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Fix Android ScrollView to Measure Content Correct #30964

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Merged
PureWeen merged 1 commit into from
Aug 1, 2025
Merged

Fix Android ScrollView to Measure Content Correct #30964

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3 changes: 2 additions & 1 deletion src/Controls/src/Core/ScrollView/ScrollView.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -515,7 +515,8 @@ Size ICrossPlatformLayout.CrossPlatformArrange(Rect bounds)
return bounds.Size;
}

Size IContentView.CrossPlatformMeasure(double widthConstraint, double heightConstraint) => ((ICrossPlatformLayout)this).CrossPlatformMeasure(widthConstraint, heightConstraint);
Size IContentView.CrossPlatformMeasure(double widthConstraint, double heightConstraint) =>
((ICrossPlatformLayout)this).CrossPlatformMeasure(widthConstraint, heightConstraint);

Size IContentView.CrossPlatformArrange(Rect bounds) =>
((ICrossPlatformLayout)this).CrossPlatformArrange(bounds);
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31 changes: 13 additions & 18 deletions src/Core/src/Handlers/ScrollView/ScrollViewHandler.Android.cs
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Expand Up @@ -25,14 +25,12 @@ protected override void ConnectHandler(MauiScrollView platformView)
{
base.ConnectHandler(platformView);
platformView.ScrollChange += ScrollChange;
platformView.CrossPlatformArrange = VirtualView.CrossPlatformArrange;
}

protected override void DisconnectHandler(MauiScrollView platformView)
{
base.DisconnectHandler(platformView);
platformView.ScrollChange -= ScrollChange;
platformView.CrossPlatformArrange = null;
}

public override Size GetDesiredSize(double widthConstraint, double heightConstraint)
Expand Down Expand Up @@ -234,7 +232,10 @@ static void InsertInsetView(IScrollViewHandler handler, IScrollView scrollView,

Size ICrossPlatformLayout.CrossPlatformMeasure(double widthConstraint, double heightConstraint)
{
var scrollView = VirtualView;
if (VirtualView is not { } scrollView)
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@rmarinho rmarinho Aug 1, 2025

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This fires before we set a VirtualView?

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@PureWeen PureWeen Aug 1, 2025

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no, we can definitely remove this check

Let's see if it passes tests and if so I'll remove

{
return Size.Zero;
}

var padding = scrollView.Padding;

Expand All @@ -243,31 +244,25 @@ Size ICrossPlatformLayout.CrossPlatformMeasure(double widthConstraint, double he
return new Size(padding.HorizontalThickness, padding.VerticalThickness);
}

// Exclude the padding while measuring the internal content ...
var measurementWidth = widthConstraint - padding.HorizontalThickness;
var measurementHeight = heightConstraint - padding.VerticalThickness;

var result = (scrollView as ICrossPlatformLayout).CrossPlatformMeasure(measurementWidth, measurementHeight);

// ... and add the padding back in to the final result
var fullSize = new Size(result.Width + padding.HorizontalThickness, result.Height + padding.VerticalThickness);
var scrollOrientation = scrollView.Orientation;
var contentWidthConstraint = scrollOrientation is ScrollOrientation.Horizontal or ScrollOrientation.Both ? double.PositiveInfinity : widthConstraint;
var contentHeightConstraint = scrollOrientation is ScrollOrientation.Vertical or ScrollOrientation.Both ? double.PositiveInfinity : heightConstraint;
var contentSize = scrollView.MeasureContent(scrollView.Padding, contentWidthConstraint, contentHeightConstraint, !double.IsInfinity(contentWidthConstraint), !double.IsInfinity(contentHeightConstraint));

if (double.IsInfinity(widthConstraint))
{
widthConstraint = result.Width;
widthConstraint = contentSize.Width;
}

if (double.IsInfinity(heightConstraint))
{
heightConstraint = result.Height;
heightConstraint = contentSize.Height;
}

return fullSize.AdjustForFill(new Rect(0, 0, widthConstraint, heightConstraint), scrollView.PresentedContent);
return contentSize.AdjustForFill(new Rect(0, 0, widthConstraint, heightConstraint), scrollView.PresentedContent);
}

Size ICrossPlatformLayout.CrossPlatformArrange(Rect bounds)
{
return (VirtualView as ICrossPlatformLayout).CrossPlatformArrange(bounds);
}
Size ICrossPlatformLayout.CrossPlatformArrange(Rect bounds) =>
(VirtualView as ICrossPlatformLayout)?.CrossPlatformArrange(bounds) ?? Size.Zero;
}
}
31 changes: 31 additions & 0 deletions src/Core/src/Layouts/LayoutExtensions.cs
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Expand Up @@ -167,6 +167,37 @@ public static Size MeasureContent(this IContentView contentView, Thickness inset
return new Size(contentSize.Width + inset.HorizontalThickness, contentSize.Height + inset.VerticalThickness);
}

internal static Size MeasureContent(
this IContentView contentView,
Thickness inset,
double widthConstraint,
double heightConstraint,
bool constrainPresentedContentWidthToExplicitDimsOnContentView,
bool constrainPresentedContentHeightToExplicitDimsOnContentView)
{
var content = contentView.PresentedContent;

if (Dimension.IsExplicitSet(contentView.Width) && constrainPresentedContentWidthToExplicitDimsOnContentView)
{
widthConstraint = contentView.Width;
}

if (Dimension.IsExplicitSet(contentView.Height) && constrainPresentedContentHeightToExplicitDimsOnContentView)
{
heightConstraint = contentView.Height;
}

var contentSize = Size.Zero;

if (content != null)
{
contentSize = content.Measure(widthConstraint - inset.HorizontalThickness,
heightConstraint - inset.VerticalThickness);
}

return new Size(contentSize.Width + inset.HorizontalThickness, contentSize.Height + inset.VerticalThickness);
}

public static void ArrangeContent(this IContentView contentView, Rect bounds)
{
if (contentView.PresentedContent == null)
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17 changes: 5 additions & 12 deletions src/Core/src/Platform/Android/MauiScrollView.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -97,7 +97,11 @@ public void SetOrientation(ScrollOrientation orientation)
{
if (_hScrollView == null)
{
_hScrollView = new MauiHorizontalScrollView(Context, this);
_hScrollView = new MauiHorizontalScrollView(Context, this)
{
FillViewport = true
};

_hScrollView.HorizontalFadingEdgeEnabled = HorizontalFadingEdgeEnabled;
_hScrollView.SetFadingEdgeLength(HorizontalFadingEdgeLength);
SetHorizontalScrollBarVisibility(_horizontalScrollVisibility);
Expand Down Expand Up @@ -229,15 +233,6 @@ protected override void OnLayout(bool changed, int left, int top, int right, int
hScrollViewHeight = _isBidirectional ? Math.Max(hScrollViewHeight, scrollViewContentHeight) : hScrollViewHeight;
_hScrollView.Layout(0, 0, hScrollViewWidth, hScrollViewHeight);
}

if (CrossPlatformArrange == null)
{
return;
}

var destination = Context!.ToCrossPlatformRectInReferenceFrame(left, top, right, bottom);

CrossPlatformArrange(destination);
}

public void ScrollTo(int x, int y, bool instant, Action finished)
Expand Down Expand Up @@ -321,8 +316,6 @@ void IOnScrollChangeListener.OnScrollChange(NestedScrollView? v, int scrollX, in
{
OnScrollChanged(scrollX, scrollY, oldScrollX, oldScrollY);
}

internal Func<Graphics.Rect, Graphics.Size>? CrossPlatformArrange { get; set; }
}

internal class MauiHorizontalScrollView : HorizontalScrollView, IScrollBarView
Expand Down
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