linux: Set scale factor to the value in gsettings

atom/browser/atom_browser_main_parts_linux.cc

@@ -0,0 +1,64 @@
+// Copyright (c) 2014 GitHub, Inc. All rights reserved.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#include "atom/browser/atom_browser_main_parts.h"
+
+#include "base/command_line.h"
+#include "base/strings/string_number_conversions.h"
+#include "library_loaders/libgio.h"
+#include "ui/gfx/switches.h"
+
+namespace atom {
+
+namespace {
+
+const char* kInterfaceSchema = "org.gnome.desktop.interface";
+const char* kScaleFactor = "scale-factor";
+
+}  // namespace
+
+void AtomBrowserMainParts::SetDPIFromGSettings() {
+  LibGioLoader libgio_loader;
+
+  // Try also without .0 at the end; on some systems this may be required.
+  if (!libgio_loader.Load("libgio-2.0.so.0") &&
+      !libgio_loader.Load("libgio-2.0.so")) {
+    VLOG(1) << "Cannot load gio library. Will fall back to gconf.";
+    return;
+  }
+
+  GSettings* client = libgio_loader.g_settings_new(kInterfaceSchema);
+  if (!client) {
+    VLOG(1) << "Cannot create gsettings client.";
+    return;
+  }
+
+  gchar** keys = libgio_loader.g_settings_list_keys(client);
+  if (!keys) {
+    g_object_unref(client);
+    return;
+  }
+
+  // Check if the "scale-factor" settings exsits.
+  gchar** iter = keys;
+  while (*iter) {
+    if (strcmp(*iter, kScaleFactor) == 0)
+      break;
+    iter++;
+  }
+
+  if (*iter) {
+    guint scale_factor = libgio_loader.g_settings_get_uint(
+        client, kScaleFactor);
+    if (scale_factor >= 1) {
+      base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
+          switches::kForceDeviceScaleFactor, base::UintToString(scale_factor));
+    }
+  }
+
+  g_strfreev(keys);
+  g_object_unref(client);
+}
+
+}  // namespace atom