root/ui/base/x/selection_owner.cc

DEFINITIONS

1. atom_cache_
2. RetrieveTargets
3. TakeOwnershipOfSelection
4. ClearSelectionOwner
5. OnSelectionRequest
6. OnSelectionClear

// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/base/x/selection_owner.h"

#include <X11/Xlib.h>
#include <X11/Xatom.h>

#include "base/logging.h"
#include "ui/base/x/selection_utils.h"

namespace ui {

namespace {

const char kMultiple[] = "MULTIPLE";
const char kTargets[] = "TARGETS";

const char* kAtomsToCache[] = {
  kMultiple,
  kTargets,
  NULL
};

}  // namespace

SelectionOwner::SelectionOwner(Display* x_display,
                               Window x_window,
                               Atom selection_name)
    : x_display_(x_display),
      x_window_(x_window),
      selection_name_(selection_name),
      atom_cache_(x_display_, kAtomsToCache) {
}

SelectionOwner::~SelectionOwner() {
  // If we are the selection owner, we need to release the selection so we
  // don't receive further events. However, we don't call ClearSelectionOwner()
  // because we don't want to do this indiscriminately.
  if (XGetSelectionOwner(x_display_, selection_name_) == x_window_)
    XSetSelectionOwner(x_display_, selection_name_, None, CurrentTime);
}

void SelectionOwner::RetrieveTargets(std::vector<Atom>* targets) {
  for (SelectionFormatMap::const_iterator it = format_map_.begin();
       it != format_map_.end(); ++it) {
    targets->push_back(it->first);
  }
}

void SelectionOwner::TakeOwnershipOfSelection(
    const SelectionFormatMap& data) {
  XSetSelectionOwner(x_display_, selection_name_, x_window_, CurrentTime);

  if (XGetSelectionOwner(x_display_, selection_name_) == x_window_) {
    // The X server agrees that we are the selection owner. Commit our data.
    format_map_ = data;
  }
}

void SelectionOwner::ClearSelectionOwner() {
  XSetSelectionOwner(x_display_, selection_name_, None, CurrentTime);
  format_map_ = SelectionFormatMap();
}

void SelectionOwner::OnSelectionRequest(const XSelectionRequestEvent& event) {
  // Incrementally build our selection. By default this is a refusal, and we'll
  // override the parts indicating success in the different cases.
  XEvent reply;
  reply.xselection.type = SelectionNotify;
  reply.xselection.requestor = event.requestor;
  reply.xselection.selection = event.selection;
  reply.xselection.target = event.target;
  reply.xselection.property = None;  // Indicates failure
  reply.xselection.time = event.time;

  // Get the proper selection.
  Atom targets_atom = atom_cache_.GetAtom(kTargets);
  if (event.target == targets_atom) {
    // We have been asked for TARGETS. Send an atom array back with the data
    // types we support.
    std::vector<Atom> targets;
    targets.push_back(targets_atom);
    RetrieveTargets(&targets);

    XChangeProperty(x_display_, event.requestor, event.property, XA_ATOM, 32,
                    PropModeReplace,
                    reinterpret_cast<unsigned char*>(&targets.front()),
                    targets.size());
    reply.xselection.property = event.property;
  } else if (event.target == atom_cache_.GetAtom(kMultiple)) {
    // TODO(erg): Theoretically, the spec claims I'm supposed to handle the
    // MULTIPLE case, but I haven't seen it in the wild yet.
    NOTIMPLEMENTED();
  } else {
    // Try to find the data type in map.
    SelectionFormatMap::const_iterator it =
        format_map_.find(event.target);
    if (it != format_map_.end()) {
      XChangeProperty(x_display_, event.requestor, event.property,
                      event.target, 8,
                      PropModeReplace,
                      const_cast<unsigned char*>(
                          reinterpret_cast<const unsigned char*>(
                              it->second->front())),
                      it->second->size());
      reply.xselection.property = event.property;
    }
    // I would put error logging here, but GTK ignores TARGETS and spams us
    // looking for its own internal types.
  }

  // Send off the reply.
  XSendEvent(x_display_, event.requestor, False, 0, &reply);
}

void SelectionOwner::OnSelectionClear(const XSelectionClearEvent& event) {
  DLOG(ERROR) << "SelectionClear";

  // TODO(erg): If we receive a SelectionClear event while we're handling data,
  // we need to delay clearing.
}

}  // namespace ui