gWidgets (version 0.0-54.2)

gmenu: Constructors to make menubars or toolbars

Description

A menubar or toolbar are created using these constructors. These are specified using a lists, and these may be seen as simply mapping these lists into the corresponding widget.

Usage

gmenu(menulist,  popup = FALSE, action=NULL, container = NULL, ..., 
toolkit = guiToolkit())
gtoolbar (toolbarlist, style = c("both", "icons", "text",
	 "both-horiz"), 
	 action=NULL, container = NULL, 
    ..., toolkit = guiToolkit()) 
gaction(label, tooltip = NULL, icon = NULL, key.accel = NULL, 
        handler = NULL, action = NULL, parent=NULL, ...,
        toolkit = guiToolkit())

Arguments

menulist

A list defining a menu bar

popup

Logical indicating if this should return a popup menu

toolbarlist

A list defining a toolbar

style

What style to use

action

Passed to menubar handlers

container

Container to attach widget to. Should be a gwindow instance.

label

Label for action item

tooltip

tooltip

icon

icon to decorate instance of action

key.accel

keyboard accelerator. If specified, a parent window must also be specified.

parent

Needed if key.accel is specified

handler

Handler called when object attached to action is activated

…

Passed to the add method of the container

toolkit

Which GUI toolkit to use

Details

The gaction constructor creates reusable objects for use with buttons, menubars and toolbars. Once constructed, the main methods are svalue, and svalue<- for getting and setting the label text and enabled<- which can changes whether the widgets depending on the action are sensitive to user input. An action object contains a label, an optional icon, an optional keyboard accelerator, a handler and a parent window. The handler does not have the widget from which it is called passed in to the obj component of the first argument, but one can parametrize the argument with the action argument. The icon, tooltip, and keyboard accelerator are very much toolkit and OS dependent, and so may not always be available by the widget using the gaction object. The keyboard accelerator may use modifiers Control, Alt or Shift along with a letter, such as Control-c. For gWidgetstcltk the value is passed to tkbind. For gWidgetsQt the value is passed to Qt$QKeySequence. For gWidgetsRGtk2 the value is parsed and manipulated. The keyboard accelerator requires a parent container so that the corresponding window for which the accelerator applies can be found.

The lists defining a menubar or toolbar are very similar.

Each is a list with named components. A component is a terminal node if it a) is a gaction instance or b) has a handler component, which is a function to be called (without arguments) when the menu item or toolbar item is selected. Optionally, an icon component can be given specifying a stock icon to accompany the text. A non-null component named separator will also indicate a terminal node. In this case, a visible separator will be displayed.

A menubar list can use the hierarchical nature of a list to generate submenus. For toolbars this is not the case.

These constructors map the list into the widget. The methods for the constructors refer to these list defining the widget.

The svalue method returns the list.

The svalue<- method can be used to change the list, and hence redo the menubar.

The "[" method refers to the components of the list.

The "[<-" method can be used to change pieces of the menubar or toolbar.

The add method with signature (obj,lst) or (obj,gmenu.instance) can be used to apped to the current menubar/toolbar. The second argument is a list or an gmenu or gtoolbar instance.

The delete method can be used to delete part of the menubar/toolbar. The value argument can be either a character vector with the top-level names to delete, or a named list, or an instance of either gmenu or gtoolbar.

Popular usage reserves toolbars and menubars for top-level windows -- not dialog sub windows, or sub groups within a GUI -- as such, the container, specified at construction, should be a top-level gwindow instance

Examples

# NOT RUN {
 mbl <- list()
 mbl$File$Open$handler = function(h,...) print("open")
 mbl$File$Quit$handler = function(h,...) print("quit")
 mbl$File$Quit$icon = "quit"
 mbl$Edit$Find$handler = function(h,...) print("Find")
 mbl$Edit$Replace$handler = function(h,...) print("Replace")

 w <- gwindow("gmenu test")
 mb <- gmenu(mbl, container=w)

 tbl <- list()
 tbl$New <- list(icon="new",handler = function(...) print("new"))
 tbl$Print <- list(icon="print",handler = function(...) print("print"))

 tb <- gtoolbar(tbl, container=w)

 ## example of using gaction
 ## works in gWidgetstcltk, but much  better in gWidgetsRGtk2

 ## stub for handler
f <- function(h,...) print("stub")

## some actions. The icon is optional, as is tooltip
aOpen <-  gaction(label="Open",   icon="open",  handler=f)
aClose <- gaction(label="Close",  icon="close", handler=f)
aQuit  <- gaction(label="Quit",   icon="quit",  handler=function(h,...) dispose(w))
aCut <-   gaction(label="Cut",    icon="cut",   handler=f)
aCopy <-  gaction(label="Copy",   icon="copy",  handler=f)
aPaste <- gaction(label="Paste",  icon="paste", handler=f)

## set up groups of actions so that they can be disabled/enabled
## all at once
allActionsGroup <- list(aOpen, aClose, aQuit, aCut, aCopy, aPaste)
editActionsGroup <- list(aCut, aCopy, aPaste)

## define menubar list
ml <- list(File = list(
             open = aOpen,
             close = aClose,
             sep = list(separator = TRUE), # must be named component
             quit = aQuit),
           Edit = list(
             copy = aCopy,
             paste = aPaste))

## toolbar list has only one level
tl <- list(
   Open=aOpen, 
   sep = list(separator = TRUE), # must be named component
   Quit = aQuit)

## set up main window
w <- gwindow()
gmenu(ml, container = w)
gtoolbar(tl, container = w)

## Now add a widget
gbutton(action = aQuit, container = w)

## disable a group of action
sapply(editActionsGroup, function(i) enabled(i) <- FALSE)

# }