[1.16] How would I convert a map in game to an external image?

[TheHook]

I am trying to convert a map that I would create while on a server to an external image to use later. I have tried to approach this in a couple ways. I tried to take a screenshot whenever there's a map in my inventory using getStackInSlot(), but I have no clue how I would do that. I tried doing KeyBinding.setKeyBindState(minecraft.gameSettings.keyBindScreenshot.getKeyCode(), true); and the same for KeyBinding.onTick(....keyBindScreenshot.getKeyCode()), but they never worked. Any idea on how to use this?

 

I also attempted to use the class MapData, but I don't know how I would rebuild the map image using the information there.

 

To be clear, this is not on a singleplayer world, so I can't just convert the .dat file stored locally in my .minecraft folder. This is a map that is created in my inventory on a server.

[TheHook]

How do I create an instance of MapItemRenderer?

 

Edit: Figured it out. I updated the map texture using a MapData instance of the map. func_228089_a_ is in a private package. Now what should I do?  Also, referring to my screenshot approach, how would I use it correctly? 

Edited November 1, 2020 by TheHook

[TheHook]

 

On 11/1/2020 at 3:42 AM, diesieben07 said:

Well, you can't literally use those methods, because they draw on the screen. You need to look at what they do and replicate it.

I think you may be misunderstanding me. I am not trying to create a map in the program, but the map already exists in my inventory. I am trying to convert that map to an external image for later use. Is there any easier way to do this than to replicate an API method?

[TheHook]

1 hour ago, diesieben07 said:

Considering this functionality does not already exist in Minecraft: No.

There is absolutely no way that I can maybe rebuild an image from whatever data I have available to me with the conditions I described?

 

If that's the case, then I'll go ahead with the screenshot approach. 

On 11/1/2020 at 3:42 AM, diesieben07 said:

Well, a screenshot would be of the entire game, not just the map. But you'll want to look into glReadPixels.

Let me clarify again. For the screenshot approach, once the "map is in inventory" flag is raised, I would take a screenshot automatically within the program. Is the KeyBinding approach incorrect?

[TheHook]

1 minute ago, diesieben07 said:

You want to take a screenshot automatically when the map is in the inventory. I don't know what you want a key binding for then.

Yes, what would API would I use to do that is my question.

[TheHook]

2 minutes ago, diesieben07 said:

Of course you can. But you need to program a method that does it.

How would you recommend approaching this? Maybe taking the colors byte array from MapData and parsing it into a 2D array in which each member is a set of RGBa values representing a "grid of colors"? How would I rebuild that into a png/jpg file?

[TheHook]

 

3 minutes ago, diesieben07 said:

glReadPixels, like I said. Look at ScreenshotHelper for how to do it.

 

Exactly. That's what the code I told you to look at before does.

 

Look into BufferdImage and friends.

Beautiful, thank you. I'll get started right away on implementation. I think you can close this thread now, if I have more questions, I can just make another one.

[TheHook]

I am trying to use ScreenshotHelper methods createScreenshot and saveScreenshot, but it's only creating a blank file.

Framebuffer buffer = new Framebuffer(minecraft.displayWidth, minecraft.displayHeight, true);
ScreenShotHelper.createScreenshot(minecraft.displayHeight, minecraft.displayWidth, buffer);
ScreenShotHelper.saveScreenshot(gameDirectory, "screenshot.png", minecraft.displayWidth, minecraft.displayHeight, buffer);

This is what I'm doing. I'm pretty sure the issue is the buffer argument. I'm not too sure what the correct value should be. What am I doing wrong here? I know createScreenshot returns a BufferedImage, but is that BufferedImage the actual screenshot?

 

I attached the result png of this code:

Edited November 3, 2020 by TheHook

[TheHook]

Alright, I decided against the screenshot method and I'm using MapData to convert colors to a 2D array of rgb values. However, the colors array is always empty. 

MapData mapData = new MapData(minecraft.player.inventory.getStackInSlot(0).getDisplayName()); //where the map is
mapData.readFromNBT(minecraft.player.inventory.getStackInSlot(0).serializeNBT()); //added this after the array was empty, still doesn't work
byte[] mapColors = mapData.colors;
System.out.println("The color ID of " + mapData.mapName + " at " + index + " is: " + mapColors[index]); //index increments every time this code block is called.

This is the code I'm using. It makes sense as to why a static call to colors would be empty because the MapData constructor doesn't construct it. readFromNBT() assigns values to it, this I understand. I think the value I'm giving to it is incorrect, because the colors array is still empty, with the output produced has index incrementing, but the color ID is always 0. The map created is not in a blank world, I created a random world with no modifications and it still outputs 0. What should I do?

[TheHook]

17 hours ago, diesieben07 said:

This makes zero sense. The display name is not involved here at all.

It's the argument of the constructor in the MapData class, "String mapname".

 

17 hours ago, diesieben07 said:

You need to call FilledMapItem.getMapData.

Is FilledMapItem an API class?