Window Width

The value for WINDOW WIDTH is used in the screen handling to determine how the cursor moves to the next position on the screen for the input of the next value for the same attribute in a window. The number entered is the number of cursor positions, counting left to right, top to bottom, that are skipped in order to get to the next position for that attribute. Take the following example:-

Staff No	Grade	Date of Birth
(1) ~~~~	(2) ~~~~~~~~~~~	(3) ~~~~~~~~~~
(4) ~~~~	(5) ~~~~~~~~~~~	(6) ~~~~~~~~~~
(7) ~~~~	(8) ~~~~~~~~~~~	(9) ~~~~~~~~~~

In this example we have a window 3 lines long, each with 3 attributes giving us 9 fields to the window. Each position has its relative number (1 - 9) displayed against it in parentheses. To get from the first line of input for GRADE to the second line of input GRADE, the cursor must go from position 2 to position 5. To go from the second to the third line the cursor goes to position 8. The difference in both cases is 3. Indeed, this difference of 3 will apply to every field in the window. It is this value that is entered for WINDOW.WIDTH.

In the example on the previous screen, the window was laid out in the standard way. That is one logical line for each physical line on the screen. However, it is possible to cater for other different layouts. The following example has four logical lines to a physical line.

Amounts received : (1) ~~~~~ (2) ~~~~~ (3) ~~~~~

As before, the value for WINDOW.WIDTH is determined by the number of cursor positions to skip when going from the field on one logical line to the same field on the next logical line. In this instance, the next prompt after 1 is 2, after 2 is 3, etc. In each case the difference is 1. It is this difference of 1 that gives WINDOW.WIDTH its value. Note that on the window the physical width appears to be 3 but it is the logical width that is required.

Another situation would be where two separate windows were maintained side by side as in the following example.

Units Bought	Discount	Area	Unit Sales
(1) ~~~~	(2) ~~~~	(3) ~~	(4) ~~~~~~
(5) ~~~~	(6) ~~~~	(7) ~~	(8) ~~~~~~
(9) ~~~~	(10) ~~~~	(11) ~~	(12) ~~~~~~

In this example, 2 windows are placed on the screen side by side, each one is separate. The first window contains UNITS BOUGHT and DISCOUNT. To get from the first field of UNITS BOUGHT to the second field, the cursor goes from 1 to 5, from second to third, the cursor goes from 5 to 9. In each case the difference is 4. So 4 is entered for WINDOW.WIDTH. The value 4 also applies to the second window as well. For AREA, the prompt goes from 3 to 7 and from 7 to 11. In each case the difference is 4.

It cannot be stressed highly enough that the window width is the offset applied to EVERY line in the window. The use of the intervening cursor prompts is of no significance. It is the constancy of the intervals that is crucial. Should the cursor offset NOT be consistent in the screen that the user has painted, one way of getting around this problem is to incorporate dummy prompts into the screen.

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