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REFGUIDE
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Chapter 1: What's Really Happening 5
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CHAPTER ONE: WHAT'S REALLY HAPPENING?
Until now, you may have only used HyperPAD and its applications (the
pads) to simplify your computing environment. Pad users do not
necessarily need to understand the inner workings of HyperPAD. They just
type into fields and push buttons.
As a pad author, you will explore the internal workings of the Browser
and learn to control your applications by writing scripts using the
PADtalk scripting language. You will also be introduced to the message
passing system which controls execution of these scripts.
Let's take a quick look at a pad from an authoring perspective.
Each pad is made up of a number of screens which the user interacts with
by pressing keys, moving the mouse, and clicking mouse buttons. Each of
these user-initiated events is translated into a message and sent to the
objects that make up HyperPAD. For example, if you select a button by
pressing ENTER, the select message is sent to that button.
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Chapter 1: What's Really Happening 6
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When an object receives a message, one of two things will occur. The
object will either ignore the message because you haven't defined any
actions to be executed when that message is received, or the object will
execute preassigned actions. As you will learn, an object only performs
actions defined in its script.
WHAT IS PADTALK?
As a pad author, you will use PADtalk scripts to define the actions that
occur when objects receive certain messages. For example, when the Home
button is selected by pressing ENTER, the select message is sent to the
Home button, telling it that it has been selected. Since the button's
script understands this message, the statements in the script are
executed and the Home pad is opened and displayed.
You will create your scripts using the HyperPAD language called PADtalk.
Unlike most programming languages, it is understandable and English-
like. Even non-programmers can understand and use PADtalk.
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Chapter 1: What's Really Happening 7
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WHAT DO YOU USE IT FOR?
Some general types of applications you can create with PADtalk and
HyperPAD are:
0 PC interfaces for launching DOS and Windows programs
0 Customized DOS shells for managing files and directories
0 Interactive computer-based training systems
0 Information bases
0 Software prototypes
0 Front ends for corporate information systems
In order to create your own applications using PADtalk, you must
understand objects, their relationship to each other, message passing,
and the object hierarchy. Therefore, it is very important to understand
the material in this chapter and the two chapters that follow: "PADtalk
Scripts" and "The Object Hierarchy."
Before exploring the object hierarchy, we will discuss the family of
HyperPAD objects and introduce you to its members.
OBJECTS
Generally, an object is something that receives and responds to
messages. All HyperPAD objects have properties that allow you to modify
their visual appearance and behavior. You can alter the properties of
objects, including object scripts, with the Info dialog boxes accessible
through the Objects menu.
Buttons, fields, pages, backgrounds, pads and even HyperPAD itself are
objects, receiving and passing messages. Messages travel between objects
along a predetermined path called the object hierarchy. Below, we will
discuss the objects, the hierarchy into which they're arranged and the
HyperPAD environment.
PAD
The word "pad" is an acronym for Personal Application Design. Pads are
the basic HyperPAD file structure. All applications designed with
HyperPAD, several dozen of which came in your package, are pads. Each
pad is made up of at least one background and one page.
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Chapter 1: What's Really Happening 8
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BACKGROUND
Backgrounds contain those elements (buttons, fields, text, and paint)
that recur on numerous pages throughout the pad. For example, if you
want your pad's users to be able to quit from every page in your pad,
you may place a Quit button on the background(s) in that pad.
Backgrounds can also serve as templates for pads, defining where
information is placed and what the pad looks like, since each page is
overlaid on top of a background.
PAGE
Pages form the bulk of a pad and in general display the pad's
information. Pages contain elements (text, paint, buttons, and fields)
that are unique to that page. Furthermore, pages contain all the text
from both background and page fields.
FIELD
A field is a container used to display or retrieve textual information.
Although each field is placed on its own transparent layer, it "belongs"
to either a page or a background. Regardless of where the field is
located, the information it holds is always stored on the page.
BUTTON
Buttons are objects that respond to user input by executing some pre-
defined action(s). Each button is placed on its own layer, which belongs
to either a page or a background.
OTHER HYPERPAD OBJECTS
HyperPAD also contains the following objects: menu bar, status bar,
message box and tool box.
HOW TO REFER TO OBJECTS
When writing scripts, you can refer to all objects, except pads, by
name, number, or ID. Pads must be referred to by their DOS filename. In
the sections below, each method is described.
QUALIFYING OBJECTS
When referring to objects, you may need to specify where they are in
your pad. For example, if you want to change the color of a button, you
must specify whether the button is on the page or the background:
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Chapter 1: What's Really Happening 9
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set the color of page button 1 to red;
set the color of background button 1 to red;
If you do not specify the whereabouts of a button or field, HyperPAD
assumes you want the one on the background. Thus, the following
statements refer to the same object:
set the color of field 1 to red;
set the color of background field 1 to red;
When referring to a page, you may need to specify what background the
page is on:
go to page 1;
go to page 1 of background 2;
If you do not specify which background a page belongs to, HyperPAD
assumes you want the one nearest the front of the pad. For example,
"page 1" and "page 1 of background 2" are not necessarily the same page.
OBJECT NAMES
Although names are optional for all objects except pads, it is usually
helpful to give your objects a name that describes their purpose. That
way, it's easy to refer to them from within a script.
To modify an object name in the Object Info dialog box:
1. Select the Pad, Bkgnd, Page, Button, or Field Info command from the
Objects menu.
2. Highlight the Name text box and type in the object's name.
3. Select the << Ok >> button.
Once a name is assigned to an object, you can use that name in a script.
For example:
go to pad "C:\MYPAD.PAD";
set the color to page button "Last Name" to red;
put "wow" into page field "Expression";
go to page "Preferences";
go to page "Setup" of background "Options";
Note: When using an object's name in a script, you must enclose it in
quotation marks.
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Chapter 1: What's Really Happening 10
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OBJECT NUMBERS
Each object within a pad can be referred to by a number based on its
position relative to the other objects in its class. For example, page 1
is the first page in a pad. As you edit your pads by copying, cutting,
pasting, and creating pages, the numbers of the pages will change to
reflect their new positions.
Backgrounds are assigned an object number based on the order of their
creation. For example, background 1 was the first background created
when you selected New Pad. Background numbers change only if you delete
a background from a pad by deleting each page belonging to that
background.
Buttons and fields are assigned object numbers corresponding to their
layer on either the page or background. The object layer closest to the
page or to the background is assigned the number 1 (i.e. page field 1,
page button 1). As you use the Cut, Copy, Bring Closer and Send Farther
commands, the object numbers assigned to the buttons and fields are
altered to reflect their new positions.
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Since object numbers change constantly throughout pad creation, using
them to refer to objects within a script is not the most reliable
method. Determine an object's number by opening the Object Info dialog
box for that object.
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Chapter 1: What's Really Happening 11
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Examples of objects referred to by their number:
set the color of page button 1 to red;
set the color of field 1 to blue;
go to page 137;
go to page 3 of background 4;
OBJECT ID NUMBERS
When an object is created (this includes being copied, pasted and
cloned) HyperPAD assigns it a unique identification number. An object's
ID number cannot be altered and is never duplicated. Using this number
to refer to an object in a script is foolproof because it will never
change.
You can retrieve an object's ID number by opening the Object Info dialog
box.
Examples of objects being referenced by their IDs:
set the color of page id 5 to red;
put "wow" into field id 3;
go to page id 45;
go to page id 4 of background id 5;
go to background id 1;
READY TO SCRIPT
Now that you have a general introduction to HyperPAD objects, we will
introduce you to HyperPAD scripts.