首先看一下效果:
任意控件可以附加一个文字在控件的右上角,并带有红色背景
第一步,新建一个空的wpf项目:
第二步,创建一个类,取名为badge:
第三步,将badge的父类设置成 System.Windows.Documents.Adorner
public class Badge : Adorner
{
public Badge(UIElement adornedElement) : base(adornedElement)
{
}
}
里面的adornedElement表示badge后面附加的对象
关于Adorner这个类的说明,微软给了相应的教程 https://learn.microsoft.com/zh-cn/dotnet/desktop/wpf/controls/adorners-overview?view=netframeworkdesktop-4.8
也可以F11查看Adorner类的说明.
第4步,给badge添加一个Content的附加属性:
public static readonly DependencyProperty ContentProperty;
static Badge()
{
ContentProperty = DependencyProperty.RegisterAttached("Content", typeof(string), typeof(Badge),
new FrameworkPropertyMetadata(string.Empty, new PropertyChangedCallback(ContentChangedCallBack)));
}
public static string GetContent(DependencyObject obj)
{
return (string)obj.GetValue(ContentProperty);
}
public static void SetContent(DependencyObject obj, string value)
{
obj.SetValue(ContentProperty, value);
}
第5步,实现content的回调方法:
private static void ContentChangedCallBack(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var target = d as FrameworkElement;
if (target != null)
{
if (target.IsLoaded)
{
var layer = AdornerLayer.GetAdornerLayer(target);
if (layer != null)
{
var Adorners = layer.GetAdorners(target);
if (Adorners != null)
{
foreach (var adorner in Adorners)
{
if (adorner is Badge)
{
layer.Remove(adorner);
}
}
}
layer.Add(new Badge(target));
}
}
else
{
target.Loaded += (sender, ae) =>
{
var layer = AdornerLayer.GetAdornerLayer(target);
if (layer != null)
{
var Adorners = layer.GetAdorners(target);
if (Adorners != null)
{
foreach (var adorner in Adorners)
{
if (adorner is Badge)
{
layer.Remove(adorner);
}
}
}
layer.Add(new Badge(target));
}
};
}
}
}
第6步,重写一下OnRender方法:
protected override void OnRender(DrawingContext drawingContext)
{
var element = this.AdornedElement as FrameworkElement;
Rect adornedElementRect = new Rect(element.DesiredSize);
var point = adornedElementRect.TopRight;
point.X = adornedElementRect.Right - element.Margin.Left - element.Margin.Right;
SolidColorBrush renderBrush = new SolidColorBrush(Colors.Red);
Pen renderPen = new Pen(new SolidColorBrush(Colors.Red), 0.5);
double renderRadius = 5;
var content = this.AdornedElement.GetValue(Badge.ContentProperty).ToString();
FormattedText formattedText = new FormattedText(content, CultureInfo.GetCultureInfo("zh-cn"), FlowDirection.LeftToRight, new Typeface("Verdana"), 10, Brushes.White);
var textWidth = formattedText.Width;
var textHeight = formattedText.Height;
var rectangleSizeWidth = textWidth < 15 ? 15 : textWidth;
var rectangleSizeHeight = textHeight < 15 ? 15 : textHeight;
var size = new Size(rectangleSizeWidth, rectangleSizeHeight);
Rect rect = new Rect(new Point(point.X - rectangleSizeWidth / 2, point.Y - rectangleSizeHeight / 2), size);
drawingContext.DrawRoundedRectangle(renderBrush, renderPen, rect, renderRadius, renderRadius);
drawingContext.DrawText(formattedText, new Point(point.X - textWidth / 2, point.Y - textHeight / 2));
}
这段代码就是在目标控件的右上角绘制一个带圆角的rectangle,背景色为红色,再绘制一个文本用来显示content.
第7步,运用到项目中:
<StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
<cc:CornerButton ButtonType="OutLine" Width="200" Height="30"
cc:Badge.Content="{Binding ElementName=textbox1, Path=Text, UpdateSourceTrigger=PropertyChanged}" Margin="10"/>
<cc:CornerTextBox x:Name="textbox1" Width="200" Height="30" Text="12"
VerticalContentAlignment="Center" WaterText="BadgeContent"/>
</StackPanel>
cc是表示badge所在的命名空间,然后你就会发现,你改变textbox的值的时候,badge会跟着textbox的值发生变化哦.
项目github地址:bearhanQ/WPFFramework: Share some experience (github.com)
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