为 winforms ComboBox 中的单个项目着色? [英] Colour Individual Items in a winforms ComboBox?

问题描述

我有一个两难选择，我有一个包含许多组合框的表单，其中包含在某些情况下可能无效/过时的信息/选项/项目.

I have a dilemma whereby I have a form which contains a number of comboboxes that contain information/options/items that may be invalid/out-of-date in certain circumstances.

我不能简单地从项目中删除过时的信息，但我确实希望在选项无效时为用户提供视觉线索.

I can't simply remove the out-of-date information from the items, but I do want to give the user a visual-clue when options are invalid.

我想在项目中着色(可能是红色)以表明是否 &当它们无效时.我不一定需要阻止用户选择无效选项，只需让他们在视觉上意识到他们正在这样做.

I was thinking of colouring in the Items (probably red) to indicate if & when they are invalid. I don't necessarily need to prevent a user from selecting an invalid option, just make them visually aware that they are doing so.

这能做到吗?你能 - 动态地 - 改变组合框项目的颜色吗?

Can this be done? Can you - dyamically - change the colo(u)r of combobox items?

谢谢，

推荐答案

你可以试试 ComboBox 的 DrawItem 事件.将您的日期列在清单上，并将它们与 ID 进行比较，然后刷您的项目.

You may try DrawItem event of ComboBox. Keep your dates on a list and compare them with ID's and brush your items.

private void comboBox1_DrawItem(object sender, DrawItemEventArgs e)
{    
    // Draw the background 
    e.DrawBackground();        

    // Get the item text    
    string text = ((ComboBox)sender).Items[e.Index].ToString();

    // Determine the forecolor based on whether or not the item is selected    
    Brush brush;
    if (YourListOfDates[e.Index] < DateTime.Now)// compare  date with your list.  
    {
        brush = Brushes.Red;
    }
    else
    {
        brush = Brushes.Green;
    }

    // Draw the text    
    e.Graphics.DrawString(text, ((Control)sender).Font, brush, e.Bounds.X, e.Bounds.Y);
}

触发此事件(感谢@Bolu)

To fire this event (thanks to @Bolu)

你需要改变 ComboBox.DrawMode到 OwnerDrawFixed/OwnerDrawVariable 到触发 comboBox_DrawItem

You need to change ComboBox.DrawMode to OwnerDrawFixed/OwnerDrawVariable to fire the comboBox_DrawItem

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