Map Item Data

Play 0x33, server → client.

play · 0x33 · clientbound (server → client)

Updates a map item identified by itemDamage (the map id) with its scale, locked flag, icons such as player markers, and an optional rectangle of color data given by columns, rows, x, and y. The server sends it when a player holds a map or the map content changes. The client updates the map texture.

Sent by the server, read by the client. Listen for it with client.on("MapItemData", (data) => …) on the receiving side.

Fields

Field	Type	Notes
`itemDamage`	VarInt	Map ID; match the filled map item’s `map_id` component.
`scale`	Byte	Map scale, 0 to 4.
`locked`	Boolean	Whether the map is locked.
`icons`	MapIcon[] or null	Optional map markers; `null` omits the icon list.
`columns`	UByte	Image width; `0` omits the remaining image fields.
`rows`	UByte	Image height; present when `columns` is nonzero.
`x`	UByte	Left edge of the image region; present when `columns` is nonzero.
`y`	UByte	Top edge of the image region; present when `columns` is nonzero.
`data`	Byte[]	Length-prefixed palette indices, row by row; present when `columns` is nonzero.

Icon entries

When icons is an array, each entry has these fields:

Field	Wire type	Meaning
`type`	VarInt	Map decoration type ID; `subscriptionType` is accepted when writing.
`x`	Byte	Signed horizontal map coordinate.
`z`	Byte	Signed vertical map coordinate.
`direction`	UByte	Marker direction.
`displayName`	Optional anonymous NBT	Marker label; omit or use `null` when absent.

icons: null writes no icon list, while icons: [] writes an empty list. With columns: 0, omit rows, x, y, and data; this lets you update the icons without image pixels. With image data, data.length must equal columns * rows and each byte is a Minecraft map palette index. See Maps for RGB conversion and region bounds.

const mapId = 1;
await client.sendPacket("MapItemData", {
  itemDamage: mapId,
  scale: 0,
  locked: false,
  icons: [{ type: 0, x: 0, z: 0, direction: 0, displayName: null }],
  columns: 0,
});

Send it

import { helpers } from "mc-protocol";

const mapId = 1;
await client.sendPacket("SetPlayerInventory", {
  slotId: 0,
  contents: helpers.createMapSlot(mapId, { name: "Red map" }),
});
await client.sendPacket("MapItemData", helpers.createMapPacket(
  mapId,
  Array(128 * 128).fill("#ff0000"),
  { format: "rgb" },
));

The map ID must match the map_id component of the filled map slot. The helper converts RGB pixels to palette indices and fills the packet fields. For partial images, icon-only updates, and option details, see Maps.

Field aliases listed under Notes are accepted as alternative keys when writing.

Source: src/Core/Versions/776/Packets/play/clientbound/MapItemData.ts