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Line Control
The line control can be displayed as a line or as a filled (optional) rectangle.

• Syntax:
  

  Control Add Line, hDlg, id&, txt$, x, y, xx, yy, 
                                     style&, extsytle& CALL callback
  

• Source Code Example:
  This short example creates a complete application with a single line. When clicked, the line control responds with a message. This tutorial page discusses most of the statements used, however the DDT, Controls, Messages, and Callback tutorials provide background information that may be helpful in understanding the example.

     #Compile Exe
     #Include "Win32API.inc"
     Global hDlg As Dword
     Function PBMain() As Long
        Dialog New Pixels, 0, "Line Test",300,300,200,200, _
                                        %WS_SysMenu, 0 To hDlg
        Control Add Line, hDlg, 100,"", 50,50,100,2, _
                                       %SS_Notify Or %WS_Border
        Dialog Show Modal hDlg Call DlgProc 
     End Function
  
     CallBack Function DlgProc() As Long
        If Cb.Msg = %WM_Command And Cb.Ctl = 100 And _
                          Cb.CtlMsg = %STN_Clicked Then
           MsgBox "Clicked!"
        End If
     End Function 
  

  Note that the #INCLUDE "Win32API.inc" is required because it contains the %STN_CLICKED message named constant.

  An additional example of a callback function is provided further down this page.

• Visual Examples:
  And here are a few examples of what you can do with the line control in PowerBASIC. Variations on the Control Add Line statement were used to create the examples. In some cases, other Control statements were used to modify the results.

  

Arguments
The Control Add statement is used to create all new controls. Here are the statement's arguments and any special significance to the line control.

• hDlg
  The dialog handle to which the line control is to be added. The value was returned by the DIALOG NEW statement.

• id&
  The id& argument is a control identifier assigned by the programmer. It must be a value of 1-65535. Values of 100+ are suggested, as PowerBASIC pre-assigns identifiers with special meaning. Numeric equates are suggested over the use of literal values.

• txt$
  An ampersand can also be included in txt$, such as "&Stop", to specify a hot key Alt-S. But since a line control cannot get focus, using the hotkey will give focus to the next control in the tab order.

  The line control does not display text, so the txt$ argument is usually set to "". However, any entered txt$ value can be accessed using the GET/SET TEXT statements. This provides the application with a control-specific property that can used for any purpose.

• x,y and xx,yy
  The integer x,y and xx,yy dimensions use the same units as the parent dialog. (x,y) is the upper/left coordinates of the control. (xx,yy) is the width/height of the control.

• style& and extstyle&
  The style& and extstyle& arguments (listed below) are optional. If not supplied, default values are used (see the table below). If values are supplied, they completely replace default values (i.e., the entered values are not in addition to the default values).

  To get the line control to respond to Control Set Color you must include %ss_notify in the style setting.

• CALL
  The "CALL callback" section is optional. If not supplied, the callback function of the parent dialog is used. An example callback function for line controls is provided further down this page. The #MESSAGE COMMAND compiler directive can be used to prevent sending %WS_NOTIFY messages to the callback function. By default, both %WS_NOTIFY and %WS_COMMAND messages are sent.

Line-Specific PowerBASIC Statements
Although PowerBASIC provides control-specific statements for some controls (Treeview, Imagelist, ...), there are no LINE PowerBASIC statements.

Messages, Notifications, Styles, and ExtSstyles
There are four types of named constants in the following table. All are pulled from the MSDN web site.

• Notifications - event notifications a control receives
• Messages - controls may send these
• Styles - affect the visual look of a control
• ExtStyles - additional values that affect the visual look

The first column contains control-specific named constants and the second column contains generic window named constants (line controls are windows).

Also, if the PowerBASIC Help file has an entry on the value, it is highlighted in yellow. If the value was noted in PowerBASIC Help as a default value, it is also shown in bold text.

In the values for notifications, descriptions starting with -n and -c refer to events received through the %wm_notify and %wm_command messages. By default, PowerBASIC controls can receive both of these messages.

And here is a short description of many of the named constants corresponding to notifications, styles, and extstyle - particularly those discussed in the PowerBASIC Help topics.

    %ss_blackframe         - black box (frame color)
    %ss_blackrect          - black filled box
    %ss_etchedframe        - etched edge style (default)
    %ss_etchedhorz         - horizontal edges with etched edge style
    %ss_etchedvert         - vertical edges with etched edge style.
    %ss_grayframe          - gray box (screen background color)
    %ss_grayrect           - gray filled box
    %ss_noprefix           - prevent & interpretation
    %ss_notify             - allows %stn_clicked/%stn_dblclk messages
    %ss_whiteframe         - white box (window background)
    %ss_whiterect          - white filled box
    %stn_clicked           -c mouse click
    %stn_dblclk            -c double slick
    %stn_disable           -c when control has been disabled
    %stn_enable            -c when control has been enabled
    %wm_ctlcolorstatic     -  about to be drawn
    %ws_ex_clientedge      - apply sunken edge border
    %ws_ex_left            - generic left-aligned properties
    %ws_ex_right           - generic right-aligned properties
    %ws_ex_staticedge      - apply 3D border
    %ws_ex_transparent     - draw controls/windows beneath control first
    ss_rightjust           - fix bottom-right on resize

Callback Function
A control can have its own callback function, or use the parent dialog callback function.

A control callback function should return TRUE to indicate it has processed the message. This prevents unnecessarily calling the dialog callback function, which will process the message if no control callback function is available, or if the control callback function returns FALSE.

By default, both %WM_COMMAND and %WM_NOTIFY messages are received. However, if the #MESSAGE COMMAND compiler directive is invoked, the %WM_NOTIFY messages will not be available.

In addition, %ss_notify must be included in style& to receive the %stn_clicked and %stn_dblclk messages.

Here's a sample line control callback function.

   CallBack Function cbLine()
      Select Case CB.MSG
         Case %WM_COMMAND
            Select Case CB.CTLMSG
               Case %stn_clicked
               Case %stn_dblclk
               Case %stn_disable
               Case %stn_enable
         End Select
      End Select
   End Function

In each Case section, add the statements the application needs to respond to the event. Also, be sure to add "Function=1" as appropriate to indicate that the event was handled by the callback function.

CONTROL Statement Syntax
The following table lists the various Control statements (except the ADD statements). Most, but not all, can be used with the line control. A one-line description of the statement and then its syntax are presented.

CONTROL DISABLE	disable
	hDlg, id&
CONTROL ENABLE	enable	hDlg, id&
CONTROL GET CHECK	check state	hDlg, id& TO iResult1&
CONTROL GET CLIENT	top/left location	hDlg, id& TO wide&, high&
CONTROL GET LOC	top/left location	hDlg, id& TO x&, y&
CONTROL GET SIZE	width/height	hDlg, id& TO width&, height&
CONTROL GET TEXT	text	hDlg, id& TO txt$
CONTROL GET USER	get user data	hDlg, id&, index& TO retvar&
CONTROL HANDLE	window handle for control id	hDlg, id& TO hCtl&
CONTROL KILL	remove control	hDlg, id&
CONTROL POST	put message in queue (non-blocking)	hDlg, id&, Msg&, wParam&, lParam&
CONTROL REDRAW	schedule redraw of control	hDlg, id&
CONTROL SEND	send message to control, wait for processing	hDlg, id&, Msg&, wParam&, lParam& TO iResult2&
CONTROL SET CHECK	set check for 3state or checkbox	hDlg, id&, checkstate&
CONTROL SET CLIENT	change size to specific client area size	hDlg, id&, wide&, high&
CONTROL SET COLOR	set fg/bg color	hDlg, id&, fgcolor&, bgcolor&
CONTROL SET FOCUS	set focus	hDlg, id&
CONTROL SET FONT	select font for a control	hDlg, id&, fonthandle&
CONTROL SET LOC	relocate control within dialog	hDlg, id&, x&, y&
CONTROL SET OPTION	set check state of option control	hDlg, id&, minid&, maxid&
CONTROL SET SIZE	change control size	hDlg, id&, width&, height&
CONTROL SET TEXT	change control text	hDlg, id&, text$
CONTROL SET USER	set user data	hDlg, id&, index&, uservalue&
CONTROL SHOW STATE	toggle visibility	hDlg, id&, showstate& TO iResult3&

If you have any suggestions or corrections, please let me know.