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| 1 // Copyright 2013 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #include "chrome/browser/net/client_hints.h" |
| 6 |
| 7 #include <locale> |
| 8 |
| 9 #include "base/bind.h" |
| 10 #include "base/strings/stringprintf.h" |
| 11 #include "base/task_runner_util.h" |
| 12 #include "content/public/browser/browser_thread.h" |
| 13 #include "ui/gfx/screen.h" |
| 14 |
| 15 namespace { |
| 16 |
| 17 float FetchScreenInfoOnUIThread() { |
| 18 DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI)); |
| 19 // TODO(bengr): Consider multi-display scenarios. |
| 20 gfx::Display display = gfx::Screen::GetNativeScreen()->GetPrimaryDisplay(); |
| 21 return display.device_scale_factor(); |
| 22 } |
| 23 |
| 24 } // namespace |
| 25 |
| 26 const char ClientHints::kDevicePixelRatioHeader[] = "CH-DPR"; |
| 27 |
| 28 ClientHints::ClientHints() |
| 29 : weak_ptr_factory_(this) { |
| 30 } |
| 31 |
| 32 ClientHints::~ClientHints() { |
| 33 } |
| 34 |
| 35 void ClientHints::Init() { |
| 36 // TODO(bengr): Observe the device pixel ratio in case it changes during |
| 37 // the Chrome session. |
| 38 RetrieveScreenInfo(); |
| 39 } |
| 40 |
| 41 bool ClientHints::RetrieveScreenInfo() { |
| 42 DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO)); |
| 43 return content::BrowserThread::PostTaskAndReplyWithResult( |
| 44 content::BrowserThread::UI, |
| 45 FROM_HERE, |
| 46 base::Bind(&FetchScreenInfoOnUIThread), |
| 47 base::Bind( |
| 48 &ClientHints::UpdateScreenInfo, weak_ptr_factory_.GetWeakPtr())); |
| 49 } |
| 50 |
| 51 const std::string& ClientHints::GetDevicePixelRatioHeader() const { |
| 52 return screen_hints_; |
| 53 } |
| 54 |
| 55 void ClientHints::UpdateScreenInfo(float device_pixel_ratio_value) { |
| 56 if (device_pixel_ratio_value <= 0.0) |
| 57 return; |
| 58 std::string device_pixel_ratio = base::StringPrintf("%.2f", |
| 59 device_pixel_ratio_value); |
| 60 // Make sure the Client Hints value doesn't change |
| 61 // according to the machine's locale |
| 62 std::locale locale; |
| 63 for (std::string::iterator it = device_pixel_ratio.begin(); |
| 64 it != device_pixel_ratio.end(); ++it) { |
| 65 if (!std::isdigit(*it, locale)) |
| 66 *it = '.'; |
| 67 } |
| 68 screen_hints_ = device_pixel_ratio; |
| 69 } |
| 70 |
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