blob: f879ce6083ccc1d2e62b72a1e6278974b2be8ec6 [file] [log] [blame]
// Copyright 2020 The Chromium OS 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 <string>
#include <base/no_destructor.h>
#include <base/optional.h>
#include <base/scoped_native_library.h>
#include <chromeos/libhandwriting/handwriting_interface.h>
#include "chrome/knowledge/handwriting/handwriting_interface.pb.h"
#include "ml/mojom/handwriting_recognizer.mojom.h"
#include "ml/util.h"
namespace ml {
// A singleton proxy class for the handwriting DSO.
// Usage:
// auto* const hwr_library = HandwritingLibrary::GetInstance();
// if (hwr_library->GetStatus() == HandwritingLibrary::kOk) {
// // Do the real handwriting here.
// recognizer = hwr_library->CreateHandwritingRecognizer();
// ...
// } else {
// // Otherwise, use HandwritingLibrary::GetStatus() to get the error type.
// // Maybe return "not installed".
// ...
// }
class HandwritingLibrary {
enum class Status {
kOk = 0,
kUninitialized = 1,
kLoadLibraryFailed = 2,
kFunctionLookupFailed = 3,
kNotSupported = 4,
// Default handwriting model directory on rootfs.
static constexpr char kHandwritingDefaultModelDir[] =
~HandwritingLibrary() = default;
// Returns whether HandwritingLibrary is supported.
static constexpr bool IsHandwritingLibrarySupported() {
return (IsUseLibHandwritingEnabled() || IsUseLibHandwritingDlcEnabled()) &&
// Returns whether HandwritingLibrary is supported for unit tests.
static constexpr bool IsHandwritingLibraryUnitTestSupported() {
return IsUseLibHandwritingEnabled() && !IsAsan();
// Returns bool of use.ondevice_handwriting.
static constexpr bool IsUseLibHandwritingEnabled() {
// Returns bool of use.ondevice_handwriting_dlc.
static constexpr bool IsUseLibHandwritingDlcEnabled() {
// Gets the singleton HandwritingLibrary. The singleton is initialized with
// `model_path` on the first call to GetInstance; for the rest of the calls,
// the `model_path` is ignored, and the existing singleton is returned.
// The `model_path` should be either a path on rootfs or a path returned by
// DlcService.
static HandwritingLibrary* GetInstance(
const std::string& model_path = kHandwritingDefaultModelDir);
// Get whether the library is successfully initialized.
// Initially, the status is `Status::kUninitialized` (this value should never
// be returned).
// If can not be loaded, return `kLoadLibraryFailed`. This
// usually means on-device handwriting is not supported.
// If the functions can not be successfully looked up, return
// `kFunctionLookupFailed`.
// Return `Status::kOk` if everything works fine.
Status GetStatus() const;
// The following public member functions define the interface functions of
// the library. Function `InitHandwritingRecognizerLibrary`
// and `DeleteHandwritingResultData` do not need interfaces because the client
// won't call it.
// Creates and returns a handwriting recognizer which is needed for using the
// other interface. The memory is owned by the user and should be deleted
// using `DestroyHandwritingRecognizer` after usage.
HandwritingRecognizer CreateHandwritingRecognizer() const;
// Load the models with `spec` stores the language, the path to the data files
// of the model (machine learning models, configurations etc.).
// Returns true if HandwritingRecognizer is correctly loaded and
// initialized. Returns false otherwise.
bool LoadHandwritingRecognizer(
HandwritingRecognizer recognizer,
chromeos::machine_learning::mojom::HandwritingRecognizerSpecPtr spec)
// Sends the specified `request` to `recognizer`, if succeeds, `result` (which
// should not be null) is populated with the recognition result.
// Returns true if succeeds, otherwise returns false.
bool RecognizeHandwriting(
HandwritingRecognizer recognizer,
const chrome_knowledge::HandwritingRecognizerRequest& request,
chrome_knowledge::HandwritingRecognizerResult* result) const;
// Destroys the handwriting recognizer created by
// `CreateHandwritingRecognizer`. Must be called if the handwriting recognizer
// will not be used anymore, otherwise there will be memory leak.
void DestroyHandwritingRecognizer(HandwritingRecognizer recognizer) const;
friend class base::NoDestructor<HandwritingLibrary>;
FRIEND_TEST(HandwritingLibraryTest, CanLoadLibrary);
// Initialize the handwriting library.
explicit HandwritingLibrary(const std::string& root_path);
// Currently HandwritingLibrary is supported only when the "sanitizer" is not
// enabled (see
static constexpr bool IsAsan() { return __has_feature(address_sanitizer); }
base::Optional<base::ScopedNativeLibrary> library_;
Status status_;
const base::FilePath model_path_;
// Store the interface function pointers.
// TODO(honglinyu) as pointed out by cjmcdonald@, we should group the pointers
// into a single `HandwritingInterface` struct and make it optional, i.e.,
// declaring something like |base::Optional<HandwritingInterface> interface_|.
CreateHandwritingRecognizerFn create_handwriting_recognizer_;
LoadHandwritingRecognizerFn load_handwriting_recognizer_;
RecognizeHandwritingFn recognize_handwriting_;
DeleteHandwritingResultDataFn delete_handwriting_result_data_;
DestroyHandwritingRecognizerFn destroy_handwriting_recognizer_;
} // namespace ml