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Fix an issue that deleting an emoji may crash the app #34508

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Jul 25, 2022
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Fix an issue that deleting an emoji may crash the app #34508

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6c1d6cc
fix a problem that deleting an emoji crashes the app
yeatse Jul 8, 2022
6f604cb
Add tests
yeatse Jul 8, 2022
e8c4a37
Update shell/platform/darwin/ios/framework/Source/FlutterTextInputPlu…
yeatse Jul 9, 2022
a28afd0
remove composed characters only if they are emojis
yeatse Jul 9, 2022
8e59927
update comments
yeatse Jul 9, 2022
1382921
update test case to cover the leading thai vowel
yeatse Jul 10, 2022
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18 changes: 18 additions & 0 deletions shell/platform/darwin/ios/framework/Source/FlutterTextInputPlugin.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,8 @@
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

#include "unicode/uchar.h"
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@dnfield since you jumped in, how do you feel about including this library? I've been trying to think of another way to check if it's an emoji without importing this but also reinventing the wheel. I guess it's okay?

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This seems fine to me. This is what ICU is for and there's no getting around having ICU in a flutter app


#include "flutter/fml/logging.h"
#include "flutter/fml/platform/darwin/string_range_sanitization.h"

Expand Down Expand Up @@ -1896,6 +1898,22 @@ - (void)deleteBackward {
NSRange oldRange = ((FlutterTextRange*)oldSelectedRange).range;
if (oldRange.location > 0) {
NSRange newRange = NSMakeRange(oldRange.location - 1, 1);

// We should check if the last character is a part of emoji.
// If so, we must delete the entire emoji to prevent the text from being malformed.
NSRange charRange = fml::RangeForCharacterAtIndex(self.text, oldRange.location - 1);
UChar32 codePoint;
BOOL gotCodePoint = [self.text getBytes:&codePoint
maxLength:sizeof(codePoint)
usedLength:NULL
encoding:NSUTF32StringEncoding
options:kNilOptions
range:charRange
remainingRange:NULL];
if (gotCodePoint && u_hasBinaryProperty(codePoint, UCHAR_EMOJI)) {
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Why is this getting applied only to emoji?

Aren't there other multi-byte characters that are not emoji that we'd want to apply this to?

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From #34508 (comment), languages with diacritical marks will expect a backward deletion should only delete one part of the composed character, such as Thai and Hebrew.

We have two ways to distinguish this behavior from emoji's:

  1. check if the byte is a diacritical mark (and other properties I don't know yet)
  2. check if the byte is not in an emoji

I chose the second one to keep consistency with android (see FlutterTextUtils.getOffsetBefore)

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Ahhh ok this makes sense.

newRange = NSMakeRange(charRange.location, oldRange.location - charRange.location);
}

_selectedTextRange = [[FlutterTextRange rangeWithNSRange:newRange] copy];
[oldSelectedRange release];
}
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35 changes: 35 additions & 0 deletions shell/platform/darwin/ios/framework/Source/FlutterTextInputPluginTest.mm
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Expand Up @@ -406,6 +406,41 @@ - (void)testStandardEditActions {
XCTAssertEqualObjects(substring, @"bbbbaaaabbbbaaaa");
}

- (void)testDeletingBackward {
NSDictionary* config = self.mutableTemplateCopy;
[self setClientId:123 configuration:config];
NSArray<FlutterTextInputView*>* inputFields = self.installedInputViews;
FlutterTextInputView* inputView = inputFields[0];

[inputView insertText:@"ឹ😀 text 🥰👨‍👩‍👧‍👦🇺🇳ดี "];
[inputView deleteBackward];
[inputView deleteBackward];

// Thai vowel is removed.
XCTAssertEqualObjects(inputView.text, @"ឹ😀 text 🥰👨‍👩‍👧‍👦🇺🇳ด");
[inputView deleteBackward];
XCTAssertEqualObjects(inputView.text, @"ឹ😀 text 🥰👨‍👩‍👧‍👦🇺🇳");
[inputView deleteBackward];
XCTAssertEqualObjects(inputView.text, @"ឹ😀 text 🥰👨‍👩‍👧‍👦");
[inputView deleteBackward];
XCTAssertEqualObjects(inputView.text, @"ឹ😀 text 🥰");
[inputView deleteBackward];

XCTAssertEqualObjects(inputView.text, @"ឹ😀 text ");
[inputView deleteBackward];
[inputView deleteBackward];
[inputView deleteBackward];
[inputView deleteBackward];
[inputView deleteBackward];
[inputView deleteBackward];

XCTAssertEqualObjects(inputView.text, @"ឹ😀");
[inputView deleteBackward];
XCTAssertEqualObjects(inputView.text, @"ឹ");
[inputView deleteBackward];
XCTAssertEqualObjects(inputView.text, @"");
}

- (void)testPastingNonTextDisallowed {
NSDictionary* config = self.mutableTemplateCopy;
[self setClientId:123 configuration:config];
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6 changes: 6 additions & 0 deletions testing/ios/IosUnitTests/IosUnitTests.xcodeproj/xcshareddata/xcschemes/IosUnitTests.xcscheme
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Expand Up @@ -78,6 +78,12 @@
ReferencedContainer = "container:IosUnitTests.xcodeproj">
</BuildableReference>
</BuildableProductRunnable>
<CommandLineArguments>
<CommandLineArgument
argument = "--icu-data-file-path=Frameworks/Flutter.framework/icudtl.dat"
isEnabled = "YES">
Comment on lines +83 to +84
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Is this needed?

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@yeatse yeatse Jul 23, 2022 •
edited
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Yes. Without this the test will fail due to failing to load the ICU data file. Maybe we should file another issue to get rid of this later.

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Filed flutter/flutter#108221

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I think this is fine - in other tests we use the command line argument to load the ICU data file (see run_tests.py).

</CommandLineArgument>
</CommandLineArguments>
</LaunchAction>
<ProfileAction
buildConfiguration = "Release"
Expand Down