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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 = '.'; | |
Avi (use Gerrit)
2013/10/04 21:59:01
:( I wish we could StringPrintf according to a pro
| |
67 } | |
68 screen_hints_ = device_pixel_ratio; | |
69 } | |
70 | |
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