Ooui-tws-port/Ooui.Forms/Renderers/LabelRenderer.cs

using System;
using System.ComponentModel;
using System.Diagnostics;
using Ooui.Forms.Extensions;
using Xamarin.Forms;

using NativeLabel = Ooui.Span;

namespace Ooui.Forms.Renderers
{
    public class LabelRenderer : ViewRenderer<Xamarin.Forms.Label, NativeLabel>
    {
        SizeRequest _perfectSize;

        bool _perfectSizeValid;

        public override SizeRequest GetDesiredSize (double widthConstraint, double heightConstraint)
        {
            // System.Console.WriteLine($"Label.GetDesiredSize ({widthConstraint}, {heightConstraint})");
            if (!_perfectSizeValid) {
                var size = Element.Text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes, double.PositiveInfinity, double.PositiveInfinity);
                size.Width = Math.Ceiling (size.Width);
                size.Height = Math.Ceiling (size.Height);
                _perfectSize = new SizeRequest (size, new Size (Element.FontSize, Element.FontSize));
                _perfectSizeValid = true;
            }

            var widthFits = widthConstraint >= _perfectSize.Request.Width;
            var heightFits = heightConstraint >= _perfectSize.Request.Height;

            if (widthFits && heightFits)
                return _perfectSize;

            var resultRequestSize = Element.Text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes, widthConstraint, heightConstraint);
            var result = new SizeRequest (resultRequestSize, resultRequestSize);
            var tinyWidth = Math.Min (10, result.Request.Width);
            result.Minimum = new Size (tinyWidth, result.Request.Height);

            if (widthFits || Element.LineBreakMode == LineBreakMode.NoWrap)
                return result;

            bool containerIsNotInfinitelyWide = !double.IsInfinity (widthConstraint);

            if (containerIsNotInfinitelyWide) {
                bool textCouldHaveWrapped = Element.LineBreakMode == LineBreakMode.WordWrap || Element.LineBreakMode == LineBreakMode.CharacterWrap;
                bool textExceedsContainer = result.Request.Width > widthConstraint;

                if (textExceedsContainer || textCouldHaveWrapped) {
                    var expandedWidth = Math.Max (tinyWidth, widthConstraint);
                    result.Request = new Size (expandedWidth, result.Request.Height);
                }
            }

            return result;
        }

        protected override void OnElementChanged (ElementChangedEventArgs<Xamarin.Forms.Label> e)
        {
            if (e.NewElement != null) {
                if (Control == null) {
                    SetNativeControl (new NativeLabel ());
                }

                UpdateText ();
                UpdateTextColor ();
                UpdateFont ();

                UpdateLineBreakMode ();
                UpdateAlignment ();
            }

            base.OnElementChanged (e);
        }

        protected override void OnElementPropertyChanged (object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged (sender, e);

            if (Control == null)
                return;

            if (e.PropertyName == Xamarin.Forms.Label.HorizontalTextAlignmentProperty.PropertyName)
                UpdateAlignment ();
            else if (e.PropertyName == Xamarin.Forms.Label.VerticalTextAlignmentProperty.PropertyName)
                UpdateAlignment ();
            else if (e.PropertyName == Xamarin.Forms.Label.TextColorProperty.PropertyName)
                UpdateTextColor ();
            else if (e.PropertyName == Xamarin.Forms.Label.FontProperty.PropertyName)
                UpdateFont ();
            else if (e.PropertyName == Xamarin.Forms.Label.TextProperty.PropertyName)
                UpdateText ();
            else if (e.PropertyName == Xamarin.Forms.Label.FormattedTextProperty.PropertyName)
                UpdateText ();
            else if (e.PropertyName == Xamarin.Forms.Label.LineBreakModeProperty.PropertyName)
                UpdateLineBreakMode ();
        }

        protected override void SetBackgroundColor (Xamarin.Forms.Color color)
        {
            Style.BackgroundColor = color.ToOouiColor (Colors.Clear);
        }

        void UpdateAlignment ()
        {
            this.Style.Display = "table";
            Control.Style.Display = "table-cell";
            this.Style.TextAlign = Element.HorizontalTextAlignment.ToOouiTextAlign ();
            Control.Style.VerticalAlign = Element.VerticalTextAlignment.ToOouiVerticalAlign ();
        }

        void UpdateLineBreakMode ()
        {
            _perfectSizeValid = false;
            //switch (Element.LineBreakMode)
            //{
            //    case LineBreakMode.NoWrap:
            //        Control.LineBreakMode = UILineBreakMode.Clip;
            //        Control.Lines = 1;
            //        break;
            //    case LineBreakMode.WordWrap:
            //        Control.LineBreakMode = UILineBreakMode.WordWrap;
            //        Control.Lines = 0;
            //        break;
            //    case LineBreakMode.CharacterWrap:
            //        Control.LineBreakMode = UILineBreakMode.CharacterWrap;
            //        Control.Lines = 0;
            //        break;
            //    case LineBreakMode.HeadTruncation:
            //        Control.LineBreakMode = UILineBreakMode.HeadTruncation;
            //        Control.Lines = 1;
            //        break;
            //    case LineBreakMode.MiddleTruncation:
            //        Control.LineBreakMode = UILineBreakMode.MiddleTruncation;
            //        Control.Lines = 1;
            //        break;
            //    case LineBreakMode.TailTruncation:
            //        Control.LineBreakMode = UILineBreakMode.TailTruncation;
            //        Control.Lines = 1;
            //        break;
            //}
        }

        bool isTextFormatted;
        void UpdateText ()
        {
            _perfectSizeValid = false;

            if (Element.FormattedText != null) {
                Control.Text = Element.Text;
                isTextFormatted = true;
            }
            else {
                Control.Text = Element.Text;
                isTextFormatted = false;
            }
        }

        void UpdateFont ()
        {
            if (isTextFormatted)
                return;
            _perfectSizeValid = false;

            Element.SetStyleFont (Element.FontFamily, Element.FontSize, Element.FontAttributes, Control.Style);
        }

        void UpdateTextColor ()
        {
            if (isTextFormatted)
                return;

            _perfectSizeValid = false;

            var textColor = (Xamarin.Forms.Color)Element.GetValue (Xamarin.Forms.Label.TextColorProperty);

            Control.Style.Color = textColor.ToOouiColor(Xamarin.Forms.Color.Black);
        }
    }
}