我已经使用这个blog 完成了这项工作。
在 PCL 中：创建一个名为 ImageEntry 的类
using System;
using System.Collections.Generic;
using System.Text;
using Xamarin.Forms;
namespace ImageEntry
{
public class ImageEntry1 : Entry
{
public ImageEntry1()
{
this.HeightRequest = 50;
}
public static readonly BindableProperty ImageProperty =
BindableProperty.Create(nameof(Image), typeof(string), typeof(ImageEntry1), string.Empty);
public static readonly BindableProperty LineColorProperty =
BindableProperty.Create(nameof(LineColor), typeof(Xamarin.Forms.Color), typeof(ImageEntry1), Color.White);
public static readonly BindableProperty ImageHeightProperty =
BindableProperty.Create(nameof(ImageHeight), typeof(int), typeof(ImageEntry1), 40);
public static readonly BindableProperty ImageWidthProperty =
BindableProperty.Create(nameof(ImageWidth), typeof(int), typeof(ImageEntry1), 40);
public static readonly BindableProperty ImageAlignmentProperty =
BindableProperty.Create(nameof(ImageAlignment), typeof(ImageAlignment), typeof(ImageEntry1), ImageAlignment.Left);
public Color LineColor
{
get { return (Color)GetValue(LineColorProperty); }
set { SetValue(LineColorProperty, value); }
}
public int ImageWidth
{
get { return (int)GetValue(ImageWidthProperty); }
set { SetValue(ImageWidthProperty, value); }
}
public int ImageHeight
{
get { return (int)GetValue(ImageHeightProperty); }
set { SetValue(ImageHeightProperty, value); }
}
public string Image
{
get { return (string)GetValue(ImageProperty); }
set { SetValue(ImageProperty, value); }
}
public ImageAlignment ImageAlignment
{
get { return (ImageAlignment)GetValue(ImageAlignmentProperty); }
set { SetValue(ImageAlignmentProperty, value); }
}
}
public enum ImageAlignment
{
Left,
Right
}
}
在android中创建一个名为ImageEntryRenderer的类
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.Graphics;
using Android.Graphics.Drawables;
using Android.OS;
using Android.Runtime;
using Android.Support.V4.Content;
using Android.Views;
using Android.Widget;
using ImageEntry;
using ImageEntry.Droid;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
[assembly: ExportRenderer(typeof(ImageEntry1), typeof(ImageEntryRenderer))]
namespace ImageEntry.Droid
{
public class ImageEntryRenderer : EntryRenderer
{
ImageEntry1 element;
public ImageEntryRenderer(Context context) : base(context)
{
}
protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
{
base.OnElementChanged(e);
if (e.OldElement != null || e.NewElement == null)
return;
element = (ImageEntry1)this.Element;
var editText = this.Control;
if (!string.IsNullOrEmpty(element.Image))
{
switch (element.ImageAlignment)
{
case ImageAlignment.Left:
editText.SetCompoundDrawablesWithIntrinsicBounds(GetDrawable(element.Image), null, null, null);
break;
case ImageAlignment.Right:
editText.SetCompoundDrawablesWithIntrinsicBounds(null, null, GetDrawable(element.Image), null);
break;
}
}
editText.CompoundDrawablePadding = 25;
Control.Background.SetColorFilter(element.LineColor.ToAndroid(), PorterDuff.Mode.SrcAtop);
}
private BitmapDrawable GetDrawable(string imageEntryImage)
{
int resID = Resources.GetIdentifier(imageEntryImage, "drawable", this.Context.PackageName);
var drawable = ContextCompat.GetDrawable(this.Context, resID);
var bitmap = ((BitmapDrawable)drawable).Bitmap;
return new BitmapDrawable(Resources, Bitmap.CreateScaledBitmap(bitmap, element.ImageWidth * 2, element.ImageHeight * 2, true));
}
}
}
在IOS中创建一个名为ImageEntryRenderer的类
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using CoreAnimation;
using CoreGraphics;
using Foundation;
using ImageEntry;
using ImageEntry.iOS;
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;
[assembly: ExportRenderer(typeof(ImageEntry1), typeof(ImageEntryRenderer))]
namespace ImageEntry.iOS
{
public class ImageEntryRenderer : EntryRenderer
{
ImageEntry1 element;
public ImageEntryRenderer()
{
}
protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
{
base.OnElementChanged(e);
if (e.OldElement != null || e.NewElement == null)
return;
var element = (ImageEntry1)this.Element;
var textField = this.Control;
if (!string.IsNullOrEmpty(element.Image))
{
switch (element.ImageAlignment)
{
case ImageAlignment.Left:
textField.LeftViewMode = UITextFieldViewMode.Always;
textField.LeftView = GetImageView(element.Image, element.ImageHeight, element.ImageWidth);
break;
case ImageAlignment.Right:
textField.RightViewMode = UITextFieldViewMode.Always;
textField.RightView = GetImageView(element.Image, element.ImageHeight, element.ImageWidth);
break;
}
}
textField.BorderStyle = UITextBorderStyle.None;
CALayer bottomBorder = new CALayer
{
Frame = new CGRect(0.0f, element.HeightRequest - 1, this.Frame.Width, 1.0f),
BorderWidth = 2.0f,
BorderColor = element.LineColor.ToCGColor()
};
textField.Layer.AddSublayer(bottomBorder);
textField.Layer.MasksToBounds = true;
}
private UIView GetImageView(string imagePath, int height, int width)
{
var uiImageView = new UIImageView(UIImage.FromBundle(imagePath))
{
Frame = new RectangleF(0, 0, width, height)
};
UIView objLeftView = new UIView(new System.Drawing.Rectangle(0, 0, width + 10, height));
objLeftView.AddSubview(uiImageView);
return objLeftView;
}
}
}
在 XAML 中添加了入口代码：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:ImageEntry"
BackgroundColor="#2f4259"
x:Class="ImageEntry.MainPage">
<ContentPage.Content>
<ScrollView>
<StackLayout Padding="40" Spacing="10">
<local:ImageEntry1 TextColor="White"
Image="user"
Placeholder="Emil"
HorizontalOptions="FillAndExpand"/>
</StackLayout>
</ScrollView>
</ContentPage.Content>
</ContentPage>
附上here上的示例项目，快乐编码:)