TabControl.DrawItem not firing on user painted TabControl

问题

Hey, I've been trying to paint my own TabControl to get rid of the 3D Shadow but I am not having much success. The DrawItem event isn't firing at the moment. Do I have to shoot it myself? How do I do that?

Code:

namespace NCPad
{
    public partial class NCE_TabControl : TabControl
    {
        Rectangle TabBoundary;
        RectangleF TabTextBoundary;

        public NCE_TabControl()
        {
            InitializeComponent();
            this.SetStyle(ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint | ControlStyles.DoubleBuffer, true);
            this.DrawMode = TabDrawMode.OwnerDrawFixed;
            this.Paint += new PaintEventHandler(this.OnPaint);
            this.DrawItem += new DrawItemEventHandler(this.OnDrawItem);
        }

        protected void OnPaint(object sender, PaintEventArgs e)
        {
            Graphics g = e.Graphics;
            g.FillRectangle(new SolidBrush(Color.Red), e.ClipRectangle);
        }

        protected void OnDrawItem(object sender, DrawItemEventArgs e)
        {
            Graphics g = e.Graphics;
            g.FillRectangle(new SolidBrush(Color.Blue), this.TabBoundary);
            MessageBox.Show("hi");
        }

        protected override void OnLayout(LayoutEventArgs levent)
        {
            base.OnLayout(levent);

            this.TabBoundary = this.GetTabRect(0);
            this.TabTextBoundary = (RectangleF)this.GetTabRect(0);
        }
    }
}

回答1:

I'm not sure on this, but I believe if you specify the ControlStyles.UserPaint bit to true, then the DrawItem won't fire. The other ControlStyles (AllPaintingInWmPaint and DoubleBuffer) have dependencies on each other, though, so you would need to leave them off as well. However, not setting the UserPaint bit to true will result in the Paint event not getting fired. What I have been doing is overriding the OnPaintBackground method:

public partial class NCE_TabControl : TabControl
{
    Rectangle TabBoundary;
    RectangleF TabTextBoundary;
    StringFormat format = new StringFormat(); //for tab header text

    public NCE_TabControl()
    {   InitializeComponent();         
        this.SetStyle(ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint | ControlStyles.DoubleBuffer, true);
        this.DrawMode = TabDrawMode.OwnerDrawFixed;
        this.format.Alignment = StringAlignment.Center;
        this.format.LineAlignment = StringAlignment.Center;
    }

    protected override void OnPaintBackground(PaintEventArgs pevent)
    {
        Graphics g = pevent.Graphics;
        g.FillRectangle(new SolidBrush(Color.Red), 0, 0, this.Size.Width, this.Size.Height);

        foreach (TabPage tp in this.TabPages)
        {
            //drawItem
            int index = this.TabPages.IndexOf(tp);

            this.TabBoundary = this.GetTabRect(index);
            this.TabTextBoundary = (RectangleF)this.GetTabRect(index);

            g.FillRectangle(new SolidBrush(Color.LightBlue), this.TabBoundary);
            g.DrawString("tabPage " + index.ToString(), this.Font, new SolidBrush(Color.Black), this.TabTextBoundary, format);
        }
    }
}

I think this will work for you, but there may be other methods of doing it as well.

回答2:

In order to get DrawItem event fired, set DrawMode = OwnerDrawFixed on the Tab Control http://msdn.microsoft.com/en-us/library/system.windows.forms.tabcontrol.drawitem.aspx

回答3:

One simple way is to change the TabControl's Appearance property to either Buttons or FlatButtons and set the DrawMode badk to Normal.

来源：https://stackoverflow.com/questions/3115321/tabcontrol-drawitem-not-firing-on-user-painted-tabcontrol

标签

winforms

tabcontrol