UserPaint a TextBox - issue with WM_PRINT

[Bob Dankert]

I am creating a custom textbox that requires me to handle the OnPaint
mechanism. Currently, I am using WM_PRINT to draw the text in the textbox
and am running into a problem. The text will never follow the font that is
specified by the textbox, it is always the same no matter what I change it
to. Is there some way to get WM_PRINT to use the font that the textbox is
set with?

I stripped down the code for my class to the following to show the issue:
using System;
using System.Windows.Forms;
namespace TransTextBox
{
public class MyTextBox : TextBox
{
public MyTextBox()
{
this.SetStyle(ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint |
ControlStyles.DoubleBuffer | ControlStyles.SupportsTransparentBackColor,
true);
}
protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
{
System.IntPtr hdc = e.Graphics.GetHdc();
this.SetStyle(ControlStyles.UserPaint, false);
try
{
const Int32 WM_PRINT = 0x0317;
const long PRF_CLIENT = 0x00000004;
Message m = Message.Create(this.Handle, WM_PRINT, hdc, new
System.IntPtr(PRF_CLIENT));
this.WndProc(ref m);
}
catch { }
finally
{
e.Graphics.ReleaseHdc(hdc);
this.SetStyle(ControlStyles.UserPaint, true);
}
}
}
}

I appreciate any help - thanks.

Bob Dankert

 

[Bob Dankert]

I'm not really sure how the code seems similar?? After looking at that code
sample, it seems like it is creating bitmaps to display everything - I
didn't see any mention of WM_PRINT.

The code is certainly creative as far as accomplishing a transparent
textbox, though.

Anyways, I'm still having the same issue.

Bob

 

[Jeffrey Tan[MSFT]]

Hi Bob,

Thanks for your post.

Yes, I can reproduce out your problem on my side with your code snippet.

If we use Reflector to view Control.Font property, we can see the root
cause:

public virtual void set_Font([MarshalAs(UnmanagedType.CustomMarshaler,
MarshalType="", MarshalTypeRef=typeof(Control.ActiveXFontMarshaler),
MarshalCookie="")] Font value)
{
Font font1 = (Font) this.Properties.GetObject(Control.PropFont);
Font font2 = this.Font;
bool flag1 = false;
if (value == null)
{
if (font1 != null)
{
flag1 = true;
}
}
else if (font1 == null)
{
flag1 = true;
}
else
{
flag1 = !value.Equals(font1);
}
if (flag1)
{
this.Properties.SetObject(Control.PropFont, value);
if
(this.Properties.ContainsObject(Control.PropFontHandleWrapper))
{
this.Properties.SetObject(Control.PropFontHandleWrapper,
null);
}
if (!font2.Equals(value))
{
if
(this.Properties.ContainsInteger(Control.PropFontHeight))
{
this.Properties.SetInteger(Control.PropFontHeight,
(value == null) ? -1 : value.Height);
}
this.OnFontChanged(EventArgs.Empty);
}
else if (this.IsHandleCreated &&
!this.GetStyle(ControlStyles.UserPaint))
{
this.SendMessage(0x30, this.FontHandle, 0);
}
}
}
Yes, in the last line, Winform code determines if UserPaint is enabled. If
it is true, it will not send 0x30(WM_SETFONT) message to refresh the
painting.

For this issue, we can explicitly send a 0x30(WM_SETFONT) message to enable
the font. Like this:

[DllImport("user32.dll", CharSet=CharSet.Auto)]
public static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr
wParam, IntPtr lParam);

protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
{
SendMessage(this.Handle, 0x30, this.Font.ToHfont(), IntPtr.Zero);
System.IntPtr hdc = e.Graphics.GetHdc();
this.SetStyle(ControlStyles.UserPaint, false);
try
{
const Int32 WM_PRINT = 0x0317;
const long PRF_CLIENT = 0x00000004;
Message m = Message.Create(this.Handle, WM_PRINT, hdc, new
System.IntPtr(PRF_CLIENT));
this.WndProc(ref m);
}
catch { }
finally
{
e.Graphics.ReleaseHdc(hdc);
this.SetStyle(ControlStyles.UserPaint, true);
}
}
This works well on my side.

Additionally, if you want to do the painting ourselves, please refer to the
link below:
"27.15 When I set a TextBox to Readonly or set Enabled to false, the text
color is gray. How can I force it to be the color specified in the
ForeColor property of the TextBox."
http://www.syncfusion.com/FAQ/WindowsForms/FAQ_c94c.aspx

Hope this helps
================================================================
Thank you for your patience and cooperation. If you have any questions or
concerns, please feel free to post it in the group. I am standing by to be
of assistance.

Best regards,
Jeffrey Tan
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.

 

[Bob Dankert]

Thanks a lot for the help, Jeffrey. I never realized you could view the
code of the framework - this is definately nice to know! Out of curiousity,
which tools did you use to view the code of the Font property?

Thanks,

Bob

Hi Bob,

Thanks for your post.

Yes, I can reproduce out your problem on my side with your code snippet.

If we use Reflector to view Control.Font property, we can see the root
cause:

public virtual void set_Font([MarshalAs(UnmanagedType.CustomMarshaler,
MarshalType="", MarshalTypeRef=typeof(Control.ActiveXFontMarshaler),
MarshalCookie="")] Font value)
{
Font font1 = (Font) this.Properties.GetObject(Control.PropFont);
Font font2 = this.Font;
bool flag1 = false;
if (value == null)
{
if (font1 != null)
{
flag1 = true;
}
}
else if (font1 == null)
{
flag1 = true;
}
else
{
flag1 = !value.Equals(font1);
}
if (flag1)
{
this.Properties.SetObject(Control.PropFont, value);
if
(this.Properties.ContainsObject(Control.PropFontHandleWrapper))
{
this.Properties.SetObject(Control.PropFontHandleWrapper,
null);
}
if (!font2.Equals(value))
{
if
(this.Properties.ContainsInteger(Control.PropFontHeight))
{
this.Properties.SetInteger(Control.PropFontHeight,
(value == null) ? -1 : value.Height);
}
this.OnFontChanged(EventArgs.Empty);
}
else if (this.IsHandleCreated &&
!this.GetStyle(ControlStyles.UserPaint))
{
this.SendMessage(0x30, this.FontHandle, 0);
}
}
}
Yes, in the last line, Winform code determines if UserPaint is enabled. If
it is true, it will not send 0x30(WM_SETFONT) message to refresh the
painting.

For this issue, we can explicitly send a 0x30(WM_SETFONT) message to
enable
the font. Like this:

[DllImport("user32.dll", CharSet=CharSet.Auto)]
public static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr
wParam, IntPtr lParam);

protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
{
SendMessage(this.Handle, 0x30, this.Font.ToHfont(), IntPtr.Zero);
System.IntPtr hdc = e.Graphics.GetHdc();
this.SetStyle(ControlStyles.UserPaint, false);
try
{
const Int32 WM_PRINT = 0x0317;
const long PRF_CLIENT = 0x00000004;
Message m = Message.Create(this.Handle, WM_PRINT, hdc, new
System.IntPtr(PRF_CLIENT));
this.WndProc(ref m);
}
catch { }
finally
{
e.Graphics.ReleaseHdc(hdc);
this.SetStyle(ControlStyles.UserPaint, true);
}
}
This works well on my side.

Additionally, if you want to do the painting ourselves, please refer to
the
link below:
"27.15 When I set a TextBox to Readonly or set Enabled to false, the text
color is gray. How can I force it to be the color specified in the
ForeColor property of the TextBox."
http://www.syncfusion.com/FAQ/WindowsForms/FAQ_c94c.aspx

Hope this helps
================================================================
Thank you for your patience and cooperation. If you have any questions or
concerns, please feel free to post it in the group. I am standing by to be
of assistance.

Best regards,
Jeffrey Tan
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.

 

[Lloyd Dupont]

I see you've got your answer!

Anyway here is where is the WM_PRINT message in
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
switch (m.Msg)
{
case Win32.WM_PAINT:
myPaintedFirstTime = true;
if (!myUpToDate || !myCaretUpToDate)
GetBitmaps(); =========>>>> Win32.CaptureWindow(this, myBitmap);
.......

 

[Jeffrey Tan[MSFT]]

Hi Bob,

I am glad I can help you. Actually, I got the "source code" from Reflector.
Reflector is a decompiler which decompiles the IL code in assembly into
C#, VB.net or any other high level .net language.

So we can use it to view the .Net Framework source code with it. It is
definitely a must have tool for .Net developer. You can get this tool from
http://www.aisto.com/roeder/dotnet/

Hope this helps

Best regards,
Jeffrey Tan
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.

 

[Bob Dankert]

Lloyd - I only see the code handling the WM_PAINT (paint, not print) message in that code???
I see you've got your answer!

Anyway here is where is the WM_PRINT message in
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
switch (m.Msg)
{
case Win32.WM_PAINT:
myPaintedFirstTime = true;
if (!myUpToDate || !myCaretUpToDate)
GetBitmaps(); =========>>>> Win32.CaptureWindow(this, myBitmap);
.......

 

[Lloyd Dupont]

as you see in WM_PAINT there is a call to GetBitmaps().
I write (as an hint) GetBimtap next to it.
That means, if you look in the code of GetBitmap() you will see it callls Win32.CaptureWindow() that send the WM_PRINT message to the control.

On top of that code "handle" WM_PAINT, yes, but how do you think it *actually* does the painting?
By "sending" WM_PRINT to the win32 control, hey!



Lloyd - I only see the code handling the WM_PAINT (paint, not print) message in that code???
I see you've got your answer!

Anyway here is where is the WM_PRINT message in
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
switch (m.Msg)
{
case Win32.WM_PAINT:
myPaintedFirstTime = true;
if (!myUpToDate || !myCaretUpToDate)
GetBitmaps(); =========>>>> Win32.CaptureWindow(this, myBitmap);
.......