Supporting high dpi favicons in Instant Extended.

chrome/common/favicon/favicon_url_parser.cc

Index: chrome/common/favicon/favicon_url_parser.cc
diff --git a/chrome/common/favicon/favicon_url_parser.cc b/chrome/common/favicon/favicon_url_parser.cc
new file mode 100644
index 0000000000000000000000000000000000000000..679a7413c7b7ca51fb73dfc9cbda357575c4928e
--- /dev/null
+++ b/chrome/common/favicon/favicon_url_parser.cc
@@ -0,0 +1,140 @@
+// 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/common/favicon/favicon_url_parser.h"
+
+#include "base/strings/string_number_conversions.h"
+#include "chrome/common/favicon/favicon_types.h"
+#include "net/url_request/url_request.h"
+#include "ui/base/layout.h"
+#include "ui/gfx/favicon_size.h"
+#include "ui/webui/web_ui_util.h"
+
+namespace {
+
+// Parameters which can be used in chrome://favicon path. See file
+// "chrome/browser/ui/webui/favicon_source.h" for a description of
+// what each does.
+const char kIconURLParameter[] = "iconurl/";
+const char kLargestParameter[] = "largest/";
+const char kOriginParameter[] = "origin/";
+const char kSizeParameter[] = "size/";
+
+// Default size of the favicon.
+const int kFaviconSizeInDip = gfx::kFaviconSize;
+
+// 2x size of the favicon.
+const int kFaviconSizeInDip2x = gfx::kFaviconSize * 2;
+
+// 4x size of the favicon.
+const int kFaviconSizeInDip4x = gfx::kFaviconSize * 4;
+
+// Returns true if |search| is a substring of |path| which starts at
+// |start_index|.
+bool HasSubstringAt(const std::string& path,
+                    size_t start_index,
+                    const std::string& search) {
+  return path.compare(start_index, search.length(), search) == 0;
+}
+
+}  // namespace
+
+namespace chrome {
+
+bool ParseFaviconPath(const std::string& path,
+                      int icon_types,
+                      ParsedFaviconPath* parsed) {
+  parsed->is_icon_url = false;
+  parsed->url = "";
+  parsed->size_in_dip = kFaviconSizeInDip;
+  parsed->scale_factor = ui::SCALE_FACTOR_100P;
+  parsed->path_index = -1;
+
+  if (path.empty())
+    return false;
+
+  size_t parsed_index = 0;
+  if (HasSubstringAt(path, parsed_index, kLargestParameter)) {
+    parsed_index += strlen(kLargestParameter);
+    parsed->size_in_dip = 0;
+  } else if (HasSubstringAt(path, parsed_index, kSizeParameter)) {
+    parsed_index += strlen(kSizeParameter);
+
+    size_t slash = path.find("/", parsed_index);
+    if (slash == std::string::npos)
+      return false;
+
+    size_t scale_delimiter = path.find("@", parsed_index);
+    std::string size_str;
+    std::string scale_str;
+    if (scale_delimiter == std::string::npos) {
+      // Support the legacy size format of 'size/aa/' where 'aa' is the desired
+      // size in DIP for the sake of not regressing the extensions which use it.
+      size_str = path.substr(parsed_index, slash - parsed_index);
+    } else {
+      size_str = path.substr(parsed_index, scale_delimiter - parsed_index);
+      scale_str = path.substr(scale_delimiter + 1,
+                              slash - scale_delimiter - 1);
+    }
+
+    if (!base::StringToInt(size_str, &parsed->size_in_dip))
+      return false;
+
+    if (parsed->size_in_dip != kFaviconSizeInDip4x &&
+        parsed->size_in_dip != kFaviconSizeInDip2x) {
+      // Only 64x64, 32x32 and 16x16 icons are supported.
+      parsed->size_in_dip = kFaviconSizeInDip;
+    }
+
+    if (!scale_str.empty())
+      webui::ParseScaleFactor(scale_str, &parsed->scale_factor);
+
+    // Return the default favicon (as opposed to a resized favicon) for
+    // favicon sizes which are not cached by the favicon service.
+    // Currently the favicon service caches:
+    // - favicons of sizes "kFaviconSizeInDip * scale factor" px of type FAVICON
+    //   where scale factor is one of FaviconUtil::GetFaviconScaleFactors().
+    // - the largest TOUCH_ICON / TOUCH_PRECOMPOSED_ICON
+    if (parsed->size_in_dip != kFaviconSizeInDip &&
+        icon_types == chrome::FAVICON)
+      return false;
+
+    parsed_index = slash + 1;
+  }
+
+  if (HasSubstringAt(path, parsed_index, kIconURLParameter)) {
+    parsed_index += strlen(kIconURLParameter);
+    parsed->is_icon_url = true;
+    parsed->url = path.substr(parsed_index);
+  } else {
+    // URL requests prefixed with "origin/" are converted to a form with an
+    // empty path and a valid scheme. (e.g., example.com -->
+    // http://example.com/ or http://example.com/a --> http://example.com/)
+    if (HasSubstringAt(path, parsed_index, kOriginParameter)) {
+      parsed_index += strlen(kOriginParameter);
+      std::string possibly_invalid_url = path.substr(parsed_index);
+
+      // If the URL does not specify a scheme (e.g., example.com instead of
+      // http://example.com), add "http://" as a default.
+      if (!GURL(possibly_invalid_url).has_scheme())
+        possibly_invalid_url = "http://" + possibly_invalid_url;
+
+      // Strip the path beyond the top-level domain.
+      parsed->url = GURL(possibly_invalid_url).GetOrigin().spec();
+    } else {
+      parsed->url = path.substr(parsed_index);
+    }
+  }
+
+  // The parsed index needs to be returned in order to allow Instant Extended
+  // to translate favicon URLs using advanced parameters.
+  // Example:
+  //   "chrome-search://favicon/size/16@2x/<renderer-id>/<most-visited-id>"
+  // would be translated to:
+  //   "chrome-search://favicon/size/16@2x/<most-visited-item-with-given-id>".
+  parsed->path_index = parsed_index;
+  return true;
+}
+
+}  // namespace chrome