1 // Copyright 2012 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 // Class for finding and caching Windows explorer icons. The IconManager
6 // lives on the UI thread but performs icon extraction work on the file thread
7 // to avoid blocking the UI thread with potentially expensive COM and disk
12 // Windows files have icons associated with them that can be of two types:
13 // 1. "Per class": the icon used for this file is used for all files with the
14 // same file extension or class. Examples are PDF or MP3 files, which use
15 // the same icon for all files of that type.
16 // 2. "Per instance": the icon used for this file is embedded in the file
17 // itself and is unique. Executable files are typically "per instance".
19 // Files that end in the following extensions are considered "per instance":
23 // The IconManager will do explicit icon loads on the full path of these files
24 // and cache the results per file. All other file types will be looked up by
25 // file extension and the results will be cached per extension. That way, all
26 // .mp3 files will share one icon, but all .exe files will have their own icon.
28 // POSIX files don't have associated icons. We query the OS by the file's
31 // The IconManager can be queried in two ways:
32 // 1. A quick, synchronous check of its caches which does not touch the disk:
33 // IconManager::LookupIcon()
34 // 2. An asynchronous icon load from a file on the file thread:
35 // IconManager::LoadIcon()
37 // When using the second (asynchronous) method, callers must supply a callback
38 // which will be run once the icon has been extracted. The icon manager will
39 // cache the results of the icon extraction so that subsequent lookups will be
42 // Icon bitmaps returned should be treated as const since they may be referenced
43 // by other clients. Make a copy of the icon if you need to modify it.
45 #ifndef CHROME_BROWSER_ICON_MANAGER_H_
46 #define CHROME_BROWSER_ICON_MANAGER_H_
51 #include "base/files/file_path.h"
52 #include "base/memory/weak_ptr.h"
53 #include "base/task/cancelable_task_tracker.h"
54 #include "chrome/browser/icon_loader.h"
55 #include "ui/gfx/image/image.h"
61 IconManager(const IconManager&) = delete;
62 IconManager& operator=(const IconManager&) = delete;
66 // Synchronous call to examine the internal caches for the icon. Returns the
67 // icon if we have already loaded it, or null if we don't have it and must
68 // load it via LoadIcon(). The returned bitmap is owned by the IconManager and
69 // must not be free'd by the caller. If the caller needs to modify the icon,
70 // it must make a copy and modify the copy.
71 gfx::Image* LookupIconFromFilepath(const base::FilePath& file_path,
72 IconLoader::IconSize size,
75 using IconRequestCallback = base::OnceCallback<void(gfx::Image)>;
77 // Asynchronous call to lookup and return the icon associated with file. The
78 // work is done on the file thread, with the callbacks running on the thread
79 // this function is called.
82 // 1. This does *not* check the cache.
83 // 2. The returned bitmap pointer is *not* owned by callback. So callback
84 // should never keep it or delete it.
85 // 3. The gfx::Image pointer passed to the callback will be null if decoding
87 base::CancelableTaskTracker::TaskId LoadIcon(
88 const base::FilePath& file_name,
89 IconLoader::IconSize size,
91 IconRequestCallback callback,
92 base::CancelableTaskTracker* tracker);
95 gfx::Image* DoLookupIconFromFilepath(const base::FilePath& file_path,
96 IconLoader::IconSize size,
99 void OnIconLoaded(IconRequestCallback callback,
100 base::FilePath file_path,
101 IconLoader::IconSize size,
104 const IconLoader::IconGroup& group);
107 CacheKey(const IconLoader::IconGroup& group,
108 IconLoader::IconSize size,
111 // Used as a key in the map below, so we need this comparator.
112 bool operator<(const CacheKey &other) const;
114 IconLoader::IconGroup group;
115 IconLoader::IconSize size;
119 std::map<base::FilePath, IconLoader::IconGroup> group_cache_;
120 std::map<CacheKey, gfx::Image> icon_cache_;
122 base::WeakPtrFactory<IconManager> weak_factory_{this};
125 #endif // CHROME_BROWSER_ICON_MANAGER_H_