| // Copyright 2013 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 "chrome/browser/net/client_hints.h" |
| |
| #include <locale> |
| |
| #include "base/bind.h" |
| #include "base/strings/stringprintf.h" |
| #include "base/task_runner_util.h" |
| #include "content/public/browser/browser_thread.h" |
| #include "ui/gfx/screen.h" |
| |
| namespace { |
| |
| float FetchScreenInfoOnUIThread() { |
| DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI)); |
| // TODO(bengr): Consider multi-display scenarios. |
| gfx::Display display = gfx::Screen::GetNativeScreen()->GetPrimaryDisplay(); |
| return display.device_scale_factor(); |
| } |
| |
| } // namespace |
| |
| const char ClientHints::kDevicePixelRatioHeader[] = "CH-DPR"; |
| |
| ClientHints::ClientHints() |
| : weak_ptr_factory_(this) { |
| } |
| |
| ClientHints::~ClientHints() { |
| } |
| |
| void ClientHints::Init() { |
| // TODO(bengr): Observe the device pixel ratio in case it changes during |
| // the Chrome session. |
| RetrieveScreenInfo(); |
| } |
| |
| bool ClientHints::RetrieveScreenInfo() { |
| DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO)); |
| return content::BrowserThread::PostTaskAndReplyWithResult( |
| content::BrowserThread::UI, |
| FROM_HERE, |
| base::Bind(&FetchScreenInfoOnUIThread), |
| base::Bind( |
| &ClientHints::UpdateScreenInfo, weak_ptr_factory_.GetWeakPtr())); |
| } |
| |
| const std::string& ClientHints::GetDevicePixelRatioHeader() const { |
| return screen_hints_; |
| } |
| |
| void ClientHints::UpdateScreenInfo(float device_pixel_ratio_value) { |
| if (device_pixel_ratio_value <= 0.0) |
| return; |
| std::string device_pixel_ratio = base::StringPrintf("%.2f", |
| device_pixel_ratio_value); |
| // Make sure the Client Hints value doesn't change |
| // according to the machine's locale |
| std::locale locale; |
| for (std::string::iterator it = device_pixel_ratio.begin(); |
| it != device_pixel_ratio.end(); ++it) { |
| if (!std::isdigit(*it, locale)) |
| *it = '.'; |
| } |
| screen_hints_ = device_pixel_ratio; |
| } |
| |