fix voice control delete line command does not delete line correctly (#24831)

Author: chunhtai

shell/platform/darwin/ios/framework/Source/FlutterTextInputPlugin.h

@@ -44,6 +44,10 @@
 
 @end
 
+/** A tokenizer used by `FlutterTextInputView` to customize string parsing. */
+@interface FlutterTokenizer : UITextInputStringTokenizer
+@end
+
 #if FLUTTER_RUNTIME_MODE == FLUTTER_RUNTIME_MODE_DEBUG
 FLUTTER_DARWIN_EXPORT
 #endif

shell/platform/darwin/ios/framework/Source/FlutterTextInputPlugin.mm

@@ -378,6 +378,73 @@ - (BOOL)isEqualTo:(FlutterTextRange*)other {
 }
 @end
 
+#pragma mark - FlutterTokenizer
+
+@interface FlutterTokenizer ()
+
+@property(nonatomic, assign) FlutterTextInputView* textInputView;
+
+@end
+
+@implementation FlutterTokenizer
+
+- (instancetype)initWithTextInput:(UIResponder<UITextInput>*)textInput {
+  NSAssert([textInput isKindOfClass:[FlutterTextInputView class]],
+           @"The FlutterTokenizer can only be used in a FlutterTextInputView");
+  self = [super initWithTextInput:textInput];
+  if (self) {
+    _textInputView = (FlutterTextInputView*)textInput;
+  }
+  return self;
+}
+
+- (UITextRange*)rangeEnclosingPosition:(UITextPosition*)position
+                       withGranularity:(UITextGranularity)granularity
+                           inDirection:(UITextDirection)direction {
+  UITextRange* result;
+  switch (granularity) {
+    case UITextGranularityLine:
+      // The default UITextInputStringTokenizer does not handle line granularity
+      // correctly. We need to implement our own line tokenizer.
+      result = [self lineEnclosingPosition:position];
+      break;
+    case UITextGranularityCharacter:
+    case UITextGranularityWord:
+    case UITextGranularitySentence:
+    case UITextGranularityParagraph:
+    case UITextGranularityDocument:
+      // The UITextInputStringTokenizer can handle all these cases correctly.
+      result = [super rangeEnclosingPosition:position
+                             withGranularity:granularity
+                                 inDirection:direction];
+      break;
+  }
+  return result;
+}
+
+- (UITextRange*)lineEnclosingPosition:(UITextPosition*)position {
+  // Gets the first line break position after the input position.
+  NSString* textAfter = [_textInputView
+      textInRange:[_textInputView textRangeFromPosition:position
+                                             toPosition:[_textInputView endOfDocument]]];
+  NSArray<NSString*>* linesAfter = [textAfter componentsSeparatedByString:@"\n"];
+  NSInteger offSetToLineBreak = [linesAfter firstObject].length;
+  UITextPosition* lineBreakAfter = [_textInputView positionFromPosition:position
+                                                                 offset:offSetToLineBreak];
+  // Gets the first line break position before the input position.
+  NSString* textBefore = [_textInputView
+      textInRange:[_textInputView textRangeFromPosition:[_textInputView beginningOfDocument]
+                                             toPosition:position]];
+  NSArray<NSString*>* linesBefore = [textBefore componentsSeparatedByString:@"\n"];
+  NSInteger offSetFromLineBreak = [linesBefore lastObject].length;
+  UITextPosition* lineBreakBefore = [_textInputView positionFromPosition:position
+                                                                  offset:-offSetFromLineBreak];
+
+  return [_textInputView textRangeFromPosition:lineBreakBefore toPosition:lineBreakAfter];
+}
+
+@end
+
 // A FlutterTextInputView that masquerades as a UITextField, and forwards
 // selectors it can't respond to to a shared UITextField instance.
 //
@@ -629,7 +696,7 @@ - (BOOL)canBecomeFirstResponder {
 
 - (id<UITextInputTokenizer>)tokenizer {
   if (_tokenizer == nil) {
-    _tokenizer = [[UITextInputStringTokenizer alloc] initWithTextInput:self];
+    _tokenizer = [[FlutterTokenizer alloc] initWithTextInput:self];
   }
   return _tokenizer;
 }

shell/platform/darwin/ios/framework/Source/FlutterTextInputPluginTest.m

@@ -133,6 +133,16 @@ - (NSMutableDictionary*)mutableTemplateCopy {
                                                                    [FlutterTextInputView class]]];
 }
 
+- (FlutterTextRange*)getLineRangeFromTokenizer:(id<UITextInputTokenizer>)tokenizer
+                                       atIndex:(NSInteger)index {
+  UITextRange* range =
+      [tokenizer rangeEnclosingPosition:[FlutterTextPosition positionWithIndex:index]
+                        withGranularity:UITextGranularityLine
+                            inDirection:UITextLayoutDirectionRight];
+  XCTAssertTrue([range isKindOfClass:[FlutterTextRange class]]);
+  return (FlutterTextRange*)range;
+}
+
 #pragma mark - Tests
 
 - (void)testSecureInput {
@@ -818,4 +828,41 @@ - (void)testFlutterTextInputViewDirectFocusToBackingTextInput {
   XCTAssertEqual(inputView.receivedNotificationTarget, backing);
 }
 
+- (void)testFlutterTokenizerCanParseLines {
+  FlutterTextInputView* inputView = [[FlutterTextInputView alloc] init];
+  inputView.textInputDelegate = engine;
+  id<UITextInputTokenizer> tokenizer = [inputView tokenizer];
+
+  // The tokenizer returns zero range When text is empty.
+  FlutterTextRange* range = [self getLineRangeFromTokenizer:tokenizer atIndex:0];
+  XCTAssertEqual(range.range.location, 0u);
+  XCTAssertEqual(range.range.length, 0u);
+
+  [inputView insertText:@"how are you\nI am fine, Thank you"];
+
+  range = [self getLineRangeFromTokenizer:tokenizer atIndex:0];
+  XCTAssertEqual(range.range.location, 0u);
+  XCTAssertEqual(range.range.length, 11u);
+
+  range = [self getLineRangeFromTokenizer:tokenizer atIndex:2];
+  XCTAssertEqual(range.range.location, 0u);
+  XCTAssertEqual(range.range.length, 11u);
+
+  range = [self getLineRangeFromTokenizer:tokenizer atIndex:11];
+  XCTAssertEqual(range.range.location, 0u);
+  XCTAssertEqual(range.range.length, 11u);
+
+  range = [self getLineRangeFromTokenizer:tokenizer atIndex:12];
+  XCTAssertEqual(range.range.location, 12u);
+  XCTAssertEqual(range.range.length, 20u);
+
+  range = [self getLineRangeFromTokenizer:tokenizer atIndex:15];
+  XCTAssertEqual(range.range.location, 12u);
+  XCTAssertEqual(range.range.length, 20u);
+
+  range = [self getLineRangeFromTokenizer:tokenizer atIndex:32];
+  XCTAssertEqual(range.range.location, 12u);
+  XCTAssertEqual(range.range.length, 20u);
+}
+
 @end