Improve scroll performance on Windows 10 with high precision touchpads.

content/browser/renderer_host/legacy_render_widget_host_win.cc

 // Copyright (c) 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 "content/browser/renderer_host/legacy_render_widget_host_win.h"
 
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/win/windows_version.h"
 #include "content/browser/accessibility/browser_accessibility_manager_win.h"
@@ skipping 57 matching lines @@
     ::EnableWindow(hwnd(), TRUE);
   }
 }
 
 HWND LegacyRenderWidgetHostHWND::GetParent() {
   return ::GetParent(hwnd());
 }
 
 void LegacyRenderWidgetHostHWND::Show() {
   ::ShowWindow(hwnd(), SW_SHOW);
+  if (direct_manipulation_helper_)
+    direct_manipulation_helper_->Activate(hwnd());
 }
 
 void LegacyRenderWidgetHostHWND::Hide() {
   ::ShowWindow(hwnd(), SW_HIDE);
 }
 
 void LegacyRenderWidgetHostHWND::SetBounds(const gfx::Rect& bounds) {
   gfx::Rect bounds_in_pixel = gfx::win::DIPToScreenRect(bounds);
   ::SetWindowPos(hwnd(), NULL, bounds_in_pixel.x(), bounds_in_pixel.y(),
                  bounds_in_pixel.width(), bounds_in_pixel.height(),
                  SWP_NOREDRAW);
+  if (direct_manipulation_helper_)
+    direct_manipulation_helper_->SetBounds(bounds_in_pixel);
 }
 
 void LegacyRenderWidgetHostHWND::OnFinalMessage(HWND hwnd) {
   if (host_) {
     host_->OnLegacyWindowDestroyed();
     host_ = NULL;
   }
   delete this;
 }
 
@@ skipping 20 matching lines @@
       reinterpret_cast<void **>(window_accessible_.Receive()));
   DCHECK(SUCCEEDED(hr));
 
   if (!BrowserAccessibilityState::GetInstance()->IsAccessibleBrowser()) {
     // Attempt to detect screen readers or other clients who want full
     // accessibility support, by seeing if they respond to this event.
     NotifyWinEvent(EVENT_SYSTEM_ALERT, hwnd(), kIdScreenReaderHoneyPot,
                    CHILDID_SELF);
   }
 
+  // Direct Manipulation is enabled on Windows 10+. The CreateInstance function
+  // returns NULL if Direct Manipulation is not available.
+  direct_manipulation_helper_.reset(
+      gfx::win::DirectManipulationHelper::CreateInstance());
+  if (direct_manipulation_helper_)
+    direct_manipulation_helper_->Initialize(hwnd());
+
   return !!SUCCEEDED(hr);
 }
 
 // static
 ui::WindowEventTarget* LegacyRenderWidgetHostHWND::GetWindowEventTarget(
     HWND parent) {
   return reinterpret_cast<ui::WindowEventTarget*>(ui::ViewProp::GetValue(
       parent, ui::WindowEventTarget::kWin32InputEventTarget));
 }
 
@@ skipping 96 matching lines @@
     // If the parent did not handle non client mouse messages, we call
     // DefWindowProc on the message with the parent window handle. This
     // ensures that WM_SYSCOMMAND is generated for the parent and we are
     // out of the picture.
     if (!handled &&
          (message >= WM_NCMOUSEMOVE && message <= WM_NCXBUTTONDBLCLK)) {
       ret = ::DefWindowProc(GetParent(), message, w_param, l_param);
       handled = TRUE;
     }
   }
+
+  if (direct_manipulation_helper_ &&
+      (message == WM_MOUSEWHEEL || message == WM_MOUSEHWHEEL)) {
+    direct_manipulation_helper_->HandleMouseWheel(hwnd(), message, w_param,
+        l_param);
+  }
   return ret;
 }
 
 LRESULT LegacyRenderWidgetHostHWND::OnMouseLeave(UINT message,
                                                  WPARAM w_param,
                                                  LPARAM l_param) {
   mouse_tracking_enabled_ = false;
   LRESULT ret = 0;
   if ((::GetCapture() != GetParent()) && GetWindowEventTarget(GetParent())) {
     // We should send a WM_MOUSELEAVE to the parent window only if the mouse
@@ skipping 118 matching lines @@
   // generate the legacy WM_VSCROLL/WM_HSCROLL messages.
   // We add these styles to ensure that trackpad/trackpoint scrolling
   // work.
   long current_style = ::GetWindowLong(hwnd(), GWL_STYLE);
   ::SetWindowLong(hwnd(), GWL_STYLE,
                   current_style | WS_VSCROLL | WS_HSCROLL);
   return 0;
 }
 
 }  // namespace content