Mouse tracking in tab control?

[Todd Wasson]

I'd like to access graphs that show up in a large tab control. How can I track the mouse position in a tab control? I've tried intercepting %WM_MOUSEMOVE from the main dialog callback that owns the tab, but of course, it will not receive these messages when over the tab's (client?) area. There are no %TCM/TCN type messages for this. Also have tried intercepting ANY messages from within the tab's callback itself, but am getting nothing. Any ideas?
Thanks,
Todd

[This message has been edited by Todd Wasson (edited May 18, 2000).]

[Chris Boss]

Todd;

You have to "subclass" the Tab control and then process the mouse messages before they are passed on to the Tab controls window procedure.

Search the forum for more info about subclassing.



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[Todd Wasson]

This is the code I'm using. Aren't the tabs subclassed already when using DDT this way? What gets me is that the callback functions cbTab1, cbTab2, and cbTab3 don't ever BEEP. Nothing is reaching these callbacks as far as I can see. You mention grabbing the messages BEFORE they reach the tab callbacks via subclassing. I'll keep reading!
Thanks,
Todd

'-----TabEx.bas----
#COMPILE EXE
#INCLUDE "commctrl.inc"
#INCLUDE "TabDDT.inc"
    GLOBAL hDlg AS LONG
    GLOBAL TEXT AS STRING
    GLOBAL hTabDlg1 AS LONG
    GLOBAL hTabDlg2 AS LONG
    GLOBAL hTabDlg3 AS LONG
%IDC_TAB = 1000


DECLARE CALLBACK FUNCTION MainDlgProc

FUNCTION PBMAIN
    LOCAL th AS TABHDR
    LOCAL hTab AS LONG

    ' Main dialog
    DIALOG NEW 0, "DDT - Tab Example",,,400, 300, %WS_SYSMENU OR %WS_MINIMIZEBOX OR %DS_CENTER TO hDlg

    ' Tab control
    hTab = TabCtrl(hDlg, %IDC_TAB, 20, 20, 300, 200)

    ' Tab - dialog 1
    DIALOG NEW hTab, "Tab nr. 1",,,400, 300, %WS_CHILD OR %WS_VISIBLE  TO hTabDlg1
    CONTROL ADD LABEL, hTabDlg1, -1, "This is Tab 1", 5,25,50,14
    ' Tab - dialog 2
    DIALOG NEW hTab, "Tab nr. 2",,,400, 300, %WS_CHILD OR %WS_VISIBLE TO hTabDlg2
    CONTROL ADD LABEL, hTabDlg2, -1, "This is Tab 2", 5,5,50,14
    ' Tab - dialog 3
    DIALOG NEW hTab, "Tab nr. 3",,,400,300, %WS_CHILD OR %WS_VISIBLE TO hTabDlg3
    CONTROL ADD BUTTON, hTabDlg3, 100, "A big button",50,50, 90,90
    th.lID = %IDC_TAB
    th.cDialogs = 3

    th.DlgHdr(0).hTabDlg       = hTabDlg1
    th.DlgHdr(0).lpfnCallback  = CODEPTR(cbTab1)

    th.DlgHdr(1).hTabDlg       = hTabDlg2
    th.DlgHdr(1).lpfnCallback  = CODEPTR(cbTab2)

    th.DlgHdr(2).hTabDlg       = hTabDlg3
    th.DlgHdr(2).lpfnCallback  = CODEPTR(cbTab3)

    InitTabControl hDlg, th

    DIALOG SHOW MODAL hDlg CALL MainDlgProc

END FUNCTION

CALLBACK FUNCTION MainDlgProc

    SELECT CASE CBMSG
        CASE %WM_NOTIFY

            OnTabNotify CBHNDL, CBLPARAM
        CASE %WM_COMMAND
            SELECT CASE LOWRD(CBWPARAM)
            END SELECT
  END SELECT

END FUNCTION

CALLBACK FUNCTION cbTab1
BEEP
    SELECT CASE CBMSG

        CASE %WM_INITDIALOG
        CASE %WM_COMMAND
            SELECT CASE LOWRD(CBWPARAM)
           END SELECT
  END SELECT

END FUNCTION


CALLBACK FUNCTION cbTab2
BEEP
  SELECT CASE CBMSG

         CASE %WM_INITDIALOG
         CASE %WM_COMMAND
              SELECT CASE LOWRD(CBWPARAM)
              END SELECT
  END SELECT

END FUNCTION

CALLBACK FUNCTION cbTab3
BEEP
  SELECT CASE CBMSG

         CASE %WM_INITDIALOG
         CASE %WM_COMMAND
              SELECT CASE LOWRD(CBWPARAM)
              END SELECT
  END SELECT

END FUNCTION

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[This message has been edited by Todd Wasson (edited May 18, 2000).]

[Lance Edmonds]

Tab controls use notification messages (%WM_NOTIFY), not %WM_COMMAND messages. Also, specifying a callback for a control is not the same as subclassing a control - a DDT control callback receives messages from the specified control that it's parent callback would have otherwise received. Control callbacks are designed to break a dialog callback into a bunch of more manageable and separated functions.

Subclassing is a technique of intercepting messages before they are passed to the control own window procedure, thus providing a way to alter the behaviour of an existing instance of a control.

The messages that your own callbacks' receive originate from the controls own window procedure, in response to messages it receives from the application's message quque.

For (a simplistic) example, a button control may get a %WM_MOUSEDOWN followed by a %WM_MOUSEUP message, and in turn it sends a %WM_COMMAND|%BN_CLICKED message to the dialog callback (or the button callback if one exists).

This is 'elementary' windows theory - consult Petzold for a detailed description of how each window class must implement it's own window procedure.

Creating a whole new control class based on an existing class is call superclassing, and that is another whole topic by itself, but it opens another avenue for creating custom controls.


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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Todd Wasson]

Thanks, Lance. Will hit the book and search for SetWindowLong() now.
Todd

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