protected override void OnPaint(PaintEventArgs e)
{
if (!PInvoke.VisualStylesEnabled())
{
base.OnPaint(e);
return;
}
IntPtr hTheme = PInvoke.OpenThemeData(Handle, "Button");
if (hTheme == IntPtr.Zero)
{
base.OnPaint(e);
return;
}
SizeF sz;
// Text needs to be measured here because e.Graphics will soon be tied up with GetHdc()
if (Text != null && Text.Length > 0)
{
sz = e.Graphics.MeasureString(Text, Font, DisplayRectangle.Width - 17, StringFormat.GenericDefault);
}
else
{
sz = new SizeF(); // have to set sz or else compiler will complain
}
// You'd think the height should be (Height - (Font.Height/2)), but using full Height gives a size consistent with FlatStyle.System XP GroupBox'es
PInvoke.Rect rBounds = new PInvoke.Rect(0, Font.Height / 2, Width, Height);
PInvoke.Rect rClip = new PInvoke.Rect(e.Graphics.VisibleClipBounds);
IntPtr hDC = e.Graphics.GetHdc();
PInvoke.DrawThemeBackground(hTheme, hDC, PInvoke.BP_GROUPBOX, (Enabled ? PInvoke.GBS_NORMAL : PInvoke.GBS_DISABLED),
ref rBounds, ref rClip);
if (Text != null && Text.Length > 0)
{
RectangleF rText = new RectangleF(7, 0, sz.Width + 3.2F, sz.Height);
PInvoke.Rect wrText = new PInvoke.Rect(rText);
// Redraw the background over the border where text will be displayed
if (BackColor == Color.Transparent)
{
PInvoke.DrawThemeParentBackground(Handle, hDC, ref wrText);
e.Graphics.ReleaseHdc(hDC);
}
else
{
e.Graphics.ReleaseHdc(hDC);
using (SolidBrush sb = new SolidBrush(BackColor))
e.Graphics.FillRectangle(sb, rText);
}
Color textColor;
if (Enabled)
{
PInvoke.ColorRef rColor = new PInvoke.ColorRef();
PInvoke.GetThemeColor(hTheme, PInvoke.BP_GROUPBOX, PInvoke.GBS_NORMAL, PInvoke.TMT_TEXTCOLOR, ref rColor);
textColor = rColor.ToColor();
}
else // GetThemeColor (... GBS_DISABLED ...) always returns the default color - so use GrayText
{
textColor = SystemColors.GrayText;
}
rText.Inflate(-0.8F, 0); rText.Offset(0.4F, 0);
using (SolidBrush sb = new SolidBrush(textColor))
e.Graphics.DrawString(Text, Font, sb, rText, StringFormat.GenericDefault);
}
else
{
e.Graphics.ReleaseHdc(hDC);
}
PInvoke.CloseThemeData(hTheme);
}