Use ByteBuffers in term.blit

This is about 5-6x faster than using a String as we don't need to
allocate and copy multiple times. In the grand scheme of things, still
vastly overshadowed by the Lua interpreter, but worth doing.

src/main/java/dan200/computercraft/core/apis/TermMethods.java

@@ -14,6 +14,7 @@ import dan200.computercraft.shared.util.StringUtil;
 import org.apache.commons.lang3.ArrayUtils;
 
 import javax.annotation.Nonnull;
+import java.nio.ByteBuffer;
 
 /**
  * A base class for all objects which interact with a terminal. Namely the {@link TermAPI} and monitors.
@@ -283,9 +284,9 @@ public abstract class TermMethods
      * }</pre>
      */
     @LuaFunction
-    public final void blit( String text, String textColour, String backgroundColour ) throws LuaException
+    public final void blit( ByteBuffer text, ByteBuffer textColour, ByteBuffer backgroundColour ) throws LuaException
     {
-        if( textColour.length() != text.length() || backgroundColour.length() != text.length() )
+        if( textColour.remaining() != text.remaining() || backgroundColour.remaining() != text.remaining() )
         {
             throw new LuaException( "Arguments must be the same length" );
         }
@@ -294,7 +295,7 @@ public abstract class TermMethods
         synchronized( terminal )
         {
             terminal.blit( text, textColour, backgroundColour );
-            terminal.setCursorPos( terminal.getCursorX() + text.length(), terminal.getCursorY() );
+            terminal.setCursorPos( terminal.getCursorX() + text.remaining(), terminal.getCursorY() );
         }
     }
 

src/main/java/dan200/computercraft/core/terminal/Terminal.java

@@ -11,6 +11,7 @@ import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.network.PacketBuffer;
 
 import javax.annotation.Nonnull;
+import java.nio.ByteBuffer;
 
 public class Terminal
 {
@@ -191,7 +192,7 @@ public class Terminal
         return palette;
     }
 
-    public synchronized void blit( String text, String textColour, String backgroundColour )
+    public synchronized void blit( ByteBuffer text, ByteBuffer textColour, ByteBuffer backgroundColour )
     {
         int x = cursorX;
         int y = cursorY;

src/main/java/dan200/computercraft/core/terminal/TextBuffer.java

@@ -5,6 +5,8 @@
  */
 package dan200.computercraft.core.terminal;
 
+import java.nio.ByteBuffer;
+
 public class TextBuffer
 {
     private final char[] text;
@@ -42,6 +44,19 @@ public class TextBuffer
         }
     }
 
+    public void write( ByteBuffer text, int start )
+    {
+        int pos = start;
+        start = Math.max( start, 0 );
+        int length = text.remaining();
+        int end = Math.min( start + length, pos + length );
+        end = Math.min( end, this.text.length );
+        for( int i = start; i < end; i++ )
+        {
+            this.text[i] = (char) (text.get( i - pos ) & 0xFF);
+        }
+    }
+
     public void write( TextBuffer text )
     {
         int end = Math.min( text.length(), this.text.length );

src/test/java/dan200/computercraft/core/terminal/TerminalTest.java

@@ -5,6 +5,7 @@
  */
 package dan200.computercraft.core.terminal;
 
+import dan200.computercraft.api.lua.LuaValues;
 import dan200.computercraft.shared.util.Colour;
 import dan200.computercraft.utils.CallCounter;
 import io.netty.buffer.Unpooled;
@@ -293,7 +294,7 @@ class TerminalTest
         CallCounter callCounter = new CallCounter();
         Terminal terminal = new Terminal( 4, 3, callCounter );
 
-        terminal.blit( "test", "1234", "abcd" );
+        blit( terminal, "test", "1234", "abcd" );
 
         assertThat( terminal, allOf(
             textMatches( new String[] {
@@ -322,7 +323,7 @@ class TerminalTest
 
         terminal.setCursorPos( 2, 1 );
         callCounter.reset();
-        terminal.blit( "hi", "11", "ee" );
+        blit( terminal, "hi", "11", "ee" );
 
         assertThat( terminal, allOf(
             textMatches( new String[] {
@@ -354,13 +355,13 @@ class TerminalTest
 
         terminal.setCursorPos( 2, -5 );
         callCounter.reset();
-        terminal.blit( "hi", "11", "ee" );
+        blit( terminal, "hi", "11", "ee" );
         assertThat( terminal, old.matches() );
         callCounter.assertNotCalled();
 
         terminal.setCursorPos( 2, 5 );
         callCounter.reset();
-        terminal.blit( "hi", "11", "ee" );
+        blit( terminal, "hi", "11", "ee" );
         assertThat( terminal, old.matches() );
         callCounter.assertNotCalled();
     }
@@ -584,7 +585,7 @@ class TerminalTest
     {
         Terminal writeTerminal = new Terminal( 2, 1 );
 
-        writeTerminal.blit( "hi", "11", "ee" );
+        blit( writeTerminal, "hi", "11", "ee" );
         writeTerminal.setCursorPos( 2, 5 );
         writeTerminal.setTextColour( 3 );
         writeTerminal.setBackgroundColour( 5 );
@@ -614,7 +615,7 @@ class TerminalTest
     void testNbtRoundtrip()
     {
         Terminal writeTerminal = new Terminal( 10, 5 );
-        writeTerminal.blit( "hi", "11", "ee" );
+        blit( writeTerminal, "hi", "11", "ee" );
         writeTerminal.setCursorPos( 2, 5 );
         writeTerminal.setTextColour( 3 );
         writeTerminal.setBackgroundColour( 5 );
@@ -687,6 +688,11 @@ class TerminalTest
         assertEquals( 5, Terminal.getColour( 'Z', Colour.LIME ) );
     }
 
+    private static void blit( Terminal terminal, String text, String fg, String bg )
+    {
+        terminal.blit( LuaValues.encode( text ), LuaValues.encode( fg ), LuaValues.encode( bg ) );
+    }
+
     private static final class TerminalBufferSnapshot
     {
         final String[] textLines;