private NSAttributedString GetAttributedText(NSAttributedStringTarget target)
{
if (target == NSAttributedStringTarget.UILabel && UseInlinesFastPath && LineHeight == 0 && CharacterSpacing == 0)
{
// Fast path in case everything can be set directly on UILabel without using NSAttributedString.
return(null);
}
else
{
var mutableAttributedString = new NSMutableAttributedString(Text);
mutableAttributedString.BeginEditing();
mutableAttributedString.AddAttributes(GetAttributes(target), new NSRange(0, mutableAttributedString.Length));
// Apply Inlines
foreach (var inline in GetEffectiveInlines())
{
mutableAttributedString.AddAttributes(inline.inline.GetAttributes(), new NSRange(inline.start, inline.end - inline.start));
}
mutableAttributedString.EndEditing();
return(mutableAttributedString);
}
}
private UIStringAttributes GetAttributes(NSAttributedStringTarget target)
{
var attributes = new UIStringAttributes();
// We only apply these values to NSTextStorage, as they're already applied to UILabel.
// See: UpdateFont, UpdateTextColor, etc.
if (target == NSAttributedStringTarget.NSTextStorage)
{
attributes.Font = _currentFont;
attributes.ForegroundColor = _currentColor;
}
if (target == NSAttributedStringTarget.NSTextStorage || LineHeight != 0)
{
var paragraphStyle = new NSMutableParagraphStyle()
{
MinimumLineHeight = (nfloat)LineHeight,
Alignment = TextAlignment.ToNativeTextAlignment(),
LineBreakMode = GetLineBreakMode(),
};
// For unknown reasons, the LineBreakMode must be set to WordWrap
// when applied to a NSTextStorage for text to wrap (but not when applied to a UILabel).
if (target == NSAttributedStringTarget.NSTextStorage)
{
paragraphStyle.LineBreakMode = UILineBreakMode.WordWrap;
}
if (LineStackingStrategy != LineStackingStrategy.MaxHeight)
{
paragraphStyle.MaximumLineHeight = (nfloat)LineHeight;
}
attributes.ParagraphStyle = paragraphStyle;
if (Font != null)
{
// iOS puts text at the bottom of the line box, whereas Windows puts it at the top.
// Empirically this offset gives similar positioning to Windows.
// Note: Descender is typically a negative value.
var verticalOffset = LineHeight - Font.LineHeight + Font.Descender;
// For unknown reasons, the verticalOffset must be divided by 2
// when applied to a UILabel (but not when applied to a NSTextStorage).
if (target == NSAttributedStringTarget.UILabel)
{
verticalOffset /= 2;
}
// Because we're trying to move the text up (toward the top of the line box),
// we only set BaselineOffset to a positive value.
// A negative value indicates that the the text is already bottom-aligned.
attributes.BaselineOffset = Math.Max(0, (float)verticalOffset);
}
}
if (CharacterSpacing != 0)
{
//CharacterSpacing is in 1/1000 of an em, iOS KerningAdjustment is in points. 1 em = 12 points
attributes.KerningAdjustment = (CharacterSpacing / 1000f) * 12;
}
return(attributes);
}
