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Xamarin.Forms — Borderless Editor Using Custom Renderer

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Xamarin.Forms — Borderless Editor Using Custom Renderer

Custom renderers let Xamarin.Forms apps keep a native look and feel. Learn how to use them to set up a borderless editor feature.

· Mobile Zone ·
Free Resource

Introduction

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Xamarin.Forms code runs on multiple platforms, each of which has its own filesystem. This means that reading and writing files are the most easily done tasks using native file APIs on each platform. Alternatively, embedded resources are also a simpler solution to distribute the data files with an app.

Custom Renderers

Xamarin.Forms user interfaces are rendered using the native controls of the target platform, allowing Xamarin.Forms applications to retain the appropriate look and feel for each platform. Custom Renderers let developers override this process to customize the appearance and behavior of Xamarin.Forms controls on each platform. Read the docs for more information.

Prerequisites

  • Visual Studio 2017 (Windows or Mac)

Setting Up a Xamarin.Forms Project

Start by creating a new Xamarin.Forms project. You’ll learn more by going through the steps yourself.

Choose the  Cross-platform App project under Visual C#-->Cross-platform in the New Project dialog.

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Now select the Blank App and choose Portable Class Library(PCL).

Subsequently, go to the solution. In there, you get all the files and sources of your project (PCL). Now, select XAML page and double-click to open the MainPage.Xaml page.

You now have a basic Xamarin.Forms app. Click the Play button to try it out.

In this step, create a default Editor control with a border.

Now, write the following code:

MainPage.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:XamarinFormsEditor"
             x:Class="XamarinFormsEditor.MainPage">
    <ContentPage.Content>
        <StackLayout>
            <StackLayout HorizontalOptions="CenterAndExpand" VerticalOptions="StartAndExpand">
                <Image  x:Name="imgBanner" HeightRequest="300" WidthRequest="300"></Image>
                <Editor Text="Enter Some text here..." HeightRequest="100" BackgroundColor="LightGray"></Editor>
            </StackLayout>
        </StackLayout>
    </ContentPage.Content>
</ContentPage>


Click the Play button to try it out:

Image title

Create a Custom Editor

Now, create an Inherit class form Editor to customize the Editor control.

Go to Solution—>PCL—>Right click—>New—>Class—>XEditor.cs.

Now, write the following code:

XEditor.cs

using Xamarin.Forms;
namespace XamarinFormsEditor.Controls
{
    public class XEditor:Editor
    {
    }
}


Making Your Android Implementation

Create an inherit Class form, EditorRenderer, for customizing the Editor control.

Go to Solution.Droid—>Class—> XEditorRenderer.cs.

Now, write the code given below:

XEditorRenderer.cs

using Xamarin.Forms;
using XamarinFormsEditor.Controls;
using XamarinFormsEditor.Droid.Helpers;
using Xamarin.Forms.Platform.Android;
using Android.Graphics.Drawables;

[assembly: ExportRenderer(typeof(XEditor), typeof(XEditorRenderer))]
namespace XamarinFormsEditor.Droid.Helpers
{
    public class XEditorRenderer: EditorRenderer
    {
        protected override void OnElementChanged(ElementChangedEventArgs<Editor> e)
        {
            base.OnElementChanged(e);
            if (Control != null)
            {
                Control.Background = new ColorDrawable(Android.Graphics.Color.Transparent);
            }
        }
    }
}


Setting Up the User Interface

Now, add a Customized Editor control to your app. Go to MainPage.Xaml and write the following code:

MainPage.Xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:XamarinFormsEditor"
             xmlns:Controls="clr-namespace:XamarinFormsEditor.Controls"
             x:Class="XamarinFormsEditor.MainPage">
    <ContentPage.Content>
        <StackLayout>
            <StackLayout HorizontalOptions="CenterAndExpand" VerticalOptions="StartAndExpand">
                <Image  x:Name="imgBanner" HeightRequest="300" WidthRequest="300"></Image>
                <Controls:XEditor Text="Enter Some text here..." HeightRequest="100" BackgroundColor="LightGray"></Controls:XEditor>
            </StackLayout>
        </StackLayout>
    </ContentPage.Content>
</ContentPage>


Go to MainPage.Xaml.cs and write the following code (optional):

MainPage.Xaml.cs

using Xamarin.Forms;

namespace XamarinFormsEditor
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            imgBanner.Source = ImageSource.FromResource("XamarinFormsEditor.images.banner.png");
        }
    }
}


Click the Play button to try it out:

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I hope you understand how to create a borderless editor using custom renderers.

Thanks for reading. Please share comments and feedback.

Topics:
xamarin ,mobile app development ,mobile ,cross platform development ,tutorial

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