从字典更改名称到友好名称的Winform绑定下拉列表

Question

Using .net 4.0 I have a win form combobox where I am binding from a dictionary, this is working fine. However, I would like to change the name of what the user sees in the dropdown.

For example.. I would like the dropdown to say 10%, 20%, 30% ... 100%.

Here is my class that has the percentages and respective height values.

    enum SizeType : int
    {
        Height_10_Pct = 40,
        Height_20_Pct = 80,
        Height_30_Pct = 120,
        Height_40_Pct = 160,
        Height_50_Pct = 200,
        Height_60_Pct = 240,
        Height_70_Pct = 280,
        Height_80_Pct = 320,
        Height_90_Pct = 360,
        Height_100_Pct = 400)
    }

Creating the dictionary item

    public static Dictionary<string, int> ThumbSizeOptions = new Dictionary<string, int>(BuildThumbSizeOptions());

    public static Dictionary<string, int> BuildThumbSizeOptions()
    {
        ThumbSizeOptions = new Dictionary<string, int>();    
        foreach (SizeType val in Enum.GetValues(typeof(SizeType)))
        {
            ThumbSizeOptions.Add(val.ToString(), (int)((val)));
        }
        return ThumbSizeOptions;
    }

Code to bind in the combo box in the Win Form:

     ddlThumbSize.DataSource = new BindingSource(ThumbSizePref.ThumbSizeOptions, null);
     ddlThumbSize.DisplayMember = "Key";
     ddlThumbSize.ValueMember = "Value";

Thank you in advance.

Answer 1

Try the ListControl.Format event: ( ComboBox is a ListControl )

ddlThumbSize.Format += (s, e) => {
   e.Value += " %";
};

Answer 2

1. In your particular case you can simply use String.Format("{0}%", ((int)val) >> 2) as a key in the Dictionary :

    ThumbSizeOptions.Add(String.Format("{0}%", ((int)val) >> 2), (int)val); 

2. More general way is to use a custom attribute. Code for you:

    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property | AttributeTargets.Method)] public sealed class EnumDisplayNameAttribute : Attribute { public readonly string Displayname; public EnumDisplayNameAttribute(string displayname) { Displayname = displayname; } public static EnumDisplayNameAttribute Get<T>(T item) { FieldInfo member = typeof(T).GetField(item.ToString()); if (member == null) return null; object[] attrs = member.GetCustomAttributes(typeof(EnumDisplayNameAttribute), true); return attrs.Length == 0 ? null : attrs[0] as EnumDisplayNameAttribute; } } enum SizeType : int { [EnumDisplayName("10%")] Height_10_Pct = 40, [EnumDisplayName("20%")] Height_20_Pct = 80, [EnumDisplayName("30%")] Height_30_Pct = 120, [EnumDisplayName("40%")] Height_40_Pct = 160, [EnumDisplayName("50%")] Height_50_Pct = 200, [EnumDisplayName("60%")] Height_60_Pct = 240, [EnumDisplayName("70%")] Height_70_Pct = 280, [EnumDisplayName("80%")] Height_80_Pct = 320, [EnumDisplayName("90%")] Height_90_Pct = 360, [EnumDisplayName("100%")] Height_100_Pct = 400 } public static Dictionary<string, int> ThumbSizeOptions = new Dictionary<string, int>(BuildThumbSizeOptions()); public static Dictionary<string, int> BuildThumbSizeOptions() { ThumbSizeOptions = new Dictionary<string, int>(); foreach (SizeType val in Enum.GetValues(typeof(SizeType))) { ThumbSizeOptions.Add(EnumDisplayNameAttribute.Get(val).Displayname, (int)val); } return ThumbSizeOptions; } 

Answer 3

In your BuildThumbSizeOptions() you can calculate your comboxbox values like this:

public static Dictionary<string, int> BuildThumbSizeOptions()
{
    ThumbSizeOptions = new Dictionary<string, int>();

    var max = (double)SizeType.Height_100_Pct;
    foreach (int val in Enum.GetValues(typeof(SizeType)))
    {
        double perc = 100.0 / max * (double)val;
        ThumbSizeOptions.Add(perc + "%", val);
    }
    return ThumbSizeOptions;
}

The way you do it now has no dynamic.

Extending this function you can throw away your static enum SizeType and use only one variable which holds the maximum (100%) height.

public static double MAXIMUM_HEIGHT = 400.0;
public static Dictionary<string, int> BuildThumbSizeOptions()
{
    ThumbSizeOptions = new Dictionary<string, int>();

    for (int perc = 10; perc <= 100; perc += 10)
    {
        var size = MAXIMUM_HEIGHT / 100.0 * perc;
        ThumbSizeOptions.Add(perc + "%", (int)size);
    }
    return ThumbSizeOptions;
}

Hope it helps although there are other answers ;-)