32. Boxes, menus and drawings

Yes, all right, I won't do the menu... I don't think you realise how long it takes to do the menu, but no, it doesn't matter, I'll hang the picture now. If the menus are late for lunch it doesn't matter, the guests can all come and look at the picture till they are ready, right?

...John Cleese and Connie Booth, Fawlty Towers

One harmless effect, though not very special, is to ask the player a yes/no question. To do this, print up the question and then call the library routine YesOrNo, which returns true/false accordingly.

The status line is perhaps the most distinctive feature of Infocom games in play. This is the (usually highlighted) bar across the top of the screen. Usually, the game automatically prints the current game location, and either the time or the score and number of turns taken. It has the score/turns format unless the directive

Statusline time;

About character graphic drawings: on some machines, text will by default be displayed in a proportional font (i.e., one in which the width of a letter depends on what it is, so that for example an 'i' will be narrower than an 'm'). If you want to display a diagram made up of letters, such as a map, the spacing may then be wrong. The statement font off ensures that any fancy font is switched off and that a fixed-pitch one is being used: after this, font on restores the usual state.

A distinctive feature of later Infocom games was their use of epigrams. The assembly language required to produce this effect is easy but a nuisance, so there is an Inform statement to do it, box. For example,

box "I might repeat to myself, slowly and soothingly,"
    "a list of quotations beautiful from minds profound;"
    "if I can remember any of the damn things."
    ""
    "-- Dorothy Parker";

A snag with printing boxes is that if you do it in the middle of a turn then it will probably scroll half-off the screen by the time the game finishes printing for the turn. The right time to do so is just after the prompt (usually >) is printed, when the screen will definitely scroll no more. You could use the Prompt: slot in LibraryMessages to achieve this, but a more convenient way is to put your box-printing into the entry point AfterPrompt (called at this time each turn).

Sometimes one would like to provide a menu of text options (for instance, when producing instructions which have several topics, or when giving clues). This can be done with the DoMenu routine, which imitates the traditional "Invisiclues'' style. By setting pretty_flag=0 you can make a simple text version instead; a good idea for machines with very small screens. Here is a typical call to DoMenu:

DoMenu("There is information provided on the following:^
        ^     Instructions for playing
        ^     The history of this game
        ^     Credits^",
        HelpMenu, HelpInfo);

The second routine, HelpInfo above, should simply look at menu_item (1 to 3 above) and print the text for that selection. After this returns, normally the game prints "Press [Space] to return to menu'' but if the value 2 is returned it doesn't wait, and if the value 3 is returned it automatically quits the menu as if Q had been pressed. This is useful for juggling submenus about.

Menu items can safely launch whole new menus, and it is easy to make a tree of these (which will be needed when it comes to providing hints across any size of game).

Finally, you can change the text style. The statement for this is style and its effects are loosely modelled on the VT100 (design of terminal). The style can be style roman, style bold, style reverse or style underline. Again, poor terminals may not be able to display these, so you shouldn't hide crucial information in them.