winfrom实现模拟点击下拉框

创建下拉框控件

ComboBox comboBox1 = new ComboBox();
comboBox1.Items.Add("选项1");
comboBox1.Items.Add("选项2");
comboBox1.Items.Add("选项3");
comboBox1.Location = new Point(10, 10);
this.Controls.Add(comboBox1);

模拟鼠标点击下拉箭头

[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern void mouse_event(uint dwFlags, uint dx, uint dy, uint cButtons, uint dwExtraInfo);

private const uint MOUSEEVENTF_LEFTDOWN = 0x02;
private const uint MOUSEEVENTF_LEFTUP = 0x04;

private void button1_Click(object sender, EventArgs e)
{
    // 获取下拉箭头位置
    Point point = new Point(comboBox1.Right - 15, comboBox1.Bottom - 15);
    // 模拟鼠标点击下拉箭头
    mouse_event(MOUSEEVENTF_LEFTDOWN | MOUSEEVENTF_LEFTUP, (uint)point.X, (uint)point.Y, 0, 0);
}

模拟鼠标点击下拉项

private const uint MOUSEEVENTF_MOVE = 0x0001;
private const uint MOUSEEVENTF_ABSOLUTE = 0x8000;
private const uint MOUSEEVENTF_LEFTDOWN = 0x0002;
private const uint MOUSEEVENTF_LEFTUP = 0x0004;

private void button2_Click(object sender, EventArgs e)
{
    // 获取下拉项位置
    Point point = comboBox1.PointToScreen(new Point(5, 5));
    // 模拟鼠标点击下拉项
    mouse_event(MOUSEEVENTF_MOVE | MOUSEEVENTF_ABSOLUTE, (uint)(65535 * point.X / Screen.PrimaryScreen.Bounds.Width), (uint)(65535 * point.Y / Screen.PrimaryScreen.Bounds.Height), 0, 0);
    mouse_event(MOUSEEVENTF_LEFTDOWN | MOUSEEVENTF_LEFTUP, 0, 0, 0, 0);
}

注意：在模拟鼠标点击下拉项时，需要将下拉框控件的位置转换为屏幕坐标。