Bug 855975 part.11 Sort out the if statement which checks whether the native keydown message needs to be handled without following char messages r=jimm

widget/windows/KeyboardLayout.cpp

@@ -548,6 +548,9 @@ NativeKey::NativeKey(nsWindowBase* aWidget,
     keyboardLayout->ConvertNativeKeyCodeToKeyNameIndex(mOriginalVirtualKeyCode);
 
   keyboardLayout->InitNativeKey(*this, mModKeyState);
+
+  mIsDeadKey = keyboardLayout->IsDeadKey(mOriginalVirtualKeyCode, mModKeyState);
+  mIsPrintableKey = KeyboardLayout::IsPrintableCharKey(mOriginalVirtualKeyCode);
 }
 
 UINT
@@ -874,6 +877,35 @@ NativeKey::HandleKeyUpMessage(bool* aEventDispatched) const
   return DispatchKeyEvent(keyupEvent, &mMsg);
 }
 
+bool
+NativeKey::NeedsToHandleWithoutFollowingCharMessages() const
+{
+  MOZ_ASSERT(mMsg.message == WM_KEYDOWN || mMsg.message == WM_SYSKEYDOWN);
+
+  // Enter and backspace are always handled here to avoid for example the
+  // confusion between ctrl-enter and ctrl-J.
+  if (mDOMKeyCode == NS_VK_RETURN || mDOMKeyCode == NS_VK_BACK) {
+    return true;
+  }
+
+  // If any modifier keys which may cause printable keys becoming non-printable
+  // are not pressed, we don't need special handling for the key.
+  if (!mModKeyState.IsControl() && !mModKeyState.IsAlt() &&
+      !mModKeyState.IsWin()) {
+    return false;
+  }
+
+  // If the key event causes dead key event, we don't need to dispatch keypress
+  // event.
+  if (mIsDeadKey) {
+    return false;
+  }
+
+  // Even if the key is a printable key, it might cause non-printable character
+  // input with modifier key(s).
+  return IsPrintableKey();
+}
+
 bool
 NativeKey::DispatchKeyPressEventsWithKeyboardLayout(
                         const UniCharsAndModifiers& aInputtingChars,

widget/windows/KeyboardLayout.h

@@ -296,6 +296,14 @@ public:
   {
     return (mMsg.message == WM_KEYDOWN || mMsg.message == WM_SYSKEYDOWN);
   }
+  bool IsDeadKey() const { return mIsDeadKey; }
+  /**
+   * IsPrintableKey() returns true if the key may be a printable key without
+   * any modifier keys.  Otherwise, false.
+   * Please note that the event may not cause any text input even if this
+   * returns true.  E.g., it might be dead key state or Ctrl key may be pressed.
+   */
+  inline bool IsPrintableKey() const { return mIsPrintableKey; }
   WORD GetScanCode() const { return mScanCode; }
   uint8_t GetVirtualKeyCode() const { return mVirtualKeyCode; }
   uint8_t GetOriginalVirtualKeyCode() const { return mOriginalVirtualKeyCode; }
@@ -340,6 +348,15 @@ public:
                         const UniCharsAndModifiers& aInputtingChars,
                         const EventFlags& aExtraFlags) const;
 
+  /**
+   * Checkes whether the key event down message is handled without following
+   * WM_CHAR messages.  For example, if following WM_CHAR message indicates
+   * control character input, the WM_CHAR message is unclear whether it's
+   * caused by a printable key with Ctrl or just a function key such as Enter
+   * or Backspace.
+   */
+  bool NeedsToHandleWithoutFollowingCharMessages() const;
+
   /**
    * Dspatces keydown event.  Retrns true if the event is consumed.
    * Otherwise, false.
@@ -385,6 +402,8 @@ private:
 
   WORD    mScanCode;
   bool    mIsExtended;
+  bool    mIsDeadKey;
+  bool    mIsPrintableKey;
 
   NativeKey()
   {

widget/windows/nsWindow.cpp

@@ -6463,8 +6463,6 @@ LRESULT nsWindow::OnKeyDown(const MSG &aMsg,
       return noDefault;
   }
 
-  UINT virtualKeyCode = nativeKey.GetOriginalVirtualKeyCode();
-  bool isDeadKey = keyboardLayout->IsDeadKey(virtualKeyCode, aModKeyState);
   EventFlags extraFlags;
   extraFlags.mDefaultPrevented = noDefault;
   MSG msg;
@@ -6473,10 +6471,7 @@ LRESULT nsWindow::OnKeyDown(const MSG &aMsg,
                           PM_NOREMOVE | PM_NOYIELD);
   // Enter and backspace are always handled here to avoid for example the
   // confusion between ctrl-enter and ctrl-J.
-  if (DOMKeyCode == NS_VK_RETURN || DOMKeyCode == NS_VK_BACK ||
-      ((aModKeyState.IsControl() || aModKeyState.IsAlt() || aModKeyState.IsWin())
-       && !isDeadKey && KeyboardLayout::IsPrintableCharKey(virtualKeyCode)))
-  {
+  if (nativeKey.NeedsToHandleWithoutFollowingCharMessages()) {
     // Remove a possible WM_CHAR or WM_SYSCHAR messages from the message queue.
     // They can be more than one because of:
     //  * Dead-keys not pairing with base character
@@ -6518,13 +6513,14 @@ LRESULT nsWindow::OnKeyDown(const MSG &aMsg,
         return false;
       }
 #ifdef DEBUG
-      if (KeyboardLayout::IsPrintableCharKey(virtualKeyCode)) {
+      if (nativeKey.IsPrintableKey()) {
         nsPrintfCString log(
-          "virtualKeyCode=0x%02X, inputtingChar={ mChars=[ 0x%04X, 0x%04X, "
-          "0x%04X, 0x%04X, 0x%04X ], mLength=%d }, wParam=0x%04X",
-          virtualKeyCode, inputtingChars.mChars[0], inputtingChars.mChars[1],
-          inputtingChars.mChars[2], inputtingChars.mChars[3],
-          inputtingChars.mChars[4], inputtingChars.mLength, msg.wParam);
+          "OriginalVirtualKeyCode=0x%02X, inputtingChar={ mChars=[ 0x%04X, "
+          "0x%04X, 0x%04X, 0x%04X, 0x%04X ], mLength=%d }, wParam=0x%04X",
+          nativeKey.GetOriginalVirtualKeyCode(), inputtingChars.mChars[0],
+          inputtingChars.mChars[1], inputtingChars.mChars[2],
+          inputtingChars.mChars[3], inputtingChars.mChars[4],
+          inputtingChars.mLength, msg.wParam);
         if (!inputtingChars.mLength) {
           log.Insert("length is zero: ", 0);
           NS_ERROR(log.get());
@@ -6565,15 +6561,14 @@ LRESULT nsWindow::OnKeyDown(const MSG &aMsg,
     return static_cast<LRESULT>(result);
   }
   else if (!aModKeyState.IsControl() && !aModKeyState.IsAlt() &&
-            !aModKeyState.IsWin() &&
-            KeyboardLayout::IsPrintableCharKey(virtualKeyCode)) {
+            !aModKeyState.IsWin() && nativeKey.IsPrintableKey()) {
     // If this is simple KeyDown event but next message is not WM_CHAR,
     // this event may not input text, so we should ignore this event.
     // See bug 314130.
     return PluginHasFocus() && noDefault;
   }
 
-  if (isDeadKey) {
+  if (nativeKey.IsDeadKey()) {
     return PluginHasFocus() && noDefault;
   }