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Hi,
I got the following code from Niklas Lindquist
CBitmap *bm = new CBitmap;
bm->LoadBitmap((UINT) IDD_BITMAP);
CDC *cdcwindow = this->GetDC();
CDC cdcimage;
cdcimage.CreateCompatibleDC(cdcwindow);
CBitmap *oldbit = cdcimage.SelectObject(bm);
cdcimage.SetDCBrushColor(RGB(125,125,125));
COLORREF cr = cdcimage.GetPixel(0,0);
LPVOID bitptr = NULL;
if (bitptr == NULL)
bitptr = new char[4000];
bm->GetBitmapBits(4000,bitptr);
cdcimage.FloodFill(0,0,cr);
bm = cdcimage.SelectObject(oldbit);
What I am trying to do is fill the background of a Bitmap with a Gray Color
When I look at what is in the bitmap via bm->GetBitmapBits I see a whole buch of white Color
e.g. FF FF FF 00 FF FF FF 00 this pattern continues for many many bytes
After execution of the Floodfill shouldn't the white be whats in the current brush which is gray so that
FF FF FF 00 is now 80 80 80 00
When I look at that adddress in code it still FF FF FF 00
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i think you need to select a brush (specifically, GetStockObject(DC_BRUSH)) into the DC before calling SetDCBrushColor.
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I believe this is the code I gave you here[^]
CDC cdcimage;
cdcimage.CreateCompatibleDC(&cdcwindow);
COLORREF clrFill = RGB(128, 128, 128);
CBrush brush;
brush.CreateSolidBrush(clrFill);
CBrush *pOldBrush = cdcimage.SelectObject(&brush);
CBitmap *oldbit = cdcimage.SelectObject(&m_bitmap);
COLORREF clr = cdcimage.GetPixel(0, 0);
cdcimage.ExtFloodFill(0, 0, clr, FLOODFILLSURFACE);
cdcimage.SelectObject(oldbit);
cdcimage.SelectObject(pOldBrush);
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OK I have a boat load of code, it works, bit its unaware of vectors etc.
I have a vector template that fully supports all standard operators, including scalars
I have a matrix template that supports all standard operators, including vectors and scalars
So give some matrix<template_class> m
int rows=m.data.size()
int cols=m.data[0].size();
what can we do to make m become reduced row echelon form
no back substitution yet, I just wanted to see a vector way to identify a pivot from m
and make it reduced form
this way I it should be easier to find the rank etc.
So as I see it we need to find a pivot
My matrix works with std::swap for any 2 rows
My m[] returns a vector, m[][] returns template_class
m = m + v[] works
m = m + template_class works
so do the other operators
I made it assignable by element or row
BTW my vector and matrix templates are parallel, hence the reason I wanted to leverage them
http://www.contract-developer.tk
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Hi.
I am very new to C and C++, what is the best way of downloading data from a HTTP server, meaning, how to i download the HTML from http://www.google.com?
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Have a look at the MFC classes CHttpFile and CHttpConnection ...
also, look at this article on CP : Retrieving a file via. HTTP[^]
Max.
Watched code never compiles.
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Hi. i am developing to a linux device, is there any way without MFC?
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Well, since it's a Windows development site, I assume you were developing for Windows.
on linux, yeah, there's probably something that does it; but it's probably more complicated.
a quick googling returns this : http://curl.haxx.se/[^] or this : http://rosettacode.org/wiki/Web_scraping[^]
just to give you a good start.
good luck.
Watched code never compiles.
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One way would be with URLDownloadToFile(). Other ways exist, too.
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"Man who follows car will be exhausted." - Confucius
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I'd recommend cURL, it's got an interface only it's programmer could love but it's actually fairly easy to do what you want to do. Run, don't walk to http://curl.haxx.se/[^] and download it. Actually if you're using Linux it's probably available as a package in your distro.
Cheers,
Ash
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very simple and good article for achieving your goal :-
AmHttpUtilities[^]
"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
Never mind - my own stupidity is the source of every "problem" - Mixture
cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
Support CRY- Child Relief and You
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I have the following code:
class A
{
public:
A(void);
~A(void);
};
class B
{
public:
B(void);
~B(void);
};
void testfunction(A* x){};
I want to be able to directly use:
B* x;
testfunction(x);
instead of doing an explicit cast, like
B* x;
testfunction((A*)x);
Is there a way to do this. I tried using a conversion constructor in testclass (i.e. A::A(B)) but that didn't work, also I tried defining a A* operator in B but that also failed. Is there any way I can do this?
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Why do you want to do something like that ? A and B are two completely different classes so, why do you want to be able to pass a B to a function expecting an A object ? It's a bit like asking how can I convert an apple to a car, it doesn't make any sense.
If the objects are related in some way, then I would suggest that they have a common base class and that your function expect a pointer to the base class. Then you can pass a pointer to an instance of A or a pointer to an instance of B but the function will treat them as a pointer to the base class.
But if the class are unrelated, I think you are making a very bad design decision.
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The project is bigger than what I've written down. I know it's usually not safe but we're sure the memory layout of the classes permit this forced cast and that it actually works. My questions still stands. Also, the question is how (if at all) this can be done, not whether it is safe or not.
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Also, the function expects a pointer to an A object, not an A object itself. I'm just looking for a way to tell the compiler I want the (A*) operator implicitly cast so I don't have to change the whole project (which is pretty big).
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Arkh wrote: I know it's usually not safe but we're sure the memory layout of the classes permit this forced cast and that it actually works.
Then state this relation giving them a common base class or interface. 
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.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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Arkh wrote: but we're sure the memory layout of the classes permit this forced cast and that it actually works
Honnestly, that's a receipt for disaster: if later you have a programmer who wants to document the class and innocently swap two variables of your class, you are doomed. This is an extremly bad practice, and that's one of the reason why type safety is so strong in C++.
Anyway, you still didn't answer the question: WHY do you want something like that ? It doesn't make any sense that your function accept a pointer to A and you pass a pointer to B making believe the function that it is a pointer to A 
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Ok here goes. We're migrating our software to run on more platforms. Initially we had something like:
class A : public B {};
void function(B* x) {};
Obviously
A* y;
function(y);
used to work. Now we have some wrapper classes, call them xA (over A) and xB (over B). Therefore:
class xA : protected A {};
class xB : protected B {};
void function(xB* x){};
Since xA is not derived from xB, calling the function as before no longer works.
xA* x;
function(x);
function((xB*)x);
The protected in the inheritence between the base and wrapper classes is necesarry. All functions in A and B are overwritten in xA and xB respectively but no new members are added. This is part of the specs.
Now can you answer the question?
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Why don't you keep your function as it was ? This way you can pass a pointer to xA or a pointer to xB which both inherit from B.
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Because in our software we should no longer have access to classes A and B, only to xA and xB. Classes A and B are specific to the platform we're using now. On other platforms we have classes, say, C and D. But we want to make our software run on all platforms, so functio(B* x) would make no sense in our code if we were running it on the second platform. Any ideas on how to make it work? Anyone?
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I think you still have a bad design decision: your base class should be independant of any platform but these are abstract classes (they can't be instanciated). Then, for each platform, you would create another class which inherits from the base class. Suppose you want to create a class to display a window (both on Windows and Linux). You would do something like this:
class CWindow
{
};
class CWinWindow : public CWindow
{
};
class CLinWindow : public CWindow
{
};
Your function receives a pointer to a CWindow object but should care about the fact that it is for windows or Linux. Then, you should redefine the behavior of your window through virtual functions. Both child classes implements functions like show(..) or move(..) in their own specific way. The rest of your program should in fact only manipulate CWindow pointers.
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both platforms coincidentaly have the same functions in classes and so on, so our design works. only the class names differ. the design works(tested), we just need to get rid of the explicit casts.
more specifically, in our code we use something like:
#ifdef PLATFORM1
class A : protected AfromPlatform1
#else
class A : protected AfromPlatform2
#endif
{
void f();
}
void A::f()
{
#ifdef PLATFORM1
AfromPlatform1::f();
#else
AfromPlatform2::f();
#endif
}
This works, trust me, as I said before, it's tested.
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What are trying to do? What about a good OOP tutorial?
Explicitely casting a pointer of an unrelated object is always a bad idea (well using unitialized pointers, as you did is evene worse).
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.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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Can you declare the constructor to take void* instead of void? All pointer types can be passed as void*, and in C also the other way around.
Of course, I agree with others that what you are doing is a bad idea but hey, we're all grown ups (I hope)
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