Refactor X11ForeignWindowManager (Reland)

ui/base/x/x11_window_event_manager.cc

Index: ui/base/x/x11_window_event_manager.cc
diff --git a/ui/base/x/x11_window_event_manager.cc b/ui/base/x/x11_window_event_manager.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4fc0c559772acd478825f3890bb65ffefa05f3c1
--- /dev/null
+++ b/ui/base/x/x11_window_event_manager.cc
@@ -0,0 +1,111 @@
+// Copyright 2014 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/x11_window_event_manager.h"
+
+#include <stddef.h>
+#include <X11/Xlib.h>
+#include <X11/Xlib-xcb.h>
+#include <xcb/xcb.h>
+
+#include "base/compiler_specific.h"
+#include "base/memory/singleton.h"
+
+namespace ui {
+
+XScopedEventSelector::XScopedEventSelector(XID xid, uint32_t event_mask)
+    : xid_(xid), event_mask_(event_mask) {
+  XWindowEventManager::GetInstance()->SelectEvents(xid_, event_mask_);
+}
+
+XScopedEventSelector::~XScopedEventSelector() {
+  XWindowEventManager::GetInstance()->DeselectEvents(xid_, event_mask_);
+}
+
+// static
+XWindowEventManager* XWindowEventManager::GetInstance() {
+  return base::Singleton<XWindowEventManager>::get();
+}
+
+class XWindowEventManager::MultiMask {
+ public:
+  MultiMask() {
+    for (int i = 0; i < kMaskSize; i++)
+      mask_bits_[i] = 0;
+  }
+
+  ~MultiMask() {}
+
+  void AddMask(uint32_t mask) {
+    for (int i = 0; i < kMaskSize; i++) {
+      if (mask & (1 << i))
+        mask_bits_[i]++;
+    }
+  }
+
+  void RemoveMask(uint32_t mask) {
+    for (int i = 0; i < kMaskSize; i++) {
+      if (mask & (1 << i)) {
+        DCHECK(mask_bits_[i]);
+        mask_bits_[i]--;
+      }
+    }
+  }
+
+  uint32_t ToMask() const {
+    uint32_t mask = NoEventMask;
+    for (int i = 0; i < kMaskSize; i++) {
+      if (mask_bits_[i])
+        mask |= (1 << i);
+    }
+    return mask;
+  }
+
+ private:
+  static constexpr auto kMaskSize = 25;
+
+  int mask_bits_[kMaskSize];
+
+  DISALLOW_COPY_AND_ASSIGN(MultiMask);
+};
+
+XWindowEventManager::XWindowEventManager() {}
+XWindowEventManager::~XWindowEventManager() {}
+
+void XWindowEventManager::SelectEvents(XID xid, uint32_t event_mask) {
+  std::unique_ptr<MultiMask>& mask = mask_map_[xid];
+  if (!mask)
+    mask.reset(new MultiMask());
+  uint32_t old_mask = mask_map_[xid]->ToMask();
+  mask->AddMask(event_mask);
+  AfterMaskChanged(xid, old_mask);
+}
+
+void XWindowEventManager::DeselectEvents(XID xid, uint32_t event_mask) {
+  DCHECK(mask_map_.find(xid) != mask_map_.end());
+  std::unique_ptr<MultiMask>& mask = mask_map_[xid];
+  uint32_t old_mask = mask->ToMask();
+  mask->RemoveMask(event_mask);
+  AfterMaskChanged(xid, old_mask);
+}
+
+void XWindowEventManager::AfterMaskChanged(XID xid, uint32_t old_mask) {
+  uint32_t new_mask = mask_map_[xid]->ToMask();
+  if (new_mask == old_mask)
+    return;
+
+  XDisplay* display = gfx::GetXDisplay();
+  xcb_connection_t* connection = XGetXCBConnection(display);
+  auto cookie = xcb_change_window_attributes(connection, xid, XCB_CW_EVENT_MASK,
+                                             &new_mask);
+  // Window |xid| may already be destroyed at this point, so the
+  // change_attributes request may give a BadWindow error.  In this case, just
+  // ignore the error.
+  xcb_discard_reply(connection, cookie.sequence);
+
+  if (new_mask == NoEventMask)
+    mask_map_.erase(xid);
+}
+
+}  // namespace ui