[Android] Fix WebView in a grid expands beyond it's cell #32145
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Hey there @@devanathan-vaithiyanathan! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed. |
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| return false; | ||
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| // Check if URL is about:blank (case insensitive) | ||
| return string.Equals(url.Trim(), "about:blank", StringComparison.OrdinalIgnoreCase); |
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Could expand to more variants?
Examples:
- "about:blank#"
- "about:blank/"
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This will be invoked on every Navigation. The impact on performance now is minimal for the current simple string comparison, but take this into account (for example, if think in use URI parsing or more complex stuff).
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@jsuarezruiz , When the source is null, we set the default WebView source to about:blank. As a result, the OnPageFinished method always receives about:blank as the parameter. Therefore, handling additional variants such as about:blank# or about:blank/ is not necessary in this case.
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Pull Request Overview
This PR fixes an Android-specific issue where a WebView without a source would expand beyond its Grid cell boundaries. The fix reintroduces the else block that loads about:blank when there's no source, while preventing the Navigated event from firing for this default navigation.
- Restores layout bounds handling by loading
about:blankwhen WebView has no source - Adds filtering logic to suppress Navigated events for
about:blanknavigation - Includes UI test to verify WebView stays within Grid cell boundaries
Reviewed Changes
Copilot reviewed 4 out of 8 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| src/Core/src/Platform/Android/WebViewExtensions.cs | Reintroduces else block to load about:blank when WebView has no source |
| src/Core/src/Platform/Android/MauiWebViewClient.cs | Adds IsBlankNavigation helper and filters Navigated event for blank URLs |
| src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue32030.cs | Adds NUnit test to verify WebView layout behavior |
| src/Controls/tests/TestCases.HostApp/Issues/Issue32030.cs | Adds test page demonstrating WebView in Grid without source |
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src/Controls/tests/TestCases.HostApp/Issues/Issue32030.cs:1
- Corrected spelling of 'it's' to 'its' in the issue description. 'Its' is the possessive form, while 'it's' means 'it is'.
namespace Maui.Controls.Sample.Issues;
| if (string.IsNullOrWhiteSpace(url)) | ||
| return false; |
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The check IsNullOrWhiteSpace returns false for blank URLs, but the method is named IsBlankNavigation. This is counterintuitive - a null or whitespace URL could reasonably be considered 'blank'. Consider returning true for null/whitespace URLs, or rename the method to clarify its purpose (e.g., IsAboutBlankUrl).
| if (string.IsNullOrWhiteSpace(url)) | |
| return false; | |
| // Return true for null, empty, or whitespace URLs | |
| if (string.IsNullOrWhiteSpace(url)) | |
| return true; |
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| static bool IsBlankNavigation(string? url) | ||
| { | ||
| if (string.IsNullOrWhiteSpace(url)) |
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if (navigate && !IsBlankNavigation(url))
Based on this:
- url = null → IsBlankNavigation returns false → Navigated fires
- url = "about:blank" → IsBlankNavigation returns true → Navigated doesn't fire
This could break the fix from #29234 which wanted to prevent events when Source is null
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@jsuarezruiz ,
url = null → IsBlankNavigation returns false → Navigated fires
url should never be null. We’ve modified the source so that if the source is not null, it uses that source; otherwise, it uses "about:blank".
In the OnPageFinished method, url should never be null.
url = "about:blank" → IsBlankNavigation returns true → Navigated doesn’t fire
Yes, this is the expected behavior. The PR#29234 resolves the issue where Android triggered the Navigating event with a null source.
With my fix, if the source is null, we set it to "about:blank". When the URL is "about:blank", the Navigating event will not fire.
So with the current fix, it resolves both issues #32030 and #29234.
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4 participants
Note
Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!
Issue Details
After PR #29234 , the else part was removed to stop the Navigated event from triggering when the WebView had no source.
However, this caused a new issue where rendering a WebView without a source exceeded the layout bounds.
Root Cause
When the WebView was rendered without a source, the layout logic was not properly handled — causing the WebView to exceed its layout bounds.
Description of Change
This fix resolves both the layout overflow and unwanted event trigger issues.
Issues Fixed
Fixes #32030
Tested the behavior in the following platforms.