C / C++ / MFC

5-Oct-07 0:04

I am writing a dialogue based application that has several button controls on it. I want the user to be able to press several buttons at once via the keyboard and the dialogue to represent the button as being pushed for the duration of the key presses.

My plan was to use OnKeyDown to read the keyboard and determine which button is pressed. I then want to send a message to the dialogue to simulate the button being pressed by the mouse. I was intending using:

SendDlgItemMessage(IDC_BUTTON2, ON_BN_CLICKED,0,0);

to send a message to the dialoge that a button has been pressed, but I am not having much luck.

I am using Visual Studio 2005

Any answers?

Kalvin

Nishad S5-Oct-07 1:02

Nishad S

5-Oct-07 1:02

KalvinComer wrote:
SendDlgItemMessage(IDC_BUTTON2, ON_BN_CLICKED,0,0);

It is absolutely useless. Any way BN_CLICKED is the message, not ON_BN_CLICKED. And it is sent along with WM_COMMAND. Also this message should be sent to the parent (dialog). So in the OnKeyDown, you have to send this message to your own dialog, instead of the button.

BTW you need a pushing effect on the button?

- NS -

vSteve5-Oct-07 1:12

5-Oct-07 1:12

To be a little clearer:

I have a dialoge that has two buttons (BT1, BT2).

I would like it to be the case that I can:

press 1 on the keybord and BT1 depresses (and calls and associated button1 clicked method). Releasing 1 un depresses BT1.

press 2 on the keybord and BT2 depresses (and calls and associated button2 clicked method). Releasing 2 un depresses BT2.

Press and hold 1 and 2 on the keyboard, and both BT1 and BT2 depress. Releasing 1 and 2 un-dpresses BT1 and BT2.

Kalvin

Nishad S5-Oct-07 1:32

Nishad S

5-Oct-07 1:32

KalvinComer wrote:
Press and hold 1 and 2 on the keyboard, and both BT1 and BT2 depress. Releasing 1 and 2 un-dpresses BT1 and BT2

Hope the following code may suit for you...

BOOL CMyDlg::PreTranslateMessage(MSG* pMsg) 
{
    if( pMsg->message == WM_KEYDOWN )
    {
        if( pMsg->wParam == '1' )
        {
            pMsg->wParam = VK_SPACE;
            pMsg->hwnd = m_btn1.m_hWnd;
        }
        else if( pMsg->wParam == '2' )
        {
            pMsg->wParam = VK_SPACE;
            pMsg->hwnd = m_btn2.m_hWnd;
        }
    }
    else if( pMsg->message == WM_KEYUP )
    {
        if( pMsg->wParam == '1' )
        {
            pMsg->wParam = VK_SPACE;
            pMsg->hwnd = m_btn1.m_hWnd;
        }
        else if( pMsg->wParam == '2' )
        {
            pMsg->wParam = VK_SPACE;
            pMsg->hwnd = m_btn2.m_hWnd;
        }
    }
    return CDialog::PreTranslateMessage(pMsg);
}

- NS -

Nathan Holt at EMOM5-Oct-07 5:58

Nathan Holt at EMOM

5-Oct-07 5:58

KalvinComer wrote:
I have a dialoge that has two buttons (BT1, BT2).

I would like it to be the case that I can:

press 1 on the keybord and BT1 depresses (and calls and associated button1 clicked method). Releasing 1 un depresses BT1.

press 2 on the keybord and BT2 depresses (and calls and associated button2 clicked method). Releasing 2 un depresses BT2.

Press and hold 1 and 2 on the keyboard, and both BT1 and BT2 depress. Releasing 1 and 2 un-dpresses BT1 and BT2.

I would use "pushbutton like" checkboxes instead of normal buttons, because you can make them look depressed just by set their state to checked, and release them by seting their state to unchecked. This would also make the dialog useable for someone who doesn't want to use the keyboard. Your idea of handling two keys pressed at once would work, but I think it would be easier to just assign '1' and '2' as shortcut keys to the respective buttons. That way, a user could press, but not hold '1' to either press or release button 1, and similarly for button 2.

Nathan

vSteve6-Oct-07 22:23

6-Oct-07 22:23

NS17:

Thank you, your code snippet has helped me alot. The key bit I was missing was: generation of my own button down command i.e.:

pMsg->wParam = VK_SPACE;
pMsg->hwnd = m_btn1.m_hWnd;

However, can't seem to get two buttons down at the same time.

Nathan:

Thanks for your suggestion. I now have two pushlike buttons on the dialogue and it behaves just how I want it with respect to the keyboard. But with respect to the mouse can I get the control to be true whilest the mouse is over it and the LH mouse button is down, and it returns to false when the mouse LH button is released.

I'm convinced some combination of your two solutions will get me there but after several hours work, I have got no further.

Having this dicussion has clarified my thoughts: what I need is:

A control either button or push like check box, that the rest of my app can reconise as being true or not, the control must be true only whilest the key assigned to it is pressed or the mouse button is being held down over it. If two buttons are pressed via the keyboard then both control states should be true for the duration of the press.

As some back ground: I am trying to write a simulation of a piece of hardware which has several keys. The state of which are sent regularly out over the serial port, have coded all that bit. The hardware buttons are momentary push buttons i.e. there state is high only whilst they are pressed down. So in real life the user could press more than one.

I can get the behaviour I want from the keyboard thanks to Nathan's idea, that only leaves how the control should behave in response to the mouse. Here I'd like the control to be on only when the mouse is over the control and on getting a WM_LBUTTONDOWN and the control to go off when getting the next WM_LBUTTONUP.

Any further ideas?

Kalvin

Nathan Holt at EMOM8-Oct-07 10:30

Nathan Holt at EMOM

8-Oct-07 10:30

KalvinComer wrote:
Nathan:

Thanks for your suggestion. I now have two pushlike buttons on the dialogue and it behaves just how I want it with respect to the keyboard. But with respect to the mouse can I get the control to be true whilest the mouse is over it and the LH mouse button is down, and it returns to false when the mouse LH button is released.

That makes things more complicated. When a mouse button is pressed over a control, the control captures the mouse input so that other windows don't get mouse messages. If you made a subclass of CButton that informed its parent whenever it got a mouse message, and used it for control members, you could update the state of the buttons according to the mouse state as well as the keyboard state.

I've just realized that you could also intercept mouse messages in PretranslateMessage for the same effect.

Nathan

vSteve8-Oct-07 23:34

How to avoid 3rd party frame's vestiges on my app [modified]

8-Oct-07 23:34

Nathan,

I have written an ActiveX control to provide the functionality I require, a bit of a learning curve but it's now doing just what I want.

Thanks for your help.

Kalvin

Nelek5-Oct-07 0:01

Nelek

5-Oct-07 0:01

Hi,

I have notice that, when I open the configurations tool of the 3rd party dll that I am using, if I move the window of the configurations tool, my programm is not able to refresh while the Modal DialogBox is opened. That causes that my programm (in background) acumulates vestiges of the movement of the foreground window. I have checked it out with another programs in background but it doesn't make it.

What should I look for in order to avoid that my program acumulates the tracks of the DialogBox's movement while it is opened? Any tip?

-- modified at 8:50 Friday 5th October, 2007

I hope you can understand what I try to say Sigh | :sigh:

Class Variable Initialization

nitin34-Oct-07 23:32

nitin3

4-Oct-07 23:32

i have declared a variable TCHAR TBuf[ 512 ] in public section of a class. How i can initialize this variable .

if i declare the variable in a local function i initialize it as TCHAR TBuf[512] = {'\0'} , in this method entire buffer (512) bytes is initialized. How to perform this kind of initialation on a class variable.

Thanks & Regards

Nelek4-Oct-07 23:43

Nelek

4-Oct-07 23:43

On the constructor of the class

MyClass::MyClass ()
{
//initialitation;
}

nitin34-Oct-07 23:58

nitin3

4-Oct-07 23:58

void MyFunc()
{
TCHAR TBuf[ 512 ] = { '\0' } ;//this method initializes the array index 0 to 511 with null
}
//in the case of a class varibale i use the following method, is there any simple step to do the same ?
class MyClass
{
public :
TCHAR TBuf[ 512 ] ;
MyClass()
{
//
int i = 512 ;
while( i > 0 )
{
TBuf[ --i ] = '\0' ;
};
}
}

Thanks & Regards

ThatsAlok5-Oct-07 0:46

ThatsAlok

5-Oct-07 0:46

better use ZeroMemory Api! or memcpy!

"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
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jhwurmbach5-Oct-07 0:53

jhwurmbach

5-Oct-07 0:53

Au contraire!
Why should one not use a C++ function instead of something more complicated and proprietary?

Though I speak with the tongues of men and of angels, and have not money, I am become as a sounding brass, or a tinkling cymbal.
George Orwell, "Keep the Aspidistra Flying", Opening words

Mark Salsbery5-Oct-07 6:03

Mark Salsbery

5-Oct-07 6:03

As DavidCrow mentioned, you can use memset().

Also, I would recommend NOT using hardcoded values like 512...
use the sizeof operator.

class MyClass
{
public :
    TCHAR TBuf[ 512 ] ;

    MyClass()
    {
        memset(TBuf, 0, sizeof(TBuf));
    }
};

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]