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      1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef UI_BASE_X_SELECTION_REQUESTOR_H_
      6 #define UI_BASE_X_SELECTION_REQUESTOR_H_
      7 
      8 #include <X11/Xlib.h>
      9 
     10 // Get rid of a macro from Xlib.h that conflicts with Aura's RootWindow class.
     11 #undef RootWindow
     12 
     13 #include <list>
     14 #include <vector>
     15 
     16 #include "base/basictypes.h"
     17 #include "base/callback.h"
     18 #include "base/memory/ref_counted_memory.h"
     19 #include "ui/base/ui_base_export.h"
     20 #include "ui/gfx/x/x11_atom_cache.h"
     21 
     22 namespace ui {
     23 class PlatformEventDispatcher;
     24 class SelectionData;
     25 
     26 // Requests and later receives data from the X11 server through the selection
     27 // system.
     28 //
     29 // X11 uses a system called "selections" to implement clipboards and drag and
     30 // drop. This class interprets messages from the statefull selection request
     31 // API. SelectionRequestor should only deal with the X11 details; it does not
     32 // implement per-component fast-paths.
     33 class UI_BASE_EXPORT SelectionRequestor {
     34  public:
     35   SelectionRequestor(Display* xdisplay,
     36                      ::Window xwindow,
     37                      ::Atom selection_name,
     38                      PlatformEventDispatcher* dispatcher);
     39   ~SelectionRequestor();
     40 
     41   // Does the work of requesting |target| from the selection we handle,
     42   // spinning up the nested message loop, and reading the resulting data
     43   // back. |out_data| is allocated with the X allocator and must be freed with
     44   // XFree(). |out_data_bytes| is the length in machine chars, while
     45   // |out_data_items| is the length in |out_type| items.
     46   bool PerformBlockingConvertSelection(
     47       ::Atom target,
     48       scoped_refptr<base::RefCountedMemory>* out_data,
     49       size_t* out_data_bytes,
     50       size_t* out_data_items,
     51       ::Atom* out_type);
     52 
     53   // Requests |target| from the selection that we handle, passing |parameter|
     54   // as a parameter to XConvertSelection().
     55   void PerformBlockingConvertSelectionWithParameter(
     56       ::Atom target,
     57       const std::vector< ::Atom>& parameter);
     58 
     59   // Returns the first of |types| offered by the current selection holder, or
     60   // returns NULL if none of those types are available.
     61   SelectionData RequestAndWaitForTypes(const std::vector< ::Atom>& types);
     62 
     63   // It is our owner's responsibility to plumb X11 SelectionNotify events on
     64   // |xwindow_| to us.
     65   void OnSelectionNotify(const XSelectionEvent& event);
     66 
     67  private:
     68   // A request that has been issued and we are waiting for a response to.
     69   struct PendingRequest {
     70     explicit PendingRequest(Atom target);
     71     ~PendingRequest();
     72 
     73     // Data to the current XConvertSelection request. Used for error detection;
     74     // we verify it on the return message.
     75     ::Atom target;
     76 
     77     // Called to terminate the nested message loop.
     78     base::Closure quit_closure;
     79 
     80     // The property in the returning SelectNotify message is used to signal
     81     // success. If None, our request failed somehow. If equal to the property
     82     // atom that we sent in the XConvertSelection call, we can read that
     83     // property on |x_window_| for the requested data.
     84     ::Atom returned_property;
     85 
     86     // Set to true when return_property is populated.
     87     bool returned;
     88   };
     89 
     90   // Blocks till SelectionNotify is received for the target specified in
     91   // |request|.
     92   void BlockTillSelectionNotifyForRequest(PendingRequest* request);
     93 
     94   // Our X11 state.
     95   Display* x_display_;
     96   ::Window x_window_;
     97 
     98   // The X11 selection that this instance communicates on.
     99   ::Atom selection_name_;
    100 
    101   // Dispatcher which handles SelectionNotify and SelectionRequest for
    102   // |selection_name_|. PerformBlockingConvertSelection() calls the
    103   // dispatcher directly if PerformBlockingConvertSelection() is called after
    104   // the PlatformEventSource is destroyed.
    105   // Not owned.
    106   PlatformEventDispatcher* dispatcher_;
    107 
    108   // A list of requests for which we are waiting for responses.
    109   std::list<PendingRequest*> pending_requests_;
    110 
    111   X11AtomCache atom_cache_;
    112 
    113   DISALLOW_COPY_AND_ASSIGN(SelectionRequestor);
    114 };
    115 
    116 }  // namespace ui
    117 
    118 #endif  // UI_BASE_X_SELECTION_REQUESTOR_H_
    119