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

remoting/host/linux/x_server_key_mapper.cc

Index: remoting/host/linux/x_server_key_mapper.cc
diff --git a/remoting/host/linux/x_server_key_mapper.cc b/remoting/host/linux/x_server_key_mapper.cc
new file mode 100644
index 0000000000000000000000000000000000000000..01d0a961888541ba3d2f43316e8d090c7d258b3a
--- /dev/null
+++ b/remoting/host/linux/x_server_key_mapper.cc
@@ -0,0 +1,70 @@
+// 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/x_server_key_mapper.h"
+
+#include <X11/Xlib.h>
+
+#include "base/strings/stringprintf.h"
+#include "ui/gfx/x/x11_types.h"
+
+namespace remoting {
+
+XServerKeyMapper::XServerKeyMapper(Display* display) : display_(display) {
+  int min_keycode, max_keycode, sym_per_key;

[Sergey Ulanov, 2016/09/19 21:39:00]

nit: please move sym_per_key just before XGetKeyboardMapping(). Style guide says
"We encourage you to declare them in as local a scope as possible, and as close
to the first use as possible. "
Also separate min an max variables:
 int min_keycode;
 int max_keycode;

This make code more readable.

[Yuwei, 2016/09/21 03:47:40]

Done.

+  XDisplayKeycodes(display_, &min_keycode, &max_keycode);
+  uint32_t keycode_count = max_keycode - min_keycode + 1;
+  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) {
+      available_keycodes_.push(keycode);
+    }
+  }
+}
+
+XServerKeyMapper::~XServerKeyMapper() {
+  // Clear all used key mappings.
+  KeySym empty = 0;
+  for (int keycode : used_keycodes_) {
+    XChangeKeyboardMapping(display_, keycode, 1, &empty, 1);
+  }
+  XSync(display_, false);
+}
+
+int XServerKeyMapper::AddNewCharacter(uint32_t code_point) {
+  std::string sym_hex = base::StringPrintf("U%x", code_point);
+  KeySym sym = XStringToKeysym(sym_hex.c_str());
+  if (sym == NoSymbol || available_keycodes_.empty()) {
+    return -1;
+  }
+
+  // For alphabetic characters, both the upper-case and lower-case keysyms must
+  // be defined as the character we want to type, otherwise Xlib will decide the
+  // case by checking key modifiers.
+  KeySym syms[2];
+  syms[0] = sym;  // lower-case
+  syms[1] = sym;  // upper-case
+
+  uint32_t keycode = available_keycodes_.front();
+  available_keycodes_.pop();
+
+  XChangeKeyboardMapping(display_, keycode, 2, syms, 1);
+
+  available_keycodes_.push(keycode);
+  used_keycodes_.insert(keycode);
+
+  XSync(display_, false);
+  return keycode;
+}
+
+}  // namespace remoting