/ecore_x_window_prop.c
index 151f65a8bc..b66107f262 100644
--- a/src/lib/ecore_x/xlib/ecore_x_window_prop.c
+++ b/src/lib/ecore_x/xlib/ecore_x_window_prop.c
@@ -16,6 +16,8 @@
   XChangeProperty(_ecore_x_disp, win, atom, XA_CARDINAL, 32, PropModeReplace, \
                   (unsigned char *)p_val, cnt)
 
+extern Eina_Bool clipboard_incr_start;
+
 /*
  * Set CARD32 (array) property
  */
@@ -545,6 +547,23 @@ ecore_x_window_prop_property_get(Ecore_X_Window win,
    if (_ecore_xlib_sync) ecore_x_sync();
    if (ret != Success)
      return 0;
+   if (type_ret != type)
+     {
+        /* In case of INCR (ICCCM 2.7.2), we have to delete
+         * the property to request the owner to send the data
+         * chunks.
+         * This part of code needs to be in this function, as
+         * type_ret is not returned so not known by the caller.
+         */
+        char *atom_name = ecore_x_atom_name_get(type_ret);
+        if (atom_name && !strcmp(atom_name, "INCR"))
+          {
+             clipboard_incr_start = EINA_TRUE;
+             ecore_x_window_prop_property_del(win, property);
+             num_ret = 0; /* Forcing early exit */
+          }
+        free(atom_name);
+     }
    if ((!num_ret) || (size_ret <= 0))
      {
         XFree(prop_ret);