Version 1.9 Build 1556

News	FAQ
Search	Home

Next: Text Up: Glish/Tk Previous: Listbox and Scrollbar

Subsections

Odds and Ends

This section discusses a few remaining minor widgets which are useful, but have a single function. These are grouped together in a single section because they are similar in complexity and functionality.

Label

The label widget does exactly what you would expect; it is used to insert a short text string into the interface. Here is a simple example:

    f := frame(f,side='left')
    l := label(f,'Options:')
    b1 := button(f,'continue')
    b2 := button(f,'quit')
    whenever b2->press do
        exit

This dialog is shown in Figure 11.7.

**Figure 11.7:** Label
$\begin{figure} \centerline{\psfig{figure=tklabel.eps,scale={0.7}}}\end{figure}$

The label is simply placed in the frame first, and then the buttons it describes are added to the frame. Table 11.8 show the other parameters which can be specified during the creation of a label.

Parameter	Default	Values	Description
`parent`	`F`	widget	parent of the label
`text`	`'label'`	string	label text
`justify`	`'left'`	`'center'` `'left'` `'right'`	justification of text
`padx`	`4`	dimension	horizontal padding
`pady`	`2`	dimension	vertical padding
`font`	`''`	X font	text font
`width`	`0`	integer	width in character units
`relief`	`'flat'`	`'flat'` `'ridge'` `'raised'` `'sunken'` `'groove'`	border relief
`borderwidth`	`2`	dimension	border width
`foreground`	`'black'`	X color	color of text
`background`	`'lightgrey'`	X color	background color
`anchor`	`'c'`	`'c'` `'n'` `'s'` `'e'` `'w'` `'ne'` `'nw'` `'se'` `'sw'`	location of `text`
`fill`	`'none'`	`'x'` `'y'` `'both'` `'none'`	how to expand when resized
`hlcolor`	`''`	X color	highlight color with focus
`hlbackground`	`''`	X color	highlight color without focus
`hlthickness`	`[]`	dimension	hightlight border thickness

Table 11.9 shows the events which labels accept, and as you can see from the table, labels do not generate events.

Event	I/O	Values	Description
`anchor`	$\rightarrow$	`'c'` `'n'` `'s'` `'e'` `'w'` `'ne'` `'nw'` `'se'` `'sw'`	set location of `text`
`background`	$\rightarrow$	X color	change background color
`bind`	$\rightarrow$	`<X>` `<G>`	associate Xevent `<X>` with Glish event `<G>`
`borderwidth`	$\rightarrow$	dimension	change border width
`font`	$\rightarrow$	X font	set text font
`foreground`	$\rightarrow$	X color	change foreground color
`hlbackground`	$\rightarrow$	X color	highlight color without focus
`hlcolor`	$\rightarrow$	X color	highlight color with focus
`hlthickness`	$\rightarrow$	dimension	hightlight border thickness
`justify`	$\rightarrow$	`'center'` `'left'` `'right'`	set text justification
`padx`	$\rightarrow$	dimension	set horizontal padding
`pady`	$\rightarrow$	dimension	set vertical padding
`relief`	$\rightarrow$	`'flat'` `'ridge'` `'raised'` `'sunken'` `'groove'`	change border relief
`text`	$\rightarrow$	string	set label text
`width`	$\rightarrow$	integer	set width (in character units)

Scale

The scale widget allows the user to pick a number out of a range. In other toolkits, this is called a slider. Here is an example of the creation of a scale:

    f := frame(side='left')
    v := scale(f,0,110,text='Volume')
    t := scale(f,0,110,text='Treble')
    b := scale(f,0,110,text='Bass')

The interface which this example creates is shown in Figure 11.8.

**Figure 11.8:** Scale
$\begin{figure} \centerline{\psfig{figure=tkscale.eps,scale={0.7}}}\end{figure}$

The value of the slider is posted with the value event. Here is an example,

    whenever v->value do
        print "Volume:",$value

This whenever prints out a message each time the volume is changed. Note however if you just want to get the last value of the slider, it is accessible as a member of the agent, in this case v.value. This is because the last value of each event name is retained in the agent. As a result, whenever statements are often not needed with scales. Table 11.10 lists the other construction parameters for scales, and Table 11.11 lists the scale events.

Parameter	Default	Values	Description
`parent`		widget	parent of the scale
`start`	`0.0`	float	starting integer for scale
`end`	`100.0`	float	ending integer for scale
`value`	`start`	float	initial value for the scale
`length`	`110`	integer	length of scale
`text`	`''`	string	optional label for scale
`resolution`	`1.0`	float	resolution of the scale
`orient`	`'horizontal'`	`'horizontal'` `'vertical`	orientation of scale
`width`	`'15'`	dimension	width/height of the thumb
`font`	`''`	X font	text font
`relief`	`'flat'`	`'flat'` `'ridge'` `'raised'` `'sunken'` `'groove'`	edge relief
`borderwidth`	`2`	dimension	border width
`foreground`	`'black'`	X color	color of text
`background`	`'lightgrey'`	X color	background color
`fill`	`''`	`'x'` `'y'` `'both'` `'none'`	how to expand when resized; default: expand with `orient`
`hlcolor`	`''`	X color	highlight color with focus
`hlbackground`	`''`	X color	highlight color without focus
`hlthickness`	`[]`	dimension	hightlight border thickness
`showvalue`	`T`	boolean	display the selected value?

Event	I/O	Values	Description
`background`	$\rightarrow$	X color	change background color
`bind`	$\rightarrow$	`<X>` `<G>`	associate Xevent `<X>` with Glish event `<G>`
`borderwidth`	$\rightarrow$	dimension	change border width
`end`	$\rightarrow$	integer	change ending value
`font`	$\rightarrow$	X font	set text font
`foreground`	$\rightarrow$	X color	change foreground color
`hlbackground`	$\rightarrow$	X color	highlight color without focus
`hlcolor`	$\rightarrow$	X color	highlight color with focus
`hlthickness`	$\rightarrow$	dimension	hightlight border thickness
`length`	$\rightarrow$	integer	change length of scale
`orient`	$\rightarrow$	`'horizontal'` `'vertical`	change orientation
`relief`	$\rightarrow$	`'flat'` `'ridge'` `'raised'` `'sunken'` `'groove'`	change border relief
`resolution`	$\rightarrow$	float	change resolution of scale
`showvalue`	$\rightarrow$	boolean	show/hide scale value
`start`	$\rightarrow$	integer	change starting value
`text`	$\rightarrow$	string	set scale label
`value`	$\leftarrow$	integer	value changed by user
`width`	$\rightarrow$	integer	change width/height of scale

Message

The message widget is viewed as a multi-line label. It is essentially a scratch pad for displaying several word messages to the user. For long messages, the text widget is a better choice.

Here is an example of the message widget in use:

    f := frame(side='left')
    b := button(f,'time')
    m := message(f,shell('date'))
    whenever b->press do
        m->text(shell('date'))

This simple example updates the time display in the message widget whenever the button is pressed. This looks like Figure 11.9.

**Figure 11.9:** Message
$\begin{figure} \centerline{\psfig{figure=tkmessage.eps,scale={0.7}}}\end{figure}$

In general, the text event is the primary event for the message widget. The other construction parameters are shown on Table 11.12. The message widget itself does not generate any event, but the events which it accepts are shown in Table 11.13.

Parameter	Default	Values	Description
`parent`		widget	parent of the message
`text`	`'message'`	string	text for message
`width`	`180`	dimension	width of message
`justify`	`'center'`	`'center'` `'left'` `'right'`	justification of text
`font`	`''`	X font	font of text
`padx`	`7`	dimension	horizontal padding
`pady`	`3`	dimension	vertical padding
`relief`	`'raised'`	`'flat'` `'ridge'` `'raised'` `'sunken'` `'groove'`	edge relief
`borderwidth`	`2`	dimension	border width
`foreground`	`'black'`	X color	color of text
`background`	`'lightgrey'`	X color	background color
`anchor`	`'c'`	`'c'` `'n'` `'s'` `'e'` `'w'` `'ne'` `'nw'` `'se'` `'sw'`	location of `text`
`fill`	`'none'`	`'x'` `'y'` `'both'` `'none'`	how to expand when resized
`hlcolor`	`''`	X color	highlight color with focus
`hlbackground`	`''`	X color	highlight color without focus
`hlthickness`	`[]`	dimension	hightlight border thickness

Event	I/O	Values	Description
`anchor`	$\rightarrow$	`'c'` `'n'` `'s'` `'e'` `'w'` `'ne'` `'nw'` `'se'` `'sw'`	set location of `text`
`background`	$\rightarrow$	X color	change background color
`bind`	$\rightarrow$	`<X>` `<G>`	associate Xevent `<X>` with Glish event `<G>`
`borderwidth`	$\rightarrow$	dimension	change border width
`font`	$\rightarrow$	X font	set font for text
`foreground`	$\rightarrow$	X color	change foreground color
`hlbackground`	$\rightarrow$	X color	highlight color without focus
`hlcolor`	$\rightarrow$	X color	highlight color with focus
`hlthickness`	$\rightarrow$	dimension	hightlight border thickness
`justify`	$\rightarrow$	`'center'` `'left'` `'right'`	set justification for text
`padx`	$\rightarrow$	dimension	set horizontal padding around text
`pady`	$\rightarrow$	dimension	set vertical padding around text
`relief`	$\rightarrow$	`'flat'` `'ridge'` `'raised'` `'sunken'` `'groove'`	change border relief
`text`	$\rightarrow$	string	set text
`width`	$\rightarrow$	integer	set width (in character units)

Entry

The entry provides slots where the user can type in text. The script can then retrieve this text when it is needed. Here is a more complex example:

    f := frame()
    ef := frame(f,side='left')
    b := button(ef,'ls')
    en := entry(ef)
    lbf := frame(f,side='left')             # **
    lb := listbox(lbf,width=32)             # **
    sb := scrollbar(lbf)                    # **
    whenever b->press, en->return do
        {
        lb->delete("start","end")
        dir := en->get()
        files := shell('if [ -r',dir,'];then ls -1F',dir,';else exit 1;fi')
        if ( ! files::status )
            lb->insert(files)
        else
            en->insert('*BAD DIRECTORY* ','start')
        }
    whenever sb->scroll do                  # **
        lb->view($value)                    # **
    whenever lb->yscroll do                 # **
        sb->view($value)                    # **

In this example, first note that the lines tagged with ** are nearly identical to the listbox plus scrollbar example in § 11.4.2. The remaining lines setup a button and an entry widget. Next the listbox plus scrollbar dialog from the previous example is used. In this dialog, the user enters a directory in the entry widget, and the contents of the directory shows up in the listbox (see Figure 11.10).

The mechanics of this are controlled by the first whenever. Whenever the user presses the button or hits the <return> key in the entry widget, the listbox is cleared, the string from the entry widget is retrieved, an ls is done on the directory, and if it succeeds, the output is used to fill the listbox otherwise an error is indicated in the entry widget. The complicated shell() command which actually does the ls just checks to see if the directory exists, and if it does exist, the ls is done, otherwise the shell command exits with a non-zero status.

**Figure 11.10:** Entry
$\begin{figure} \centerline{\psfig{figure=tkentry.eps,scale={0.7}}}\end{figure}$

This example shows three of the entry widget events, get, insert, and return. The get event returns the contents of the entry widget and the insert event inserts text into the entry widget. The second parameter to insert is optional, and it specifies where to insert the string. By default, the string is inserted at the end. The return event is generated when the user hits the <return> key in the entry widget. Table 11.14 list all of the parameters to entry(), and Table 11.15 lists the entry widget events.

Parameter	Default	Values	Description
`parent`		widget	parent of the entry
`width`	`0`	integer	width in character units
`justify`	`'center'`	`'center'` `'left'` `'right'`	justification of text
`font`	`''`	X font	font of text
`relief`	`'raised'`	`'flat'` `'ridge'` `'raised'` `'sunken'` `'groove'`	edge relief
`borderwidth`	`2`	dimension	border width
`foreground`	`'black'`	X color	color of text
`background`	`'lightgrey'`	X color	background color
`disabled`	`F`	boolean	is inactivated?
`show`	`T`	boolean	show typed characters?
`exportselection`	`F`	boolean	export to X clipboard?
`fill`	`'x`	`'x'` `'y'` `'both'` `'none'`	how to expand when resized
`hlcolor`	`''`	X color	highlight color with focus
`hlbackground`	`''`	X color	highlight color without focus
`hlthickness`	`[]`	dimension	hightlight border thickness

Event	I/O	Values	Description
`background`	$\rightarrow$	X color	change background color
`bind`	$\rightarrow$	`<X>` `<G>`	associate Xevent `<X>` with Glish event `<G>`
`borderwidth`	$\rightarrow$	dimension	change border width
`delete`	$\rightarrow$	string	delete indicated character, use 2 strings to delete range
`disable`	$\rightarrow$		disable widget, must be balanced by `enable`
`disabled`	$\rightarrow$	boolean	set state, disable ( `T`) or enable ( `F`)
`enable`	$\rightarrow$		enable widget, must be balanced by `disable`
`exportselection`	$\rightarrow$	boolean	export selection to X clipboard?
`font`	$\rightarrow$	X font	change text font
`foreground`	$\rightarrow$	X color	change foreground color
`get`	$\Leftrightarrow$		get current contents
`hlbackground`	$\rightarrow$	X color	highlight color without focus
`hlcolor`	$\rightarrow$	X color	highlight color with focus
`hlthickness`	$\rightarrow$	dimension	hightlight border thickness
`insert`	$\rightarrow$	string	insert item, optional 2nd param insert index
`justify`	$\rightarrow$	`'center'` `'left'` `'right'`	set justification for text
`relief`	$\rightarrow$	`'flat'` `'ridge'` `'raised'` `'sunken'` `'groove'`	change border relief
`return`	$\leftarrow$	string	generated when user hits return, returns contents
`show`	$\rightarrow$	boolean	show typed characters?
`view`	$\rightarrow$	record	scrollbar update event
`width`	$\rightarrow$	integer	entry width in character units
`xscroll`	$\leftarrow$	double	information for horizontal scrollbar update

Notice in Table 11.15 that the entry widget generates the events necessary to connect a horizontal scrollbar to the entry widget. This is done in a way analogous to connecting a vertical scrollbar to the listbox, i.e. change yscroll to xscroll.

Next: Text Up: Glish/Tk Previous: Listbox and Scrollbar Contents Index