** 1 page regular, HBASIC 5 tutorial / 736 words **

When is a dialog not a dialog? Paul Jones looks to find the 
answer...

Click goes the mouse!

last issue we looked at the basic structure of PDO explaining how 
the program works. This time let's think of some ways it could be 
improved:

** BL on **
* Keyboard shortcuts: These are a useful addition to most 
programs.
* An information dialog, like the one we created back in AC#5!
* A registration dialog to remind people to pay for software they 
use.
** BL off

The PDO structure makes it easy to add new features and you should 
remember this when programming your own projects. First we have to 
make a modification to the main loop:

** PROG1.GIF here ** 
Now, instead of simply waiting for messages, we can also get input 
from the keyboard! If we get a keyboard input now, our program 
will jump to a subroutine called do_keybd with the key pressed as 
a parameter. If you're not sure of parameters, subroutines or 
functions, re-read AC#6.

** PROG2.GIF here ** 
Whenever a button is pressed, the value is displayed in an alert 
box. Using this method you can press the desired key combinations 
and write down their values for use in the program. Here's what I 
got for the following combinations:

** BL on **
* [Alternate]+O 6144
* [Alternate]+L 9728
* [Alternate]+S 7936
* [Alternate]+V 12032
* [Alternate]+P 6400
* [Alternate]+Q 4096
* [Alternate]+A 7680
** BL off **

Now, we can edit the subroutine so these values are used to go to 
the required item in ProcessUserMenus.

** PROG3.GIF here ** 
We get a value in, find which item it belongs to and jump to the 
processing menu. For example, if we get 12032 in, we know this 
value is unique to [Alternate]+V and can proceed as if the "View 
file" option had been selected by the user via the drop down 
menus.

Oh no, more dialog boxes!...

If you compile and run this modified version you'll encounter a 
problem. If you press a combination key, followed by a key without 
a combination key, for example, if you press [Alternate]+O then, 
after the alert box has been displayed, you press D, the same 
alert which came up for the keyboard shortcut combination will be 
displayed again for an invalid key!
We do some object checking to find out if the currently pressed 
button is a valid key, then jump to that menu item in 
ProcessUserMenus...

** PROG4.GIF here ** 
At the start of the routine the variable id is set to 0. If any of 
the shortcuts have been selected then id is set to 1 and the 
routine will jump to ProcessUserMenus. If an invalid shortcut has 
been selected it will be ignored because id is not set to 1. Next 
we need to change two lines in ProcessUserMenus:

** PROG5.GIF here ** 
Both these will display a dialog box from the RSC file. If the 
About option is selected (via the menu option or new shortcut 
routine) the info dialog is displayed and this is also the case 
for the register dialog. The "regcode" in the register dialog is 
the name of the default edit field, which we'll look at in more 
detail next issue. The current PDO source code is on the Reader 
Disk.

** Boxout 1 **
Shareware delays

Shareware delay can take various guises. One of the most common is 
a dialog box on screen which reminds the user of their 
obligations. These often incorporate a time delay of some sort, 
for example, a progress bar which prevents the user from 
dismissing or bypassing the dialog immediately. Happily these are 
easy to implement. Take a look at the PDO source in the dialog 
subroutine you will see the line:

** NP on ** junk=FNobjc_draw(tree&,0,10,x,y,w,h)
** NP off **

This simply just draws the dialog on screen, another command ** NP 
on ** form_do ** NP off ** enables the user to interact with the 
dialog. If we simply display the dialog then wait in a loop, we 
have effectively created a shareware delay! As for the progression 
bar, we can have an object in the box which via another GEM 
command we can change the size of.

A variation of the shareware delay is included in GEMBench which 
displays "Register" in a flashing colour and you can also add this 
to your own programs - I'll be covering this next time around.
** End boxout 1 **