Fixed cursor jumping to end issue

[tusharonly]

PR Description

Fixed cursor jumping to end issue in URL text field. When editing a character in the middle of the URL, the cursor would automatically move to the end, making it difficult to edit URLs.

Root Cause: The didUpdateWidget method in EnvironmentTriggerField was recreating the TextEditingController on every text change, always positioning the cursor at the end.

Solution: Modified the controller update logic to:

• Preserve the current cursor position when text is updated from user input
• Only reset cursor to end when switching between different requests (keyId changes)
• Ensure cursor position stays within valid bounds using .clamp(0, newText.length)
• Avoid unnecessary controller updates when text hasn't actually changed

Related Issues

• Closes Typing or Removing any character in between URL textfield moves the cursor to the end unexpectedly. #924

Checklist

• I have gone through the contributing guide

• I have updated my branch and synced it with project main branch before making this PR

• I am using the latest Flutter stable branch (run flutter upgrade and verify)

• I have run the tests (flutter test) and all tests are passing

Added/updated tests?

We encourage you to add relevant test cases.

• No, and this is why: This is a UI interaction fix that addresses cursor positioning behavior. The existing tests continue to pass and validate the text field functionality. Additional widget tests for cursor position preservation could be added in a future enhancement.

OS on which you have developed and tested the feature?

• Windows

• macOS

• Linux

[Copilot]

Pull request overview

This PR fixes a cursor positioning bug where editing text in the middle of a URL field would cause the cursor to jump to the end. The fix preserves the cursor position during text updates while still resetting it when switching between different requests.

Key Changes:

• Modified didUpdateWidget to distinguish between keyId changes (new request) and value changes (same request being edited)
• Added cursor position preservation logic that clamps the cursor offset within valid bounds
• Updated indentation in the ExtendedTextField widget

---

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[Copilot]

Missing comma after the obscureText parameter. This will cause a syntax error and prevent the code from compiling.

Add a comma after widget.obscureText:

obscureText: widget.obscureText,

Suggested change

	obscureText: widget.obscureText
	obscureText: widget.obscureText,

[Copilot]

Creating a new controller without disposing the old one will cause a memory leak. When the keyId changes, the old controller should be disposed before assigning a new one.

Consider adding:

if (oldWidget.keyId != widget.keyId) {
  // Key changed - dispose old controller and create new one
  if (widget.controller == null) {
    controller.dispose();
  }
  controller = widget.controller ??
      TextEditingController.fromValue(TextEditingValue(
          text: widget.initialValue!,
          selection: TextSelection.collapsed(
              offset: widget.initialValue!.length)));
}

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 2 comments.

---

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[Copilot]

The cursor position preservation logic doesn't account for text selection ranges (when text is highlighted). The code only preserves baseOffset but ignores extentOffset, which means any text selection will be lost and collapsed to a cursor position.

Consider preserving the full selection when possible:

final currentSelection = controller.selection;
final newText = widget.initialValue ?? '';

if (controller.text != newText) {
  // Preserve selection range, ensuring it's within bounds
  final newBaseOffset = currentSelection.baseOffset.clamp(0, newText.length);
  final newExtentOffset = currentSelection.extentOffset.clamp(0, newText.length);
  
  controller.value = TextEditingValue(
    text: newText,
    selection: TextSelection(
      baseOffset: newBaseOffset,
      extentOffset: newExtentOffset,
    ),
  );
}

Suggested change

	final newOffset =
	currentSelection.baseOffset.clamp(0, newText.length);
	controller.value = TextEditingValue(
	text: newText,
	selection: TextSelection.collapsed(offset: newOffset),
	final newBaseOffset = currentSelection.baseOffset.clamp(0, newText.length);
	final newExtentOffset = currentSelection.extentOffset.clamp(0, newText.length);
	controller.value = TextEditingValue(
	text: newText,
	selection: TextSelection(
	baseOffset: newBaseOffset,
	extentOffset: newExtentOffset,
	),

[Copilot]

The cursor position preservation logic introduced in this PR lacks test coverage. While there are existing tests that verify text updates, there are no tests that specifically validate that the cursor position is preserved when text is updated (the main fix of this PR).

Consider adding a test case like:

testWidgets('Testing EnvironmentTriggerField preserves cursor position on text update',
    (WidgetTester tester) async {
  final fieldKey = GlobalKey<EnvironmentTriggerFieldState>();
  
  await tester.pumpWidget(
    Portal(
      child: MaterialApp(
        home: Scaffold(
          body: EnvironmentTriggerField(
            key: fieldKey,
            keyId: 'testKey',
            initialValue: 'hello world',
          ),
        ),
      ),
    ),
  );
  
  // Set cursor to position 5 (middle of text)
  fieldKey.currentState!.controller.selection = 
      TextSelection.collapsed(offset: 5);
  
  // Update the text value
  await tester.pumpWidget(
    Portal(
      child: MaterialApp(
        home: Scaffold(
          body: EnvironmentTriggerField(
            key: fieldKey,
            keyId: 'testKey',
            initialValue: 'hello world!',
          ),
        ),
      ),
    ),
  );
  
  // Verify cursor is still at position 5
  expect(fieldKey.currentState!.controller.selection.baseOffset, 5);
});