Supporting high dpi favicons in Instant Extended.

chrome/common/favicon_url_parser.cc

+// 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_url_parser.h"
+
+#include "base/strings/string_number_conversions.h"
+#include "chrome/common/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/";
+
+// 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) {
+  if (search.empty())
+    return false;
+
+  if (start_index + search.size() >= path.size())
+    return false;
+
+  return (path.compare(start_index, search.size(), search) == 0);
+}
+
+}  // namespace
+
+namespace chrome {
+
+bool ParseFaviconPath(const std::string& path,

[samarth, 2013/06/14 21:54:46]

Yikes! Are there no tests for this?  Please add some unit tests.  It should be
simple enough.

[pedro (no code reviews), 2013/06/18 22:35:13]

Done.

+                      bool supports_origin_parameter,
+                      int icon_types,
+                      bool* is_icon_url,

[samarth, 2013/06/14 21:54:46]

Rather than taking in a slew of output params, how about a ParsedFaviconURL
struct that has the output?

[pedro (no code reviews), 2013/06/18 22:35:13]

I wasn't happy with it too. Thanks for the suggestion. It really makes the code
more readable!

+                      std::string* url,
+                      int* size_in_dip,
+                      ui::ScaleFactor* scale_factor,
+                      std::string* params) {
+  DCHECK_EQ(16, gfx::kFaviconSize);
+
+  *is_icon_url = false;
+  *url = "";
+  *size_in_dip = 16;
+  *scale_factor = ui::SCALE_FACTOR_100P;
+  *params = "";
+
+  if (path.empty())
+    return false;
+
+  size_t parsed_index = 0;
+  if (HasSubstringAt(path, parsed_index, kLargestParameter)) {
+    parsed_index += strlen(kLargestParameter);
+    *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, size_in_dip))
+      return false;
+
+    if (*size_in_dip != 64 && *size_in_dip != 32) {
+      // Only 64x64, 32x32 and 16x16 icons are supported.
+      *size_in_dip = 16;
+    }
+
+    if (!scale_str.empty())
+      webui::ParseScaleFactor(scale_str, 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 "16 * scale factor" px of type FAVICON
+    //   where scale factor is one of FaviconUtil::GetFaviconScaleFactors().
+    // - the largest TOUCH_ICON / TOUCH_PRECOMPOSED_ICON
+    if (*size_in_dip != 16 && icon_types == chrome::FAVICON)
+      return false;
+
+    parsed_index = slash + 1;
+  }
+
+  if (HasSubstringAt(path, parsed_index, kIconURLParameter)) {
+    parsed_index += strlen(kIconURLParameter);
+    *is_icon_url = true;
+    *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)) {
+      // The format of favicon URLs used in Instant Extended does not support

[samarth, 2013/06/14 21:54:46]

We don't use it today. What's wrong with leaving support in?

This function is complex and does a ton of stuff already. Add yet another switch
to its behavior just adds more complexity.

[pedro (no code reviews), 2013/06/18 22:35:13]

Removed the |supports_origin_parameter|.

+      // the origin parameter.
+      if (!supports_origin_parameter)
+        return false;
+
+      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.
+      *url = GURL(possibly_invalid_url).GetOrigin().spec();
+    } else {
+      *url = path.substr(parsed_index);
+    }
+  }
+
+  // The favicon parameters need to be returned in order to allow Instant

[samarth, 2013/06/14 21:54:46]

I find this confusing. I think it would be more natural to return how much of
the URL was actually consumed. The caller can use that value intelligently.

[pedro (no code reviews), 2013/06/18 22:35:13]

Done.

+  // Extended to translate favicon URLs using such parameters.
+  // Example: "chrome-search://favicon/size/16@2x/1234" would be translated to
+  // "chrome-search://favicon/size/16@2x/<most-visited-item-with-id-1234>".
+  // The value of |params| in this case would be "size/16@2x/" (without the
+  // leading slash).
+  *params = path.substr(0, parsed_index);
+  return true;
+}
+
+}  // namespace chrome