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)
        {
            if (!_perfectSizeValid) {
                _perfectSize = GetPerfectSize ();
                _perfectSize.Minimum = new Size (Math.Min (10, _perfectSize.Request.Width), _perfectSize.Request.Height);
                _perfectSizeValid = true;
            }

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

            if (widthFits && heightFits)
                return _perfectSize;

            var result = base.GetDesiredSize (widthConstraint, heightConstraint);
            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;
        }

        SizeRequest GetPerfectSize ()
        {
            return new SizeRequest (new Size (100, 22));
        }

        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 (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)
        {
            if (color == Xamarin.Forms.Color.Default)
                Style.BackgroundColor = Colors.Clear;
            else
                Style.BackgroundColor = color.ToOouiColor();
        }

        void UpdateAlignment ()
        {
            Control.Style.TextAlign = Element.HorizontalTextAlignment.ToOouiTextAlign ();
            Control.Style.VerticalAlign = Element.VerticalTextAlignment.ToOouiTextAlign ();
        }

        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;

            var values = Element.GetValues (Xamarin.Forms.Label.FormattedTextProperty, Xamarin.Forms.Label.TextProperty, Xamarin.Forms.Label.TextColorProperty);
            var formatted = values[0] as FormattedString;
            if (formatted != null) {
                Control.Text = (string)values[1];
                isTextFormatted = true;
            }
            else {
                Control.Text = (string)values[1];
                isTextFormatted = false;
            }
        }

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

            Element.SetStyleFont (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);
        }
    }
}