Form and Form Builder modules

HtkPDF distinguishes two uses of PDF forms:

Filling in a form: completing the interactive fields already present in a PDF you have received (an administrative declaration, a contract, a purchase order, and so on);
Creating a form: adding interactive fields to a PDF that does not have any yet.

Both modules are available from the Editing category of the Dashboard.

Filling in a form

The Form module (a stylus-on-clipboard icon) lists the interactive fields detected on the current page and makes filling them in easier.

Automatic detection

At each page change, HtkPDF analyses the form fields present and shows them in the sidebar. The list gives:

a type (icon) according to the nature of the field: text, checkbox, multiple choice, signature;
the internal name of the field;
its current value.

If no field is detected on the page, a "No field detected on this page" message is shown.

Entering values

Two complementary methods exist for filling in a field:

Directly in the PDF: click a field in the view on the left and type the value — this is the standard behaviour of a PDF form;
Through the list: click an entry in the sidebar to scroll the document to the field's area and highlight it. Entry is then done directly in the visible field.

The list is refreshed automatically at each page change or after an operation that would modify the fields (a reset, and so on).

Clearing the fields

Two destructive actions are available in the Actions section:

Clear page: erases the content of every field on the page currently displayed;
Clear whole document: erases every field of the document.

These actions do not erase the fields themselves — only the values they contain. The form therefore remains usable for a new entry.

Tip: if you are filling in several copies of the same form, use Clear whole document between each entry to reset cleanly.

Form Builder

The Form Builder module lets you add interactive fields to any PDF. Useful for turning a static document (letter, contract, record sheet) into a digital form intended to be returned filled in.

Adding a field

Three field types are offered in the Add section:

Add Text Field: a free entry area (answer, name, address, and so on);
Add Checkbox: a binary yes/no choice;
Add Button: an interactive area useful for actions or simple choices.

Click the matching button to insert an empty field in the center of the current page. The field is named automatically Field 1, Field 2, and so on. You can then move or resize it directly in the PDF view.

Inspecting and editing a field

The sidebar lists every field of the current page. Click an entry to:

show the Properties section above the list;
automatically scroll the PDF view to the selected field.

The Properties section contains:

Field Name: the internal identifier of the field. Editable; the change is applied immediately;
Default value (text fields only): the value shown when the form is opened;
Read-only: a switch preventing the field from being modified by a user (useful for labels or informative pre-filled fields);
Delete Field: removes the field from the document.

Any change in the Properties section is applied in real time to the corresponding annotation.

Best practices

Name your fields: by default, fields are labelled Field 1, Field 2, and so on. If you plan to process the returned forms automatically (CSV export, scripted parsing), give them meaningful names (surname, first_name, date_of_birth) before distribution;
Visual consistency: align the fields by eye while moving them in the view — the tool shows no alignment guides;
Test before distributing: once creation is finished, switch to the Form module to check that all your fields are detected and usable.

Confirming and history

Like the other editing modules:

changes are reflected immediately in the PDF view;
the Undo / Redo buttons at the top of the sidebar let you step back;
a checkpoint is added to the History when you confirm with Apply; Back leaves the module and discards the changes;
changes stay in pending changes until they are explicitly saved (⌘S).

Limitations

HtkPDF does not (at this stage) offer the creation of drop-down list or digital signature fields through the Form Builder; only the Text, Checkbox and Button types are available. To sign a PDF, use the dedicated Sign module.
The Form module shows the fields present, but does not let you resize or rename a field. For that, switch to the Form Builder.
Automatic calculations between fields (sums, formulas) are not exposed in the interface.

Screenshots

2 screenshots — click to enlarge