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Minimum Profit: Creating interactive dialog boxes

This document is a reference to the mp.form() function and associated tools that ease interaction with the user from inside the Minimum Profit Text Editor.

Alert boxes

Alert boxes are simple popups or message notifications that interrupts the user with a message. Their usage is trivial:

 	mp.alert("It's coffee time!!!");

Confirmation boxes

Confirmation boxes are simple forms that show a message and ask for confirmation. The user response is returned as an integer value. Its use is also trivial:

 	local r = mp.confirm("File has changed. Save changes?");

The returned values can be 1 if user said yes, 2 if user said no, and 0, if used cancelled.

Open and save file boxes

Open and save file boxes are system-dependent dialog boxes that show a prompt and ask for a filename to open or save into. They both return the file name on confirmation or NULL on cancellation:

 	local r = mp.openfile("File to open:");

 	local s = mp.savefile("Save as:");

Forms

Forms can be created in MP by using the mp.form() function. It implements a simplified, common interface for GUI and text modes while trying to be as useful as possible.

The following is an example taken from mp_search.mpsl:

 	local t = mp.form( [
 		{ 'label'	=> L("Text to seek:"),
 		  'type'	=> 'text',
 		  'history'	=> 'search' },
 		{ 'label'	=> L("Case sensitive") ~ ':',
 		  'type'	=> 'checkbox',
 		  'value'	=> mp.config.case_sensitive_search }
 	] );

As can be seen, mp.form() accepts a list of hashes describing the fields to be shown to the user and returns an array with the filled values. On user cancellation, mp.form() return NULL; otherwise, an array with the same number of elements as the array sent as argument is returned, having each entered value in each element.

The following widget types exist:

text

A field to enter text.

password

A field to enter text, but hiding its input.

checkbox

A field to enter yes/no values.

list

A field to select an element from a given list of values.

Every widget can have some common attributes:

value

The initial value.

label

A text string to be shown near the field, describing it.

Other attributes can exist for each widget.

Depending on the driver, a dialog box can show OK and Cancel buttons, and accept cancellation by hitting the escape hey.

Text widgets

Text widgets are used, unsurprisingly, for entering free text. No limit exist on the string size nor the accepted character set. If a value attribute is set, it's shown as the default value, allowing edition.

The following additional attributes can be used in text widgets:

history

A tag marking the history set. Every time a dialog is accepted (i.e. not cancelled), the entered value is stored in the history set named by this attribute. History is accesible by pressing the cursor-up and cursor-down keys.

Example:

 	local r = mp.form(
 		[
 			{
 	 		'type'	=> 'text',
 	 		'label'	=> 'Enter your name:'
 	 		}
 		]
 	);

 	if (r != NULL)
 		mp.alert('Your name is ' ~ r[0] ~ '!');

Password widgets

Password widgets are the same as text widgets, but its content is not shown. For each character, an asterisk or similar placeholder character is shown. No history attributes are allowed.

Example:

 	local r = mp.form(
 		[
 			{
 			'type'	=> 'text',
 			'label'	=> 'Login:'
 			},
 			{
 			'type'	=> 'password',
 			'label'	=> 'Password:'
 			}
 		]
 	);

 	if (r != NULL)
 		login_into_system(r[0], r[1]);

Checkbox widgets

Checkbox widgets are used to set alternatives, i.e., values that can be true or false. Depending on the driver, they are shown as real checkboxes or [Y/N] questions. The initial value can be non-zero for true and zero for false. On return, the value can be 1 or 0.

 	local r = mp.form(
 		[
 			{
 			'type'	=> 'text',
 			'label'	=> 'Tab size:',
			'value'	=> 8
 			},
 			{
 			'type'	=> 'checkbox',
 			'label'	=> 'Convert to spaces:',
			'value'	=> 0
 			}
 		]
 	);

List widgets

List widgets are used to select one from an array of values. The value attribute is the initially selected item from the supplied list.

The additional attributes are:

list

The mandatory list of values, as an array of strings.

On return, the value is the subscript of the selected item.

Example:

 	local r = mp.form(
 		[
 			{
 			'type'	=> 'list',
 			'label'	=> 'Which C source file to open:',
 			'list'	=> glob("*.c"),
 			'value'	=> 0
 			},
 			{
 			'type'	=> 'checkbox',
 			'label'	=> 'Read only:',
 			'value'	=> 0
 			}
 		]
 	);