1 files changed, 129 insertions, 0 deletions
diff --git a/widget/windows/WindowHook.cpp b/widget/windows/WindowHook.cpp
new file mode 100644
index 0000000000..b2a3167d31
--- /dev/null
+++ b/widget/windows/WindowHook.cpp
@@ -0,0 +1,129 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "WindowHook.h"
+#include "nsWindow.h"
+#include "nsWindowDefs.h"
+
+namespace mozilla {
+namespace widget {
+
+nsresult
+WindowHook::AddHook(UINT nMsg, Callback callback, void *context) {
+  MessageData *data = LookupOrCreate(nMsg);
+
+  if (!data)
+    return NS_ERROR_OUT_OF_MEMORY;
+
+  // Ensure we don't overwrite another hook
+  NS_ENSURE_TRUE(nullptr == data->hook.cb, NS_ERROR_UNEXPECTED);
+
+  data->hook = CallbackData(callback, context);
+
+  return NS_OK;
+}
+
+nsresult
+WindowHook::RemoveHook(UINT nMsg, Callback callback, void *context) {
+  CallbackData cbdata(callback, context);
+  MessageData *data = Lookup(nMsg);
+  if (!data)
+    return NS_ERROR_UNEXPECTED;
+  if (data->hook != cbdata)
+    return NS_ERROR_UNEXPECTED;
+  data->hook = CallbackData();
+
+  DeleteIfEmpty(data);
+  return NS_OK;
+}
+
+nsresult
+WindowHook::AddMonitor(UINT nMsg, Callback callback, void *context) {
+  MessageData *data = LookupOrCreate(nMsg);
+  return (data && data->monitors.AppendElement(CallbackData(callback, context)))
+         ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
+}
+
+nsresult
+WindowHook::RemoveMonitor(UINT nMsg, Callback callback, void *context) {
+  CallbackData cbdata(callback, context);
+  MessageData *data = Lookup(nMsg);
+  if (!data)
+    return NS_ERROR_UNEXPECTED;
+  CallbackDataArray::index_type idx = data->monitors.IndexOf(cbdata);
+  if (idx == CallbackDataArray::NoIndex)
+    return NS_ERROR_UNEXPECTED;
+  data->monitors.RemoveElementAt(idx);
+  DeleteIfEmpty(data);
+  return NS_OK;
+}
+
+WindowHook::MessageData *
+WindowHook::Lookup(UINT nMsg) {
+  MessageDataArray::index_type idx;
+  for (idx = 0; idx < mMessageData.Length(); idx++) {
+    MessageData &data = mMessageData[idx];
+    if (data.nMsg == nMsg)
+      return &data;
+  }
+  return nullptr;
+}
+
+WindowHook::MessageData *
+WindowHook::LookupOrCreate(UINT nMsg) {
+  MessageData *data = Lookup(nMsg);
+  if (!data) {
+    data = mMessageData.AppendElement();
+
+    if (!data)
+      return nullptr;
+
+    data->nMsg = nMsg;
+  }
+  return data;
+}
+
+void
+WindowHook::DeleteIfEmpty(MessageData *data) {
+  // Never remove a MessageData that has still a hook or monitor entries.
+  if (data->hook || !data->monitors.IsEmpty())
+    return;
+
+  MessageDataArray::index_type idx;
+  idx = data - mMessageData.Elements();
+  NS_ASSERTION(idx < mMessageData.Length(), "Attempted to delete MessageData that doesn't belong to this array!");
+  mMessageData.RemoveElementAt(idx);
+}
+
+bool
+WindowHook::Notify(HWND hWnd, UINT nMsg, WPARAM wParam, LPARAM lParam,
+                   MSGResult& aResult)
+{
+  MessageData *data = Lookup(nMsg);
+  if (!data)
+    return false;
+
+  uint32_t length = data->monitors.Length();
+  for (uint32_t midx = 0; midx < length; midx++) {
+    data->monitors[midx].Invoke(hWnd, nMsg, wParam, lParam, &aResult.mResult);
+  }
+
+  aResult.mConsumed =
+    data->hook.Invoke(hWnd, nMsg, wParam, lParam, &aResult.mResult);
+  return aResult.mConsumed;
+}
+
+bool
+WindowHook::CallbackData::Invoke(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam,
+                                 LRESULT *aResult) {
+  if (!cb)
+    return false;
+  return cb(context, hWnd, msg, wParam, lParam, aResult);
+}
+
+} // namespace widget
+} // namespace mozilla
+