如何从WPF中的多分辨率.ico文件中选择正确的大小图标？

问题描述

如果我有一个多分辨率图标文件（.ico），我怎样才能确保WPF选择合适尺寸的文件？设置Image的宽度和高度是否会强制它，或者WPF是否只调整ico文件中的第一个图标？

If I have a multi-resolution icon file (.ico), how can I insure that WPF picks the right sized one? Does setting the width and height of the Image force it, or does WPF simply resize the first icon in the ico file?

这是我目前正在使用的（它有效，但我想避免调整大小，如果这是正在发生的事情。）

This is what I'm using currently (it works, but I'd like to avoid the resizing if that's what's happening).

<MenuItem.Icon>
    <Image Source="MyIcons.ico" Width="16" Height="16"  />
</MenuItem.Icon>

如果可能，我想在Xaml中声明这一点，而无需为其编码。

I'd like to declare this in Xaml if possible without having to code for it.

推荐答案

我使用简单的标记扩展：

I use simple Markup Extension for that:

/// <summary>
/// Simple extension for icon, to let you choose icon with specific size.
/// Usage sample:
/// Image Stretch="None" Source="{common:Icon /Controls;component/icons/custom.ico, 16}"
/// Or:
/// Image Source="{common:Icon Source={Binding IconResource}, Size=16}"
/// </summary>
public class IconExtension : MarkupExtension
{
    private string _source;

    public string Source
    {
        get
        {
            return _source;
        }
        set
        {
            // Have to make full pack URI from short form, so System.Uri recognizes it.
           _source = "pack://application:,,," + value;
        }
    }

    public int Size { get; set; }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        var decoder = BitmapDecoder.Create(new Uri(Source),
                                           BitmapCreateOptions.DelayCreation,
                                           BitmapCacheOption.OnDemand);

        var result = decoder.Frames.SingleOrDefault(f => f.Width == Size);
        if (result == default(BitmapFrame))
        {
            result = decoder.Frames.OrderBy(f => f.Width).First();
        }

        return result;
    }

    public IconExtension(string source, int size)
    {
        Source = source;
        Size = size;
    }

    public IconExtension() { }
}

Xaml用法：

<Image Stretch="None"
       Source="{common:Icon Source={Binding IconResource},Size=16}"/>

或

<Image Stretch="None"
       Source="{common:Icon /ControlsTester;component/icons/custom-reports.ico, 16}" />

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