wpf 如何7步写一个badge控件-编程知识

wpf 如何7步写一个badge控件

news/2024/11/13 10:51:18/文章来源:https://www.cnblogs.com/lvpp13/p/18354811

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>