c#winform - textbox控件添加背景图片

 

===========================从textbox类继承处理绘制背景消息====================    class MyTextBox : TextBox    {        const int WM_ERASEBKGND = 0x0014;        private Image backImage;        [DisplayName("背景图片。")]        public Image BackImage        {            get { return backImage; }            set { backImage = value; }        }        protected void OnEraseBkgnd(Graphics gs)        {            gs.FillRectangle(Brushes.White, 0, 0, this.Width, this.Height); //填充为白色，防止图片太小出现重影            if (backImage != null) gs.DrawImage(backImage, 0, 0); //绘制背景。            gs.Dispose();        }        protected override void WndProc(ref Message m)        {            if (m.Msg == WM_ERASEBKGND) //绘制背景            {                OnEraseBkgnd(Graphics.FromHdc(m.WParam));                m.Result = (IntPtr)1;            }            base.WndProc(ref m);        }    }==================窗口类里设置控件的字体颜色等=============================        const int WM_CTLCOLOREDIT = 0x0133;        const int TRANSPARENT = 0x1;        const int NULL_BRUSH = 0x5;        [DllImport("gdi32")]        static extern int SetBkMode(IntPtr hdc, int bkMode);        [DllImport("gdi32")]        static extern int SetTextColor(IntPtr hdc, int color);        [DllImport("gdi32")]        static extern IntPtr GetStockObject(int fnobject);        protected override void WndProc(ref Message m)        {            if (m.Msg == WM_CTLCOLOREDIT && m.LParam == myTextBox1.Handle)//类型为EDIT(TextBox)            {                SetBkMode(m.WParam, TRANSPARENT);//设置背景透明                SetTextColor(m.WParam,0xFF);     //字体颜色为红色                m.Result = GetStockObject(NULL_BRUSH);                return;            }            else base.WndProc(ref m);        }