Windows Host Touch Injection

remoting/host/touch_injector_win.h

Index: remoting/host/touch_injector_win.h
diff --git a/remoting/host/touch_injector_win.h b/remoting/host/touch_injector_win.h
new file mode 100644
index 0000000000000000000000000000000000000000..bab298a6c1770b3fe9f1baf0ed0f07ac467673a4
--- /dev/null
+++ b/remoting/host/touch_injector_win.h
@@ -0,0 +1,109 @@
+// Copyright 2015 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.
+
+#ifndef REMOTING_HOST_TOUCH_INJECTOR_WIN_H_
+#define REMOTING_HOST_TOUCH_INJECTOR_WIN_H_
+
+#include <windows.h>
+#include <map>
+#include <vector>
+
+#include "base/memory/scoped_ptr.h"
+#include "base/scoped_native_library.h"
+
+namespace remoting {
+
+namespace protocol {
+
+class TouchEvent;
+
+}  // namespace protocol
+
+// This class calls InitializeTouchInjection() and InjectTouchInput() functions.
+// The methods are virtual for mocking.
+class TouchInjectorWinDelegate {
+ public:
+  virtual ~TouchInjectorWinDelegate();
+
+  // Determines whether Windows touch injection functions can be used.
+  // Returns a non-null TouchInjectorWinDelegate on success.
+  static scoped_ptr<TouchInjectorWinDelegate> Create();
+
+  // These match the functions in MSDN.
+  virtual BOOL InitializeTouchInjection(UINT32 max_count, DWORD dw_mode);
+  virtual DWORD InjectTouchInput(UINT32 count,
+                                 const POINTER_TOUCH_INFO* contacts);
+
+ protected:
+  // Ctor in protected scope for mocking.
+  // Ownership of |library| transfers.

[Wez, 2015/03/21 01:10:09]

You mean the delegate takes ownership of |library|? It looks more like it
actually takes a reference to it?

[Rintaro Kuroiwa, 2015/03/24 20:34:47]

Yes, the delegate takes ownership. Reworded.
NativeLibrary is a raw pointer for all platforms
https://code.google.com/p/chromium/codesearch#chromium/src/base/native_librar...

ScopedNativeLibrary doesn't have Pass() method like scoped_ptr, it only has
Release() which returns NativeLibrary type value.
https://code.google.com/p/chromium/codesearch#chromium/src/base/scoped_native...
So this object takes the ownership :)

+  TouchInjectorWinDelegate(
+      base::NativeLibrary library,
+      BOOL(NTAPI* initialize_touch_injection_func)(UINT32, DWORD),
+      BOOL(NTAPI* inject_touch_input_func)(UINT32, const POINTER_TOUCH_INFO*));
+
+ private:
+  base::ScopedNativeLibrary library_module_;
+
+  // Pointers to Windows touch injection functions.
+  BOOL(NTAPI* initialize_touch_injection_func_)(UINT32, DWORD);
+  BOOL(NTAPI* inject_touch_input_func_)(UINT32, const POINTER_TOUCH_INFO*);
+
+  DISALLOW_COPY_AND_ASSIGN(TouchInjectorWinDelegate);
+};
+
+// This class converts TouchEvent objects to POINTER_TOUCH_INFO so that it can
+// be injected using the Windows touch injection API, and calls the injection
+// functions.
+// This class expects good inputs and does not sanity check the inputs.
+// This class just converts the object and hands it off to the Windows API.
+class TouchInjectorWin {
+ public:
+  TouchInjectorWin();
+  ~TouchInjectorWin();
+
+  // Returns false if initialization of touch injection APIs fails.
+  bool Init();
+
+  // Deinitializes the object so that it can be reinitialized.
+  void Deinitialize();
+
+  // Inject touch events.
+  void InjectTouchEvent(const protocol::TouchEvent& event);
+
+  void SetInjectorDelegateForTest(
+      scoped_ptr<TouchInjectorWinDelegate> functions);
+
+ private:
+  // Helper methods called from InjectTouchEvent().
+  // If points in contact are not specified in |event|, *TouchPoints() methods
+  // will inject them as "move" events with the same values as the previous call
+  // to these methods.
+  // For example:
+  // 1. AddNewTouchPoints(id = 1)
+  // 2. AddNewTouchPoints(id = 2)
+  // Step 2 will inject move event for id = 1 and start event for id = 2.

[Wez, 2015/03/21 01:10:09]

I'd suggest rewording this to simply say something like:

"These helpers adapt Chromoting touch events, which convey changes to touch
points, to Windows touch descriptions, which must include descriptions for all
currently-active touch points, not just the changed ones."

[Rintaro Kuroiwa, 2015/03/24 20:34:47]

Done.

+  void AddNewTouchPoints(const protocol::TouchEvent& event);
+  void MoveTouchPoints(const protocol::TouchEvent& event);
+  void EndTouchPoints(const protocol::TouchEvent& event);
+  void CancelTouchPoints(const protocol::TouchEvent& event);
+
+  // Set to null when not usable.

[Wez, 2015/03/21 01:10:09]

That's somewhat tautologous; if it's NULL then it's clearly unusable. ;)
Suggest:

"Set to null if touch injection is not available from the OS."

[Rintaro Kuroiwa, 2015/03/24 20:34:47]

Done.

+  scoped_ptr<TouchInjectorWinDelegate> delegate_;
+
+  // TODO(rkuroiwa): This is a naive implementation. Check if we can achieve

[Wez, 2015/03/21 01:10:09]

nit: File a bug to make that optimization, so this TODO doesn't linger forever.
;)

[Rintaro Kuroiwa, 2015/03/24 20:34:47]

Oh right. Thanks for reminding!
Done.

+  // better performance by reducing the number of copies.
+  // To reduce the number of copies, we can have a vector of
+  // POINTER_TOUCH_INFO and a map from touch ID to index in the vector.
+  // When removing points from the vector, just swap it with the last element
+  // and resize the vector.
+  // All the POINTER_TOUCH_INFOs are stored as "move" points.
+  std::map<uint32_t, POINTER_TOUCH_INFO> touches_in_contact_;
+
+  DISALLOW_COPY_AND_ASSIGN(TouchInjectorWin);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_TOUCH_INJECTOR_WIN_H_