#lang racket
(require racket/gui/base
qresults-list
)
;Since qresults-list is an extension of list-box, you can send the same messages to it as you can send
;to a list-box%. See the manual for list-box for these messages.
;You need to define functions which will return a given column value from a row of data.
; The variable data below is expected to be a vector.
;These functions typically have the name of the column.
;For database results you need to handle the fact that
;list-box can not display sql-null so you will need to
;substitute either "" or #f. The sql-column-ref function
;from the dbutil.rkt file of ActivityLog2 does this.
(define (column1 data) (vector-ref data 0)) ;This function defines column1 as being the column at index 0.
(define (column2 data) (vector-ref data 1))
; The qcolumn struct defines a column of a qresults-list table.
; You provide qresults-list a list of these structs to define all the columns.
; The qcolumn constructor takes name, formatter and a sort-key.
; Name is a function which returns the correct value for a given column from a row of data.
;;Formatter is a function taking a row and returning a string representing
;;the value to be displayed for that row in this column.
;; You may want to enforce data types on input rather than use the formatter.
;;However, the formatter does have to handle any special cases. For example, a numeric
;;column's formatter should probably return empty string for null.
;; sort-key is function taking a row and returning a value that can be used to sort
;; this column, this can be either a string (in which case the column is
;; sorted by string< and string>, or a number in that case, the column is
;; sorted using < and >.
(define my-columns
(list
(qcolumn "Column1" column1 column1)
(qcolumn "Column2"
(lambda (row)
(if (number? (column2 row)) (number->string (column2 row)) "");This allows a cell to be blank.
)
column2)
)
)
;Create a frame to contain the table.
(define frame3 (new frame%
[label "myTable 3"]
[width 800]
[height 600]
))
(define (enable-disable-row-menu-items m) ;for actions on rows of the table.
;Some menus need to be greyed out when there is no selection. Otherwise, you get an error
;when you right click and hit an action which needs a selection.
;Each menu item which acts on one or more rows of the table should appear here, in this function.
(send info-menu-item enable (send table3 get-selected-row-index))
(send delete-menu-item enable (send table3 get-selected-row-index))
)
;Create the menu. We add items to it next.
(define row-edit-menu (new popup-menu%
(demand-callback enable-disable-row-menu-items))
)
;Keyboard shortcuts defined in menu-items which only appear in a popup menu will only work when
;the popup menu is shown. This is not an issue if you follow Apple's HIG because any item in
;a popup menu is also supposed to appear in the main menu bar. Then the
;keyboard shortcuts will be available all the time.
(define info-menu-item (new menu-item%
(label "info")
(parent row-edit-menu)
(shortcut #\i)
(callback (lambda (menu-item event)
(message-box "Info"
(~a "You have selected " (length (send table3 get-selected-row-indexes)) " rows")
#f)
))
))
(define delete-menu-item (new menu-item%
(label "Delete Row(s)")
(parent row-edit-menu)
(shortcut #\backspace); command-delete on Mac, control-backspace on Linux and Windows.
(callback (lambda (menu-item event)
(for ([row (reverse (send table3 get-selected-row-indexes))])
;Need to delete in reverse order because the rows renumber after each iteration of the loop.
;(displayln (~a "deleting row " row))
(send table3 delete-row row))
))
))
(define add-new-row (new menu-item%
(label "New row")
(parent row-edit-menu)
(shortcut #\n)
(callback (lambda (menu-item event)
(send table3 add-row (vector "" ""))
))
))
(define table3
(new (class qresults-list% (init) (super-new)
(define/override (on-double-click row-index row-data)
;on-double-click is defined in qresults-list but does nothing except return false.
;This override allows the double click to do somethig else.
(message-box "Info"
(~a "You double clicked on row " row-index " which has data: " row-data)
#f)
))
[parent frame3]
[pref-tag 'preferences-tag]
[selection-type 'multiple]
[right-click-menu row-edit-menu])
)
(send table3 setup-column-defs my-columns)
(send frame3 show #t)
;The add-row message is part of qresults-list, not the parent list-box.
(send table3 add-row (vector "R1C1" 10))
(send table3 add-row (vector "R2C1" 11))
(send table3 add-row (vector "R3C1" 12))
;(send table3 add-row (vector "" "")) ;An empty row.
(send table3 add-row (vector "R4C1" 13))
(send table3 add-row (vector "R5C1" 14))
(send table3 add-row (vector "R5C1" 15))
(send table3 add-row (vector "R6C1" 16))
(send table3 add-row (vector "R7C1" 17))
#|
If you want to insert a blank row, you still need to fill it with null types. For string types, you can use empty string.
For numeric types, you can use +nan.0 but, unfortunately, the table will display this item explicity and not as a blank
cell.
|#
