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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROME_BROWSER_ICON_LOADER_H_
#define CHROME_BROWSER_ICON_LOADER_H_
#include "base/files/file_path.h"
#include "base/functional/callback.h"
#include "base/task/single_thread_task_runner.h"
#include "base/task/task_traits.h"
#include "build/build_config.h"
#include "content/public/browser/browser_thread.h"
#include "ui/gfx/image/image.h"
////////////////////////////////////////////////////////////////////////////////
//
// A facility to read a file containing an icon asynchronously in the IO
// thread. Returns the icon in the form of an ImageSkia.
//
////////////////////////////////////////////////////////////////////////////////
class IconLoader {
public:
// An IconGroup is a class of files that all share the same icon.
#if BUILDFLAG(IS_MAC)
// On the Mac, it's the UTType's identifier. (Apps do have unique icons, just
// like in Windows, below, but `IconLoader` is never used to get their icons,
// so that case isn't handled.)
using IconGroup = std::string;
#else
// On all other platforms except Windows, and for most files on Windows, it is
// the file type (e.g. all .mp3 files share an icon, all .html files share an
// icon). On Windows, for certain file types (.exe, .dll, etc), each file of
// that type is assumed to have a unique icon. In that case, each of those
// files is a group to itself.
using IconGroup = base::FilePath::StringType;
#endif
enum IconSize {
SMALL = 0, // 16x16
NORMAL, // 32x32
LARGE, // Windows: 32x32, Linux: 48x48, Mac: Unsupported
ALL, // All sizes available
};
// The callback invoked when an icon has been read. The parameters are:
// - The icon that was loaded (IsEmpty() will be true on failure to load).
// - The determined group from the original requested path.
using IconLoadedCallback =
base::OnceCallback<void(gfx::Image, const IconGroup&)>;
// Starts the process of reading the icon. When the reading of the icon is
// complete, the IconLoadedCallback callback will be fulfilled, and the
// IconLoader will delete itself.
static void LoadIcon(const base::FilePath& file_path,
IconSize size,
float scale,
IconLoadedCallback callback);
IconLoader(const IconLoader&) = delete;
IconLoader& operator=(const IconLoader&) = delete;
private:
IconLoader(const base::FilePath& file_path,
IconSize size,
float scale,
IconLoadedCallback callback);
~IconLoader();
void Start();
// Given a file path, get the group for the given file.
static IconGroup GroupForFilepath(const base::FilePath& file_path);
// The TaskRunner that ReadIcon() must be called on.
static scoped_refptr<base::TaskRunner> GetReadIconTaskRunner();
#if !BUILDFLAG(IS_CHROMEOS)
void ReadGroup();
void ReadIcon();
#endif
#if BUILDFLAG(IS_WIN)
// Reads an icon in a sandboxed service. Use this when the file itself must
// be parsed.
void ReadIconInSandbox();
#endif
// The traits of the tasks posted to base::ThreadPool by this class. These
// operations may block, because they are fetching icons from the disk, yet
// the result will be seen by the user so they should be prioritized
// accordingly. They should not however block shutdown if long running.
static constexpr base::TaskTraits traits() {
return {base::MayBlock(), base::TaskPriority::USER_VISIBLE,
base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN};
}
// The task runner object of the thread in which we notify the delegate.
scoped_refptr<base::SingleThreadTaskRunner> target_task_runner_;
base::FilePath file_path_;
IconGroup group_;
#if !BUILDFLAG(IS_ANDROID)
IconSize icon_size_;
#endif // !BUILDFLAG(IS_ANDROID)
const float scale_;
IconLoadedCallback callback_;
};
#endif // CHROME_BROWSER_ICON_LOADER_H_
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