114 lines
4.4 KiB
C++
114 lines
4.4 KiB
C++
// 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.
|
|
//
|
|
// Class for finding and caching Windows explorer icons. The IconManager
|
|
// lives on the UI thread but performs icon extraction work on the file thread
|
|
// to avoid blocking the UI thread with potentially expensive COM and disk
|
|
// operations.
|
|
//
|
|
// Terminology
|
|
//
|
|
// Windows files have icons associated with them that can be of two types:
|
|
// 1. "Per class": the icon used for this file is used for all files with the
|
|
// same file extension or class. Examples are PDF or MP3 files, which use
|
|
// the same icon for all files of that type.
|
|
// 2. "Per instance": the icon used for this file is embedded in the file
|
|
// itself and is unique. Executable files are typically "per instance".
|
|
//
|
|
// Files that end in the following extensions are considered "per instance":
|
|
// .exe
|
|
// .dll
|
|
// .ico
|
|
// The IconManager will do explicit icon loads on the full path of these files
|
|
// and cache the results per file. All other file types will be looked up by
|
|
// file extension and the results will be cached per extension. That way, all
|
|
// .mp3 files will share one icon, but all .exe files will have their own icon.
|
|
//
|
|
// POSIX files don't have associated icons. We query the OS by the file's
|
|
// mime type.
|
|
//
|
|
// The IconManager can be queried in two ways:
|
|
// 1. A quick, synchronous check of its caches which does not touch the disk:
|
|
// IconManager::LookupIcon()
|
|
// 2. An asynchronous icon load from a file on the file thread:
|
|
// IconManager::LoadIcon()
|
|
//
|
|
// When using the second (asynchronous) method, callers must supply a callback
|
|
// which will be run once the icon has been extracted. The icon manager will
|
|
// cache the results of the icon extraction so that subsequent lookups will be
|
|
// fast.
|
|
//
|
|
// Icon bitmaps returned should be treated as const since they may be referenced
|
|
// by other clients. Make a copy of the icon if you need to modify it.
|
|
|
|
#ifndef CHROME_BROWSER_ICON_MANAGER_H_
|
|
#define CHROME_BROWSER_ICON_MANAGER_H_
|
|
|
|
#include <map>
|
|
#include <memory>
|
|
|
|
#include "base/files/file_path.h"
|
|
#include "base/macros.h"
|
|
#include "base/memory/weak_ptr.h"
|
|
#include "base/task/cancelable_task_tracker.h"
|
|
#include "chrome/browser/icon_loader.h"
|
|
#include "ui/gfx/image/image.h"
|
|
|
|
class IconManager {
|
|
public:
|
|
IconManager();
|
|
~IconManager();
|
|
|
|
// Synchronous call to examine the internal caches for the icon. Returns the
|
|
// icon if we have already loaded it, or null if we don't have it and must
|
|
// load it via LoadIcon(). The returned bitmap is owned by the IconManager and
|
|
// must not be free'd by the caller. If the caller needs to modify the icon,
|
|
// it must make a copy and modify the copy.
|
|
gfx::Image* LookupIconFromFilepath(const base::FilePath& file_path,
|
|
IconLoader::IconSize size);
|
|
|
|
using IconRequestCallback = base::Callback<void(gfx::Image*)>;
|
|
|
|
// Asynchronous call to lookup and return the icon associated with file. The
|
|
// work is done on the file thread, with the callbacks running on the thread
|
|
// this function is called.
|
|
//
|
|
// Note:
|
|
// 1. This does *not* check the cache.
|
|
// 2. The returned bitmap pointer is *not* owned by callback. So callback
|
|
// should never keep it or delete it.
|
|
// 3. The gfx::Image pointer passed to the callback will be null if decoding
|
|
// failed.
|
|
base::CancelableTaskTracker::TaskId LoadIcon(
|
|
const base::FilePath& file_name,
|
|
IconLoader::IconSize size,
|
|
const IconRequestCallback& callback,
|
|
base::CancelableTaskTracker* tracker);
|
|
|
|
private:
|
|
void OnIconLoaded(IconRequestCallback callback,
|
|
base::FilePath file_path,
|
|
IconLoader::IconSize size,
|
|
std::unique_ptr<gfx::Image> result,
|
|
const IconLoader::IconGroup& group);
|
|
|
|
struct CacheKey {
|
|
CacheKey(const IconLoader::IconGroup& group, IconLoader::IconSize size);
|
|
|
|
// Used as a key in the map below, so we need this comparator.
|
|
bool operator<(const CacheKey& other) const;
|
|
|
|
IconLoader::IconGroup group;
|
|
IconLoader::IconSize size;
|
|
};
|
|
|
|
std::map<base::FilePath, IconLoader::IconGroup> group_cache_;
|
|
std::map<CacheKey, std::unique_ptr<gfx::Image>> icon_cache_;
|
|
|
|
base::WeakPtrFactory<IconManager> weak_factory_;
|
|
|
|
DISALLOW_COPY_AND_ASSIGN(IconManager);
|
|
};
|
|
|
|
#endif // CHROME_BROWSER_ICON_MANAGER_H_
|