fix(web): allow to use file URLs on Android by ermshiperete · Pull Request #16132 · keymanapp/keyman

ermshiperete · 2026-06-23T16:17:18Z

This change fixes the blank keyboard problem on Android which was caused by using the Fetch API fetch() function which doesn't support file:// URLs. This change now uses the XMLHttpRequest class instead and sets the necessary flags on the Android side.

For Keyman for Web nothing changes compared to earlier alpha versions, which means that file URLs shouldn't be used.

This change also deletes loadKeyboardHelper.ts which wasn't used anywhere.

Note that this PR only fixes things for Android, but not iOS where we have a similar problem, but which requires a slightly different solution.

Fixes: #16096
Build-bot: skip release:web,android

User Testing

TEST_ANDROID:

Install Keyman for Android from this PR
Verify that a keyboard properly shows

TEST_WEB:

Open KeymanWeb test page, navigate to any test
Select a keyboard and verify that it displays the OSK and that the console window doesn't show errors

keymanapp-test-bot · 2026-06-23T16:17:27Z

User Test Results

Test specification and instructions

✅ TEST_ANDROID (PASSED) (notes)
✅ TEST_WEB (PASSED) (notes)

Test Artifacts

mcdurdin · 2026-06-23T16:29:17Z

+        resolve(new Response(httpRequest.response, { status: httpRequest.status }))
+      };
+      httpRequest.onerror = function () {
+        reject(new TypeError('Local request failed'))


Can we capture the error which is passed in here -- it's an Event object but there should be some error data somewhere there?

Done. Although it doesn't seem that we get error data - e is of type ProgressEvent wich derives from Event, and neither has any error data.

mcdurdin · 2026-06-23T16:30:27Z

+   * limitation of the Fetch API fetch(). On Android we still have to
+   * explicitly allow file URLs.
+   */
+  private fetch(uri: string): Promise<Response> {


I'd prefer to use this only in the Android and iOS apps (WebView) and not the Browser version

Done. Although probably need to be refined when we implement the fix for iOS.

mcdurdin · 2026-06-23T16:30:42Z

+    getSettings().setAllowFileAccessFromFileURLs(true);
+    getSettings().setAllowUniversalAccessFromFileURLs(true);


Can we add a comment on this?

Turns out we don't need setAllowUniversalAccessFromFileURLs. Added a comment for the other line.

mcdurdin · 2026-06-24T04:54:39Z

Can confirm this fix does not currently work on iOS.

This change fixes the blank keyboard problem on Android and iOS which was caused by using the Fetch API fetch() function which doesn't support file:// URLs. This change now uses the `XMLHttpRequest` class instead and sets the necessary flags on the Android side. For Keyman for Web nothing changes compared to earlier alpha versions, which means that file URLs shouldn't be used. This change also deletes `loadKeyboardHelper.ts` which wasn't used anywhere. Co-authored-by: Marc Durdin <marc@durdin.net> Fixes: #16096 Build-bot: release

This change adds a `fetchKeyboardFunc` to `DOMKeyboardLoader` that allows mobile platforms to use a different method to fetch the keyboard data. WebView's `KeymanEngine` implements fetching the URL by using `XMLHttpRequest`.

Meng-Heng · 2026-06-25T02:52:42Z

Test Results

TEST_ANDROID (PASSED):

Launch Android Studio, Pixel 9 API 35 Emulator
Drag and drop keyman-19.0.248-alpha-test-16132
Launch Keyman within the Emulator
The Euro Latin (SIL) keyboard displays without any error messages
Predictive text and typing works as expected
Navigate to Settings -> Install Keyboard or Dictionary -> Install from keyman.com -> Install Khmer Angkor keyboard
The process of downloading the keyboard work as expected
Khmer Angkor keyboard displays and types without any error messages
Switching keyboards work as expected.

TEST_WEB (PASSED):

Navigate to the Web Test page for Keymanweb_TestPullRequests/630412
View KeymanWeb use samples ->Example 1 - Toggle UI, all resources in same folder as page -> Keyboard switches and types
View Keymanweb website-oriented manual test pages -> Prediction - robust testing (prediction-mtnt) -> Keyboard switches and types + predictive text works as expected.

Note

The Test Artifacts link for Android does not work, instead I navigated to the apk through the Test checks links.

mcdurdin

This is definitely a straightforward patch; can we refactor it to be more object-oriented given our existing pattern with KeymanEngine: KeymanEngineBase?

Will we need to do similar work for fonts and lexical models?

mcdurdin · 2026-06-25T05:32:44Z

+   * Fetch API's fetch() which doesn't support file:// URLs. At least in
+   * Keyman for Android we still have to explicitly allow file URLs.
+   */
+  private fetch(uri: string): Promise<Response> {


I would prefer to have this designed as a protected function in KeymanEngineBase which we override here, in KeymanEngineBase.ts it would be something like:

protected fetch(uri: string): Promise<Response> { throw new Error('not implemented'); }

and in browser/src/KeymanEngine.ts:

protected fetch(uri: string): Promise<Response> { return window.fetch(uri); }

and then this would also be protected.

That moves the responsibility for defining what fetch does into the same place for both WebView and Browser components.

mcdurdin · 2026-06-25T06:00:53Z

The Test Artifacts link for Android does not work, instead I navigated to the apk through the Test checks links.

Tracking this in #16137 -- we were planning for Android test PRs to include the full tag in the file name:

keyman-19.0.248-alpha-test-16132.apk vs
keyman-19.0.248.apk

Note that the 'Keyman for Android apk (old PRs)' link currently works in the Test Artifacts list.

github-project-automation Bot added this to Keyman Jun 23, 2026

github-project-automation Bot moved this to Todo in Keyman Jun 23, 2026

keymanapp-test-bot Bot added the user-test-missing User tests have not yet been defined for the PR label Jun 23, 2026

keymanapp-test-bot Bot added this to the A19S32 milestone Jun 23, 2026

github-actions Bot added web/ android/ android/engine/ fix labels Jun 23, 2026

mcdurdin reviewed Jun 23, 2026

View reviewed changes

ermshiperete force-pushed the fix/web/16096_blankKeyboard branch from e225015 to 0fd21c0 Compare June 24, 2026 13:21

ermshiperete changed the title ~~fix(web): allow to use file URLs on Android and iOS~~ fix(web): allow to use file URLs on Android Jun 24, 2026

keymanapp-test-bot Bot added has-user-test user-test-required User tests have not been completed and removed user-test-missing User tests have not yet been defined for the PR labels Jun 24, 2026

fix(web): add a fetch keyboard function

79fd7c8

This change adds a `fetchKeyboardFunc` to `DOMKeyboardLoader` that allows mobile platforms to use a different method to fetch the keyboard data. WebView's `KeymanEngine` implements fetching the URL by using `XMLHttpRequest`.

ermshiperete force-pushed the fix/web/16096_blankKeyboard branch from eadcbe9 to 79fd7c8 Compare June 24, 2026 17:19

ermshiperete marked this pull request as ready for review June 24, 2026 17:21

ermshiperete requested a review from jahorton June 24, 2026 17:24

Meng-Heng self-assigned this Jun 25, 2026

keymanapp-test-bot Bot removed the user-test-required User tests have not been completed label Jun 25, 2026

Meng-Heng removed their assignment Jun 25, 2026

mcdurdin mentioned this pull request Jun 25, 2026

fix(ios): load host page, keyboards through a consistent WKURLSchemeHandler #16136

Draft

mcdurdin reviewed Jun 25, 2026

View reviewed changes

mcdurdin mentioned this pull request Jun 25, 2026

bug(android): test artifacts have missing version tag #16137

Open

		getSettings().setAllowFileAccessFromFileURLs(true);
		getSettings().setAllowUniversalAccessFromFileURLs(true);

Uh oh!

Uh oh!

Conversation

ermshiperete commented Jun 23, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

User Testing

Uh oh!

keymanapp-test-bot Bot commented Jun 23, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

User Test Results

Test Artifacts

Uh oh!

mcdurdin Jun 23, 2026

Choose a reason for hiding this comment

Uh oh!

ermshiperete Jun 24, 2026

Choose a reason for hiding this comment

Uh oh!

mcdurdin Jun 23, 2026

Choose a reason for hiding this comment

Uh oh!

ermshiperete Jun 24, 2026

Choose a reason for hiding this comment

Uh oh!

mcdurdin Jun 23, 2026

Choose a reason for hiding this comment

Uh oh!

ermshiperete Jun 24, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

mcdurdin commented Jun 24, 2026

Uh oh!

Meng-Heng commented Jun 25, 2026

Test Results

Uh oh!

mcdurdin left a comment

Choose a reason for hiding this comment

Uh oh!

mcdurdin Jun 25, 2026

Choose a reason for hiding this comment

Uh oh!

mcdurdin commented Jun 25, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

ermshiperete commented Jun 23, 2026 •

edited

Loading

keymanapp-test-bot Bot commented Jun 23, 2026 •

edited

Loading

mcdurdin commented Jun 25, 2026 •

edited

Loading