C / C++ / MFC

C^hris L^osinger31-Mar-03 3:02

C^hris L^osinger

31-Mar-03 3:02

Willem B wrote:
how can i prevent this?

delete all objects/memory that you allocate with 'new' and free all memory you allocate with 'malloc'.

-c

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Willem B31-Mar-03 3:17

Willem B

31-Mar-03 3:17

is it harmfull if i let the compiler delete it?

[]D [] []D []

C^hris L^osinger31-Mar-03 3:33

C^hris L^osinger

31-Mar-03 3:33

if you don't delete it, your program will leak memory.

-c

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Anonymous31-Mar-03 3:48

Anonymous

31-Mar-03 3:48

Willem B wrote:
is it harmfull if i let the compiler delete it?

It just won't do it: You told him that you wanted memory (new), got it (new succeeded), and now you have to tell him that you dont want it anymore (delete).
If you want it automatic, then don't new your variables!

Make colord darker/grayer

Alvaro Mendez31-Mar-03 5:34

Alvaro Mendez

31-Mar-03 5:34

Anything allocated with new or malloc is not "deleted" by the compiler. It needs to be cleaned up with "delete", "free", or you can just let it happen when the program exits. However, if the program runs for a while, more and more memory may continue to be allocated and eventually you'll run out of it, causing the program to crash.

The only memory the compiler cleans up automatically is the stack, which you can use to efficiently allocate any variable:

{
  CString s = "allocated on the stack so it will be free automatically";
  CString* p = new CString("allocated on the heap, needs to be freed with delete");
 
  delete p;  // p must be cleaned up explicitly
}  // s is automatically cleaned up here

Regards,
Alvaro

When birds fly in the right formation, they need only exert half the effort. Even in nature, teamwork results in collective laziness. -- despair.com

Brian van der Beek31-Mar-03 2:12

Brian van der Beek

31-Mar-03 2:12

I have a listctrl for logging. Logging can be activated or deactivated. When logging is deactivated, I want to make the text and background grayer grayer. I know how to use CustomDraw, but how do you make colors grayer? Anyone got a clue?

Jason Henderson31-Mar-03 3:42

Jason Henderson

31-Mar-03 3:42

Gray is an equal combination of red, green and blue color values.

Jason Henderson
"You must be the change you wish to see in the world." - Gandhi

articles profile

Brian van der Beek31-Mar-03 3:48

Brian van der Beek

31-Mar-03 3:48

Ok, but that doe not make me a lot wiser. How do I actualy translate color values to gray values or to their darker equvalents?

Jason Henderson31-Mar-03 4:23

Jason Henderson

31-Mar-03 4:23

Most GDI functions take a COLORREF which defines the color you want the GDI object to be. A COLORREF is made up of red, green and blue components and you can use the RGB(r,g,b) macro to get a COLORREF.

So basically, to make the color darker, you could decrease the red, green, and blue values by the same percentage. To make it grayer, you could extract the red, green and blue values from the original color then equalize each value toward a set value of gray, say RGB(192,192,192). Here's an example of making orange grayer:

Original Orange:
Red = 236
Green = 122
Blue = 0

Gray value:
R = 192
G = 192
B = 192

if (original value > gray value)
new value = original value - (original value - gray value)/2
else
new value = original value + (gray value - original value)/2

New values:
R = 214
G = 157
B = 96

ORIGINAL COLOR

NEW COLOR

Darken example using original orange and a percantage value of 50%:

New values:
R = 118
G = 61
B = 0

DARKENED COLOR

Jason Henderson
"You must be the change you wish to see in the world." - Gandhi

articles profile

Brian van der Beek31-Mar-03 4:40

Brian van der Beek

31-Mar-03 4:40

Thanx!! This is exactly what I was looking for. Cool | :cool:

Automatic macro increment

Maximilien31-Mar-03 4:16

Maximilien

31-Mar-03 4:16

What do you mean greyer ? Make them darker ? lighter ?

You can convert the RGB values to HSV and modify the V value to make the color darker or lighter.

Max.

Maximilien Lincourt
For success one must aquire one's self

Jesper Knudsen31-Mar-03 2:05

Jesper Knudsen

31-Mar-03 2:05

#define NEXT_INDEX ????<br />
<br />
void something()<br />
{<br />
   int A0 = NEXT_INDEX;   //compiles as: int A0 = 0<br />
   int A1 = NEXT_INDEX;   //compiles as: int A1 = 1<br />
   int A2 = NEXT_INDEX;   //compiles as: int A2 = 2<br />
   ...<br />
   ...<br />
}

Hi, how can I define NEXT_INDEX macro so that it increments by one, each time the compiler parses it?

Cedric Moonen31-Mar-03 2:25

31-Mar-03 2:25

You can use a static variable that you increment with the macro. Something that looks like:

<br />
static int StaticIndex = 0;<br />
#define NEXT_INDEX  StaticIndex++;<br />

This should work!

Jesper Knudsen31-Mar-03 2:40

Jesper Knudsen

31-Mar-03 2:40

This would increment the index at runtime. What I need is the pre-processor to increment the index as it compiles so that the indices are found at compile time and fixed at runtime.

Something like this (which will not compile..)

#define AAA 0<br />
<br />
#define NEXT_INDEX<br />
{<br />
   AAA                   //insert as AAA<br />
   #define AAA (AAA+1)   //next time it is incremented by one<br />
}

First time using NEXT_INDEX it compiles to AAA (which is 0 at first), next time I want it to compile to 1. This setup imo makes sence, but not to the compiler..

Wink | ;)

Daniel Turini31-Mar-03 7:54

Daniel Turini

31-Mar-03 7:54

IMHO, there is no way of storing information at compile time. So, there is no way of storing a numbeer, incrementing and using it at compile time.

It's not the fall that kills you: it's the sudden stop - Down by Law, Jim Jamursch (1986)

Alvaro Mendez31-Mar-03 5:44

Alvaro Mendez

31-Mar-03 5:44

I'm pretty sure there's a clever template solution to this problem, but from looking at your example, I'm thinking it doesn't need to be too complicated.

Going on the assumption that your variable will be named with the same value as it holds (such that VARn = n), then you can create a simple macro that defines it, like this:

#define DEFINE_INDEX_VAR(prefix, number)  const int prefix##number = number
 
void something()
{
  DEFINE_INDEX_VAR(A, 0);
  DEFINE_INDEX_VAR(A, 1);
...
  DEFINE_INDEX_VAR(Z, 1000);
}

Regards,
Alvaro

When birds fly in the right formation, they need only exert half the effort. Even in nature, teamwork results in collective laziness. -- despair.com

static control color

Cedric Moonen31-Mar-03 1:20

31-Mar-03 1:20

Hi !!

This is a little stupid question but I don't know how to make it Smile | :)

I derived a class from the CStatic class and I draw the control myself in the Paint() function. But know I want it to have the "normal" grey color (the color of a standard push button for exaple) in the background. Does anybody know the RGB color code of it ?

Thanks

Alin Negru31-Mar-03 1:31

Alin Negru

31-Mar-03 1:31

RGB(192, 192, 192) Smile | :)

Cedric Moonen31-Mar-03 2:18

31-Mar-03 2:18

Thanks but it's not the same gray Frown | :(

So, it's quite ugly because I use this control on a form so the colors are not exactly the same

Gunnar Bolle31-Mar-03 2:40

Gunnar Bolle

31-Mar-03 2:40

uhh, bad idea - the color depends on your os settings.

use ::GetSysColor(COLOR_BTNFACE)

that should do it.

Cedric Moonen31-Mar-03 2:54