Xamarin.Forms – ListView – CustomTextCell

This project, you can find at: https://github.com/officialdoniald/Xamarin.Forms.CustomControls

We have to create some platforms specific code (custom NavigationPage Renderer), because in the base Xamarin.Forms code, we can’t find this implementation. So first step, we have to create a class in the .NET Standard/PCL project: CustomTextCell ( https://github.com/officialdoniald/Xamarin.Forms.CustomControls/blob/master/XamarinForms.CustomControls/XamarinForms.CustomControls/ListView/CustomTextCell.cs ).

using Xamarin.Forms;

namespace XamarinForms.CustomControls.ListView

{

public class CustomTextCell : TextCell

{

public static readonly BindableProperty TextFontSizeProperty =

BindableProperty.Create(“TextFontSize”, typeof(double), typeof(CustomTextCell), default(double));

public static readonly BindableProperty DetailFontSizeProperty =

BindableProperty.Create(“DetailFontSize”, typeof(double), typeof(CustomTextCell), default(double));

public static readonly BindableProperty TextFontAttributesProperty =

BindableProperty.Create(“TextFontAttributes”, typeof(Enums.FontAttributes), typeof(CustomTextCell), default(Enums.FontAttributes));

public static readonly BindableProperty TextFontFamilyProperty =

BindableProperty.Create(“TextFontFamily”, typeof(string), typeof(CustomTextCell), default(string));

public static readonly BindableProperty DetailFontAttributesProperty =

BindableProperty.Create(“DetailFontAttributes”, typeof(Enums.FontAttributes), typeof(CustomTextCell), default(Enums.FontAttributes));

public static readonly BindableProperty DetailFontFamilyProperty =

BindableProperty.Create(“DetailFontFamily”, typeof(string), typeof(CustomTextCell), default(string));

/// <summary>

/// Set the Text font size.

/// </summary>

public double TextFontSize

{

get { return (double)GetValue(TextFontSizeProperty); }

set { SetValue(TextFontSizeProperty, value); }

}

/// <summary>

/// Set the Detail font size.

/// </summary>

public double DetailFontSize

{

get { return (double)GetValue(DetailFontSizeProperty); }

set { SetValue(DetailFontSizeProperty, value); }

}

/// <summary>

/// Set the Font Attributes of the Text.

/// </summary>

public Enums.FontAttributes TextFontAttributes

{

get { return (Enums.FontAttributes)GetValue(TextFontAttributesProperty); }

set { SetValue(TextFontAttributesProperty, value); }

}

/// <summary>

/// Set the Font Family of the Text.

/// </summary>

public string TextFontFamily

{

get { return (string)GetValue(TextFontFamilyProperty); }

set { SetValue(TextFontFamilyProperty, value); }

}

/// <summary>

/// Set the Font Attributes of the Detail.

/// </summary>

public Enums.FontAttributes DetailFontAttributes

{

get { return (Enums.FontAttributes)GetValue(DetailFontAttributesProperty); }

set { SetValue(DetailFontAttributesProperty, value); }

}

/// <summary>

/// Set the Font Family of the Detail.

/// </summary>

public string DetailFontFamily

{

get { return (string)GetValue(DetailFontFamilyProperty); }

set { SetValue(DetailFontFamilyProperty, value); }

}

}

}

Enums.FontAttributes is a custtom enum class, we can create it, but we can skip it too. You can find it at: https://github.com/officialdoniald/Xamarin.Forms.CustomControls/blob/master/XamarinForms.CustomControls/XamarinForms.CustomControls/Enums/HelperEnums.cs

Now we have to implement the platform spec. code at the various platforms.

Let’s begin with the Android site ( https://github.com/officialdoniald/Xamarin.Forms.CustomControls/blob/master/XamarinForms.CustomControls/XamarinForms.CustomControls.Android/CustomRenderer/CustomTextCellRenderer.cs ):

First, we have to implement the base class’s contructor:

public CustomTextCellRenderer() : base() { }

public CustomTextCellRenderer(System.IntPtr a, Android.Runtime.JniHandleOwnership b) : base() { }

Then we have to override the GetCellCore base function:

protected override Android.Views.View GetCellCore(Cell item, Android.Views.View convertView, ViewGroup parent, Android.Content.Context context) {

var view = (CustomTextCell)item;

if (convertView == null)

{

convertView = new BaseCellView(context, item);

}

if (convertView is BaseCellView cellView)

{

cellView.SetImageVisible(false);

cellView.MainText = view.Text;

cellView.DetailText = view.Detail;

cellView.SetMainTextColor(view.TextColor);

cellView.SetDetailTextColor(view.DetailColor);

var control = ((LinearLayout)convertView);

if (control.GetChildAt(1) is LinearLayout linearLayout)

{

var mainTextView = (TextView)linearLayout.GetChildAt(0);

var detailTextView = (TextView)linearLayout.GetChildAt(1);

mainTextView.TextSize = (float)view.TextFontSize;

detailTextView.TextSize = (float)view.DetailFontSize;

var titleTypeface = Typeface.Create(view.TextFontFamily, ConvertFontAttributesToTypefaceStyle(view.TextFontAttributes));

var detailTypeface = Typeface.Create(view.DetailFontFamily, ConvertFontAttributesToTypefaceStyle(view.DetailFontAttributes));

mainTextView.Typeface = titleTypeface;

detailTextView.Typeface = detailTypeface;

}

}

return _cellCore = convertView;

}

If we implement the custom FontAttribute enum, we have to create the ConvertFontAttributesToTypefaceStyle() function:

private TypefaceStyle ConvertFontAttributesToTypefaceStyle(Enums.FontAttributes fontAttributes) {

if (fontAttributes == Enums.FontAttributes.Bold)

{

return Android.Graphics.TypefaceStyle.Bold;

}

else if (fontAttributes == Enums.FontAttributes.BoldItalic)

{

return Android.Graphics.TypefaceStyle.BoldItalic;

}

else if (fontAttributes == Enums.FontAttributes.Italic)

{

return Android.Graphics.TypefaceStyle.Italic;

}

else return Android.Graphics.TypefaceStyle.Normal;

}

Let’s continue with the iOS site ( https://github.com/officialdoniald/Xamarin.Forms.CustomControls/blob/master/XamarinForms.CustomControls/XamarinForms.CustomControls.iOS/CustomRenderer/CustomTextCellRenderer.cs ):

The mechanism is the same, but we don’t need to implement the base class’s constructors, but we need to override the GetCell() function:

using Foundation; using UIKit;

using Xamarin.Forms;

using Xamarin.Forms.Platform.iOS;

using XamarinForms.CustomControls.iOS.CustomRenderer;

using XamarinForms.CustomControls.ListView;

[assembly: ExportRenderer(typeof(CustomTextCell), typeof(CustomTextCellRenderer))]

namespace XamarinForms.CustomControls.iOS.CustomRenderer

{

public class CustomTextCellRenderer : TextCellRenderer

{

public override UITableViewCell GetCell(Cell item, UITableViewCell reusableCell, UITableView tv)

{

var view = (CustomTextCell)item;

var cell = base.GetCell(item, reusableCell, tv);

//cell.SelectedBackgroundView = new UIView { BackgroundColor = UIColor.Red };

var TextLabel = cell.TextLabel;

var DetailTextLabel = cell.DetailTextLabel;

TextLabel.Font = UIFont.FromName(view.TextFontFamily, (int)view.TextFontSize);

DetailTextLabel.Font = UIFont.FromName(view.DetailFontFamily, (int)view.DetailFontSize);

TextLabel.AttributedText = ConvertAttributes(TextLabel.Text, view.TextFontAttributes, (int)view.TextFontSize);

DetailTextLabel.AttributedText = ConvertAttributes(DetailTextLabel.Text, view.DetailFontAttributes, (int)view.DetailFontSize);

return cell;

}

private NSMutableAttributedString ConvertAttributes(string text, Enums.FontAttributes attr, int size)

{

if (attr == Enums.FontAttributes.Bold)

{

return new NSMutableAttributedString(

str: text,

font: UIFont.BoldSystemFontOfSize(size)

);

}

else if (attr == Enums.FontAttributes.Italic)

{

return new NSMutableAttributedString(

str: text,

font: UIFont.ItalicSystemFontOfSize(size)

);

}

//else if (attr == Enums.FontAttributes.BoldItalic)

//{

// var textattr = new NSMutableAttributedString(

// str: text,

// font: UIFont.BoldSystemFontOfSize(size)

// );

// textattr.Append(new NSMutableAttributedString(

// str: text,

// font: UIFont.ItalicSystemFontOfSize(size)

// ));

// return textattr;

//}

else

{

return new NSMutableAttributedString(

str: text,

font: UIFont.SystemFontOfSize(size)

);

}

}

}

}