C / C++ / MFC

catching ctreectrl's WM_ERASEBKGND

5-Mar-09 6:22

"Here i have a variable and there i assign it something and then later somewhere it doesn't work, could you fix it for me?" - would you be able to do it? Give more details (code sniplet would be great, which does NOT mean the whole program...) if you wish for any assistance, please.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

kitkat120125-Mar-09 4:44

kitkat12012

5-Mar-09 4:44

i'm trying to create this method that erases the background of my ctreectrl by catching the WM_ERASEBKGND in the windproc function

i have this working fine, but when i start erasing the background, i start running into problems

i found out that when i receive the WM_ERASEBKGND message, it doesn't really erase the whole background, just parts of it

like if i collapsed a tree node, only the affected region would be erased, any unaffected areas will be left untouched

my question is, how do i get the rect of this "affected region" so i'd know what area to erase?

what i did before was i took the clientrect and erased everything, but this is bad since the "unaffected region" was also erased and the text on it is not repainted

thanks

Code-o-mat5-Mar-09 5:14

5-Mar-09 5:14

Did you use the DC you got with wM_ERASEBKGND?

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

kitkat120125-Mar-09 5:54

kitkat12012

5-Mar-09 5:54

right now i'm using GetDC() on the ctreectrl but i could easily change that to use the one that came from WM_ERASEBKGND

Code-o-mat5-Mar-09 5:57

5-Mar-09 5:57

Then do so (there's a HDC in either wParam or lParam, look it up), that DC probably has a clipping region selected in it which will permit any paintsings onto areas which should not be overpainted.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

kitkat120125-Mar-09 6:04

kitkat12012

5-Mar-09 6:04

cool

works perfect, thanks

one last question though, is there a way to get the rect for that region that updated?

cause i'm drawing bitmaps on the background after erasing and i need to calculate like sizes and positions and stuff for this updated region

thanks

Code-o-mat5-Mar-09 6:11

Can I make a new view of my document DYNAMICALLY and of a different class than the old view? (SDI Doc/View)

5-Mar-09 6:11

You could use CDC::GetClipBox[^] or CDC::GetBoundsRect[^] for that.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

Joseph Marzbani5-Mar-09 3:44

Joseph Marzbani

5-Mar-09 3:44

I have a SDI app with one single view, derived from CView at the execute time. now I want to create a splitter window at run time and make a new view of different class (see CRichEdit). But as I look inside the MSDN:

"In "dynamic" splitters, the views are of the same class, In "static" splitters, the views can be of different classes."

I dislike to have a splitter window initially (that's static). What do you suggest to do?

Thank you masters!

Re: Can I make a new view of my document DYNAMICALLY and of a different class than the old view? (SDI Doc/View)

led mike5-Mar-09 4:16

led mike

5-Mar-09 4:16

You probably want to read this technical note[^]

LeftMouseClk and Hold it?

Software20075-Mar-09 3:36

Software2007

5-Mar-09 3:36

Hello,
I would like to move something on a graph based on Left click mouse. This works fine, but How do I make it keep moving if the left Mmouse is still down, I want it to stop moving only when Left Mouse is up...as if I was dragging it... Do I need a timer to do this, or could this be done in other ways?

Thanks

sft

Cedric Moonen5-Mar-09 3:47

Cedric Moonen

5-Mar-09 3:47

You need to move it when the mouse is moving I guess ? If yes, when you click the button, set a flag to true, and when the button is released, reset the flag to false.
Handle every move event and check if the flag is set: if that's the case, then move your object.

If that doesn't answer your question, then please provide more information.

Cédric Moonen
Software developer

Charting control [v1.5]
OpenGL game tutorial in C++

Software20075-Mar-09 3:50

Software2007

5-Mar-09 3:50

Not a bad idea. I will give it a shot.
Thanks

sft

Joseph Marzbani5-Mar-09 3:57

Joseph Marzbani

5-Mar-09 3:57

WM_MOUSEMOVE
WM_LBUTTONUP
WM_LBUTTONDOWN
Dead | X|

Thank you masters!

Re: LeftMouseClk and Hold it? [modified]

Naveen5-Mar-09 4:14

Naveen

5-Mar-09 4:14

Software2007 wrote:
Do I need a timer to do this, or could this be done in other ways?

void CSam1Dlg::OnMouseMove(UINT nFlags, CPoint point)
{

    if( MK_LBUTTON == (MK_LBUTTON&nFlags))
    {
        // LButton is down.
    }
    CDialog::OnMouseMove(nFlags, point);
}

nave

[OpenedFileFinder] [My Blog]

Software20075-Mar-09 4:19

Software2007

5-Mar-09 4:19

Its what I wanted - works fine - thanks.

sft

modified on Thursday, March 5, 2009 12:50 PM

Different Between the operator '*' and '&'

jeansea5-Mar-09 3:25

jeansea

5-Mar-09 3:25

the two Different Code create the same result i want to know the

different between the operator '*' and '&'

the code is below:

first:

<br />
#include<iostream><br />
<br />
using namespace std;<br />
<br />
int Add(int &P1,int &P2)<br />
{<br />
	P1=5;<br />
	P2=10;<br />
	return P1+P2;<br />
}<br />
<br />
int main()<br />
{<br />
	int P1=2,P2=3;<br />
	<br />
	cout<<"As Parameter Before The P1 is:"<<P1<<" P2 is:"<<P2<<endl;<br />
<br />
	int Sum=Add(P1,P2);<br />
	cout<<"P1 Parameter After The P1 is: "<<P1<<" P2 is:"<<P2<<endl;<br />
}<br />

Second:

<br />
#include<iostream><br />
<br />
using namespace std;<br />
<br />
int Add(int *P1,int *P2)<br />
{<br />
	*P1=5;<br />
	*P2=10;<br />
	return *P1+*P2;<br />
}<br />
<br />
int main()<br />
{<br />
<br />
		int *P1,*P2;<br />
<br />
		int PA=2,PB=3;<br />
<br />
		P1=&PA;<br />
<br />
		P2=&PB;<br />
	<br />
	cout<<"As Parameter Before The P1 is:"<<*P1<<" P2 is:"<<*P2<<endl;<br />
<br />
	int Sum=Add(P1,P2);<br />
	cout<<"P1 Parameter After The P1 is: "<<*P1<<" P2 is:"<<*P2<<endl;<br />
}<br />

end the variable P1 and P2 's value are all change .

could you tell me the difference between them

thank you Laugh | :laugh:

Cedric Moonen5-Mar-09 3:45

Cedric Moonen

5-Mar-09 3:45

The difference is in how you will access the variable in your function: if you pass the variables by reference (using &), you can access the variables directly. If you pass the pointer to the variables (using *), then in your function you will receive the pointer.

Cédric Moonen
Software developer

Charting control [v1.5]
OpenGL game tutorial in C++

Re: Different Between the operator '*' and '&' [modified]

«_Superman_»5-Mar-09 17:42

«_Superman_»

5-Mar-09 17:42

It is more neat sometimes to use &.
Take this simple example of a multiply function.

Using *

double multiply(double *x, double *y)
{
    return *x * *y; 
}

double d = multiply(&a, &b);

Using &

double multiply(double &x, double &y)
{
    return x * y; 
}

double d = multiply(a, b);

«_Superman_»
I love work. It gives me something to do between weekends.

PIEBALDconsult5-Mar-09 3:47

PIEBALDconsult

5-Mar-09 3:47

* is backward compatible with C. Big Grin | :-D

Edit: I was off by one character, I meant to indicate that C doesn't support references.

modified on Thursday, March 5, 2009 9:56 AM

Cedric Moonen5-Mar-09 3:50

Cedric Moonen

5-Mar-09 3:50

You can use pointers in C too (thus using the '*' is valid in C).

Cédric Moonen
Software developer

Charting control [v1.5]
OpenGL game tutorial in C++

PIEBALDconsult5-Mar-09 3:55

PIEBALDconsult

5-Mar-09 3:55

Ah, I'm not awake yet, coffee just finished dripping.

I must have meant it the other way around. I only dabbled in C++ a little, and not recently.

bulg5-Mar-09 7:02

bulg

5-Mar-09 7:02

I can't believe there're people who know C and not C++ still! Smile | :)