Listener Panel Commands
There are a few commands that are specific to the Listener panel.
Please note that commands that read from or write to the Listener panel are described in the I/O section, because they are also used to read from and write to files.
Common commands that output to the Listener panel are PRINT, TYPE, and SHOW.
Common commands that read from the Listener panel are READ, READLIST, and READQUOTE.
CLEARTEXT
Also: CT
Clears the Listener panel; no inputs.
Syntax
CLEARTEXT
Description
CLEARTEXT clears all text and places the cursor in the upper left corner of the Listener panel. CLEARTEXT is the same as the command TYPE CHAR 12.
Examples
REPEAT 5 [PR [GOOD EVENING]] CLEARTEXT
HTML
Creates and outputs a HTML sequence; two inputs.
Syntax
HTML tagname text
Description
HTML wraps the text into the HTML tag that is its first input; then, it wraps the resulting text into two HTML escape characters (see TYPE), and outputs the result. The result can be used as input to all commands that print, like PRINT, ALERT, or READPROMPT.
HTML is a shortcut for (WORD CHAR 8 "< :tagname "> :text "|</| :tagname "> CHAR 8).
Note: Logo itself is a web page; therefore, it interacts with all HTML that you print; if you are careless, you may distort the entire Logo page.
See also WEBLINK.
Examples
PRINT HTML “B “|Visit us!| Visit us!
KEY
Reports the code of the last key that the user typed; no inputs.
Syntax
KEY
Description
KEY reports the key code of the last key that the user typed. If you call KEY multiple times, the reported value is the empty word. Thus, you can call KEY only once for each key that the user typed.
KEY reports special key codes as a word, like TAB, F1, or ENTER.
Note: In early versions of Terrapin Logo, KEY used to report a numeric value. Logo reports the actual key.
See also READCHAR.
Examples
KEY Result: ENTER
SETTEXTCOLOR
Also: SETTC
Sets the text color for Listener output; expects between one input and two inputs, but parentheses are needed if not called with two inputs.
Syntax
SETTEXTCOLOR foreground background
(SETTEXTCOLOR foreground)
Description
SETTEXTCOLOR sets the foreground and background colors, which subsequent print commands will use. SETTEXTCOLOR takes a color name: one of 138 standard Web color names (see COLORS) or a list of up to four values, one each for Red, Green, and Blue, plus an optional alpha value. The color values may vary from 0 to 255, and the alpha value is between 0 and 1.
Use TEXTCOLOR to retrieve the current text colors.
Examples
(SETTEXTCOLOR “RED) PR [THIS IS IN RED] (SETTEXTCOLOR “BLACK)
SETTEXTFONT
Sets the Listener font; expects between zero inputs and three inputs, but parentheses are needed if not called with three inputs.
Syntax
SETTEXTFONT name size attributes
(SETTEXTFONT name size)
(SETTEXTFONT name)
(SETTEXTFONT)
(SETTEXTFONT [name size attributes])
(SETTEXTFONT [name size])
(SETTEXTFONT [name])
(SETTEXTFONT [])
Description
SETTEXTFONT defines the font that the Listener uses. The first input is the font name. This font should be present in the system. If the font is not present, the operating system selects a similar font for you. The second input is the font size, given in points, while the third is one of the following values:
| Value | Effect | Value | Effect |
|---|---|---|---|
| 0 | regular | 4 | underlined |
| 1 | bold | 5 | bold underlined |
| 2 | italics | 6 | italics underlined |
| 3 | bold italics | 7 | bold italics underlined |
SETTEXTFONT can also be called with fewer than three inputs; in that case, the size is set to 10 points, and the attributes are set to 0. Calling SETTEXTFONT with no inputs causes the font to be reset to the default font. Also, calling SETTEXTFONT with a list of zero to three elements is possible to match the output of TEXTFONT with the input to SETTEXTFONT. See also TEXTFONT and FONTS.
Examples
SETTEXTFONT “TIMES 14 1 PR “HELLO
TEXTCOLOR
Reports the text foreground and background colors; no inputs.
Syntax
TEXTCOLOR
Description
TEXTCOLORS reports the foreground and background colors that the Listener uses when printing text as a two-element list, each element being a four-element list of RGBA color values. See also SETTEXTCOLOR.
Examples
TEXTCOLOR Result: [[0 0 0 1] [255 255 255 1]]
TEXTFONT
Reports the font used for output; no inputs.
Syntax
TEXTFONT
Description
TEXTFONT reports the font that output commands use as a three-element list. See also SETTEXTFONT.
Examples
TEXTFONT Result: [CONSOLAS 12 0]
WEBLINK
Creates and outputs a HTML web link; expects between one input and two inputs, but parentheses are needed if not called with one input.
Syntax
WEBLINK link
(WEBLINK link text)
Description
WEBLINK creates a clickable HTML link of its first input. If the second input is present, it uses the text of the second input as a clickable text; otherwise, it uses the link itself as clickable text. The resulting text is the output of WEBLINK; it can be used as input to all commands that print, like PRINT, ALERT, or READPROMPT.
WEBLINK is a shortcut for (WORD CHAR 8 "|<a href="| :link "| target="_blank">| :text "|</a>| CHAR 8).
If the first input does not start with letters and a colon (like e.g. ftp: or http:), Logo inserts the text “https://” at the beginning. This lets you use web links like www.terrapinlogo.com without the “https://” prefix; Logo adds it for you.
Note: Logo itself is a web page; therefore, it interacts with all HTML that you print; if you are careless, you may distort the entire Logo page.
See also HTML.
Examples
PRINT (WEBLINK “www.example.com “|Visit us!|) Visit us!