图像未出现在所选项目组合框中

Question

我创建了一个显示图像的组合框，但所选项目的图像没有出现。

我从路径获取图像并将它们保存在一个数组中。这是代码：

private void popolaDivise()
        {

            Image[] images = System.IO.Directory.GetFiles("divise\")
                        .Select(file => System.Drawing.Image.FromFile(file))
                        .ToArray();
            cmbDivisaGruppo.DisplayImages(images);
            cmbDivisaGruppo.DropDownHeight = 200;
        }

displayImages是自定义class的一个方法叫ComboBoxTools，我报代码：

public static class ComboBoxTools
    {
        // Margins around owner drawn ComboBoxes.
        private const int MarginWidth = 4;
        private const int MarginHeight = 4;

        #region Display Images

        // Set up the ComboBox to display images.
        public static void DisplayImages(this ComboBox cbo, Image[] images)
        {
            // Make the ComboBox owner-drawn.
            cbo.DrawMode = DrawMode.OwnerDrawVariable;

            // Add the images to the ComboBox's items.
            //cbo.Items.Clear();
            foreach (Image image in images) cbo.Items.Add(image);

            // Subscribe to the DrawItem event.
            cbo.MeasureItem += cboDrawImage_MeasureItem;
            cbo.DrawItem += cboDrawImage_DrawItem;
        }

        // Measure a ComboBox item that is displaying an image.
        private static void cboDrawImage_MeasureItem(object sender, MeasureItemEventArgs e)
        {
            if (e.Index < 0) return;

            // Get this item's image.
            ComboBox cbo = sender as ComboBox;
            Image img = (Image)cbo.Items[e.Index];
            e.ItemHeight = img.Height + 2 * MarginHeight;
            e.ItemWidth = img.Width + 2 * MarginWidth;
        }

        // Draw a ComboBox item that is displaying an image.
        private static void cboDrawImage_DrawItem(object sender, DrawItemEventArgs e)
        {
            if (e.Index < 0) return;

            // Clear the background appropriately.
            e.DrawBackground();

            // Draw the image.
            ComboBox cbo = sender as ComboBox;
            Image img = (Image)cbo.Items[e.Index];
            int hgt = e.Bounds.Height - 2 * MarginHeight;
            float scale = hgt / img.Height;
            float wid = img.Width * scale;
            RectangleF rect = new RectangleF(
                e.Bounds.X + MarginWidth,
                e.Bounds.Y + MarginHeight,
                wid, hgt);
            e.Graphics.InterpolationMode = InterpolationMode.HighQualityBilinear;
            e.Graphics.DrawImage(img, rect);

            // Draw the color's name to the right.
            using (Font font = new Font(cbo.Font.FontFamily,
                cbo.Font.Size * 0.85f))
            {
                using (StringFormat sf = new StringFormat())
                {
                    string[] colori = new string[] { "Nero", "Rosso", "Bianco", "Arancione", "Giallo", "Verde", "Azzurro", "Verde chiaro", "Blu", "Blu scuro" };
                    sf.Alignment = StringAlignment.Near;
                    sf.LineAlignment = StringAlignment.Center;
                    int x = hgt + 2 * MarginWidth;
                    int y = e.Bounds.Y + e.Bounds.Height / 2;
                    e.Graphics.TextRenderingHint = TextRenderingHint.AntiAliasGridFit;
                    e.Graphics.DrawString(colori[e.Index], font,
                        Brushes.Black, x, y, sf);
                }
            }

            // Draw the focus rectangle if appropriate.
            e.DrawFocusRectangle();
        }

        #endregion Display Images
    }

如何显示与所选项目关联的图像？

Answer 1

您可以使用以下方法在您的组合框中查找事件：

ComboBoxSelectedIndexChanged()
{
   // find image of selected index by parsing the name : 
   switch(Combobox.selectedValue)
   {
      case "Nero": …
      case "Rosso": …

   // draw your image here
}

您必须为该函数定义一个名称并将其绑定到 ComboBox.SelectedIndexChanged 事件。

图像未出现在所选项目组合框中

Image does not appear in selected item combobox

c#

combobox

winforms