fix(Android): Restrict CommandBar content width to prevent primary commands overflow

[Copilot]

Problem

On Android, when a CommandBar contains long content (such as a TextBlock with a lengthy title), the content was not width-constrained. This caused the content to expand indefinitely, pushing primary command buttons off-screen and making them inaccessible to users.

Before:

After:

Root Cause

The _contentContainer (a Border element) in CommandBarRenderer.Android.cs was created with HorizontalAlignment.Left to properly measure based on child content size, but it lacked a MaxWidth constraint. This allowed content to grow without bounds within the native Android Toolbar, causing layout overflow.

Solution

Implemented dynamic content width constraint by:

1. Added ToolbarLayoutListener - Monitors the native Toolbar for layout changes (rotation, resize, menu updates)

2. Added UpdateContentMaxWidth() - Calculates available space for content by accounting for:

   • Navigation icon (back button): ~56dp when present
   • Primary command buttons: ~48dp each
   • Toolbar padding: ~32dp total
   • Converts physical pixels to logical pixels for proper XAML sizing

3. Automatic recalculation - MaxWidth is updated whenever:

   • The toolbar layout changes
   • Primary or secondary commands are updated
   • Navigation elements are added/removed

This ensures the content is properly constrained while preserving the existing TextTrimming behavior (ellipsis) on TextBlock elements.

Testing

• Added runtime test When_CommandBar_Has_Long_Content_Then_PrimaryCommands_Remain_Visible() that verifies:
  • Content MaxWidth is set and reasonable
  • Content doesn't exceed toolbar bounds
  • Primary commands remain visible within screen bounds
• Existing samples (CommandBar_LongTitle.xaml, CommandBar_With_Long_Sentences.xaml) can be used for manual verification

Fixes

Closes #21654

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Android Native command bar content width not restricted, pushing primary commands out of screen bounds</issue_title>
<issue_description>### Current behavior 🐛

Command bar is based NativeDefaultCommandBar. Content is a text block. When content text is long, it pushes the primary commands out of screen bounds

Expected behavior 🎯

The content is cut off and ... added when width is beyond available space, without pushing the back button or primary commands out of bounds

How to reproduce it (as minimally and precisely as possible) 🔬

CommandBar.zip

Simply create a command bar with a long text block.

Workaround 🛠️

No response

Renderer 🎨

• Skia
• Native

Affected platforms 📱💻🖥️

Android

Uno.Sdk version (and other relevant versions) 📦

No response

IDE version 🧑‍💻

No response

Anything else we need to know? 💬

No response</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #21654

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