TextEditingDelta Support for the Web #28527
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@@ -440,6 +440,15 @@ class AutofillInfo { | |
| } | ||
| } | ||
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| /// Replaces a range of text in the original string with the text given in the | ||
| /// replacement string. | ||
| String _replace(String originalText, String replacementText, int start, int end) { | ||
| final String textStart = originalText.substring(0, start); | ||
| final String textEnd = originalText.substring(end, originalText.length); | ||
| final String newText = textStart + replacementText + textEnd; | ||
| return newText; | ||
| } | ||
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| class TextEditingDeltaState { | ||
| const TextEditingDeltaState({ | ||
| this.oldText = '', | ||
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@@ -452,6 +461,80 @@ class TextEditingDeltaState { | |
| this.composingExtent = -1, | ||
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| }); | ||
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| static TextEditingDeltaState inferDeltaState(EditingState newEditingState, EditingState? lastEditingState, TextEditingDeltaState? lastTextEditingDeltaState) { | ||
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| TextEditingDeltaState newTextEditingDeltaState = lastTextEditingDeltaState ?? TextEditingDeltaState(oldText: lastEditingState!.text!); | ||
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| final bool previousSelectionWasCollapsed = lastEditingState?.baseOffset == lastEditingState?.extentOffset; | ||
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| if (newTextEditingDeltaState.deltaText.isEmpty && newTextEditingDeltaState.deltaEnd != -1) { | ||
| // We are removing text. | ||
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| final int deletedLength = newTextEditingDeltaState.oldText.length - newEditingState.text!.length; | ||
| newTextEditingDeltaState = newTextEditingDeltaState.copyWith(deltaStart: newTextEditingDeltaState.deltaEnd - deletedLength); | ||
| } else if (newTextEditingDeltaState.deltaText.isNotEmpty && !previousSelectionWasCollapsed) { | ||
| // We are replacing text at a selection. | ||
| newTextEditingDeltaState = newTextEditingDeltaState.copyWith(deltaStart: lastEditingState!.baseOffset); | ||
| } | ||
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| // If we are composing then set the delta range to the composing region we captured in compositionupdate. | ||
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| final bool isCurrentlyComposing = newTextEditingDeltaState.composingOffset != -1 && newTextEditingDeltaState.composingOffset != newTextEditingDeltaState.composingExtent; | ||
| if (newTextEditingDeltaState.deltaText.isNotEmpty && previousSelectionWasCollapsed && isCurrentlyComposing) { | ||
| newTextEditingDeltaState = newTextEditingDeltaState.copyWith(deltaStart: newTextEditingDeltaState.composingOffset, deltaEnd: newTextEditingDeltaState.composingExtent); | ||
| } | ||
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| final bool isDeltaRangeEmpty = newTextEditingDeltaState.deltaStart == -1 && newTextEditingDeltaState.deltaStart == newTextEditingDeltaState.deltaEnd; | ||
| if (!isDeltaRangeEmpty) { | ||
| // To verify the range of our delta we should compare the newEditingState's | ||
| // text with the delta applied to the oldText. If they differ then capture | ||
| // the correct delta range from the newEditingState's text value. | ||
| // | ||
| // We can assume the deltaText for additions and replacements to the text value | ||
| // are accurate. What may not be accurate is the range of the delta. | ||
| // | ||
| // We can think of the newEditingState as our source of truth. | ||
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Contributor
There was a problem hiding this comment. Is this whole comment explaining the situation of double space inserting a period? Maybe add that as an example in the comment somewhere. And/or, be sure that this is thoroughly tested so that future developers can understand your intention (and not break it).
Contributor
Author
There was a problem hiding this comment. Add a test for this case and the accent menu case. |
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| final String textAfterDelta = _replace( | ||
| newTextEditingDeltaState.oldText, newTextEditingDeltaState.deltaText, | ||
| newTextEditingDeltaState.deltaStart, | ||
| newTextEditingDeltaState.deltaEnd); | ||
| final bool isDeltaVerified = textAfterDelta == newEditingState.text!; | ||
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| if (!isDeltaVerified) { | ||
| // 1. Find all matches for deltaText. | ||
| // 2. Apply matches/replacement to oldText until oldText matches the | ||
| // new editing state's text value. | ||
| final RegExp deltaTextPattern = RegExp(r'' + newTextEditingDeltaState.deltaText + r''); | ||
| for (final Match match in deltaTextPattern.allMatches(newEditingState.text!)) { | ||
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Contributor
There was a problem hiding this comment. So in the example of double space inserting a period, the matches here will be all periods in the text, and you're trying to find the one that is new?
Contributor
Author
There was a problem hiding this comment. in the case of double space inserting a period the When we have the matched ranges we iterate through them and apply the |
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| String textAfterMatch; | ||
| int actualEnd; | ||
| final bool isMatchWithinOldTextBounds = match.start >= 0 && match.end <= newTextEditingDeltaState.oldText.length; | ||
| if (!isMatchWithinOldTextBounds) { | ||
| actualEnd = match.start + newTextEditingDeltaState.deltaText.length - 1; | ||
| textAfterMatch = _replace( | ||
| newTextEditingDeltaState.oldText, | ||
| newTextEditingDeltaState.deltaText, | ||
| match.start, | ||
| actualEnd, | ||
| ); | ||
| } else { | ||
| actualEnd = match.end; | ||
| textAfterMatch = _replace( | ||
| newTextEditingDeltaState.oldText, | ||
| newTextEditingDeltaState.deltaText, | ||
| match.start, | ||
| actualEnd, | ||
| ); | ||
| } | ||
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| if (textAfterMatch == newEditingState.text!) { | ||
| newTextEditingDeltaState = newTextEditingDeltaState.copyWith(deltaStart: match.start, deltaEnd: actualEnd); | ||
| break; | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| return newTextEditingDeltaState; | ||
| } | ||
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| final String oldText; | ||
| final String deltaText; | ||
| final int deltaStart; | ||
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@@ -1083,88 +1166,11 @@ abstract class DefaultTextEditingStrategy implements TextEditingStrategy { | |
| _appendedToForm = true; | ||
| } | ||
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| void handleChange(html.Event event) { | ||
| assert(isEnabled); | ||
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| final EditingState newEditingState = EditingState.fromDomElement(activeDomElement); | ||
| final TextEditingDeltaState newTextEditingDeltaState = TextEditingDeltaState.inferDeltaState(newEditingState, lastEditingState, lastTextEditingDeltaState); | ||
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| if (newEditingState != lastEditingState) { | ||
| lastEditingState = newEditingState; | ||
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Can you add a comment explaining this class, and also a comment below explaining inferDeltaState?
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It seems like the point of this class is to represent the json that will be sent to the framework, so maybe mention that in the comment.