2
* Copyright 2013 Google Inc.
4
* Licensed under the Apache License, Version 2.0 (the "License");
5
* you may not use this file except in compliance with the License.
6
* You may obtain a copy of the License at
8
* http://www.apache.org/licenses/LICENSE-2.0
10
* Unless required by applicable law or agreed to in writing, software
11
* distributed under the License is distributed on an "AS IS" BASIS,
12
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13
* See the License for the specific language governing permissions and
14
* limitations under the License.
17
// Author: jud@google.com (Jud Porter)
19
#ifndef NET_INSTAWEB_REWRITER_PUBLIC_CRITICAL_IMAGES_BEACON_FILTER_H_
20
#define NET_INSTAWEB_REWRITER_PUBLIC_CRITICAL_IMAGES_BEACON_FILTER_H_
22
#include "net/instaweb/rewriter/public/common_filter.h"
23
#include "net/instaweb/rewriter/public/critical_finder_support_util.h"
24
#include "net/instaweb/util/public/basictypes.h"
25
#include "pagespeed/kernel/base/string_util.h"
27
namespace net_instaweb {
34
// Inject javascript for detecting above the fold images after the page has
35
// loaded. Also adds pagespeed_url_hash attributes that the beacon sends
36
// back to the server. This allows the beacon to work despite image URL
37
// rewriting or inlining.
38
class CriticalImagesBeaconFilter : public CommonFilter {
40
static const char* kImageOnloadCode;
42
static const char kCriticalImagesBeaconAddedCount[];
44
explicit CriticalImagesBeaconFilter(RewriteDriver* driver);
45
virtual ~CriticalImagesBeaconFilter();
47
virtual void DetermineEnabled(GoogleString* disabled_reason);
49
static void InitStats(Statistics* statistics);
51
virtual void StartDocumentImpl() { }
52
virtual void EndDocument();
53
virtual void StartElementImpl(HtmlElement* element) { }
54
virtual void EndElementImpl(HtmlElement* element);
55
virtual const char* Name() const { return "CriticalImagesBeacon"; }
57
// Returns true if this filter is going to inject a beacon. Filters that need
58
// to disabled when beaconing run, like the rendered_image_dimensions filter,
59
// can check this function.
60
static bool ShouldApply(RewriteDriver* rewrite_driver);
63
// Clear all state associated with filter.
66
// Adds the beaconing javascript just before the current element if it has
67
// not already been added and insert_beacon_js_ is true.
68
void MaybeAddBeaconJavascript(HtmlElement* element);
70
BeaconMetadata beacon_metadata_;
71
StringSet image_url_hashes_;
72
bool insert_beacon_js_;
73
// The total number of times the beacon is added.
74
Variable* critical_images_beacon_added_count_;
76
bool added_beacon_js_;
78
DISALLOW_COPY_AND_ASSIGN(CriticalImagesBeaconFilter);
81
} // namespace net_instaweb
83
#endif // NET_INSTAWEB_REWRITER_PUBLIC_CRITICAL_IMAGES_BEACON_FILTER_H_