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There is nothing magical about it.
Any shape is drawn using a pen and a brush.
In the first code snippet you did not select a pen.
So it used the default pen.
A device context does have multiple objects like pen, brush, font, bitmap, region etc.
«_Superman_»
I love work. It gives me something to do between weekends.
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Un Suthee wrote: Another question: CDC can have multiple GDI objects ?
A device context has a multiple GDI objects associated with it, but only one of each different obejct type. That is, there's one pen, one brush, one font etc. Each time you select a new one, it replaces the one that was previously selected. The return value from SelectObject is a pointer to the object that was previously selected, so you can select it back into the DC when you're finished with the object you selected. Here's an example using your code:
void DrawEllipse( CBitmap& outBitmap, CClientDC& dc, CPoint start, CPoint end, COLORREF color, int lineWidth )
{
CDC memdc;
memdc.CreateCompatibleDC( &dc );
outBitmap.CreateCompatibleBitmap( &dc, 500, 500 );
memdc.SelectObject( &outBitmap );
memdc.FillSolidRect( CRect( 0, 0, 500, 500 ), RGB( 255, 255, 255 ) );
CPen pen( PS_SOLID, lineWidth, color );
CPen* oldPen = memdc.SelectObject( &pen );
memdc.Ellipse( start.x, start.y, end.x, end.y );
memdc.SelectObject( oldPen );
memdc.DeleteDC();
}
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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Un Suthee wrote: How to draw an eclipse
You should use different algorithms depending on the nature of the eclipse, is it solar eclipse or lunar one? 
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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Groan... 
Iain.
Codeproject MVP for C++, I can't believe it's for my lounge posts...
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I'm kinda surprised. In your first code, you don't select any pen, then wonder why it uses the default one.
In the second one, you create and select a pen, then get surprised when it is used...
But I'd raise two more points. In your second code, you should keep track of the return value of the SelectObject call, and select the "old" pen back in.
Imagine the function that calls your DrawEllipse function. Imagine it has chosen to use a bright pink pen. Then it calls your code. And suddenly you're using a different colour. All because you didn't tidy up after yourself.
In this case, you'll probably get away with it, as the DC will be destroyed. But it's bad practise.
You've made the same error with the SelectObject (&outBmp) call. Where's the matching SelectObject (pOldBitmap)?
Lastly, why are you passing CClientDC as a parameter? If you made your function have the parent class CDC as a parameter, it will be more flexible in the future, at no cost to yourself. Feel free to use a CClientDC in the outer function, but DrawEllipse makes no use of the specialisation, so get rid of it.
Good luck,
Iain.
Codeproject MVP for C++, I can't believe it's for my lounge posts...
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thanks all of you. Really.
Btw, I must be extremely tired on the day I wrote this post as I spelled ellipse as eclipse. 
Un
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how to use the interface of efs with vc6 ？ where can I find some sample code?
modified on Tuesday, March 3, 2009 8:52 PM
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I am currently developing an application using C++ and MFC. I am thinking about using the library called ChartDirectory. It is from a company called Advanced Software Engineering. This library offers a variety of classes for drawing charts. The company is in Hong King and I have never heard of them. They offer there documentation in both CHM format and in HTML format. I had problems reading the documentation in CHM format. It may have been that the file I down loaded was corrupt. I down loaded it a second time and it did not help. The HTML documentation, on the surface, looks good. However, I found a link that did not work. Therefore, I am not getting good vibes about their software.
I was wondering if anybody out there has used it, or even heard of it. If so, could you please tell me what you think about it.
Thanks
Bob
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i have this formview with a ctreectrl in it and i need to change the tree's background to use a bitmap
i've found a couple of tutorials on how to do this, but they all involve deriving a class from ctreectrl and overriding either the OnPaint or the OnEraseBkgnd methods.
i can't do this since i'm not allowed to create a new class, so i'm stuck with changing stuff on the ctreectrl's parent window (formview)
i tried catching the notifications using ON_NOTIFY(WM_ERASEBKGND, IDC_TREE1, OnEraseBkgnd2) but it doesn't seem to work
i also tried changing the background in customdraw, but i could only get it to work during CDDS_PREPAINT and that produces some major painting issues
any suggestions? thanks
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Well, you could try subclassing the window itself, i mean, use SetWindowLong[^] with GWL_WNDPROC to change the tree's windowproc to a method written by yourself which handles WM_PAINT and/or WM_ERASEBKGND and passes everything else to the original window procedure...so something like:
...
WNDPROC OriginalProc = (WNDPROC)SetWindowLong(m_myTree, GWL_WNDPROC, (LONG_PTR)MyTreeProc);
...
LRESULT CALLBACK MyTreeProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{
if (Msg == WM_ERASEBKGND)
{
...
} else return CallWindowProc(OriginalProc, hWnd, Msg, wParam, lParam);
}
> 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. <
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Hey Friends
Is it possible to disable events of a HTMLElement?
Let's say in html code, there are events defined for some html elements
Let's say <a href="some link" onselect="something here">Click Here</a>
Now i host a webbrowser in my dialog based app and i do not want custom onselect event to be fired(i.e something here above)
may be something we can do with
IHTMLElement * pElem = NULL;
IHTMLElement2 * pElem2 = NULL;
IHTMLElement3 * pElem3 = NULL;
all above interfaces have put_ functions but if i pass NULL, it means to them default behavior (i.e onselect="something here")
or i can define function in my .cpp file to be called
i do not want any of the above
i just want htmlelement not to call
onselect="something here"
that's it
Any Ideas?
Regards
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There isn't one place where all events are received. You can only divert one event at a time if you want to deal with events.
However, IHTMLElement3 has disabled attribute that you can set to TRUE. This will disable any interaction with that IHTMLElement. Of course, first you have to reach that element.
Other than that you can set the parent window as disabled and then you would not be able to do anything with that HTML control.
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hi
thanks for the help
i do not want to disable complete html element
i just want to disable a specific dhtml event
onclick, onfocus seperately
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Use detachEvent but you have to find the event first.
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yeah thanks
will try it now and will update
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IHTMLElement * pElem;
IHTMLElement2 * pElem2;
//Get pElem & pElem2
CString vl_sHelper("onclick");
COleVariant vl_oOnClick;
pElem->get_onmouseover(&vl_oOnClick);// This should get the onclick event?
pElem2->detachEvent(vl_sHelper.AllocSysString(),vl_oOnClick);//COleVariant to IDispatch* sounds strange to compiler
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It does because it is.
Why COleVariant, can't you use VARIANT of type VT_DISPATCH? It is easier.
And pElem and pElem2 should be the same element.
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yeah thanks
compiled and ran successfully detachEvent returns SUCCESS
however, seems something is missing
it still calls the event written in html 
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hey buddy
thanks for the help
found a workaround
1st find out the event
then
get outer html
modify outer html
put it back
not good
but works
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It is not a bad solution. However, detachEvent should work as well. It works if you would write from JavaScript code in HTML page. But, any solution is a good solution as long as it does the job efficiently. 
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Hello from a self-taught MFC bumbler...
I have to prototype a simple dialog-based MFC app which will serve as a front-end to an old dinosaur 3rd-party
MDI GUI app. Without naming names, lets call the 3rd-party app ABF. (More background at the bottom)
I have been able to inventory the main system windows for the main ABF window, and all its child windows, including the MDI frame,
menu bars, status line, and various pop-up output windows (CEdits) which show the user success/failure messages. Ive been successful
sizing/min/maxing all these windows, so I can pretty much drive what the user sees in ABF from my MyAPP, which, btw, appears
to the user simply as a clamped-on toolbar on the right of the main ABF window.
Ive been mostly successful driving all the necessary ABF menu pulldowns, providing the input keystrokes and Mouseclicks, and then
reading the output window(s) for success/failure strings. All except for a few specific cases. These problem cases are why
Im posting here. Essentially, I have been successful with...
*) Finding the main ABF window, and any/all child windows owned by such.
*) popping ABF to the top, and sending keys to invoke menu pulldowns, fill in edit boxes with
data, and send {ENTER} to OK and close the dialog.
*) Finding and reading the new output window that tells the success/failure of the operation. (& creates disk files)
Here are the rough (extracted ) lines from my code to do this.
<br />
DWORD tWNDthread = ::GetWindowThreadProcessId(hwndTARGET,0);
BOOL bAttached = AttachThreadInput(GetCurrentThreadId(),tWNDthread,TRUE);
::SetForegroundWindow(hwndTARGET);
::SetFocus(hwndTARGET);
AttachThreadInput(GetCurrentThreadId(),tWNDthread,FALSE);
::SendInput(KBn,&KBa[0],sizeof(INPUT));
...After that, like I said, I can inventory all child windows of hwndTARGET, and find the new output window, which has a main CEdit. I read
this CEdit, and it tells me the success or failure of the operation I just invoked.
Like I said this works, MOSTLY. The only time it doesn't work is when the user invokes a menu-pulldown of his own, and a big fat
dialog box is already presented to the user. When this is the case, My apps normal SendKeys dont make it to the main window, nor the
child dialog. (I dont know where they end up). What I do know, is that my interface is hosed. What Id like to do is prefix my SendKeys
with a few ESCAPES, so I can close all child dialogs before I try and invoke my own pulldowns. But this doesnt work. I dont know why.
So, before I spend far too many of my man-days trying to debug this, I thought Id post here and get some expert opinion.
So, here are my specific questions.
A) When ABF has some dialog window sitting in front, it DOESNT appear anywhere in the Main-ABF-Window's child window list. (???) Thus, I
dont know that it even exists (so I cant detect the problem state). What calls can I use to know if such a window is on-top.
B) Are these dialog windows totally invisible to me? Or can I do some inventory of windows owned by the ABF THREAD, (and not the
main ABF WINDOW). Is this where I should be focusing my strategy?
C) Ive been able to read CEdits (only) from some other ABF Main-Window-owned child dialogs, but there are [X]checkboxes that I need to read
the state of. I can change the state of them (because mostly everything has an accellerator key thankfully), but I dont know how to READ
the state of the checkboxes when the dialog is on top. Same goes for comboboxes and other std dialog elements.
OK, I guess thats enough to get me going again.
All answers are much appreciated. Remember, I havent had any formal MS education. My windows knowledge is all self-taught
through MFC-by-example books and the likes.
Dave (from Pittsburgh)
p.s. Running MFC6.0 on NTsp2
(p.p.s. If you're in Pittsburgh, a little *paid* consultation time might be considered.  Im behind schedule)
DaveB 412-374-6781
-----more background------
ABF is a 15 year old product that we paid a boxcar full of money to have qualified for use in a safety-critical
development process. Its designed to have a user in front of it, who reads inputs through his eyes. He will then
do ABF menu pulldowns, which invoke dialog boxes where he enters the data he sees, etc. In the end, the outputs go
through a tedious validation and verification process. Its very painful and tedious, and very prone to human error,
because the operator has enter roughtly 175000 data-items for a typical job. We're pretty locked-in to this
product. Because of this, we're assured that the ABF product is NEVER going to change, or be upgraded for us.
Also, because of our formal development process, I cannot just hack the ABF fileformat. Im FORCED to enter data through the
ABF tool. It provides a ton of unknown data-checks and conversions. I just want to bypass the error-prone user-input part.
I was awarded some research funds to try and develop an APP which will try and drive ABF from another dialog app.
If I can get even a modest prototype functioning, my Co will sponsor a rigorous development plan which will employ some real
programmers to design a formal-interface. Ive got to proof the concept first, however.
"Help Me Obi-Wan-CodProjbi, you're my only hope."
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If I understand Windows and dialogs and menus correctly, modal dialogs and popped-up menus have their own message loop (it's called a modal loop because the application enters a different mode when menus or modal dialogs are displayed). Again if I understand correctly, these will swallow all the messages you send to the main window and discard them or something.
So - I suspect you're hosed when modal dialogs or menus are displayed.
But I could be wrong
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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Yes, most of these dialogs ARE modal. But I can stuff my whole begin-to-end keysequence
into a single SendInput sequence, and the main loop will forward subsequent keystrokes to any newly created
modal child dialog. For example, If I stuff SendInput with "{ALT}FGMyFile.xyz{ENTER}", then:
a) the sequence {ALT}FG Executes the FILE --> Generate File modal dialog. (which *IS* Modal)
b) then, within that dialog, the keys "MyFile.xyz" get stuffed into the first (default)
output filename CEditbox
c) and the final {ENTER} closes that modal dialog (because the OK button has the WantReturn property), and thus
the dirty deed is accomplished.
So, I get success when I do SENDINPUT of "{ALT}FGMyFile.xyz{ENTER}"
But I get failure when I do SENDINPUT of "{ALT}FGMyFile.xyz"
followed by another SENDINPUT of "{ENTER}"
The second SENDINPUT still tries to send to the main ABF hwTARGET, but its fubar'd
by the Modal dialog, which now has input focus, but which isnt catching any further input from my app(???).
Evidently, the Generate-File modal dialog isnt a child-window of the main app window. (but of something else instead???).
It doesnt appear after all my EnumerateChildWindows callbacks.
My questions really are. Are these dialogs *really* still children of the main window, (but maybe they're
hidden somehow, and not subject to EnumerateChildWindows?) Maybe I can find them through more painfull digging...
-or- are the modal dialogs NOT child windows of the main window, but of the main application thread instead.
And is there a way to enumerate *all* child windows of the main thread(s)? And if I find them, can I
send them direct KEY messages. (like {ESCAPE}s, just to close em)
p.s. Yes, I know a SETFOCUS followed by a targetless SENDKEYS is very sloppy, especially if the user decides
to do some multitasking, or if there are other apps around which steal input focus. Id much rather send directed
WM_KEYDN/UP messages, but I havent been able to make that work, especially since there's no security relationship
between my app and the ABF app.
All I want to do is be able to detect if there are any active modal ABF child windows, and send them {ESCAPE}
messages to close em down before my app can try its own commands.
Thanks for the response though. I learn tons from every reply.
-Dave
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Wibble - you've done a lot of this SendInput stuff, haven't you! Let me commend you on your fortitiude
The only thing I'll ask is if a Windows macro app like this one[^] can do what you've been trying to get working? Knowing if something's possible (or not) can help...
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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Hey Buddy
Yes you are at correct place, but i may not be of much help.
SendInput is a risky thing as you have faced already
If you get HWND of the target window, then you can treat them with your own classes
Let's say you get an edit box
CEdit* vl_pEdit = (CEdit*)CWnd::FromHandle(targethWnd);
if(vl_pEdit && IsWindow(vl_pEdit->m_hWnd))
{
//you have got CEdit
//Call GetWindowText or SetWindow Text
}
Same would be applicable to CheckBoxes
Use CButton::GetCheck() for getting state
Also
to Click on a Dialog Box, given below is an encrypt from experts exchange which requires subsription and hence pasting below
http://www.experts-exchange.com/Programming/Languages/Q_20572990.html[^]
So you can do many things without SendInput & that too in a reliable way.
However it seems you have developed functionality using SendInput and hence this information may be of little use to you, still posting here, whatever i can.
-----------------------Starts-----------------
The proper WM_COMMAND for a button click is:
PostMessage(hWndParent, WM_COMMAND, MAKEWPARAM(nID, BN_CLICKED), hWndButton);
but the lazy version is:
PostMessage(hWndParent, WM_COMMAND, nID, 0);
... assuming the parent doesn't check hWndButton. gotenks got that one.
Assuming we're dealing with a dialog box using standard button IDs, you should use IDOK for nID. Other standard values for nID include IDCANCEL, IDABORT, IDIGNORE, IDYES, IDNO, IDCLOSE. Although, if the ID is custom, it could be any value.
> ::PostMessage(hWnd,WM_LBUTTONDOWN,WM_COMMAND,MAKELONG(x,y));
> //" ::PostMessage(hWnd,WM_LBUTTONDOWN,MK_LBUTTON,MAKELONG(x,y)); "
> also tried.
> ::PostMessage(hWnd,WM_LBUTTONUP,NULL,MAKELONG(x,y));
> ::PostMessage(hWndParent,WM_LBUTTONDOWN,WM_COMMAND,MAKELPARAM(x,y));
> ::PostMessage(hWndParent,WM_LBUTTONUP,WM_COMMAND,MAKELPARAM(x,y));
This'll simulate a button click:
SetForegroundWindow(hWndParent);
PostMessage(hWndButton, WM_LBUTTONDOWN, MK_LBUTTON, MAKELPARAM(1,0));
PostMessage(hWndButton, WM_LBUTTONUP, 0, MAKELPARAM(1,0));
SetForegroundWindow() brings up and activates the window before it handles the mouse click.
Although, if that fails, the button might be off the screen. If that happens, you should call this beforehand:
SetWindowPos(hWndParent, 0, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOZORDER | SWP_SHOWWINDOW);
This'll move the window to the upper-left-hand corner of the screen.
If you're trying to close one certain dialog, then you should have no trouble doing so. But if you're trying to click any given button, chances are that you're gonna run into trouble sooner or later.
Until then, good luck!
Regards
-----------------------Ends-----------------
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