Select theme resources from ResourceBundle at requested scale factor.

chrome/browser/ui/webui/theme_source.cc

 // Copyright (c) 2012 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/ui/webui/theme_source.h"
 
 #include "base/memory/ref_counted_memory.h"
 #include "base/message_loop.h"
+#include "base/string_number_conversions.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/resources_util.h"
 #include "chrome/browser/themes/theme_service.h"
 #include "chrome/browser/themes/theme_service_factory.h"
 #include "chrome/browser/ui/webui/ntp/ntp_resource_cache.h"
 #include "chrome/browser/ui/webui/ntp/ntp_resource_cache_factory.h"
 #include "chrome/common/url_constants.h"
 #include "content/public/browser/browser_thread.h"
 #include "googleurl/src/gurl.h"
 #include "ui/base/resource/resource_bundle.h"
+#include "ui/base/resource/resource_handle.h"
 #include "ui/base/theme_provider.h"
 
 using content::BrowserThread;
 
+namespace {
+
 // use a resource map rather than hard-coded strings.
 static const char* kNewTabCSSPath = "css/new_tab_theme.css";
 static const char* kNewIncognitoTabCSSPath = "css/incognito_new_tab_theme.css";
 
-static std::string StripQueryParams(const std::string& path) {
+std::string StripQueryParams(const std::string& path) {
   GURL path_url = GURL(std::string(chrome::kChromeUIScheme) + "://" +
                        std::string(chrome::kChromeUIThemePath) + "/" + path);
   return path_url.path().substr(1);  // path() always includes a leading '/'.
 }
 
+std::string ParsePathAndScale(const std::string& path, float* scale_factor) {
+  // Our path may include cachebuster arguments, so trim them off.
+  std::string uncached_path = StripQueryParams(path);
+
+  // Detect and parse resource string ending in @<scale>x.
+  std::size_t pos = uncached_path.rfind('@');
+  if (pos != std::string::npos &&
+      uncached_path[uncached_path.length()-1] == 'x') {
+    double scale_d;
+    if (scale_factor &&
+        base::StringToDouble(
+            uncached_path.substr(pos + 1, uncached_path.length() - pos - 2),
+            &scale_d)) {
+      *scale_factor = scale_d;
+    }
+    // Strip scale factor specification from path.
+    uncached_path = uncached_path.substr(0, pos);
+  }
+  return uncached_path;
+}
+
+}  // namespace
+
 ////////////////////////////////////////////////////////////////////////////////
 // ThemeSource, public:
 
 ThemeSource::ThemeSource(Profile* profile)
     : DataSource(chrome::kChromeUIThemePath, MessageLoop::current()),
       profile_(profile->GetOriginalProfile()) {
   css_bytes_ = NTPResourceCacheFactory::GetForProfile(profile)->GetNewTabCSS(
       profile->IsOffTheRecord());
 }
 
 ThemeSource::~ThemeSource() {
 }
 
 void ThemeSource::StartDataRequest(const std::string& path,
                                    bool is_incognito,
                                    int request_id) {
-  // Our path may include cachebuster arguments, so trim them off.
-  std::string uncached_path = StripQueryParams(path);
+  // Default scale factor if not specified.
+  float scale_factor = 1;
+  std::string uncached_path = ParsePathAndScale(path, &scale_factor);
 
   if (uncached_path == kNewTabCSSPath ||
       uncached_path == kNewIncognitoTabCSSPath) {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
     DCHECK((uncached_path == kNewTabCSSPath && !is_incognito) ||
            (uncached_path == kNewIncognitoTabCSSPath && is_incognito));
 
     SendResponse(request_id, css_bytes_);
     return;
   } else {
     int resource_id = ResourcesUtil::GetThemeResourceId(uncached_path);
     if (resource_id != -1) {
-      SendThemeBitmap(request_id, resource_id);
+      SendThemeBitmap(request_id, resource_id, scale_factor);
       return;
     }
   }
   // We don't have any data to send back.
   SendResponse(request_id, NULL);
 }
 
 std::string ThemeSource::GetMimeType(const std::string& path) const {
-  std::string uncached_path = StripQueryParams(path);
+  std::string uncached_path = ParsePathAndScale(path, NULL);
 
   if (uncached_path == kNewTabCSSPath ||
       uncached_path == kNewIncognitoTabCSSPath) {
     return "text/css";
   }
 
   return "image/png";
 }
 
 MessageLoop* ThemeSource::MessageLoopForRequestPath(
     const std::string& path) const {
-  std::string uncached_path = StripQueryParams(path);
+  std::string uncached_path = ParsePathAndScale(path, NULL);
 
   if (uncached_path == kNewTabCSSPath ||
       uncached_path == kNewIncognitoTabCSSPath) {
     // We generated and cached this when we initialized the object.  We don't
     // have to go back to the UI thread to send the data.
     return NULL;
   }
 
   // If it's not a themeable image, we don't need to go to the UI thread.
   int resource_id = ResourcesUtil::GetThemeResourceId(uncached_path);
   if (!ThemeService::IsThemeableImage(resource_id))
     return NULL;
 
   return DataSource::MessageLoopForRequestPath(path);
 }
 
 bool ThemeSource::ShouldReplaceExistingSource() const {
   // We currently get the css_bytes_ in the ThemeSource constructor, so we need
   // to recreate the source itself when a theme changes.
   return true;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // ThemeSource, private:
 
-void ThemeSource::SendThemeBitmap(int request_id, int resource_id) {
+void ThemeSource::SendThemeBitmap(int request_id,
+                                  int resource_id,
+                                  float scale_factor) {
   if (ThemeService::IsThemeableImage(resource_id)) {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
     ui::ThemeProvider* tp = ThemeServiceFactory::GetForProfile(profile_);
     DCHECK(tp);
 
+    // TODO(flackr): Pass scale factor when fetching themeable images.
     scoped_refptr<base::RefCountedMemory> image_data(tp->GetRawData(
         resource_id));
     SendResponse(request_id, image_data);
   } else {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
     const ResourceBundle& rb = ResourceBundle::GetSharedInstance();
-    SendResponse(request_id, rb.LoadDataResourceBytes(resource_id));
+    SendResponse(request_id,
+                 rb.LoadDataResourceBytes(resource_id, scale_factor));
   }
 }