public override SpecificLayout GetBestLayout(LayoutQuery query)
{
// The score of a Specific_ScrollLayout is defined in returnLayout:
// If the child layout has negative score, the Specific_ScrollLayout refuses to do a layout
// If the child layout has nonnegative score, the Specific_ScrollLayout's score equals
// (this.resultingScore * (what fraction of the child layout is visible))
if (query.MinScore.CompareTo(this.resultingScore) > 0)
{
// Demands too high of a score: no solution
return(null);
}
if (query.MaxHeight <= 0)
{
return(null);
}
// what fraction of the score of the sublayout will appear onscreen at once
double scoreFraction = Math.Max(query.MinScore.DividedBy(this.resultingScore), 0);
// what fraction of the child's height we need to include in the size of the ScrollView
double requiredHeightFraction = scoreFraction;
// the child's height divided by the ScrollView's height
double requiredHeightMultiplier;
if (requiredHeightFraction != 0)
{
requiredHeightMultiplier = 1 / requiredHeightFraction;
}
else
{
requiredHeightMultiplier = double.PositiveInfinity;
}
// the maximum child height
double maxChildHeight = query.MaxHeight * requiredHeightMultiplier;
if (query.MinimizesWidth())
{
// For a min-width query, first shrink the width as much as possible before continuing
SpecificLayout minWidth_childLayout = this.subLayout.GetBestLayout(query.New_MinWidth_LayoutQuery(query.MaxWidth, maxChildHeight, this.requiredChildScore));
if (minWidth_childLayout == null)
{
return(null);
}
query = query.WithDimensions(minWidth_childLayout.Width, minWidth_childLayout.Height);
}
SpecificLayout childLayout = this.subLayout.GetBestLayout(query.New_MinHeight_LayoutQuery(query.MaxWidth, maxChildHeight, this.requiredChildScore));
if (childLayout == null)
{
return(null);
}
if (!query.MinimizesHeight())
{
// For a max-score (or min-width) query, use as much height as was allowed
Size size = new Size(childLayout.Width, Math.Min(query.MaxHeight, childLayout.Height));
SpecificLayout result = this.makeLayout(size, childLayout);
if (query.Accepts(result))
{
return(this.prepareLayoutForQuery(result, query));
}
return(null);
}
else
{
// For a min-height query, use only as much size as is needed
double requiredScrollviewHeight = childLayout.Height * requiredHeightFraction;
Size size = new Size(childLayout.Width, requiredScrollviewHeight);
SpecificLayout result = this.makeLayout(size, childLayout);
if (!query.Accepts(result))
{
// Check for possible rounding error
SpecificLayout larger = this.makeLayout(new Size(size.Width, size.Height + this.pixelSize), childLayout);
if (query.Accepts(larger))
{
return(this.prepareLayoutForQuery(larger, query));
}
return(null);
}
return(this.prepareLayoutForQuery(result, query));
}
}
