如何使用C＃在列表框上繪制水印

Question

是否可以在ListBox上繪制水印文本或圖像，在下面的列表框中，它包含幾個文件擴展名相同的文件（文件類型，在本例中為.abc），所以我想將文件擴展名繪制為水印

任何建議或指導將不勝感激， 謝謝您的時間.. :)

Answer 1

該示例應完全滿足您的需求：

public Form1()
{
  InitializeComponent();

  // Example Item
  listBox1.Items.Add("c:\\Folder1\\example1.abc");
  listBox1.Items.Add("c:\\Folder1\\example2.abc");
  listBox1.Items.Add("c:\\Folder1\\example3.abc");
  listBox1.Items.Add("c:\\Folder1\\example4.abc");
  listBox1.Items.Add("c:\\Folder1\\example5.abc");
  listBox1.Items.Add("c:\\Folder1\\example6.abc");

  // Without this listBox1.DrawItem won't fire
  listBox1.DrawMode = DrawMode.OwnerDrawVariable;

  // Subscribe event
  listBox1.DrawItem += listBox1_DrawItem;
}

private void listBox1_DrawItem(object sender, DrawItemEventArgs e)
{
  // Make sure listbox contains items
  if (listBox1.Items.Count == 0)
    return;

  // In this example ext will be ".abc"
  string ext = Path.GetExtension(listBox1.Items[0].ToString());

  // Draw items
  e.DrawBackground();
  e.DrawFocusRectangle();
  e.Graphics.DrawString(listBox1.Items[e.Index].ToString(), e.Font, SystemBrushes.WindowText, e.Bounds.Location);

  // Transparence
  // 255 = Full Visible
  //  0  = Invisible
  Color clr = Color.FromArgb(20, Color.Red);

  // Modify the position, font and Brush to your need
  e.Graphics.DrawString(ext, SystemFonts.DefaultFont, new SolidBrush(clr), new PointF(200F, 200F));
}