Question

我想在WPF中创建一个简单的UserControl，如下所示：一个图像（比方说128x128），上面有另一个图像，更小（48x48）。我们称它们为imgMain和imgOverlay（小的）。

现在我想将UserControl放在任何WPF应用程序中，并能够更改图像及其大小。我在我的usercontrol中放了两个属性，很高兴看到它们在VS2010设计器中以正确的形式出现。但是当我尝试使用设计器放置图像时，控件不会刷新并保持白色。如果我尝试在运行时从代码中执行它，那就相同。

我阅读了几篇关于DependencyProperties和所有（我并不熟悉的东西）的帖子，但他们似乎总是希望在图像变化时有更多的逻辑。我想要的东西非常简单，只有视觉效果。

以下是我为这些属性所做的事情：

叠加层的大小

public Size OverlaySize
{
   get
   {
      return new Size(imgOverlay.Width, imgOverlay.Height);
   }
   set
   {
      imgOverlay.Width = value.Width;
      imgOverlay.Height = value.Height;
   }
}

主要和叠加的图像

public Image ImageMain
{
    get
    {
        return imgMain;
    }
    set
    {
        imgMain = value;
    }
}

public Image ImageOverlay
{
    get
    {
        return imgOverlay;
    }
    set
    {
        imgOverlay = value;
    }
}

Answer 1

你真的必须去做整个DependencyProperty舞蹈。对于那个很抱歉。 WPF引入了自己的事件系统，它自己的属性系统并让你使用它。我一开始觉得很困惑。然后只是单调乏味。等等......我会看看能不能为你挖出一些相似的代码...

行。这个小类用作图像控件，根据绑定的值显示不同的图像...

xaml代码：

<UserControl x:Class="DesignPerformanceViewer.Controls.BooleanImage"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300">
    <Grid>
       <Image Name="image" Height="11" VerticalAlignment="Center" HorizontalAlignment="Center" SnapsToDevicePixels="True"/>
    </Grid>
</UserControl>

整个DependencyProperty舞蹈背后的代码......

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.ComponentModel;

namespace DesignPerformanceViewer.Controls
{
    /// <summary>
    /// Interaction logic for BooleanImage.xaml
    /// </summary>
    public partial class BooleanImage : UserControl
    {
        private static readonly DependencyProperty TrueSourceProperty = DependencyProperty.Register("TrueSource", typeof(ImageSource), typeof(BooleanImage));
        private static readonly DependencyProperty TrueToolTipProperty = DependencyProperty.Register("TrueToolTip", typeof(string), typeof(BooleanImage));
        private static readonly DependencyProperty FalseSourceProperty = DependencyProperty.Register("FalseSource", typeof(ImageSource), typeof(BooleanImage));
        private static readonly DependencyProperty FalseToolTipProperty = DependencyProperty.Register("FalseToolTip", typeof(string), typeof(BooleanImage));
        private static readonly DependencyProperty ValueProperty = DependencyProperty.Register("Value", typeof(bool), typeof(BooleanImage),
            new PropertyMetadata(false, new PropertyChangedCallback(OnValuePropertyChanged), new CoerceValueCallback(OnValueCoerceValueCallback)),
            new ValidateValueCallback(OnValueValidateValueCallback));

        public ImageSource TrueSource {  get { return (ImageSource)GetValue(TrueSourceProperty); } 
            set 
            { 
                SetValue(TrueSourceProperty, value);
            } 
        }
        public ImageSource FalseSource { get { return (ImageSource)GetValue(FalseSourceProperty); } set { SetValue(FalseSourceProperty, value); } }
        public string TrueToolTip { get { return (string)GetValue(TrueToolTipProperty); } set { SetValue(TrueToolTipProperty, value); } }
        public string FalseToolTip { get { return (string)GetValue(FalseToolTipProperty); } set { SetValue(FalseToolTipProperty, value); } }
        public bool Value 
        { 
            get { return (bool)GetValue(ValueProperty); } 
            set 
            { 
                SetValue(ValueProperty, value);
            } 
        }

        public BooleanImage()
        {
            InitializeComponent();
        }

        private static void OnValuePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var self = (BooleanImage) d;
            var newValue = (bool) e.NewValue;
            self.image.Source = newValue ? self.TrueSource : self.FalseSource;
            self.ToolTip = newValue ? self.TrueToolTip : self.FalseToolTip;
        }       

        private static object OnValueCoerceValueCallback(DependencyObject d, object baseValue)
        {
            if (!(baseValue is bool))
            {
                return false;
            }
            var boolValue = (bool) baseValue;
            var self = (BooleanImage)d;
            self.image.Source = boolValue ? self.TrueSource : self.FalseSource;
            self.ToolTip = boolValue ? self.TrueToolTip : self.FalseToolTip;
            return boolValue;
        }
        private static bool OnValueValidateValueCallback(object value)
        {
            return true;
        }
    }
}

usercontrol中的图像属性

1 个答案: