Message

Section: User Contributed Perl Documentation (3)
Updated: 2021-01-27
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NAME

Tk::Message - Create and manipulate Message widgets

SYNOPSIS

$message = $parent->Message(?options?);

STANDARD OPTIONS

-anchor        -font   -highlightthickness     -takefocus
-background     -foreground     -padx   -text
-borderwidth    -highlightbackground    -pady   -textvariable
-cursor -highlightcolor -relief -width

See Tk::options for details of the standard options.

WIDGET-SPECIFIC OPTIONS

Name: aspect
Class: Aspect
Switch: -aspect: Specifies a non-negative integer value indicating desired aspect ratio for the text. The aspect ratio is specified as 100*width/height. 100 means the text should be as wide as it is tall, 200 means the text should be twice as wide as it is tall, 50 means the text should be twice as tall as it is wide, and so on. Used to choose line length for text if width option isn't specified. Defaults to 150.
Name: justify
Class: Justify
Switch: -justify: Specifies how to justify lines of text. Must be one of left, center, or right. Defaults to left. This option works together with the anchor, aspect, padX, padY, and width options to provide a variety of arrangements of the text within the window. The aspect and width options determine the amount of screen space needed to display the text. The anchor, padX, and padY options determine where this rectangular area is displayed within the widget's window, and the justify option determines how each line is displayed within that rectangular region. For example, suppose anchor is e and justify is left, and that the message window is much larger than needed for the text. The the text will displayed so that the left edges of all the lines line up and the right edge of the longest line is padX from the right side of the window; the entire text block will be centered in the vertical span of the window.
Name: width
Class: Width
Switch: -width: Specifies the length of lines in the window. The value may have any of the forms acceptable to Tk_GetPixels. If this option has a value greater than zero then the aspect option is ignored and the width option determines the line length. If this option has a value less than or equal to zero, then the aspect option determines the line length.

DESCRIPTION

The Message method creates a new window (given by the $widget argument) and makes it into a message widget. Additional options, described above, may be specified on the command line or in the option database to configure aspects of the message such as its colors, font, text, and initial relief. The message command returns its $widget argument. At the time this command is invoked, there must not exist a window named $widget, but $widget's parent must exist.

A message is a widget that displays a textual string. A message widget has three special features. First, it breaks up its string into lines in order to produce a given aspect ratio for the window. The line breaks are chosen at word boundaries wherever possible (if not even a single word would fit on a line, then the word will be split across lines). Newline characters in the string will force line breaks; they can be used, for example, to leave blank lines in the display.

The second feature of a message widget is justification. The text may be displayed left-justified (each line starts at the left side of the window), centered on a line-by-line basis, or right-justified (each line ends at the right side of the window).

The third feature of a message widget is that it handles control characters and non-printing characters specially. Tab characters are replaced with enough blank space to line up on the next 8-character boundary. Newlines cause line breaks. Other control characters (ASCII code less than 0x20) and characters not defined in the font are displayed as a four-character sequence \xhh where hh is the two-digit hexadecimal number corresponding to the character. In the unusual case where the font doesn't contain all of the characters in ``0123456789abcdef\x'' then control characters and undefined characters are not displayed at all.

WIDGET METHODS

The Message method creates a widget object. This object supports the configure and cget methods described in Tk::options which can be used to enquire and modify the options described above. The widget also inherits all the methods provided by the generic Tk::Widget class.

DEFAULT BINDINGS

When a new message is created, it has no default event bindings: messages are intended for output purposes only.

BUGS

Tabs don't work very well with text that is centered or right-justified. The most common result is that the line is justified wrong.

KEYWORDS

message, widget