| Subject | Re: USE of ENTER KEY |
| From | Mervyn Bick <invalid@invalid.invalid> |
| Date | Tue, 21 Feb 2017 16:09:18 +0200 |
| Newsgroups | dbase.getting-started |
| Attachment(s) | test_grid_callback.wfm |
On 2017-02-21 8:53 AM, Mustansir Ghor wrote: > Hello Everyone > > In a grid which event will be fired on pressing the "ENTER" key If you open a form with a grid in the designer and select the grid you will be able to see all the events in the Inspector. Most of the events are triggered by mouse clicks. A grid does not have key and onKey events which can be used to test for the Enter key for an entryfield. The grid's only event that is triggered by the Enter key is the onSelChange event. Pressing the Enter key when a grid has focus moves the cursor to the next field in the selected row. When the Enter key is pressed while the cursor is on the last field in the row focus moves to the first field in the next row. Each time the Enter key is pressed the onSelChange event fires. Unfortunately the onSelChange also fires if the user clicks on an unselected cell and there is no easy way to tell if the event fired because the Enter key was pressed, if the Tab key was pressed or if the mouse was clicked. It needs a bit of coding but there is a way to trap for the Enter key (actually any key) in a grid if you are using dBASE 8 or higher. Using the CALLBACK command you can install a keyboard hook which allows you to see all the keyboard input to the grid. A little example is attached. Pressing the Tab key will move the selected cell and the onSelChange event will fire. Clicking on an unselected cell will fire the onSelChange event. Pressing the Enter key will trigger the onSelChange event but it will also be trapped by the keyboard hook. Keyboard hooks are a powerful tool for dBASE programmers. One can even use them to "swallow" keystrokes so that they never get passed on tho Windows for action. Mervyn. | |
if file('test_grid_callback.dbf') // drop table test_grid_callback endif if not file('test_grid_callback.dbf') create table test_grid_callback (id autoinc,job_no character(5),customer character(15),address1 character(15),address2 character(15),address3 character(15),; description character(50),complete boolean) use test_grid_callback generate 200 go top for n = 1 to 200 replace job_no with '1'+str(N,3,0,'0') SKIP next go top replace customer with 'Abel' SKIP replace customer with 'Baker' SKIP replace customer with 'Charlie' SKIP replace customer with 'Delta' SKIP replace customer with 'Echo' SKIP use endif clear ** END HEADER -- do not remove this line // // Generated on 2017-02-21 // parameter bModal local f f = new test_rid_callbackForm() if (bModal) f.mdi = false // ensure not MDI f.readModal() else f.open() endif class test_rid_callbackForm of FORM with (this) canClose = class::FORM_CANCLOSE onOpen = class::FORM_ONOPEN height = 31.6818 left = 39.8571 top = 2.5 width = 134.8571 text = "" scrollBar = 2 // Auto endwith this.TEST_GRID_CALLBACK1 = new QUERY(this) with (this.TEST_GRID_CALLBACK1) left = 2.0 top = 1.0 sql = 'select * from "test_grid_callback.DBF"' active = true endwith this.GRID1 = new GRID(this) with (this.GRID1) onSelChange = class::GRID1_ONSELCHANGE dataLink = form.test_grid_callback1.rowset height = 22.5 left = 12.0 top = 6.0 width = 103.0 endwith this.rowset = this.test_grid_callback1.rowset function form_onOpen() clear #include winuser.h if type("dBGetCurrentThreadId") # "FP" extern CULONG dBGetCurrentThreadId() kernel32 from "GetCurrentThreadId" endif if type("dBGetWindowLong") # "FP" extern CLONG dBGetWindowLong(CHANDLE, CINT) user32 from "GetWindowLongW" endif if type("dBSetWindowsHookEx") # "FP" extern CLONG dBSetWindowsHookEx(CINT, CPTR, CHANDLE, CULONG) user32 from "SetWindowsHookExW" endif if type("dBUnhookWindowsHookEx") # "FP" extern CLOGICAL dBUnhookWindowsHookEx(CHANDLE) user32 from "UnhookWindowsHookEx" endif if type("dBCallNextHookEx") # "FP" extern CLONG dBCallNextHookEx(CHANDLE, CINT, CUINT, CUINT) user32 from "CallNextHookEx" endif CALLBACK CLONG hookWndProc(CINT, CUINT, CUINT) OBJECT this this.hookProc = GetCallAddress(class::HOOKWNDPROC) this.hInst = dBGetWindowLong(this.hwnd, GWL_HINSTANCE) this.hook = dBSetWindowsHookEx(WH_KEYBOARD, this.hookProc, this.hInst, dBGetCurrentThreadId()) form.grid1.setFocus() return function GRID1_onSelChange() ? 'grid1 onSelChange' return function form_canClose dBUnhookWindowsHookEx(this.hook) return true function hookWndproc(hCode, wParam, lParam) if wParam = VK_RETURN and hcode = 0 and not bitset(lparam,31) if upper(form.activeControl.name) = 'GRID1' ? form.activeControl.name + ' Enter pressed' endif endif return dBCallNextHookEx(this.hook, hCode, wParam, lParam) endclass | |