ui/base/x/selection_requestor.h

   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. The result is stored in |out_data|.
  44   // |out_data_items| is the length of |out_data| in |out_type| items.
  45   bool PerformBlockingConvertSelection(
  46       ::Atom target,
  47       scoped_refptr<base::RefCountedMemory>* out_data,
  48       size_t* out_data_items,
  49       ::Atom* out_type);
  50
  51   // Requests |target| from the selection that we handle, passing |parameter|
  52   // as a parameter to XConvertSelection().
  53   void PerformBlockingConvertSelectionWithParameter(
  54       ::Atom target,
  55       const std::vector< ::Atom>& parameter);
  56
  57   // Returns the first of |types| offered by the current selection holder, or
  58   // returns NULL if none of those types are available.
  59   SelectionData RequestAndWaitForTypes(const std::vector< ::Atom>& types);
  60
  61   // It is our owner's responsibility to plumb X11 SelectionNotify events on
  62   // |xwindow_| to us.
  63   void OnSelectionNotify(const XSelectionEvent& event);
  64
  65  private:
  66   // A request that has been issued and we are waiting for a response to.
  67   struct PendingRequest {
  68     explicit PendingRequest(Atom target);
  69     ~PendingRequest();
  70
  71     // Data to the current XConvertSelection request. Used for error detection;
  72     // we verify it on the return message.
  73     ::Atom target;
  74
  75     // Called to terminate the nested message loop.
  76     base::Closure quit_closure;
  77
  78     // The property in the returning SelectNotify message is used to signal
  79     // success. If None, our request failed somehow. If equal to the property
  80     // atom that we sent in the XConvertSelection call, we can read that
  81     // property on |x_window_| for the requested data.
  82     ::Atom returned_property;
  83
  84     // Set to true when return_property is populated.
  85     bool returned;
  86   };
  87
  88   // Blocks till SelectionNotify is received for the target specified in
  89   // |request|.
  90   void BlockTillSelectionNotifyForRequest(PendingRequest* request);
  91
  92   // Our X11 state.
  93   Display* x_display_;
  94   ::Window x_window_;
  95
  96   // The X11 selection that this instance communicates on.
  97   ::Atom selection_name_;
  98
  99   // Dispatcher which handles SelectionNotify and SelectionRequest for
 100   // |selection_name_|. PerformBlockingConvertSelection() calls the
 101   // dispatcher directly if PerformBlockingConvertSelection() is called after
 102   // the PlatformEventSource is destroyed.
 103   // Not owned.
 104   PlatformEventDispatcher* dispatcher_;
 105
 106   // A list of requests for which we are waiting for responses.
 107   std::list<PendingRequest*> pending_requests_;
 108
 109   X11AtomCache atom_cache_;
 110
 111   DISALLOW_COPY_AND_ASSIGN(SelectionRequestor);
 112 };
 113
 114 }  // namespace ui
 115
 116 #endif  // UI_BASE_X_SELECTION_REQUESTOR_H_