pokecrystal-board/docs/menu.md

# Everything you've ever wanted to know about menus*

**\* but were afraid to ask**


## Contents

- [ScrollingMenu](#scrollingmenu)
- [\_2DMenu](#_2dmenu)
- [DoNthMenu/SetUpMenu](#donthmenusetupmenu)
- [VerticalMenu](#verticalmenu)
- [Misc/Generic](#miscgeneric)


## `ScrollingMenu`

This is the only menu that does scrolling. It doesn't draw any `TextBox` around the menu.

Structure:

```asm
.MenuHeader:
	db MENU_BACKUP_TILES ; flags
	menu_coords 2, 4, SCREEN_WIDTH - 1, 13
	dw .MenuData
	db 1 ; default option

.MenuData:
	db 0 ; flags
	db 5, 0 ; rows, columns
	db 1 ; horizontal spacing
	dba Items
	dba Function1
	dba Function2
	dba Function3
```

`wMenuDataFlags`:

```
7: Select is functional
6: Start is functional
5: Call Function3
4: Show arrows on the right-hand side
3: D-Left is functional
2: D-Right is functional
1: Call Function3 only if [wSwitchItem] is 0
0: Call Function1 to display the cancel entry
```

If the columns entry in `MenuData` of a scrolling menu is 0, `Function2` isn't called either. It doesn't affect the position of the arrows.

Call state for functions in `MenuData` of `ScrollingMenu`:

```
All of them:
[wMenuSelection] = Current item. -1 is the CANCEL item.
[wMenuSelectionQuantity] = Quantity of the current item.

Function1: Called to display a menu entry.
de = Cursor position in TileMap

Function2: Called to display the quantity of a menu entry.
de = Cursor position in TileMap + columns

Function3: Called to display anything else, whenever the cursor is moved.
```

There is no register of importance that should be preserved in any of these functions.

The `; horizontal spacing` item in each `MenuData` is a misnomer. It changes how the `Items` struct looks.

If it's 1:

```
db entries not including cancel
db entry1
db entry2
db -1 ; cancel
...
```

If it's 2:

```
db entries not including cancel
db entry1, quantity1
db entry2, quantity2
db -1 ; cancel
...
```

In case it's 1, `[wMenuSelectionQuantity]` will simply contain the next entry.

## `_2DMenu`

This, like is implied by the name, is a 2-dimensional menu, where you can move your cursor in all 4 directions. It's only used for the battle menus as well as Earl's academy.

Structure:

```asm
.MenuHeader:
	db MENU_BACKUP_TILES ; flags
	db 12, 08 ; start coords
	db 17, 19 ; end coords
	dw .MenuData
	db 1 ; default option

.MenuData:
	db STATICMENU_CURSOR ; flags
	dn 2, 2 ; rows, columns
	db 6 ; spacing
	dba Strings
	dba Function
```

`wMenuDataFlags`:

```
7: Leave one tile of spacing between the left textbox border and the text, enabling the cursor.
6: Don't leave one tile of spacing between the top textbox border and the text
5: Set bits 4 and 5 in w2DMenuFlags1 (Wrap around horizontally and vertically)
4: Unused
3: Unused
2: Unused
1: Select is functional
0: Disable B button
```

The bank for the `Strings` is generated when you call `_2DMenu`, and as such it doesn't really matter what bank you specify there (unless you callba `_2DMenu_` directly, of course).

`; spacing` is not a misnomer here, it's used to define how much space there is between columns.

`Function` is called after printing all the strings. `hl` will be pointed at the row below the last in the menu in `TileMap`. We don't know of its purpose, since it's never actually used anywhere. Only the bank number is always set to the same bank as the menu, but not used otherwise, since the address is 0.


## `DoNthMenu`/`SetUpMenu`

These are like the regular `VerticalMenu`, except they allow for creating slightly more "dynamic" menus, where the options aren't predefined, much like the `ScrollingMenu`.

Structure:

```
.MenuHeader:
	db MENU_BACKUP_TILES ; flags
	menu_coords 0, 0, 10, 7
	dw .MenuData
	db 1 ; default option

.MenuData:
	db STATICMENU_CURSOR | STATICMENU_DISABLE_B ; flags
	db 0 ; items
	dw Items
	dw DisplayFunction
	dw StringPointers
```

`wMenuDataFlags`:

```
7: Unused
6: Unused
5: Set bit 5 in w2DMenuFlags1 (Wrap around vertically)
4: Unused
3: Start is functional
2: D-left and D-right are functional
1: Unused
0: Unused
```

The `; items` entry should be left empty, as it's autogenerated with the `Items` array in `GetMenuIndexSet`.

The bottom coord (`07` in the example) is autogenerated regardless of what you specify when building the MenuBox in `AutomaticGetMenuBottomCoord`, which also calculates the `bc` passed to MenuBox, which is useless because it's calculated again by MenuBox in `GetMenuBoxDims`.

`[wWhichIndexSet]` decides which menu is used through `GetMenuIndexSet`. You can define multiple menus at the Items pointer as such:

```
Items:
db entries not including cancel
db entry1, entry2, entry3
db -1 ; cancel
db entries not including cancel for 2nd menu
db entry1, entry2, entry3, entry4
db -1 ; cancel
```

This is actively used in `MainMenu`.

`StringPointers` isn't handled by `DoNthMenu` internally. It's handled by different `DisplayFunction`s. A custom one could choose to completely ignore it.

`StringPointers` struct handled through `PlaceNthMenuStrings` as `DisplayFunction` and `MenuJumptable`:

```asm
StringPointers:
	dw FunctionToCall, PointerToString ; index 1
	dw FunctionToCall, PointerToString ; index 2
...
```

`StringPointers` struct handled through `PlaceMenuStrings`:

```asm
StringPointers:
	db "STRING1@"
	db "STRING2@"
...
```

Call state for `DisplayFunction`:
```
[wMenuSelection] = Current item. -1 is the CANCEL item.
de = Cursor position in TileMap
```

## `VerticalMenu`

This is the simplest menu. Like, the most boring. Nothing special. Just normal. …nooooooormal…

Structure:

```asm
.MenuHeader:
	db MENU_SPRITE_ANIMS | MENU_BACKUP_TILES ; flags
	menu_coords 12, 12, SCREEN_WIDTH - 1, SCREEN_HEIGHT - 1
	dw .MenuData
	db 1 ; default option

.MenuData:
	db STATICMENU_CURSOR ; flags
	db 2 ; # items
	db "GIVE@"
	db "TAKE@"
```

`wMenuDataFlags`:

```
7: Leave one tile of spacing between the left textbox border and the text
6: Don't leave one tile of spacing between the top textbox border and the text
5: Set bit 5 in w2DMenuFlags1 (Wrap around vertically)
4: Place menubox "title". See notes.
3: Unused
2: Unused
1: Select is functional
0: Disable B button
```

If bit 4 is set, a string at the end of the items array will be put at an offset from the start coord of the menu box. This string is defined like this:

```asm
	db 2 ; # items
	db "GIVE@"
	db "TAKE@"
	db 2 ; x offset
	db "TEST@"
```

This is used in the menu for selecting the character's name.

## Misc/Generic

`MenuHeader` flags (`wMenuFlags`):

```
7: Save a backup of the tiles
6: Save a backup of the tiles
5: Unused
4: Set bit 6 in w2DMenuFlags1 (Enable sprite animations)
3: Disable click sound
2: Unused
1: Unused
0: Call RestoreTileBackup when exiting the menu. This bit depends on whether bit 6 or 7 are set.
```

`w2DMenuFlags1`:

```
7: Disable checking of wMenuJoypadFilter
6: Enable sprite animations
5: Wrap around vertically
4: Wrap around horizontally
3: Set bit 7 in w2DMenuFlags2 and exit the loop if bit 5 is disabled and we tried to go too far down
2: Set bit 7 in w2DMenuFlags2 and exit the loop if bit 5 is disabled and we tried to go too far up
1: Set bit 7 in w2DMenuFlags2 and exit the loop if bit 4 is disabled and we tried to go too far left
0: Set bit 7 in w2DMenuFlags2 and exit the loop if bit 4 is disabled and we tried to go too far right
```

`w2DMenuFlags2`:

```
7: ?????
6: ?????
5: ?????
4: ?????
3: ?????
2: ?????
1: ?????
0: ?????
```