[Remoting Host] Handle text event characters that are not presented on the keyboard

remoting/host/linux/x11_keyboard_impl.cc

+// Copyright 2016 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 "remoting/host/linux/x11_keyboard_impl.h"
+
+#include <X11/extensions/XInput.h>
+#include <X11/extensions/XTest.h>
+#include <X11/XKBlib.h>
+
+#include "base/strings/stringprintf.h"
+#include "remoting/host/linux/unicode_to_keysym.h"
+#include "ui/gfx/x/x11_types.h"
+
+namespace {
+
+bool FindKeycodeForKeySym(Display* display,
+                          KeySym key_sym,
+                          uint32_t* keycode,
+                          uint32_t* modifiers) {
+  uint32_t found_keycode = XKeysymToKeycode(display, key_sym);
+
+  const uint32_t kModifiersToTry[] = {
+      0,
+      ShiftMask,
+      Mod2Mask,
+      Mod3Mask,
+      Mod4Mask,
+      ShiftMask | Mod2Mask,
+      ShiftMask | Mod3Mask,
+      ShiftMask | Mod4Mask,
+  };
+
+  // TODO(sergeyu): Is there a better way to find modifiers state?
+  for (size_t i = 0; i < arraysize(kModifiersToTry); ++i) {
+    unsigned long key_sym_with_mods;
+    if (XkbLookupKeySym(display, found_keycode, kModifiersToTry[i], nullptr,
+                        &key_sym_with_mods) &&
+        key_sym_with_mods == key_sym) {
+      *modifiers = kModifiersToTry[i];
+      *keycode = found_keycode;
+      return true;
+    }
+  }
+  return false;
+}
+
+}  // namespace
+
+namespace remoting {
+
+X11KeyboardImpl::X11KeyboardImpl(Display* display) : display_(display) {}
+
+X11KeyboardImpl::~X11KeyboardImpl() {}
+
+std::vector<uint32_t> X11KeyboardImpl::GetUnusedKeycodes() {
+  std::vector<uint32_t> unused_keycodes_;
+  int min_keycode;
+  int max_keycode;
+  XDisplayKeycodes(display_, &min_keycode, &max_keycode);
+  uint32_t keycode_count = max_keycode - min_keycode + 1;
+
+  int sym_per_key;
+  gfx::XScopedPtr<KeySym> mapping(
+      XGetKeyboardMapping(display_, min_keycode, keycode_count, &sym_per_key));
+  for (int keycode = max_keycode; keycode >= min_keycode; keycode--) {
+    bool used = false;
+    int offset = (keycode - min_keycode) * sym_per_key;
+    for (int level = 0; level < sym_per_key; level++) {
+      if (mapping.get()[offset + level]) {
+        used = true;
+        break;
+      }
+    }
+    if (!used) {
+      unused_keycodes_.push_back(keycode);
+    }
+  }
+  return unused_keycodes_;
+}
+
+void X11KeyboardImpl::PressKey(uint32_t keycode, uint32_t modifiers) {
+  XkbLockModifiers(display_, XkbUseCoreKbd, modifiers, modifiers);
+
+  XTestFakeKeyEvent(display_, keycode, True, CurrentTime);
+  XTestFakeKeyEvent(display_, keycode, False, CurrentTime);
+
+  XkbLockModifiers(display_, XkbUseCoreKbd, modifiers, 0);
+}
+
+bool X11KeyboardImpl::FindKeycode(uint32_t code_point,
+                                  uint32_t* keycode,
+                                  uint32_t* modifiers) {
+  for (uint32_t keysym : GetKeySymsForUnicode(code_point)) {
+    if (FindKeycodeForKeySym(display_, keysym, keycode, modifiers)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool X11KeyboardImpl::ChangeKeyMapping(uint32_t keycode, uint32_t code_point) {
+  KeySym sym = NoSymbol;
+  if (code_point > 0) {
+    std::string sym_hex = base::StringPrintf("U%x", code_point);
+    sym = XStringToKeysym(sym_hex.c_str());
+    if (sym == NoSymbol) {
+      // The server may not support Unicode-to-KeySym translation.
+      return false;
+    }
+  }
+
+  KeySym syms[2]{sym, sym};  // {lower-case, upper-case}
+  XChangeKeyboardMapping(display_, keycode, 2, syms, 1);
+  return true;
+}
+
+void X11KeyboardImpl::Flush() {
+  XFlush(display_);
+}
+
+void X11KeyboardImpl::Sync() {
+  XSync(display_, false);
+}
+
+}  // namespace remoting