# Inventory Form
This page is about {ref}`Inventory Layouts` dedicated `TLazForm` utilities.

This is meant to be used with {ref}`TScriptForm` with
{ref}`TScriptForm.CreateInventoryTab` and will setup a a `TLazTabSheet` on it
with several controls to configure the {ref}`Inventory Layouts`:
```{figure} ../../images/inventoryform.png
```


- - -

## TInventoryFormHelper
The `TInventoryFormHelper` type is, as it's name implies a helper type for the
`Inventory Form`.

It has a lot of methods and callbacks that are hidden by default and won't be
mentioned on this page because they are internal methods you shouldn't touch.

Do feel free to read the source code though if you so desire.


- - -

## TInventoryFormHelper.SlotImage
```pascal
function TInventoryFormHelper.SlotImage(item: String; amount: Integer): TImage;
```
Returns the sprite a slot holding `amount` of `item` is drawn with, stack text
included.

The result is kept, keyed by both the item and the amount, because a redraw asks
for the same sprites over and over and rendering the stack text is the most
expensive part of drawing a slot.


- - -

## TInventoryFormHelper.UpdateDrag
```pascal
procedure TInventoryFormHelper.UpdateDrag();
```
Draws the item being dragged at the cursor over the slot composite
{ref}`TInventoryFormHelper.UpdateBackground` built, and pushes the result to the
imagebox.

This is the path the cursor takes, so it reuses that composite rather than
rebuilding it: nothing behind the cursor changes while the cursor moves.


- - -

## TInventoryFormHelper.UpdateBackground
```pascal
procedure TInventoryFormHelper.UpdateBackground();
```
Redraws the slot composite into `TInventoryFormHelper.SlotsImg`: the gametab
background, every slot's item and the slot outlines.

All of that only changes when the layout, the selection or the drag source does,
so the composite is kept for {ref}`TInventoryFormHelper.UpdateDrag` to reuse, and
this is only called from the callbacks that change one of them.


- - -

## InventoryForm.CreateGearCombobox
```pascal
function TInventoryFormHelper.CreateGearCombobox(owner: Pointer; caption: TLazLabel = nil): TLazComboBox;
```
This is the only method from {ref}`Gear Form` you might need to use.
This will create a combobox for you whose contents auto-update with changes made
on the `Gear Form`.


- - -

## InventoryForm variable
Global {ref}`TInventoryFormHelper` variable.


- - -

## ScriptForm.CreateInventoryTab
```pascal
function TScriptForm.CreateInventoryTab(): TLazTabSheet;
```
Sets up a `TLazTabSheet` on your `TScriptForm` to configure your `Inventory Layouts`.

Example:
```pascal
{$I WaspLib/main.simba}
var
  form: TScriptForm;
begin
  form.Setup();
  form.CreateInventoryTab();
  form.Run();
end.
```
```{figure} ../../images/inventoryform.gif
```
For a more complete example check out the file `Simba/Includes/WaspLib/examples/inventory_form.simba`.