Using+a+pager+control

//by Richard Russell, July 2010//

A [|pager control] is useful if you have a child window which is too big to be displayed in its entirety. The pager control allows you to scroll into view the part of the child control in which you are interested.

A typical use of a pager control is to allow you to scroll through a toolbar which is too wide to fit across your main window. Another use, and the one I will take as an example, is to allow you to scroll through a dialogue box which would otherwise be too big.

In order to use a pager control the first step is to perform some initialisation, as follows: code format="bb4w" INSTALL @lib$+"WINLIB2" INSTALL @lib$+"WINLIB5A" ON CLOSE PROCcleanup : QUIT ON ERROR SYS "MessageBox", @hwnd%, REPORT$, 0, 48 : PROCcleanup : QUIT

REM!WC Windows Constants: CCS_NORESIZE = 4 GWL_WNDPROC = -4 ICC_PAGESCROLLER_CLASS = &1000 PGM_SETCHILD = &1401 PGN_CALCSIZE = &FFFFFC7A PGS_HORZ = 1 PGS_VERT = 0 WC_PAGESCROLLER$ = "SysPager" WM_NOTIFY = &4E WS_DLGFRAME = &400000 WS_BORDER = &800000 WS_CHILD = &40000000 WS_POPUP = &80000000 REM Enable the use of pager controls: DIM iccx{dwSize%, dwICC%} iccx.dwSize% = DIM(iccx{}) iccx.dwICC% = ICC_PAGESCROLLER_CLASS SYS "InitCommonControlsEx", iccx{} code Note that **WINLIB2** is installed for the purpose of creating the dialogue box; it is not required for the pager control itself. The **ON CLOSE** and **ON ERROR** statements ensure that the dialogue box is closed when the program is terminated. The **PROCcleanup** routine is listed below.

The next step is to create the pager control: code format="bb4w" x% = 100 y% = 100 dx% = 200 dy% = 200 hPager% = FN_createwindow(@hwnd%, WC_PAGESCROLLER$, "", x%, y%, dx%, dy%, \     \                         0, PGS_VERT OR WS_BORDER, 0) IF hPager% = 0 ERROR 100, "Cannot create pager control" code The position and size have been set to arbitrary values for the purpose of the demonstration. The **PGS_VERT** style signifies that the pager control allows vertical scrolling; if you want to enable horizontal scrolling specify the **PGS_HORZ** style (you cannot enable both at the same time).

The appearance of the pager control and its scroll buttons can be changed by sending various messages; see this [|MSDN page] for details.

Now we create the child window that we wish to scroll. In this case, purely for the purposes of the example, it is a dialogue box containing a grid of 160 pushbuttons: code format="bb4w" Dialog% = FN_newdialog("Pager test", 0, 0, 120, 1000, 8, 10000) id% = 100 FOR y% = 5 TO 980 STEP 25 FOR x% = 10 TO 100 STEP 30 PROC_pushbutton(Dialog%, STR$(id%), id%, x%, y%, 20, 18, 0) id% += 1 NEXT x%     NEXT y% code Before we display the dialogue box we need to perform a little magic on its template: code format="bb4w" Dialog%!16 = (Dialog%!16 AND NOT (WS_POPUP OR WS_DLGFRAME)) OR \ \           WS_CHILD OR CCS_NORESIZE !(Dialog%!4+8) = hPager% : REM Set parent PROC_showdialog(Dialog%) code The first line modifies the dialogue box's style; in particular the title bar is removed and it is made a child window. The second line sets the dialogue box's parent to be the pager control we created earlier.

We have to tell the pager control the dimensions of the child window it contains, so it can calculate when to display the scroll buttons. This is done as follows: code format="bb4w" DIM rc{l%,t%,r%,b%} SYS "GetWindowRect", !Dialog%, rc{} PROCsetnotify(rc.r%-rc.l%, rc.b%-rc.t%) code The **PROCsetnotify** routine is listed below.

There is just one more step, which is to 'assign' the dialogue box to the pager control: code format="bb4w" SYS "SendMessage", hPager%, PGM_SETCHILD, 0, !Dialog% code Now the pager control, containing the scrollable dialogue box, should be displayed. The rest of the program is simulated by this simple loop: code format="bb4w" REPEAT WAIT 0 UNTIL FALSE END code In practice you will want to do something rather more useful!

Here are the listings of the **PROCsetnotify** and **PROCcleanup** routines: code format="bb4w" DEF PROCsetnotify(iWidth%, iHeight%) LOCAL L%, P%, oldwndproc, newwndproc, exit, notify DIM P% 50, L% -1 SYS "GetWindowLong", @hwnd%, GWL_WNDPROC TO oldwndproc [OPT 10 .exit pop eax push oldwndproc push eax jmp "CallWindowProc" ;     .newwndproc cmp dword [esp+8],WM_NOTIFY jnz exit .notify mov edx,[esp+16] ; lParam cmp dword [edx+8],PGN_CALCSIZE jnz exit mov dword [edx+16],iWidth% mov dword [edx+20],iHeight% ret 16 ]     SYS "SetWindowLong", @hwnd%, GWL_WNDPROC, newwndproc ENDPROC DEF PROCcleanup Dialog% += 0 : IF Dialog% PROC_closedialog(Dialog%) hPager% += 0 : IF hPager% PROC_closewindow(hPager%) ENDPROC code Needless to say, you should incorporate in the **PROCcleanup** routine any cleanup operations needed by the rest of your program.