显示列表框中的图像 [英] Displaying an image from a list box

问题描述

我有一个下拉列表，其中包含不同的内容.例如:

雨伞
盖帽
衬衫
足球等.

上面可以是列表框的内容.我想做的是，当我单击雨伞时，我想在图像框中显示雨伞的图像.而且我想像列表框项==雨伞那样进行操作，然后应显示雨伞的图像.

但是我做不到！有人可以帮我提供代码吗?

感谢大家的努力:-)

I have a drop down list of different things. For example:

umbrella
cap
shirt
football etc..

The above can be the contents of the list box. What I want to do is that when I click on umbrella, I want to display the image of umbrella in the image box. And I want to do it in the way as if the list box item == umbrella, then the image of umbrella should display.

But I can''t do this! Can some body please help me with the code?

Everybody''s effort is appreciated :-)

推荐答案

以下是一些示例WPF代码:

Here''s some sample WPF code:

<StackPanel Orientation="Vertical">
    <ListBox ItemsSource="{Binding Objects}"

            SelectedIndex="{Binding CurrentIndex}" />
    <Image Source="{Binding ObjectImage}" />
</StackPanel>

这是视图模型(或数据源)中的相应代码:

Here''s the corresponding code in the view-model (or data source) :

public string[] Objects { get; set; }

private int currentIndex;

public int CurrentIndex
{
    get { return currentIndex; }

    set
    {
        if (currentIndex == value)
            return;

        currentIndex = value;
        FirePropertyChanged("CurrentIndex");
        UpdateObjectImage();
    }
}


private ImageSource objectImage;

public ImageSource ObjectImage
{
    get { return objectImage; }

    set
    {
        if (objectImage == value)
            return;

        objectImage = value;
        FirePropertyChanged("ObjectImage");
    }
}

private void UpdateObjectImage()
{
    if (CurrentIndex >= Objects.Length)
        return;

    this.ObjectImage = GetImage(Objects[CurrentIndex]);
}

private ImageSource GetImage(string name)
{
    BitmapImage image = new BitmapImage();
    image.BeginInit();
    image.UriSource = new Uri(
      String.Format(
        "pack://application:,,,/YourWpfApplicationName;component/{0}.png",
        name));
    image.EndInit();
    return image;
}

通过对我以前对Hanifuk的答复的评论作出澄清后，答案非常不同:

首先，您需要为项目创建一些类以存储在列表中.您的需求意味着它具有双重目的:在列表中显示一些文本，并提供图像显示信息.假设这是图像文件名(可能更复杂；这仅是示例).要在列表中显示该项目，您需要它来覆盖object.ToString():

Very different answer after clarification by the comment on my previous Answer by Hanifuk:

First, you need to create some class for an item to store in the list. You requirements mean that it serve dual purpose: to show some text in the list and also to provide information for image presentation. Let''s assume this is image file name (could be more complex; this is just for example). To show this item in the list, all you need it to override object.ToString():

internal class ListItemHelper {
    internal ListItemHelper(string itemText, string imageFileName) {
        this.ItemText = itemText;
        this.FImageFileName = imageFileName;
    } //ListItemHelper
    public override string ToString() {
        return ItemText;
    } //object.ToString()
    internal string ImageFileName { get {return FImageFileName;} }
    private string ItemText, FImageFileName;
} //class ListItemHelper

使用此类将信息添加到您的列表中:

Use this class to add information to your list:

MyList.Add(new ListItemHelper("First day of vacation", "2010-06-01-1343.jpg"));
//item will show int the list: First day of vacation

现在，您需要设置一个处理程序以选择列表中的项目:

Now you need to setup a handler for selection of the item in your list:

void ShowMyPicture(string source) {
/*...*/
//should be able to handle null as "nothing selected"
} //ShowMyPicture

//...

MyList.SelectionChanged += (sender, eventArgs) => {
   //you know the sender is your list box, so not afraid of the cast:
   ListBox listBox = (ListBox)sender;
   //you know the item is alway ListItemHelper, so not afraid of the cast:
   if (listBox.SelectedItem == null)
       ShowMyPicture(null);
   else {
       ListItemHelper helper = (ListItemHelper)listBox.SelectedItem;
       ShowMyPicture(helper.ImageFileName); //you probaly know what to do
   } //if
}; //MyList.SelectionChanged handler

就这样.

—SA

That''s it.

—SA

您几乎可以根据需要添加到列表项:

You can add to list items practically whatever you want:

MyList.Items.Add(MyImage);

—SA

—SA

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