Prev: Adding Edit Control to MainFrame.
Next: MFC application and Load DLL
From: David Ching on 21 Apr 2010 01:13
"Lewis Z." <lzhou8(a)gmail.com> wrote in message
news:2463fe87-ed85-49fd-9779-bea17da4612c(a)c36g2000yqm.googlegroups.com...
> Joe, thanks for the reply. I handled the drawing of the background
> image in the EraseBackground msg handler. After I figured out the
> WM_DISPLAYCHANGE, I called RedrawWindow in this msg handler. It didn't
> help all the time. Sometimes I still saw the missing image.
>

It's perfectly fine to be drawing your image in OnEraseBkgnd(). But by
chance did you cache the rect of the image? The rect would need to be
recomputed when the display is changed. Also, try calling Invalidate()
instead of RedrawWindow().


> I have basic OnPaint function, meaning it just calling
> CDialog:OnPaint(). I commented out my OnPaint function. Now the
> background image is diaplayed all the time whenever the display
> setting is changed. But new problem shows up. Calling SetDlgItemText()
> is causing problems. It shows some garbled texts unless screen is
> refreshed. (I have a timer periodically displaying texts with null
> brush to show transparent texts.)
>

Oh if you're using transparent brushes, all bets are off, since there is no
way to erase the current contents when the area needs to be repainted from
scratch. The way to start from scratch is to do ShowWindow(SW_HIDE);
followed by ShowWindow(SW_SHOW) on the offending dialog controls.

-- David

From: Lewis Z. on 21 Apr 2010 10:28
On Apr 21, 12:13 am, "David Ching" <d...(a)remove-this.dcsoft.com>
wrote:
> "Lewis Z." <lzh...(a)gmail.com> wrote in message
>
> news:2463fe87-ed85-49fd-9779-bea17da4612c(a)c36g2000yqm.googlegroups.com...
>
> > Joe, thanks for the reply. I handled the drawing of the background
> > image in the EraseBackground msg handler. After I figured out the
> > WM_DISPLAYCHANGE, I called RedrawWindow in this msg handler. It didn't
> > help all the time. Sometimes I still saw the missing image.
>
> It's perfectly fine to be drawing your image in OnEraseBkgnd().  But by
> chance did you cache the rect of the image?  The rect would need to be
> recomputed when the display is changed.  Also, try calling Invalidate()
> instead of RedrawWindow().

No, I don't. Neither I know how to do the caching. I tried
Invalidate() in OnDisplaySettingChanged(), and I didn't see any
changes.

>
> > I have basic OnPaint function, meaning it just calling
> > CDialog:OnPaint(). I commented out my OnPaint function. Now the
> > background image is diaplayed all the time whenever the display
> > setting is changed. But new problem shows up. Calling SetDlgItemText()
> > is causing problems. It shows some garbled texts unless screen is
> > refreshed. (I have a timer periodically displaying texts with null
> > brush to show transparent texts.)
>
> Oh if you're using transparent brushes, all bets are off, since there is no
> way to erase the current contents when the area needs to be repainted from
> scratch.  The way to start from scratch is to do ShowWindow(SW_HIDE);
> followed by ShowWindow(SW_SHOW) on the offending dialog controls.
>

For the string display, I want to make them transparent and also no-
flicker. Right now I set an blank string first and then set the string
I want to display. It seems to solve the issue. But I still see
garbled texts intermittently.

> -- David

Thank you.
From: Joseph M. Newcomer on 21 Apr 2010 10:51
See below...
On Wed, 21 Apr 2010 07:28:05 -0700 (PDT), "Lewis Z." <lzhou8(a)gmail.com> wrote:

>On Apr 21, 12:13�am, "David Ching" <d...(a)remove-this.dcsoft.com>
>wrote:
>> "Lewis Z." <lzh...(a)gmail.com> wrote in message
>>
>> news:2463fe87-ed85-49fd-9779-bea17da4612c(a)c36g2000yqm.googlegroups.com...
>>
>> > Joe, thanks for the reply. I handled the drawing of the background
>> > image in the EraseBackground msg handler. After I figured out the
>> > WM_DISPLAYCHANGE, I called RedrawWindow in this msg handler. It didn't
>> > help all the time. Sometimes I still saw the missing image.
>>
>> It's perfectly fine to be drawing your image in OnEraseBkgnd(). �But by
>> chance did you cache the rect of the image? �The rect would need to be
>> recomputed when the display is changed. �Also, try calling Invalidate()
>> instead of RedrawWindow().
>
>No, I don't. Neither I know how to do the caching. I tried
>Invalidate() in OnDisplaySettingChanged(), and I didn't see any
>changes.
>
>>
>> > I have basic OnPaint function, meaning it just calling
>> > CDialog:OnPaint(). I commented out my OnPaint function. Now the
>> > background image is diaplayed all the time whenever the display
>> > setting is changed. But new problem shows up. Calling SetDlgItemText()
>> > is causing problems. It shows some garbled texts unless screen is
>> > refreshed. (I have a timer periodically displaying texts with null
>> > brush to show transparent texts.)
>>
>> Oh if you're using transparent brushes, all bets are off, since there is no
>> way to erase the current contents when the area needs to be repainted from
>> scratch. �The way to start from scratch is to do ShowWindow(SW_HIDE);
>> followed by ShowWindow(SW_SHOW) on the offending dialog controls.
>>
>
>For the string display, I want to make them transparent and also no-
>flicker. Right now I set an blank string first and then set the string
>I want to display. It seems to solve the issue. But I still see
>garbled texts intermittently.
****
In general, you should not be using SetDlgItemText, but instead creating control member
variables and calling SetWindowText on those variables.

Also, you did not say if these are edit controls or static controls; you just said "string
display" which is not meaningful. Edit controls do not support SetBkMode(TRANSPARENT). I
have not done this with static controls so I can't suggest what has gone wrong, but there
are numerous internal bugs in these controls (for example: Microsoft, instead of doing an
Invalidate() and letting WM_PAINT be sent, internally "optimizes" the behavior by directly
calling the text-drawing subroutine, which is a colossally stupid move, since it presumes
that the OnPaint has not been overridden. But this is what you expect when you put
critical software decisions in the hands of beginners without adult supervision.
joe
****
>
>> -- David
>
>Thank you.
Joseph M. Newcomer [MVP]
email: newcomer(a)flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
From: Lewis Z. on 21 Apr 2010 11:16
On Apr 21, 9:51 am, Joseph M. Newcomer <newco...(a)flounder.com> wrote:
> See below...
>
>
>
>
>
> On Wed, 21 Apr 2010 07:28:05 -0700 (PDT), "Lewis Z." <lzh...(a)gmail.com> wrote:
> >On Apr 21, 12:13 am, "David Ching" <d...(a)remove-this.dcsoft.com>
> >wrote:
> >> "Lewis Z." <lzh...(a)gmail.com> wrote in message
>
> >>news:2463fe87-ed85-49fd-9779-bea17da4612c(a)c36g2000yqm.googlegroups.com....
>
> >> > Joe, thanks for the reply. I handled the drawing of the background
> >> > image in the EraseBackground msg handler. After I figured out the
> >> > WM_DISPLAYCHANGE, I called RedrawWindow in this msg handler. It didn't
> >> > help all the time. Sometimes I still saw the missing image.
>
> >> It's perfectly fine to be drawing your image in OnEraseBkgnd().  But by
> >> chance did you cache the rect of the image?  The rect would need to be
> >> recomputed when the display is changed.  Also, try calling Invalidate()
> >> instead of RedrawWindow().
>
> >No, I don't. Neither I know how to do the caching. I tried
> >Invalidate() in OnDisplaySettingChanged(), and I didn't see any
> >changes.
>
> >> > I have basic OnPaint function, meaning it just calling
> >> > CDialog:OnPaint(). I commented out my OnPaint function. Now the
> >> > background image is diaplayed all the time whenever the display
> >> > setting is changed. But new problem shows up. Calling SetDlgItemText()
> >> > is causing problems. It shows some garbled texts unless screen is
> >> > refreshed. (I have a timer periodically displaying texts with null
> >> > brush to show transparent texts.)
>
> >> Oh if you're using transparent brushes, all bets are off, since there is no
> >> way to erase the current contents when the area needs to be repainted from
> >> scratch.  The way to start from scratch is to do ShowWindow(SW_HIDE);
> >> followed by ShowWindow(SW_SHOW) on the offending dialog controls.
>
> >For the string display, I want to make them transparent and also no-
> >flicker. Right now I set an blank string first and then set the string
> >I want to display. It seems to solve the issue. But I still see
> >garbled texts intermittently.
>
> ****
> In general, you should not be using SetDlgItemText, but instead creating control member
> variables and calling SetWindowText on those variables.

Sorry I'm not aware of the difference. Could you please elaborate a
little?

>
> Also, you did not say if these are edit controls or static controls; you just said "string
> display" which is not meaningful.  Edit controls do not support SetBkMode(TRANSPARENT).  I
> have not done this with static controls so I can't suggest what has gone wrong, but there
> are numerous internal bugs in these controls (for example: Microsoft, instead of doing an
> Invalidate() and letting WM_PAINT be sent, internally "optimizes" the behavior by directly
> calling the text-drawing subroutine, which is a colossally stupid move, since it presumes
> that the OnPaint has not been overridden.  But this is what you expect when you put
> critical software decisions in the hands of beginners without adult supervision.
>                                         joe
> ****

Yes, I do use static controls for transparent effect.
SetBkMode(TRANSPARENT) is handled in OnCtlColor().

I hope this will be my last MFC project. I'm thinking to move to WPF.

>
> >> -- David
>
> >Thank you.
>
> Joseph M. Newcomer [MVP]
> email: newco...(a)flounder.com
> Web:http://www.flounder.com
> MVP Tips:http://www.flounder.com/mvp_tips.htm- Hide quoted text -
>
> - Show quoted text -

From: Joseph M. Newcomer on 21 Apr 2010 11:43
See below...
On Wed, 21 Apr 2010 08:16:59 -0700 (PDT), "Lewis Z." <lzhou8(a)gmail.com> wrote:

>On Apr 21, 9:51�am, Joseph M. Newcomer <newco...(a)flounder.com> wrote:
>> See below...
>>
>>
>>
>>
>>
>> On Wed, 21 Apr 2010 07:28:05 -0700 (PDT), "Lewis Z." <lzh...(a)gmail.com> wrote:
>> >On Apr 21, 12:13�am, "David Ching" <d...(a)remove-this.dcsoft.com>
>> >wrote:
>> >> "Lewis Z." <lzh...(a)gmail.com> wrote in message
>>
>> >>news:2463fe87-ed85-49fd-9779-bea17da4612c(a)c36g2000yqm.googlegroups.com...
>>
>> >> > Joe, thanks for the reply. I handled the drawing of the background
>> >> > image in the EraseBackground msg handler. After I figured out the
>> >> > WM_DISPLAYCHANGE, I called RedrawWindow in this msg handler. It didn't
>> >> > help all the time. Sometimes I still saw the missing image.
>>
>> >> It's perfectly fine to be drawing your image in OnEraseBkgnd(). �But by
>> >> chance did you cache the rect of the image? �The rect would need to be
>> >> recomputed when the display is changed. �Also, try calling Invalidate()
>> >> instead of RedrawWindow().
>>
>> >No, I don't. Neither I know how to do the caching. I tried
>> >Invalidate() in OnDisplaySettingChanged(), and I didn't see any
>> >changes.
>>
>> >> > I have basic OnPaint function, meaning it just calling
>> >> > CDialog:OnPaint(). I commented out my OnPaint function. Now the
>> >> > background image is diaplayed all the time whenever the display
>> >> > setting is changed. But new problem shows up. Calling SetDlgItemText()
>> >> > is causing problems. It shows some garbled texts unless screen is
>> >> > refreshed. (I have a timer periodically displaying texts with null
>> >> > brush to show transparent texts.)
>>
>> >> Oh if you're using transparent brushes, all bets are off, since there is no
>> >> way to erase the current contents when the area needs to be repainted from
>> >> scratch. �The way to start from scratch is to do ShowWindow(SW_HIDE);
>> >> followed by ShowWindow(SW_SHOW) on the offending dialog controls.
>>
>> >For the string display, I want to make them transparent and also no-
>> >flicker. Right now I set an blank string first and then set the string
>> >I want to display. It seems to solve the issue. But I still see
>> >garbled texts intermittently.
>>
>> ****
>> In general, you should not be using SetDlgItemText, but instead creating control member
>> variables and calling SetWindowText on those variables.
>
>Sorry I'm not aware of the difference. Could you please elaborate a
>little?
****
Functionally, there is no difference; from an aesthetic viewpoint, having control
variables is more consistent with MFC style (SetDlgItemText is "so Petzold", and one of
the first things you need to learn in programming MFC is that nearly everything in
Petzold's book is stylistically incompatible with MFC [and, IMNSHO, with good programming
style in general; it took me two years to overcome the bad training I got from his book])
joe
****
>
>>
>> Also, you did not say if these are edit controls or static controls; you just said "string
>> display" which is not meaningful. �Edit controls do not support SetBkMode(TRANSPARENT). �I
>> have not done this with static controls so I can't suggest what has gone wrong, but there
>> are numerous internal bugs in these controls (for example: Microsoft, instead of doing an
>> Invalidate() and letting WM_PAINT be sent, internally "optimizes" the behavior by directly
>> calling the text-drawing subroutine, which is a colossally stupid move, since it presumes
>> that the OnPaint has not been overridden. �But this is what you expect when you put
>> critical software decisions in the hands of beginners without adult supervision.
>> � � � � � � � � � � � � � � � � � � � � joe
>> ****
>
>Yes, I do use static controls for transparent effect.
>SetBkMode(TRANSPARENT) is handled in OnCtlColor().
****
Note that this will not erase what is already there! So if you want to replace the text,
you must draw the background in OnEraseBkgnd, or completely redraw it in OnPaint.
Transparent means "do not replace any pixels that are not covered by actual parts of a
character glyph", so if you had ###" and want to now draw "III' you will see something
like
*##
where the * represents the splodge of the III drawn on top of (but not replacing) the #.
And you can't use this technique to let a background of the parent window show through;
you have to invalidate the area of the parent, e.g.,

CRect r;
GetWindowRect(&r);
CWnd * parent = GetParent();
parent->ScreenToClient(&r);
parent->Invalidate(&r);

to force the parent area to redraw under the control.

Be careful what you ask for, you may get it. The behavior you are seeing with transparent
mode is EXACTLY what is SUPPOSED to happen!

Note that WPF will not necessarily simplify this; if you tried the same techniques under
WPF you would get the same result.
joe

>
>I hope this will be my last MFC project. I'm thinking to move to WPF.
>
>>
>> >> -- David
>>
>> >Thank you.
>>
>> Joseph M. Newcomer [MVP]
>> email: newco...(a)flounder.com
>> Web:http://www.flounder.com
>> MVP Tips:http://www.flounder.com/mvp_tips.htm- Hide quoted text -
>>
>> - Show quoted text -
Joseph M. Newcomer [MVP]
email: newcomer(a)flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
First  |  Prev  |  Next  |  Last
Pages: 1 2 3 4
Prev: Adding Edit Control to MainFrame.
Next: MFC application and Load DLL