get the window's rect - C / C++ / MFC Discussion Boards

Re: Transparent lines in C

Code-o-mat17-Nov-09 4:34

Code-o-mat

17-Nov-09 4:34

I assume you did not intend to target that post at me.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <

Re: Transparent lines in C

Rozis17-Nov-09 5:22

Rozis

17-Nov-09 5:22

I'll try to answer both...

Alphablend() has a parameter that determines a global transparency. Suppose I want 2 lines with different transparencies i must use Alphablend() 2 times. And drawing 2 times tranparently to the screen will change the original pixels (those that are not from the lines). In other words: I can copy the screen to the memoryDC, draw the line and alphablend it to the screen but then all pixels are changed. This is why a regionobject is required. So the solution of Rejeesh can not work.

The first suggestion of Code-o-mat is too slow. But his 2nd approach may have some opportunities. If i understand you well Code-o-mat essentially you say to me: manipulate the alpha-channel according to the line drawn... Thus if i could draw the line directly in the alpha-channel my problem would be solved. Unfortunally there's not such function... but maybe i can write one...

Maybe an approach can be: create a memoryDC, a 32-BPP bitmap and an addional 8-bit black and white bitmap. Draw the lines on the 8-bit bitmap (and also on the 32-bit bitmap) and finally merge the 8-bit image as an alpha-channel to the 32-bit bitmap. This means: no regions needed, no manual line draws and only one time comsuming operation (the merging of the alpha-channel. Sounds promissing!

Anyone any better ideas?

Re: Transparent lines in C

Code-o-mat17-Nov-09 5:35

Code-o-mat

17-Nov-09 5:35

Your idea sounds interesting but the merging process might become slow with bigger images.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <

Re: Transparent lines in C

Rozis17-Nov-09 6:17

Rozis

17-Nov-09 6:17

Code-o-mat wrote:
Your idea sounds interesting but the merging process might become slow with bigger images.

True, but my inital approach wasn't free either Smile | :)

And maybe you din't realized that, but had to do all the things per line. So 100 lines was 100 buffers, 100 regions, ... Now it seems i have: 1 buffer, no regions, and one time consumer. And the good news is the time consumer has no mults or divides, just some bit shifting. I'm sure performance will be much better... bet it will have a performance like a graphic filter (like emboss for ex.).

I'll try this out in the next days - thanks for the ideas...

Rozis

Re: Transparent lines in C

Tim Craig17-Nov-09 8:45

Tim Craig

17-Nov-09 8:45

Rozis wrote:
but MS itself disencourages this...

Microsoft discourages C++, too, but don't let that stop you. Laugh | :laugh:

You measure democracy by the freedom it gives its dissidents, not the freedom it gives its assimilated conformists.

Re: Transparent lines in C

Rozis17-Nov-09 9:41

Rozis

17-Nov-09 9:41

Tim Craig wrote:
Rozis wrote:
but MS itself disencourages this...

Microsoft discourages C++, too, but don't let that stop you.

Yep. It says: "Microsoft Windows GDI+ exposes a flat API that consists of about 600 functions, which are implemented in Gdiplus.dll and declared in Gdiplusflat.h. The functions in the GDI+ flat API are wrapped by a collection of about 40 C++ classes. It is recommended that you do not directly call the functions in the flat API. Whenever you make calls to GDI+, you should do so by calling the methods and functions provided by the C++ wrappers. Microsoft Product Support Services will not provide support for code that calls the flat API directly."

What i figure out of their documentation is that the complete GDI+ classes are internally handled by their 'flat API'. This probably means: the flat api will change without any notice.

Maybe the reason they discourages C++ is that they seem to be afraid of classes. Cool | :cool:

Re: Transparent lines in C

KingsGambit17-Nov-09 4:39

KingsGambit

17-Nov-09 4:39

May be you will have to create 32bpp DIB section and make all your drawing on it. And finally use AlphaBlend() on target DC.

get the window's rect

itay1017-Nov-09 2:46

itay10

17-Nov-09 2:46

Hi
I'm trying to get some information about the windows that working in the background.
I'm using the GetWindowRect function and it's never show me information.
here is the relevant part of my code:

BOOL CALLBACK EnumChildProc(HWND hwnd, LPARAM lParam) {<br />
<br />
	LPRECT lprect=NULL;<br />
	cout << "hwnd_Child = " << hwnd << endl;<br />
	SetWindowText(hwnd,NULL);<br />
	if(GetWindowRect(hwnd,lprect))<br />
		cout<< lprect->bottom<< endl;<br />
	<br />
	<br />
	<br />
<br />
     return TRUE; // must return TRUE; If return is FALSE it stops the recursion<br />
}

it does change the window's text but doesn't go into the if. any idea why?

by the way how can i find the buttons inside the window?

thanks
Itay

Re: get the window's rect

Richard MacCutchan17-Nov-09 3:10

Richard MacCutchan

17-Nov-09 3:10

Using this code : LPRECT lprect=NULL; You are sending a NULL pointer so that will cause GetWindowRect() to fail. Try the following instead:

RECT cRect;
if(GetWindowRect(hwnd, &cRect))
...

and on return cRect should contain the cx and cy values

Re: get the window's rect

itay1017-Nov-09 5:23

itay10

17-Nov-09 5:23

Richard MacCutchan wrote:

RECT cRect;
if(GetWindowRect(hwnd, &cRect))
...

thanks. now it is working.

Re: get the window's rect [modified]

Code-o-mat17-Nov-09 3:11

Code-o-mat

17-Nov-09 3:11

You can't get the rectangle of windows which do not belong to your own process. However, GetWindowText and SetWindowText do work between different processes. (in case you are enumerating windows of other processes also)

Additionally to what Richard MacCutchan said.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <

modified on Tuesday, November 17, 2009 9:34 AM

Re: get the window's rect

Richard MacCutchan17-Nov-09 6:22

Richard MacCutchan

17-Nov-09 6:22

Code-o-mat wrote:
You can't get the rectangle of windows which do not belong to your own process.

Strange, this restriction is not noted in the MSDN documentation, but it is noted in the doc for Get/SetWindowText()!

Re: get the window's rect

Code-o-mat17-Nov-09 6:34

Code-o-mat

17-Nov-09 6:34

I might be wrong but i think i once wanted to get the rectangle of such windows too and i couldn't get it to work so i googled around and found out that the reason was indeed that GetWindowRect can't cross processes.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <

Re: get the window's rect

CPallini17-Nov-09 3:15

CPallini

17-Nov-09 3:15

itay10 wrote:
LPRECT lprect=NULL;

itay10 wrote:
if(GetWindowRect(hwnd,lprect))

You cannot do this.
The pointer must hold the address of a valid struct.

change to:

RECT rect;
//..
if(GetWindowRect(hwnd ,&rect))
//..

BTW: why aren't you calling GetLastError?
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.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: get the window's rect

itay1017-Nov-09 5:21

itay10

17-Nov-09 5:21

thanks all it worked!

CPallini wrote:
BTW: why aren't you calling GetLastError?

I don't know, never tried. how can it help?

Re: get the window's rect

David Crow17-Nov-09 5:55

David Crow

17-Nov-09 5:55

itay10 wrote:
how can it help?

Seriously? Did you read the docs to see what it does? Since the condition in the if test evaluated to false, that would indicate that GetWindowRect() returned zero.

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"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

Re: get the window's rect

itay1017-Nov-09 7:06

itay10

17-Nov-09 7:06

i debugged it and i knew the returned value was zero, the question was why?

Re: get the window's rect

David Crow17-Nov-09 7:08

David Crow

17-Nov-09 7:08

Calling GetLastError() would have likely told you why.

Re: get the window's rect

CPallini17-Nov-09 6:03

CPallini

17-Nov-09 6:03

itay10 wrote:
CPallini wrote:
BTW: why aren't you calling GetLastError?

I don't know, never tried. how can it help?

Oh, don't worry about, it's a decorative function... Roll eyes | :rolleyes:

Re: get the window's rect

Richard MacCutchan17-Nov-09 5:39

Richard MacCutchan

17-Nov-09 5:39

CPallini wrote:
BTW: why aren't you calling GetLastError?

Real men don't need GetLastError(); what do you think CodeProject is for? Laugh | :laugh:

Re: get the window's rect

CPallini17-Nov-09 5:47

CPallini

17-Nov-09 5:47

Richard MacCutchan wrote:
Real men don't need GetLastError();

You're right: real women need GetHisLastError, while real men do need AdmitLastError.
Big Grin | :-D

Examples of SaveAs in winapi / c++

Nicola Curran17-Nov-09 2:07

Nicola Curran

17-Nov-09 2:07

Hi, I'm aiming to do something like instance a save as dialogue box have a user add input. Retrieve the file name and create the file based on the input. This is what I have so far:

OPENFILENAME _openfile;
ZeroMemory(&_openfile, sizeof(OPENFILENAME));
_openfile.lStructSize = sizeof(OPENFILENAME);
_openfile.lCustData = (DWORD)NULL;
_openfile.hwndOwner = GetFocus();
_openfile.lpstrFile = tmp;
_openfile.lpstrInitialDir = strcat(buffer, "\\Desktop\\");
_openfile.lpstrDefExt = ".xml";
_openfile.lpstrFilter = "Extensible Markup Language (*.xml)";

bool success = false;
success = GetSaveFileName(&_openfile);

HANDLE file = CreateFile(_openfile.lpstrFile, GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ, NULL, CREATE_NEW, FILE_ATTRIBUTE_NORMAL,
NULL);

What I was wondering is if anyone knew of an example of how to do this on codeproject. I can't seem to find one. Thanks for anything you can suggest. Nicola x

Re: Examples of SaveAs in winapi / c++

CPallini17-Nov-09 2:21

CPallini

17-Nov-09 2:21

What is your trouble about?
Smile | :)

Re: Examples of SaveAs in winapi / c++

Nicola Curran17-Nov-09 2:38

Nicola Curran

17-Nov-09 2:38

I cant find a full example of using GetSaveFileName, and how I can then get the file name from that (which I assumed was supposed to be passed by reference back to me?)

Have you come across an article that might help? Effectively, All i want to achieve is

Click Save as button -> GetSaveFileName()

CreateFile(filename);

but I don't know how to get the file name from the dialogue.

Re: Examples of SaveAs in winapi / c++

CPallini17-Nov-09 2:46

CPallini

17-Nov-09 2:46

Not sure I got you, anyway an usage example is here [^].
Smile | :)

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