1 files changed, 179 insertions, 0 deletions
diff --git a/ceee/ie/plugin/bho/tool_band_visibility.cc b/ceee/ie/plugin/bho/tool_band_visibility.cc
new file mode 100644
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+++ b/ceee/ie/plugin/bho/tool_band_visibility.cc
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+// Copyright (c) 2010 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 "ceee/ie/plugin/bho/tool_band_visibility.h"
+
+#include "base/logging.h"
+#include "ceee/ie/common/ie_tab_interfaces.h"
+#include "ceee/ie/common/ceee_module_util.h"
+#include "ceee/ie/plugin/toolband/tool_band.h"
+
+// The ToolBandVisibility class allows us to recover from a number of
+// features of IE that can cause our toolband to become invisible
+// unexpectedly.
+
+// A brief discussion of toolband visibility in IE.
+//
+// See MS knowledge base article Q219427 for more detail.
+//
+// IE does some interesting tricks to cache toolband layout information.  One
+// side effect of this is that sometimes it can get confused about whether a
+// toolband should be shown or not.
+//
+// In theory all that is needed to recover from this is a call to
+// IWebBrowser2::ShowBrowserBar.  Unfortunately, there are some
+// gotchas.
+//    It's not easy to tell when IE has refused to display your
+//      toolband.  The only way to be sure is to either call
+//      ShowBrowserBar on every startup or wait for some reasonable
+//      time to see if IE showed the toolband and then kick it if it
+//      didn't.
+//    In IE6, a single call to ShowBrowserBar is often not enough to
+//      unhide a hidden toolband.  It's sometimes necessary to call
+//      ShowBrowserBar THREE times (show, then hide, then show) to get
+//      things into a sane state.
+// TODO(cindylau@chromium.org): In IE6, just calling ShowBrowserBar
+//      will usually cause IE to scrunch our toolband up at the end of
+//      a line instead of giving it its own line. We can combat this
+//      by requesting to be shown on our own line, but if we do that
+//      in all cases we'll anger users who WANT our toolband to share
+//      a line with others.
+//    Some other toolbands (notably SnagIt versions 6 and 7) will
+//      cause toolbands to get hidden when opening a new tab in IE7.
+//      Visibility must be checked on every new tab and window to be
+//      sure.
+//    Calls to ShowBrowserBar are slow and we should avoid them
+//      whenever possible.
+//    Calls to ShowBrowserBar should be made from the same UI thread
+//      responsible for the browser object we use to unhide the
+//      toolband.  Failure to do this can cause the toolband to
+//      believe it belongs to a different thread than it does.
+// TODO(cindylau@chromium.org): IE tracks layout information in the
+//      registry.  When toolbands are added or removed the installing
+//      toolband MUST clear the registry (badness, including possible
+//      crashes in IE will result if not).  When this layout
+//      information is cleared all third party toolbands are hidden.
+
+// This code attempts to address all of these issues.
+// The core is the VisibilityUtil class.
+// When VisibilityUtil::CheckVisibility is called it checks for common
+// indicators that a toolband is hidden.  If it sees a smoking gun
+// it unhides the toolband.  Otherwise it creates a notification window and
+// a timer.  If a toolband doesn't report itself as active for a particular
+// browser window before the timer fires it unhides the toolband.
+
+namespace {
+const int kVisibilityTimerId = 1;
+const DWORD kVisibilityCheckDelay = 2000;  // 2 seconds.
+}  // anonymous namespace
+
+std::set<IUnknown*> ToolBandVisibility::visibility_set_;
+CComAutoCriticalSection ToolBandVisibility::visibility_set_crit_;
+
+ToolBandVisibility::ToolBandVisibility()
+    : web_browser_(NULL) {
+}
+
+ToolBandVisibility::~ToolBandVisibility() {
+  DCHECK(m_hWnd == NULL);
+}
+
+void ToolBandVisibility::ReportToolBandVisible(IWebBrowser2* web_browser) {
+  DCHECK(web_browser);
+  CComQIPtr<IUnknown, &IID_IUnknown> browser_identity(web_browser);
+  DCHECK(browser_identity != NULL);
+  if (browser_identity == NULL)
+    return;
+  CComCritSecLock<CComAutoCriticalSection> lock(visibility_set_crit_);
+  visibility_set_.insert(browser_identity);
+}
+
+bool ToolBandVisibility::IsToolBandVisible(IWebBrowser2* web_browser) {
+  DCHECK(web_browser);
+  CComQIPtr<IUnknown, &IID_IUnknown> browser_identity(web_browser);
+  DCHECK(browser_identity != NULL);
+  if (browser_identity == NULL)
+    return false;
+  CComCritSecLock<CComAutoCriticalSection> lock(visibility_set_crit_);
+  return visibility_set_.count(browser_identity) != 0;
+}
+
+void ToolBandVisibility::ClearCachedVisibility(IWebBrowser2* web_browser) {
+  CComCritSecLock<CComAutoCriticalSection> lock(visibility_set_crit_);
+  if (web_browser) {
+    CComQIPtr<IUnknown, &IID_IUnknown> browser_identity(web_browser);
+    DCHECK(browser_identity != NULL);
+    if (browser_identity == NULL)
+      return;
+    visibility_set_.erase(browser_identity);
+  } else {
+    visibility_set_.clear();
+  }
+}
+
+void ToolBandVisibility::CheckToolBandVisibility(IWebBrowser2* web_browser) {
+  DCHECK(web_browser);
+  web_browser_ = web_browser;
+
+  if (!ceee_module_util::GetOptionToolbandIsHidden() &&
+      CreateNotificationWindow()) {
+    SetWindowTimer(kVisibilityTimerId, kVisibilityCheckDelay);
+  }
+}
+
+void ToolBandVisibility::TearDown() {
+  if (web_browser_ != NULL) {
+    ClearCachedVisibility(web_browser_);
+  }
+  if (m_hWnd != NULL) {
+    CloseNotificationWindow();
+  }
+}
+
+bool ToolBandVisibility::CreateNotificationWindow() {
+  return Create(HWND_MESSAGE) != NULL;
+}
+
+void ToolBandVisibility::CloseNotificationWindow() {
+  DestroyWindow();
+}
+
+void ToolBandVisibility::SetWindowTimer(UINT timer_id, UINT delay) {
+  SetTimer(timer_id, delay, NULL);
+}
+
+void ToolBandVisibility::KillWindowTimer(UINT timer_id) {
+  KillTimer(timer_id);
+}
+
+void ToolBandVisibility::OnTimer(UINT_PTR nIDEvent) {
+  DCHECK(nIDEvent == kVisibilityTimerId);
+  KillWindowTimer(nIDEvent);
+
+  if (!IsToolBandVisible(web_browser_)) {
+    UnhideToolBand();
+  }
+  ClearCachedVisibility(web_browser_);
+  CloseNotificationWindow();
+}
+
+void ToolBandVisibility::UnhideToolBand() {
+  // Ignore ShowDW calls that are triggered by our calls here to
+  // ShowBrowserBar.
+  ceee_module_util::SetIgnoreShowDWChanges(true);
+  CComVariant toolband_class(CLSID_ToolBand);
+  CComVariant show(false);
+  CComVariant empty;
+  show = true;
+  web_browser_->ShowBrowserBar(&toolband_class, &show, &empty);
+
+  // Force IE to ignore bad caching.  This is a problem generally before IE7,
+  // and at least sometimes even in IE7 (bb1291042).
+  show = false;
+  web_browser_->ShowBrowserBar(&toolband_class, &show, &empty);
+  show = true;
+  web_browser_->ShowBrowserBar(&toolband_class, &show, &empty);
+
+  ceee_module_util::SetIgnoreShowDWChanges(false);
+}