Re: Clear text from a device context. - C / C++ / MFC Discussion Boards

Mark Salsbery14-Dec-07 8:52

14-Dec-07 8:52

Your code works for me.

In OnTimer(), I had to change

InvalidateRect(rTextRect);

to

InvalidateRect(&rTextRect);

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Clear text from a device context.

Mr Simple16-Dec-07 22:12

Mr Simple

16-Dec-07 22:12

Mark Salsbery wrote:
Your code works for me.

Really???

I have tried both but I still get the smudge either way (I have only tested on XP).

Re: Clear text from a device context.

Mark Salsbery17-Dec-07 5:50

Mark Salsbery

17-Dec-07 5:50

Yes, really Smile | :)

The change I made wasn't even necessary, since CRect has a LPRECT
operator.

I'm testing on Vista.

Is it leaving a trail of pixels or does the entire text get left
behind on previous draws?

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Clear text from a device context.

Mr Simple19-Dec-07 2:08

Mr Simple

19-Dec-07 2:08

The entire text gets left behind (in the image below I have used 'rTextRect.OffsetRect(0, 20);' to space them out a bit to show this).

http://i19.tinypic.com/8a4gh2w.jpg

Thanks
MS.

Re: Clear text from a device context.

Mark Salsbery19-Dec-07 6:14

Mark Salsbery

19-Dec-07 6:14

Hmm that shouldn't happen Smile | :)

WM_ERASEBKGND should redraw the background for the invalidated
rect when the CPaintDC is created (during the internal call
to BeginPaint().

Can you add a WM_ERASEBKGND that calls the base class method?
Then in that handler, maybe draw a rectangle at the textrect.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Clear text from a device context.

led mike12-Dec-07 7:47

led mike

12-Dec-07 7:47

Mark Salsbery wrote:
you don't need to preserve a DC between WM_PAINT messages.

ummm.... don't you mean you should not?

Re: Clear text from a device context.

Mark Salsbery12-Dec-07 7:58

Mark Salsbery

12-Dec-07 7:58

led mike wrote:
don't you mean you should not?

For the sake of this thread - yes.

Discussing owned DCs is beyond the scope of the problem/OP/thread, IMO Smile | :)

Mark

Mark Salsbery
Microsoft MVP - Visual C++

Java | [Coffee]

Re: Clear text from a device context.

Nelek12-Dec-07 3:14

Nelek

12-Dec-07 3:14

Are you using Invalidate () before calling UpdateWindow () ??

It mades the drawing surface to be erased and then repainted, so the old text will be away, and just the new "repositioned" will be drawn.

Greetings.
--------
M.D.V. Wink | ;)

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
“The First Rule of Program Optimization: Don't do it. The Second Rule of Program Optimization (for experts only!): Don't do it yet.” - Michael A. Jackson

Using SendVirtualKey method?

Benny_Lava12-Dec-07 1:03

Benny_Lava

12-Dec-07 1:03

As the subject says,

I'm building a virtual keyboard on a WINCE 5.0 device.

I'm stuck with the function keys (CTRL,SHIFT,CAPS,ALT).

I know that I gotta change some flags, but how?

I have tried SendVirtualKey(VK_CAPITAL,KeyShiftCapitalFlag); // doesn't work
and also SendVirtualKey (VK_CAPITAL,KEYEVENTF_KEYUP) // doesn't work
and also SendVirtualKey (KeyShiftCapitalFlag,KEYEVENTF_KEYUP) doesn't work

Any suggestions?

Thank you!

Multi column combo box

panthal12-Dec-07 0:33

panthal

12-Dec-07 0:33

hi,

how to use multi column combo box in a dialog? how can add strings into the multi column combo box. actually i was used this code

m_ComboBoxControl1.AddRow(ColumnString0, ColumnString1);
but it was not functioning.

can you please help me
Thanks,
Panthal

Re: Multi column combo box

Mark Salsbery12-Dec-07 6:33

Mark Salsbery

12-Dec-07 6:33

Forgive my ignorance....what multi-column combobox?

Mark

Mark Salsbery
Microsoft MVP - Visual C++

Java | [Coffee]

Re: Multi column combo box

David Crow13-Dec-07 4:52

David Crow

13-Dec-07 4:52

Mark Salsbery wrote:
what multi-column combobox?

...looks around cautiously...

Psst, Mark. It's the one over there. Suspicious | :suss:

"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: Multi column combo box

Mark Salsbery13-Dec-07 5:49

Mark Salsbery

13-Dec-07 5:49

hmm...

Mark Salsbery
Microsoft MVP - Visual C++

Java | [Coffee]

how the macro works

George_George12-Dec-07 0:03

George_George

12-Dec-07 0:03

Hello everyone,

I can not understand how the following code works and assign 100 to counter variable?

void Foo (int* input)
{
	*input = 100;

	return;
}

#define GETFOO  (Foo( &counter ), counter)

int counter;

int main()
{
	GETFOO;
	return 0;
}

thanks in advance,
George

Re: how the macro works

CPallini12-Dec-07 0:35

CPallini

12-Dec-07 0:35

the macro expands to

(Foo( &counter ), counter);

on running:

Foo(&counter) is first evaluated and it sets counter=100, then counter is evaluated giving the result 100 to the expression inside the outer braces, finally the result itself it is discarded.

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: how the macro works

George_George12-Dec-07 0:45

George_George

12-Dec-07 0:45

Thanks CPallini,

I do not understand how this statement works,

(Foo( &counter ), counter);

I have tested that the simple statement (without comment) also works. What is the benefit and function to add , and counter in macro definition?

// #define GETFOO Foo((&counter), counter)
#define GETFOO Foo(&counter)

regards,
George

Re: how the macro works

CPallini12-Dec-07 1:56

CPallini

12-Dec-07 1:56

George_George wrote:
I do not understand how this statement works,

(Foo( &counter ), counter);

Both I and toxcct gave an answer to the above.

George_George wrote:
I have tested that the simple statement (without comment) also works.

Of course.

George_George wrote:
What is the benefit and function to add , and counter in macro definition?

The difference stands in the returned value of the expression, for instance

void Foo (int* input)
{
	*input = 100;

	return;
}

#define GETFOO  (Foo( &counter ), counter)
void main()
{
int i = GETFOO;
}

will assign 100 to i.

Anyway that way of coding is simply junk.

Big Grin | :-D

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: how the macro works

George_George12-Dec-07 2:03

George_George

12-Dec-07 2:03

Cool CPallini,

Thanks!

regards,
George

Re: how the macro works

toxcct12-Dec-07 2:12

toxcct

12-Dec-07 2:12

I gave you 5 everywhere in this thread, so did I to Iian.
answering George_george deserve courage and patience !!! Poke tongue | ;-P

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Re: how the macro works

CPallini12-Dec-07 2:23

CPallini

12-Dec-07 2:23

toxcct wrote:
I gave you 5 everywhere in this thread, so did I to Iian

Only 5?
Only for this thread?
The same given to Ian?
OMG, definitely you aren't my friend!
Big Grin | :-D

toxcct wrote:
answering George_george deserve courage and patience !!!

I cannot understand the overall plan behind all his questions. When I asked to him he replied that was for technical fun.
Anyway, I have to admit Blush | :O

that some questions are quite interesting.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: how the macro works

toxcct12-Dec-07 2:30

toxcct

12-Dec-07 2:30

CPallini wrote:
OMG, definitely you aren't my friend!

please tell me this is a joke hey ! Poke tongue | ;-P

CPallini wrote:
Only 5?

i am negociating with the site administrators to leverage the votes on G_G thread up to at least 10 ! lol

BTW, please do the same to me Blush | :O

let's get stronger again that kid.

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Re: how the macro works

CPallini12-Dec-07 2:44

CPallini

12-Dec-07 2:44

toxcct wrote:
BTW, please do the same to me

Done buddy!

But you understand that it cannot be our voting guideline unless we want to be hounded out CP for violating the Competition Law.
Laugh | :laugh:

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: how the macro works

toxcct12-Dec-07 2:48

toxcct

12-Dec-07 2:48

hey, we're not enforcing anything. we're just reacting to G_G voting bad habit.
we're all good guyz here, so what's bad in this ?! lol.

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Re: how the macro works [modified]

toxcct12-Dec-07 0:50

toxcct

12-Dec-07 0:50

the , operator returns the last of its statements.
here, the macro calls the Foo function, to which the counter variable is passes by pointer (so, the counter variable is modified from within the Foo() function, but its modifications are still visible from the caller).
then, the counter variable is return (and as there is no = operator in the instruction GETFOO;, the returned value is not used, but still the counter variable is assigned with 100.

writing GETFOO; here is as if you were doing Foo(&counter);

BTW, this is very awful coding, and you should never use such macros !

and to finish, a question: how old are you ?

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modified on Wednesday, December 12, 2007 8:01:42 AM

Re: how the macro works

George_George12-Dec-07 0:59

George_George

12-Dec-07 0:59

Thanks toxcct,

I do not agree with your answer. What do you mean class Foo? I am not using any object related concepts and techniques. It is pure C code. Smile | :)

regards,
George

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