[1.7.10][1.8] Creating filled_map items pre-populated with data - How?

[sshipway]

So, I'm trying to create a new

filled_map

item, preloaded with data (it is converted from an external image file).

 

I have already created the code to convert my chosen image to an

NBTCompoundTag

corresponding to the Map Data.

 

I can obtain a new, unique mapID, and write the NBT file to the correct data/map_#.dat location:

		mapNo = (short) world.getUniqueDataId("map");

	String folderName = MinecraftServer.getServer().getFolderName();
	ISaveFormat saveFormat = MinecraftServer.getServer().getActiveAnvilConverter();
	SaveHandler saveHandler = (SaveHandler)saveFormat.getSaveLoader(folderName, false); 
	String worldsavedir = saveHandler.getWorldDirectory().getPath();
	mapFilename = worldsavedir + File.separator + "data" + File.separator + "map_" + mapNo + ".dat";
	CompressedStreamTools.writeCompressed(map,new FileOutputStream(mapFilename));

 

This then allows me to make an object in the game, should I wish:

mapItemStack = new ItemStack(Items.filled_map,1,mapNo);

 

The new object appears in the game, has the correct contents, and seems happy.

 

The problem is that, when I try to save the world, Minecraft complains that the world has been modified by something else -- the cause is the writing of the

map_#.dat

file, which must break some save-time integrity test.  It is valid NBT (because exiting Minecraft and restarting allows things to work) but clearly, I should be using some internal function to write the new map out, not the CompressedStreamTools.

 

I can create a MapData object like this:

		md = new MapData("map"); // what is the parameter for?
	md.readFromNBT(map);

 

However, I cannot identify how to write this and obtain the unique DataId.  There is a MapStorage class, and an ItemMap class, but I cannot work out how to link the MapData to these, obtain a unique ID, and force a save.

 

I can possibly do this:

		im = Items.filled_map;
	im.updateMapData(world, entity, md);

 

... but it is unclear what the 'entity' refers to, and again there seems to be no way to specify the mapNumber.  Conversely, the MapStorage class allows me to make a new mapNumber and apparently to save the maps, but I have no way to assign the MapData object to the new mapNumber.

 

Any help and pointers on this would be appreciated.  I feel like I'm so close, but blocked by a lack of documentation...

 

Steve

[Draco18s]

You'll have to excuse the obfuscated code.  This is out of an old, old project (1.6.4 actually) and I never refactored the variable names.

 

ItemMyEmptyMap.java

public ItemStack onItemRightClick(ItemStack par1ItemStack, World par2World, EntityPlayer par3EntityPlayer) {
//the string here is the key in a key->value relationship in a HashMap.  Really you can use whatever.
//the item stack here is important, as this converts the item from the empty map to the filled map.
        ItemStack itemstack1 = new ItemStack(MapsBase.OreMapItem, 1, par2World.getUniqueDataId("map"));
//get a unique name
        String s = "map_" + itemstack1.getItemDamage();
        MapData mapdata = new MapData(s);
//this line maps the specific map to its data for save/load
        par2World.setItemData(s, mapdata);

//boring stuff
        mapdata.scale = 1;
        int i = 128 * (1 << mapdata.scale);
        mapdata.xCenter = (int)(Math.round(par3EntityPlayer.posX / (double)i) * (long)i);
        mapdata.zCenter = (int)(Math.round(par3EntityPlayer.posZ / (double)i) * (long)i);
        mapdata.dimension = (byte)par2World.provider.dimensionId;
        mapdata.markDirty();
        --par1ItemStack.stackSize;
        itemstack1.setItemName("Ore Density Map ("+mapdata.xCenter+","+mapdata.zCenter+")");
        if (par1ItemStack.stackSize <= 0)
        {
            return itemstack1;
        }
        else
        {
            if (!par3EntityPlayer.inventory.addItemStackToInventory(itemstack1.copy()))
            {
                par3EntityPlayer.dropPlayerItem(itemstack1);
            }

            return par1ItemStack;
        }
    }

 

ItemMyFilledMap.java

@Override
public void updateMapData(World world, Entity player, MapData mapData) {
short short1 = 128;
//this line is likely the most important one for you
//the MapInfo object is what contains the actual pixel data displayed
MapInfo mapinfo = mapData.func_82568_a((EntityPlayer)player);
//loop, blah blah
for(x) {
	for(z) {
		int colorIndex = /*some color*/
		mapData.colors[x + z * short1] = colorIndex;
	}
}
}

[sshipway]

Many thanks!  The mystery was the correct usage of the MapData object.  Although I had managed to avoid the error in the previous code by writing the NBT file and then setting the last modification time into the past, that solution was... suboptimal

 

The function now all works, and I can generate framed-map 'pictures' in-game from external image files on the fly.

 

	public static short createMap(World world, String imgFilename , Logger logger ) {
	short mapNo;
	String mapFilename;
	NBTTagCompound map;
	MapData data;

	// build map object NBT
	map = imgToNBT(imgFilename,logger);
	if( map == null ) { return -1; } // unable to convert

	// get a new unique ID for the new map
	mapNo = (short) world.getUniqueDataId("map");

	// save the data
	data = new MapData("map_"+mapNo); 
	data.readFromNBT(map);
	world.setItemData("map_"+mapNo,data);

	return mapNo;
}

[Draco18s]

Many thanks!  The mystery was the correct usage of the MapData object.

 

Heh.  I only remember that I chewed on it back in 1.6.4, I remember almost nothing other than what I was able to glean from my code.

I did some pretty neat shit, though.   Thinking about using the ore map with this custom data block I have (er, data object, it's not a

Block

).  It'd be harder to get data into the map (using the existing prospecting method) but would have a little more permanence.

[sshipway]

While the method above works in 1.8, it seems that in 1.7 things are somewhat different.  The code will create the object in-game, but the 'map' picture displays progressively, column by column.

 

The worse part is that the map_#.dat NBT file is not written on save (though the idcounts ARE updated) and when the game is restarted, the 'map' is now a basic 0,0 blank map.

 

Clearly, under 1.7, there is something else that needs to be done in order to add the map data to the world.    Writing the map_#.dat NBT file myself only results in the previously mentioned "the world has been modified by something else" error, even if I try the trick of setting the file last modification time.

 

The other problems, of ItemFrame being an entity and its Tile* attributes being different under 1.7 and 1.8 have been solved, and that's behaving, at least...

 

V1.8 seem to me to be far easier to code for, and far more forgiving of missing or invalid data.  They seem to have coded with the expectation of mods being created.

[sshipway]

Aha!  It seems that, in Minceraft 1.7, the

data.markDirty()

call is essential -- this is what causes the initial NBT file to be written.  In Minecraft 1.8, it happens implicitly.

 

I've added this call immediately after

world.setItemData

call, and now my code also works in 1.7.10.

 

Thanks for the help -- I've posted here for the benefit of any future readers with a similar problem.

[Draco18s]

While the method above works in 1.8, it seems that in 1.7 things are somewhat different.  The code will create the object in-game, but the 'map' picture displays progressively, column by column.

 

On this, you can change that, but I wouldn't bother.  I think there's a piece that makes it so that it uses less network data, but I don't recall exactly.

I don't remember what bits to fiddle with to do it, but I did make it update slower than normal (for one of my maps).  It might be the

mapData.setColumnDirty(...)

function.