Question

我是WPF和MVVM的新手，我有以下问题

我有3个按钮
当我点击一个按钮时，它会获得CommandParameter，例如：0,1
命令SetBackGround将CommandParameter拆分为提取行和列
现在，我尝试使用具有条件的IsSelected和Background来设置Background
问题是......当我点击所有按钮时，它们设置了黄色Background，但我只需要具有正确条件的按钮，所以..

我是否需要为每个按钮设置不同的背景，或者是否存在其他方式？

谁说..如果这个条件“参数”将背景设置为黄色，其他 - 则不是。

图片

视图模型

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Windows.Input;
using Testing00.Commands;

namespace Testing00.ViewModels
{
    public class ViewModel : INotifyPropertyChanged
    {

        public ICommand SetBackGroundCommand { get; set; }
        bool LeftSelected { get; set; }
        bool RightSelected { get; set; }

        #region Methods
        int row;
        public int Row
        {
            get { return row; }
            set { row = value; }
        }

        int column;
        public int Column
        {
            get { return column; }
            set { column = value; }
        }

        public bool IsSelected
        {
            get
            {
                if (row == 0 && column == 0)
                {
                    return false;
                }
                else
                {

                    return true;
                }
            }
            set
            {
                OnPropertyChanged("IsSelected");
                OnPropertyChanged("Background");
            }
        }

        public string Background
        {
            get
            {
                return IsSelected ? "Yellow" : "Transparent";
            }
        }

        #endregion


        #region Constructor

        public ViewModel()
        {
            SetBackGroundCommand = new RelayCommand(SetBackGround, param => true);
        }

        #endregion

        private void SetBackGround(object obj)
        {
            string[] commandParametters = obj.ToString().Split(',');
            Row = Convert.ToInt32(commandParametters[0]);
            Column = Convert.ToInt32(commandParametters[1]);
            OnPropertyChanged("IsSelected");
            OnPropertyChanged("BackGround");
        }

        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }

    }
}

MainWindows

<Window x:Class="Testing00.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:TEST="clr-namespace:Testing00.ViewModels"
        xmlns:local="clr-namespace:Testing00"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <TEST:ViewModel x:Key="testVM"></TEST:ViewModel>
    </Window.Resources>
    <Grid>
        <Button Content="0,0" HorizontalAlignment="Left" Margin="84,109,0,0" VerticalAlignment="Top" Width="79" Height="81"    CommandParameter="0,0" Command="{Binding SetBackGroundCommand, Source={StaticResource testVM}}" Background="{Binding Background, Mode=OneWay, Source={StaticResource testVM}}"    />
        <Button Content="0,1" HorizontalAlignment="Left" Margin="208,109,0,0" VerticalAlignment="Top" Width="79" Height="81" CommandParameter="0,1" Command="{Binding SetBackGroundCommand, Source={StaticResource testVM}}"  Background="{Binding Background, Mode=OneWay, Source={StaticResource testVM}}" />
        <Button Content="0,2" HorizontalAlignment="Left" Margin="341,109,0,0" VerticalAlignment="Top" Width="79" Height="81"  CommandParameter="0,2" Command="{Binding SetBackGroundCommand, Source={StaticResource testVM}}"  Background="{Binding Background, Mode=OneWay, Source={StaticResource testVM}}" />
    </Grid>
</Window>

RelayCommand

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace Testing00.Commands
{
    public class RelayCommand : ICommand
    {

        Action<object> _execute;
        Func<object, bool> _canexecute;
        public RelayCommand(Action<object> execute, Func<object, bool> canexecute)
        {
            _execute = execute;
            _canexecute = canexecute;

        }
        public bool CanExecute(object parameter)
        {
            if (_canexecute != null)
            {
                return _canexecute(parameter);
            }
            else
            {
                return false;
            }
        }

        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        public void Execute(object parameter)
        {
            _execute(parameter);
        }
    }
}

Answer 1

粗略地说，并且只显示很少的代码（如果你查找ItemsControl，你可以找到更多代码），你可以像 grek40 那样说。

您的按钮将是一个usercontrol（ucMyButton），具有自己的viewmodel及其属性。

在主视图中，您将添加ItemControl，它将包含一组按钮（ObservableCollection<MyButtonViewModel> MyButtons { ..... }）

然后每个MyButtonViewModel将是一个单独的按钮，具有自己的Background属性，因此每个按钮可以单独设置

<ItemsControl x:Name="itmWrapPanel" 
            ItemsSource="{Binding MyButtons, UpdateSourceTrigger=PropertyChanged}"  

            ScrollViewer.CanContentScroll="True"
            ScrollViewer.VerticalScrollBarVisibility="Auto"
            ScrollViewer.HorizontalScrollBarVisibility="Auto"
            >
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <WrapPanel Orientation="Horizontal"  
                    Background="White" 
                    AllowDrop="True" 
                    Width="{Binding ActualWidth, ElementName=itmWrapPanel}" 
                    Height="{Binding ActualHeight, ElementName=itmWrapPanel}"  />
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>

    <ItemsControl.ItemTemplate>
        <DataTemplate  >
            <local:ucMyButton  />

        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>

是否可以使用相同的命令进行相对绑定？

1 个答案: