/// <summary>
/// Calculates the size of the window frame and client area of the RichTextBox
/// </summary>
void WmNccalcsize(ref Message m)
{
// let the richtextbox control draw the scrollbar if necessary.
base.WndProc(ref m);
// we visual styles are not enabled and BorderStyle is not Fixed3D then we have nothing more to do.
if (!this.RenderWithVisualStyles())
{
return;
}
// contains detailed information about WM_NCCALCSIZE message
NativeMethods.NCCALCSIZE_PARAMS par = new NativeMethods.NCCALCSIZE_PARAMS();
// contains the window frame RECT
NativeMethods.RECT windowRect;
if (m.WParam == IntPtr.Zero) // LParam points to a RECT struct
{
windowRect = (NativeMethods.RECT)Marshal.PtrToStructure(m.LParam, typeof(NativeMethods.RECT));
}
else // LParam points to a NCCALCSIZE_PARAMS struct
{
par = (NativeMethods.NCCALCSIZE_PARAMS)Marshal.PtrToStructure(m.LParam, typeof(NativeMethods.NCCALCSIZE_PARAMS));
windowRect = par.rgrc0;
}
// contains the client area of the control
NativeMethods.RECT contentRect;
// get the DC
IntPtr hDC = NativeMethods.GetWindowDC(this.Handle);
// open theme data
IntPtr hTheme = NativeMethods.OpenThemeData(this.Handle, "EDIT");
// find out how much space the borders needs
if (NativeMethods.GetThemeBackgroundContentRect(hTheme, hDC, NativeMethods.EP_EDITTEXT, NativeMethods.ETS_NORMAL
, ref windowRect
, out contentRect) == NativeMethods.S_OK)
{
// shrink the client area the make more space for containing text.
contentRect.Inflate(-1, -1);
// remember the space of the borders
this.borderRect = new NativeMethods.RECT(contentRect.Left - windowRect.Left
, contentRect.Top - windowRect.Top
, windowRect.Right - contentRect.Right
, windowRect.Bottom - contentRect.Bottom);
// update LParam of the message with the new client area
if (m.WParam == IntPtr.Zero)
{
Marshal.StructureToPtr(contentRect, m.LParam, false);
}
else
{
par.rgrc0 = contentRect;
Marshal.StructureToPtr(par, m.LParam, false);
}
// force the control to redraw it´s client area
m.Result = new IntPtr(NativeMethods.WVR_REDRAW);
}
// release theme data handle
NativeMethods.CloseThemeData(hTheme);
// release DC
NativeMethods.ReleaseDC(this.Handle, hDC);
}
/// <summary>
/// The border painting is done here.
/// </summary>
void WmNcpaint(ref Message m)
{
base.WndProc(ref m);
if (!this.RenderWithVisualStyles())
{
return;
}
// set the part id to TextBox
int partId = NativeMethods.EP_EDITTEXT;
// set the state id of the current TextBox
int stateId;
if (this.Enabled)
{
if (this.ReadOnly)
{
stateId = NativeMethods.ETS_READONLY;
}
else
{
stateId = NativeMethods.ETS_NORMAL;
}
}
else
{
stateId = NativeMethods.ETS_DISABLED;
}
// define the windows frame rectangle of the TextBox
NativeMethods.RECT windowRect;
NativeMethods.GetWindowRect(this.Handle, out windowRect);
windowRect.Right -= windowRect.Left; windowRect.Bottom -= windowRect.Top;
windowRect.Top = windowRect.Left = 0;
// get the device context of the window frame
IntPtr hDC = NativeMethods.GetWindowDC(this.Handle);
// define a rectangle inside the borders and exclude it from the DC
NativeMethods.RECT clientRect = windowRect;
clientRect.Left += this.borderRect.Left;
clientRect.Top += this.borderRect.Top;
clientRect.Right -= this.borderRect.Right;
clientRect.Bottom -= this.borderRect.Bottom;
NativeMethods.ExcludeClipRect(hDC, clientRect.Left, clientRect.Top, clientRect.Right, clientRect.Bottom);
// open theme data
IntPtr hTheme = NativeMethods.OpenThemeData(this.Handle, "EDIT");
// make sure the background is updated when transparent background is used.
if (NativeMethods.IsThemeBackgroundPartiallyTransparent(hTheme
, NativeMethods.EP_EDITTEXT, NativeMethods.ETS_NORMAL) != 0)
{
NativeMethods.DrawThemeParentBackground(this.Handle, hDC, ref windowRect);
}
// draw background
NativeMethods.DrawThemeBackground(hTheme, hDC, partId, stateId, ref windowRect, IntPtr.Zero);
// close theme data
NativeMethods.CloseThemeData(hTheme);
// release dc
NativeMethods.ReleaseDC(this.Handle, hDC);
// we have processed the message so set the result to zero
m.Result = IntPtr.Zero;
}