//通过文本输入框 对比度调节
        private void textBox_Contrast_TextChanged(object sender, EventArgs e)
        {
            if (this.ActiveControl != sender)
            {
                return;
            }

            if (textBox_Contrast.Text == "")
            {
                return;
            }

            int contrast = Convert.ToInt32(textBox_Contrast.Text);

            trackBar_Contrast.Value = contrast;
            MvApi.CameraSetContrast(m_hCamera, contrast);
        }