Implemented new Translate API for purely Objective-C clients.

ios/web_view/internal/translate/cwv_translation_controller.mm

+// Copyright 2017 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.
+
+#import "ios/web_view/public/cwv_translation_controller.h"

[michaeldo, 2017/05/01 18:25:37]

nit: You can replace this import with _internal.h file.

[jzw1, 2017/05/08 03:36:27]

Done.

+
+#include <string>
+
+#include "base/memory/ptr_util.h"
+#include "base/strings/string16.h"
+#include "components/translate/core/browser/translate_manager.h"
+#include "components/translate/core/browser/translate_ui_delegate.h"
+#import "ios/web_view/internal/translate/cwv_language_detection_result_internal.h"
+#import "ios/web_view/internal/translate/cwv_translation_controller_internal.h"
+#import "ios/web_view/internal/translate/cwv_translation_language_internal.h"
+#import "ios/web_view/internal/translate/web_view_translate_client.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+NSErrorDomain const CWVTranslationErrorDomain = @"com.cwv.translation.errors";

[michaeldo, 2017/05/01 18:25:37]

It looks like Chrome uses Error domains of the style "ChromeXYZError". However
since this is a library, I like the reverse DNS style, but we should use a
better name as we don't own "cwv dot com" domain name. (Written out to prevent
auto-linking.) What do you think about
"org.chromium.chromewebview.TranslationErrorDomain"?

[jzw1, 2017/05/08 03:36:28]

Sounds good.

+
+const NSInteger CWVTranslationErrorNetwork =
+    translate::TranslateErrors::NETWORK;
+const NSInteger CWVTranslationErrorInitializationError =
+    translate::TranslateErrors::INITIALIZATION_ERROR;
+const NSInteger CWVTranslationErrorUnknownLanguage =
+    translate::TranslateErrors::UNKNOWN_LANGUAGE;
+const NSInteger CWVTranslationErrorUnsupportedLanguage =
+    translate::TranslateErrors::UNSUPPORTED_LANGUAGE;
+const NSInteger CWVTranslationErrorIdenticalLanguages =
+    translate::TranslateErrors::IDENTICAL_LANGUAGES;
+const NSInteger CWVTranslationErrorTranslationError =
+    translate::TranslateErrors::TRANSLATION_ERROR;
+const NSInteger CWVTranslationErrorTranslationTimeout =
+    translate::TranslateErrors::TRANSLATION_TIMEOUT;
+const NSInteger CWVTranslationErrorUnexpectedScriptError =
+    translate::TranslateErrors::UNEXPECTED_SCRIPT_ERROR;
+const NSInteger CWVTranslationErrorBadOrigin =
+    translate::TranslateErrors::BAD_ORIGIN;
+const NSInteger CWVTranslationErrorScriptLoadError =
+    translate::TranslateErrors::SCRIPT_LOAD_ERROR;
+
+@interface CWVTranslationController ()
+
+// Convenience method to generate all supported languages from
+// |translateUIDelegate|.
+- (NSArray<CWVTranslationLanguage*>*)supportedLanguages;
+
+// Convenience method to get a language at |index| from |translateUIDelegate|.
+- (CWVTranslationLanguage*)languageAtIndex:(size_t)index;
+
+@end
+
+@implementation CWVTranslationController {
+  ios_web_view::WebViewTranslateClient* _translateClient;
+  std::unique_ptr<translate::TranslateUIDelegate> _translateUIDelegate;
+}
+
+@synthesize delegate = _delegate;
+@synthesize webState = _webState;
+
+#pragma mark - Internal Methods
+
+- (void)setWebState:(web::WebState*)webState {
+  _webState = webState;
+
+  ios_web_view::WebViewTranslateClient::CreateForWebState(_webState);
+  _translateClient =
+      ios_web_view::WebViewTranslateClient::FromWebState(_webState);
+  _translateClient->set_translation_controller(self);

[michaeldo, 2017/05/01 18:25:37]

Do we need to do any cleanup here if webState was already set. Or at least we
should document in the header that this should only be set once?

[jzw1, 2017/05/08 03:36:28]

the webstate can be set again via CWVWebView#resetWebStateWithSessionStorage.
I'm not entirely sure what cleanup needs to be done here, I'm hoping ARC takes
care of it for me?

[michaeldo, 2017/05/08 15:15:48]

If the previous webState is still alive somewhere, |self| will still be set as
the |translation_controller|. I think we should nil out the
translation_controller if |_webState| is set at the top of this method AND if
FromWebState returns a translateClient. (No need to create one, even though it
almost certainly already exists.) It seems like this could lead to problems
otherwise where we are set as the translation_controller for 2 web_states.

+}
+
+- (void)updateTranslateStep:(translate::TranslateStep)step
+             sourceLanguage:(const std::string&)sourceLanguage
+             targetLanguage:(const std::string&)targetLanguage
+                  errorType:(translate::TranslateErrors::Type)errorType
+          triggeredFromMenu:(bool)triggeredFromMenu {
+  translate::TranslateManager* manager = _translateClient->translate_manager();
+  _translateUIDelegate = base::MakeUnique<translate::TranslateUIDelegate>(
+      manager->GetWeakPtr(), sourceLanguage, targetLanguage);
+
+  CWVTranslationLanguage* source =
+      [self languageAtIndex:_translateUIDelegate->GetOriginalLanguageIndex()];
+  CWVTranslationLanguage* target =
+      [self languageAtIndex:_translateUIDelegate->GetTargetLanguageIndex()];
+
+  NSError* error;
+  if (errorType != translate::TranslateErrors::NONE) {
+    error = [NSError errorWithDomain:CWVTranslationErrorDomain
+                                code:errorType
+                            userInfo:nil];
+  }
+
+  switch (step) {
+    case translate::TRANSLATE_STEP_BEFORE_TRANSLATE: {
+      CWVLanguageDetectionResult* languageDetectionResult =
+          [[CWVLanguageDetectionResult alloc]
+                 initWithPageLanguage:source
+              suggestedTargetLanguage:target
+                   supportedLanguages:[self supportedLanguages]];
+      if ([_delegate respondsToSelector:@selector
+                     (translationController:didFinishLanguageDetectionWithResult
+                                              :error:)]) {
+        [_delegate translationController:self
+            didFinishLanguageDetectionWithResult:languageDetectionResult
+                                           error:error];
+      }
+      break;
+    }
+    case translate::TRANSLATE_STEP_TRANSLATING:
+      if ([_delegate respondsToSelector:@selector
+                     (translationController:didStartTranslationFromLanguage
+                                              :toLanguage:)]) {
+        [_delegate translationController:self
+            didStartTranslationFromLanguage:source
+                                 toLanguage:target];
+      }
+      break;
+    case translate::TRANSLATE_STEP_AFTER_TRANSLATE:
+      if ([_delegate respondsToSelector:@selector
+                     (translationController:didFinishTranslationFromLanguage
+                                              :toLanguage:error:)]) {
+        [_delegate translationController:self
+            didFinishTranslationFromLanguage:source
+                                  toLanguage:target
+                                       error:error];
+      }
+      break;
+    case translate::TRANSLATE_STEP_NEVER_TRANSLATE:
+      break;
+    case translate::TRANSLATE_STEP_TRANSLATE_ERROR:
+      break;
+  }
+}
+
+#pragma mark - Public Methodse

[michaeldo, 2017/05/01 18:25:37]

s/Methodse/Methods

[jzw1, 2017/05/08 03:36:27]

Done.

+
+- (void)translatePageFromLanguage:(CWVTranslationLanguage*)sourceLanguage
+                       toLanguage:(CWVTranslationLanguage*)targetLanguage {
+  _translateUIDelegate->Translate();

[michaeldo, 2017/05/01 18:25:37]

It looks like these parameters are dropped. This won't allow client to fix
mis-detected language or to translate to a language other than the assumed
target language.

[jzw1, 2017/05/08 03:36:28]

Actually I just haven't used these yet. I'll add a TODO here though.

[michaeldo, 2017/05/08 15:15:48]

Sounds good. Thank you.

+}
+
+- (void)revertTranslation {
+  _translateUIDelegate->RevertTranslation();
+}
+
+#pragma mark - Private Methods
+
+- (NSArray<CWVTranslationLanguage*>*)supportedLanguages {
+  NSMutableArray* supportedLanguages = [NSMutableArray array];
+  for (size_t i = 0; i < _translateUIDelegate->GetNumberOfLanguages(); i++) {
+    CWVTranslationLanguage* language = [self languageAtIndex:i];
+    [supportedLanguages addObject:language];
+  }
+
+  return [supportedLanguages copy];
+}
+
+- (CWVTranslationLanguage*)languageAtIndex:(size_t)index {
+  std::string languageCode = _translateUIDelegate->GetLanguageCodeAt(index);
+  base::string16 languageName = _translateUIDelegate->GetLanguageNameAt(index);
+  return [[CWVTranslationLanguage alloc] initWithLanguageCode:languageCode
+                                                 languageName:languageName];
+}
+
+@end