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How to get "/title actionbar" or GuiIngame.overlayMessage text?


olari
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I'm trying to get the text from the /title actionbar command to get some information that a server presents there.

From the Minecraft decompilation I've gathered that the text itself is kept and used in net.minecraft.client.gui.GuiIngame, but I don't have access to it.

public class GuiIngame {
	protected String overlayMessage; // text itself
	public void setOverlayMessage(...); // setter
	// no getter
}


The only way I can come up with to get this information is to catch the SPacketTitle itself when it arrives.
This seems like a pretty daunting task so I thought I'd ask here first for alternatives.

If networking is the only option, I would like some guidance on how to approach it.

javaw_2018-07-29_16-31-23.png

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20 minutes ago, olari said:

The only way I can come up with to get this information is to catch the SPacketTitle itself when it arrives.

You could always use reflection. Make sure to use ReflectionHelper.getPrivateValue and provide both the deobf name of the field as well as the SRG name.

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1 minute ago, V0idWa1k3r said:

You could always use reflection. Make sure to use ReflectionHelper.getPrivateValue and provide both the deobf name of the field as well as the SRG name.

Thank you very much for the hasty reply. I'll look into using reflection.

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13 minutes ago, olari said:

Thank you very much for the hasty reply. I'll look into using reflection.

Got it working!

 

String title = ReflectionHelper.getPrivateValue(GuiIngame.class, mc.ingameGUI, 8);

 

Edited by olari
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To elaborate, reflection is relatively slow/inefficient. (It's also generally a bad idea, but Minecraft's source code gives us no other options in some cases, as you've discovered.) Therefore, it should be used only when necessary, and its returned objects cached whenever possible.

Whatever Minecraft needs, it is most likely not yet another tool tier.

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2 hours ago, IceMetalPunk said:

reflection is relatively slow/inefficient.

If you do it correctly, it's pretty much as fast as normal field access.

Don't PM me with questions. They will be ignored! Make a thread on the appropriate board for support.

 

1.12 -> 1.13 primer by williewillus.

 

1.7.10 and older versions of Minecraft are no longer supported due to it's age! Update to the latest version for support.

 

http://www.howoldisminecraft1710.today/

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5 minutes ago, IceMetalPunk said:

Define "correctly"?

Store the Field instance in a static field somewhere. Calling Field#get will pretty much be the same as normal field access performance wise.

Don't PM me with questions. They will be ignored! Make a thread on the appropriate board for support.

 

1.12 -> 1.13 primer by williewillus.

 

1.7.10 and older versions of Minecraft are no longer supported due to it's age! Update to the latest version for support.

 

http://www.howoldisminecraft1710.today/

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Just now, larsgerrits said:

Store the Field instance in a static field somewhere. Calling Field#get will pretty much be the same as normal field access performance wise.

So... cache it, like I said? XD The actual reflective call is only happening once in that case, which is why it's fast. But if you were to call the reflection access methods as often as you'd otherwise call a field name, the performance drops significantly.

Whatever Minecraft needs, it is most likely not yet another tool tier.

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11 hours ago, IceMetalPunk said:

The actual reflective call is only happening once in that case, which is why it's fast.

Field#get is a "reflective call". Looking up the field is, well, a lookup.

 

11 hours ago, larsgerrits said:

Store the Field instance in a static field somewhere.

Make it final. static final fields are treated like constants by the JVM and it will inline much better.

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Here's the final code:
 

private Field overlayMessageField = null;

// Called at initialization
private void findOverlayTextField() {
    this.overlayMessageField = ReflectionHelper.findField(GuiIngame.class, "overlayMessage");
}

public String getActionbar() {
    try {
        return (String)this.overlayMessageField.get(mc.ingameGUI);
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }

    return null;
}

 

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Return an empty string instead of null.

Apparently I'm a complete and utter jerk and come to this forum just like to make fun of people, be confrontational, and make your personal life miserable.  If you think this is the case, JUST REPORT ME.  Otherwise you're just going to get reported when you reply to my posts and point it out, because odds are, I was trying to be nice.

 

Exception: If you do not understand Java, I WILL NOT HELP YOU and your thread will get locked.

 

DO NOT PM ME WITH PROBLEMS. No help will be given.

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1 hour ago, olari said:

Here's the final code:
 


private Field overlayMessageField = null;

// Called at initialization
private void findOverlayTextField() {
    this.overlayMessageField = ReflectionHelper.findField(GuiIngame.class, "overlayMessage");
}

public String getActionbar() {
    try {
        return (String)this.overlayMessageField.get(mc.ingameGUI);
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }

    return null;
}

 

  • Please make the Field instance static and final.
  • You will need to provide the SRG name, otherwise your code will fail outside the development environment.
  • That is the worst kind of error handling. This exception is impossible to occur, the field is marked accessible by ReflectionHelper. You should act accordingly (if it does happen, something has gone very wrong and it is okay to crash the game).
1 hour ago, Draco18s said:

Return an empty string instead of null.

No. What even...

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16 minutes ago, diesieben07 said:

No. What even...

Would I rather check validate that the string returned by this function is null, or display an empty string (or the string "null")?

I think I'd rather have a non-null string.

Apparently I'm a complete and utter jerk and come to this forum just like to make fun of people, be confrontational, and make your personal life miserable.  If you think this is the case, JUST REPORT ME.  Otherwise you're just going to get reported when you reply to my posts and point it out, because odds are, I was trying to be nice.

 

Exception: If you do not understand Java, I WILL NOT HELP YOU and your thread will get locked.

 

DO NOT PM ME WITH PROBLEMS. No help will be given.

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8 hours ago, diesieben07 said:

Neither should ever happen in this case.

Oh I agree it should never happen.

But if there's one thing I know about programming. "Should never happen" is not as absolute as one would think.

Edited by Draco18s

Apparently I'm a complete and utter jerk and come to this forum just like to make fun of people, be confrontational, and make your personal life miserable.  If you think this is the case, JUST REPORT ME.  Otherwise you're just going to get reported when you reply to my posts and point it out, because odds are, I was trying to be nice.

 

Exception: If you do not understand Java, I WILL NOT HELP YOU and your thread will get locked.

 

DO NOT PM ME WITH PROBLEMS. No help will be given.

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2 hours ago, Draco18s said:

Oh I agree it should never happen.

But if there's one thing I know about programming. "Should never happen" is not as absolute as one would think.

True. But if it does happen, just carrying on as if nothing was wrong is not the way to go.

This is what crash reports are for.

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21 minutes ago, diesieben07 said:

True. But if it does happen, just carrying on as if nothing was wrong is not the way to go.

This is what crash reports are for.

In which case, I would do something like this:

public String getActionbar() {
	try {
	        return (String)overlayMessageField.get(Minecraft.getMinecraft().ingameGUI);
	    } catch (IllegalAccessException e) {
	    	e.printStackTrace();
	        throw new RuntimeException("Get Message Overlay failed!");
	    }
}

If it should crash, then let it crash. Don't handle the exception, then return null, allowing other code to null-check and not crash.

Apparently I'm a complete and utter jerk and come to this forum just like to make fun of people, be confrontational, and make your personal life miserable.  If you think this is the case, JUST REPORT ME.  Otherwise you're just going to get reported when you reply to my posts and point it out, because odds are, I was trying to be nice.

 

Exception: If you do not understand Java, I WILL NOT HELP YOU and your thread will get locked.

 

DO NOT PM ME WITH PROBLEMS. No help will be given.

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Just now, Draco18s said:

In which case, I would do something like this:


public String getActionbar() {
	try {
	        return (String)overlayMessageField.get(Minecraft.getMinecraft().ingameGUI);
	    } catch (IllegalAccessException e) {
	    	e.printStackTrace();
	        throw new RuntimeException("Get Message Overlay failed!");
	    }
}

If it should crash, then let it crash. Don't handle the exception, then return null, allowing other code to null-check and not crash.

Exactly. Which is what I said above:

On 7/31/2018 at 5:58 PM, diesieben07 said:

That is the worst kind of error handling. This exception is impossible to occur, the field is marked accessible by ReflectionHelper. You should act accordingly (if it does happen, something has gone very wrong and it is okay to crash the game).

 

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