ADFA-2548 | Fix drag-and-drop crash on Android 12+ for TextViews

[jatezzz]

Description

This PR fixes a NullPointerException occurring on Android 12+ (API 31) when dropping elements onto an EditText or other TextView subclasses within the Design Editor.

The crash happens because android.widget.Editor attempts to handle the ACTION_DROP event assuming valid ClipData, which is null during internal drag operations. To prevent this, I introduced a configureForDesignMode extension function that:

• Disables focus and touch mode focus for all views.
• Explicitly disables textIsSelectable, cursorVisible, and removes the keyListener for TextView subclasses.

This ensures these components remain passive visual elements in the editor, preventing the system's text editing logic from intercepting drag events. Additionally, I refactored the Spinner listener assignment for better readability.

Details

Logic-related fix. This resolves the following crash on API 31+:
java.lang.NullPointerException: null at android.widget.Editor.onDrop(Editor.java:3089)

Before changes

Screen.Recording.2026-01-23.at.12.11.53.PM.mov

After changes

Screen.Recording.2026-01-23.at.12.14.18.PM.mov

Ticket

ADFA-2548

Observation

This fix applies to all views inheriting from TextView (e.g., Button, CheckBox, EditText), ensuring consistency across the editor.

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📝 Walkthrough

Walkthrough

Introduced a private extension function View.configureForDesignMode() in the DesignEditor that disables focusability, text editing, cursor visibility, and text selection for views in design mode. The function is applied to views during rearrangement operations, with minor formatting adjustments to listener blocks.

Changes

Cohort / File(s)	Summary
Design Mode View Configuration layouteditor/src/main/java/org/appdevforall/codeonthego/layouteditor/editor/DesignEditor.kt	Added private extension function View.configureForDesignMode() that disables focus, touch focus, and text editing capabilities (keyListener, cursor, selection) for TextView subclasses. Applied during view rearrangement. Includes minor Spinner listener formatting adjustments.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested reviewers

• Daniel-ADFA
• jomen-adfa

Poem

🐰 In design mode, views must be still,
No tapping, typing, or cursor's thrill,
An extension so neat, a helper most fine,
Makes interactive elements resign.
Arranged and disabled—perfectly mine! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title directly matches the main fix: resolving a drag-and-drop crash on Android 12+ for TextViews, which is the primary change in the changeset.
Description check	✅ Passed	The description is directly related to the changeset, explaining the NullPointerException crash, the introduced configureForDesignMode extension function, and the specific changes made to fix the issue.

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In
`@layouteditor/src/main/java/org/appdevforall/codeonthego/layouteditor/editor/DesignEditor.kt`:
- Around line 579-584: The empty override onNothingSelected in the anonymous
AdapterView.OnItemSelectedListener is flagged by detekt; update the override in
the view.onItemSelectedListener block (the onNothingSelected(parent:
AdapterView<*>?)) to include an explicit no-op comment (e.g. add a "// no-op"
comment inside the method body) so the empty override is intentional and detekt
stops flagging it, leaving the onItemSelected implementation that calls
showDefinedAttributes(view) unchanged.