Fixed Keyboard Scrolling in editors with Center or End VerticalTextAlignment

[NirmalKumarYuvaraj]

Issue Details

Sometimes, the editor cursor moves below the keyboard frame, causing it to render incorrectly. Once the editor content exceeds the editor's size, the cursor aligns properly above the keyboard frame.

Root Cause

The content offset of UITextView is set without consideration of keyboard frame. Causing the content to remain center even when the keyboard is open. As a result, the cursor goes below the keyboard frame.

Description of Change

The content offset of UITextView should be recalculated based on the keyboard frame value . We should check if the cursor's bottom position goes below the keyboard; we have to update the y position of the content offset based on the difference between the cursor's bottom position and the keyboard frame's top position. 

Validated the behaviour in the following platforms

• Android
• Windows
• iOS
• Mac

Issues Fixed

Fixes #24977

Output

Before	After
Before.mov	After.mov

[PureWeen]

/azp run

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[rmarinho]

/rebase

[rmarinho]

/azp run

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[rmarinho]

/rebase

[rmarinho]

/azp run

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[jsuarezruiz]

/azp run

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[tj-devel709]

Looks like this changed the behavior of the placeholder a tad. Looks like it is moved down a little and is being cut off a little bit on the top

Original is on the left, the diff is in the middle, and the new behavior from this PR is on the right

[tj-devel709]

So it looks like the failing tests aren't just from the placeholder, but the spacing is just not correct and not accounting for the bottom of the TextContainerInset correctly. The following gets us closer and seems like the middle adjustment is a rounding issue perhaps. Can you look into this?

		void ShouldCenterVertically()
		{
			// ContentSize.Height rounds to the nearest whole number so to keep the measurements consistent we round the adjustment as well
			var contentHeight = ContentSize.Height - Math.Round(TextContainerInset.Top, MidpointRounding.AwayFromZero);;
			var availableSpace = Bounds.Height - contentHeight * ZoomScale;
			if (availableSpace <= 0)
				return;

			TextContainerInset = VerticalTextAlignment switch
			{
				Maui.TextAlignment.Center => new UIEdgeInsets((nfloat)Math.Max(1, availableSpace / 2), TextContainerInset.Left, TextContainerInset.Bottom, TextContainerInset.Right),
				Maui.TextAlignment.End => new UIEdgeInsets((nfloat)Math.Max(1, availableSpace), TextContainerInset.Left, TextContainerInset.Bottom, TextContainerInset.Right),
				_ => TextContainerInset,
			};
		}

[tj-devel709]

This is the new diff from the code above

[jsuarezruiz]

There are more tests that would require a similar change

[NirmalKumarYuvaraj]

@jsuarezruiz , EditorPlaceholderPosition is the test case related to this PR. The other test cases are unrelated, as this PR contains code changes for UITextView, and the remaining test cases do not involve an editor in their scenarios. To confirm, I ran both test cases locally, and they passed.

[NirmalKumarYuvaraj]

@tj-devel709 , The rounding approach for middle alignment does not resolve the issue. I attempted to recalculate the position when the text alignment is set to center. Using this approach, we obtained the correct value, which is 66.25. This value is required for the test case to pass; however, the test still fails, even though the top inset value is set to 66.25.

void ShouldCenterVertically()
{
	// ContentSize.Height rounds to the nearest whole number so to keep the measurements consistent we round the adjustment as well
	var contentHeight = ContentSize.Height - Math.Round(TextContainerInset.Top, MidpointRounding.AwayFromZero);
	var availableSpace = Bounds.Height - contentHeight * ZoomScale;
	if (availableSpace <= 0)
		return;

	TextContainerInset = VerticalTextAlignment switch
	{
		Maui.TextAlignment.Center => new UIEdgeInsets((nfloat)Math.Max(1,(Bounds.Height - (ContentSize.Height - (TextContainerInset.Top + TextContainerInset.Bottom)) * ZoomScale) / 2), TextContainerInset.Left, TextContainerInset.Bottom, TextContainerInset.Right),
		Maui.TextAlignment.End => new UIEdgeInsets((nfloat)Math.Max(1, availableSpace), TextContainerInset.Left, TextContainerInset.Bottom, TextContainerInset.Right),
		_ => TextContainerInset,
	};
}

New diff from the above code

[tj-devel709]

Huh.. that looks pretty close so I'm not sure what is off here. It looks like maybe its just off by a fraction of a pixel or something like that. @PureWeen, what do you think? Good enough?

[karthikraja-arumugam]

@PureWeen, can you please share your thoughts on this?

[mattleibow]

What is zoom scale? Could that be a fraction and thus contributing some increased offset? What happens if you remove the rounding and then diff before and after? I onder if that would be closer indicating it is just the rounding and zoom.

[mattleibow]

I see this code is entirely gone, so I suppose this question is not relevant. @karthikraja-arumugam ?

[jsuarezruiz]

Failing tests:

[jsuarezruiz]

/azp run

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