Question

textbox在c#中怎么添加背景图片

Answer 1

如果是winForm的建议自己写空间  从textbox继承 下面是代码，如果是web我就不会了

=======================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);
        }

Answer 2

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);
}