如何动态更改/设置checkedListBox项前颜色

Question

我有下面的代码.我如何设置checkListBox项目前颜色取决于是否选中项目？

private void FindSelectedUserRoles()
{
        lblSelectedUser.Text = Code.CommonUtilities.getDgvStringColValue(dataGridViewUserList, "UserName").Trim();

        //iterate all roles selected user is member of
        for (int i = 0; i < checkedListRoles.Items.Count; i++)
        {
            string roleName = checkedListRoles.Items[i].ToString();
            string selectedUserRoles = Code.MemberShipManager.GetSpecificUsersRoles(lblSelectedUser.Text.Trim());

            if (selectedUserRoles.Contains(roleName))
            {
                checkedListRoles.SetItemChecked(i, true);
                //here i want to set item fore colour to green

            }
            else if (selectedUserRoles.Contains(roleName) == false)
            {
                checkedListRoles.SetItemChecked(i, false);
                //and here, i want item fore colour to remain black
            }
        }
}

Answer 1

由于自己绘制东西相当复杂，您实际上可以让原始控件自行绘制 - 只需调整颜色即可。这是我的建议：

public class CustomCheckedListBox : CheckedListBox
{
    protected override void OnDrawItem(DrawItemEventArgs e)
    {
        Color foreColor;
        if (e.Index >= 0)
        {
            foreColor = GetItemChecked(e.Index) ? Color.Green : Color.Red;
        }
        else
        {
            foreColor = e.ForeColor;
        }

        // Copy the original event args, just tweaking the fore color.
        var tweakedEventArgs = new DrawItemEventArgs(
            e.Graphics,
            e.Font,
            e.Bounds,
            e.Index,
            e.State,
            foreColor,
            e.BackColor);

        // Call the original OnDrawItem, but supply the tweaked color.
        base.OnDrawItem(tweakedEventArgs);
    }
}

Answer 2

我认为您应该尝试ListView而不是checkedListBox。它具有必要的属性，可以根据需要进行自定义。只需将Checkboxesproperty 设置为true，然后在代码中像这样添加前色：

listView1.Items[i].ForeColor = Color.Red;

Answer 3

我认为您必须这样绘制自己的图像CheckedListBox item：

public class CustomCheckedListBox : CheckedListBox
{
    public CustomCheckedListBox()
    {
        DoubleBuffered = true;
    }
    protected override void OnDrawItem(DrawItemEventArgs e)
    {            
        Size checkSize = CheckBoxRenderer.GetGlyphSize(e.Graphics, System.Windows.Forms.VisualStyles.CheckBoxState.MixedNormal);
        int dx = (e.Bounds.Height - checkSize.Width)/2;
        e.DrawBackground();
        bool isChecked = GetItemChecked(e.Index);//For some reason e.State doesn't work so we have to do this instead.
        CheckBoxRenderer.DrawCheckBox(e.Graphics, new Point(dx, e.Bounds.Top + dx), isChecked ? System.Windows.Forms.VisualStyles.CheckBoxState.CheckedNormal : System.Windows.Forms.VisualStyles.CheckBoxState.UncheckedNormal);
        using (StringFormat sf = new StringFormat { LineAlignment = StringAlignment.Center })
        {
            using (Brush brush = new SolidBrush(isChecked ? CheckedItemColor : ForeColor))
            {
                e.Graphics.DrawString(Items[e.Index].ToString(), Font, brush, new Rectangle(e.Bounds.Height, e.Bounds.Top, e.Bounds.Width - e.Bounds.Height, e.Bounds.Height), sf);
            }
        }            
    }
    Color checkedItemColor = Color.Green;
    public Color CheckedItemColor
    {
        get { return checkedItemColor; }
        set
        {
            checkedItemColor = value;
            Invalidate();
        }
    }
}

如果要CheckedColor为每个项目设置不同的CheckedColor设置，则必须存储每个项目的设置（例如在Collection中）并参考CheckedColorusing Index。但是，我认为这需要做很多工作。因此，如果您有这样的要求，ListView那就去做会更好。